A lot will depend on the movement of any storms that fire across the Hill Country this afternoon/evening and how fast the frontal boundary progresses toward Byran/College Station overnight into early tomorrow. Simple answer, we just do not know as of this morning. We will take a look at the various mesoscale/global and high resolution rapid refresh data today and see if those sort of questions can be answered before tomorrow morning. Stay Tuned!sambucol wrote:Will the rain be severe from the onset and is it forecast to arrive tomorrow morning before rush hour? Thanks.
MARCH 2018 - Pleasant Good Friday/Easter Weekend Ahead
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srainhoutx
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srainhoutx
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Tuesday morning briefing from Jeff:
A strong storm system will continue to progress across TX bringing strong to severe thunderstorms and heavy rainfall.
Slow moving surface cool front is across NW/SW TX this morning edging to the east with clusters of showers and thunderstorms ongoing along the boundary. Air mass SE of this boundary will destabilize today with strong o severe thunderstorms likely developing this afternoon across C TX into N TX. Some of these storms will approach and move into the W/NW portions of SE TX later this evening and tonight with a threat for large hail and damaging winds. Not expecting much development in the capped warm sector over the reminder of SE TX today and tonight. Rain chances will greatly increase early Wednesday as the surface front creeps into the region. Expect multiple clusters of showers and thunderstorms to develop along and ahead of this boundary. Air mass by late morning Wednesday will begin to destabilize across the warm sector as heating warms the lower levels. Instability will be increasing into Wednesday afternoon and expect to see an increase in storm intensity and organization into Wednesday afternoon and evening.
Main severe threats will be large hail and damaging winds although an isolated tornado is possible…this risk appears low. Some questions remain as to how fast the surface boundary moves across SE TX or associated thunderstorm outflows which could undercut surface based convection helping to reduce the severe threat. Storms that are able to root near the surface will likely take full potential of the instability and shear and produce some severe weather.
Heavy rainfall will also be a concern on Wednesday, but latest short range models have backed off some on overall storm totals. Will go with widespread 1-2 inches with isolated amounts of 3-4 inches where any storms may train. Moisture levels are very impressive for late March and this will likely help to promote high hourly rainfall rates which may lead to some street flooding especially in urban areas. The overall hydro setting is fairly dry and most of the rain that falls will able to be handles by local drainage systems as long as no prolonged training develops. Will likely see rises on our eastern rivers (Trinity and possibly the San Jacinto basin) where more widespread nature of the rainfall on top of wetter ground conditions will occur.
Residents are encouraged to make sure you have a way to receive warning information on Wednesday and remember to never drive into high water.
The safest place during a severe thunderstorm is in an interior room on the lowest floor of a structure away from windows.
SPC Severe Weather Outlook for Wednesday:
A strong storm system will continue to progress across TX bringing strong to severe thunderstorms and heavy rainfall.
Slow moving surface cool front is across NW/SW TX this morning edging to the east with clusters of showers and thunderstorms ongoing along the boundary. Air mass SE of this boundary will destabilize today with strong o severe thunderstorms likely developing this afternoon across C TX into N TX. Some of these storms will approach and move into the W/NW portions of SE TX later this evening and tonight with a threat for large hail and damaging winds. Not expecting much development in the capped warm sector over the reminder of SE TX today and tonight. Rain chances will greatly increase early Wednesday as the surface front creeps into the region. Expect multiple clusters of showers and thunderstorms to develop along and ahead of this boundary. Air mass by late morning Wednesday will begin to destabilize across the warm sector as heating warms the lower levels. Instability will be increasing into Wednesday afternoon and expect to see an increase in storm intensity and organization into Wednesday afternoon and evening.
Main severe threats will be large hail and damaging winds although an isolated tornado is possible…this risk appears low. Some questions remain as to how fast the surface boundary moves across SE TX or associated thunderstorm outflows which could undercut surface based convection helping to reduce the severe threat. Storms that are able to root near the surface will likely take full potential of the instability and shear and produce some severe weather.
Heavy rainfall will also be a concern on Wednesday, but latest short range models have backed off some on overall storm totals. Will go with widespread 1-2 inches with isolated amounts of 3-4 inches where any storms may train. Moisture levels are very impressive for late March and this will likely help to promote high hourly rainfall rates which may lead to some street flooding especially in urban areas. The overall hydro setting is fairly dry and most of the rain that falls will able to be handles by local drainage systems as long as no prolonged training develops. Will likely see rises on our eastern rivers (Trinity and possibly the San Jacinto basin) where more widespread nature of the rainfall on top of wetter ground conditions will occur.
Residents are encouraged to make sure you have a way to receive warning information on Wednesday and remember to never drive into high water.
The safest place during a severe thunderstorm is in an interior room on the lowest floor of a structure away from windows.
SPC Severe Weather Outlook for Wednesday:
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you can make your own meteogram by putting in your zip code & selecting options - this is for a point in far NW Harris County &I am sure it will change as the event draws nearer & short term models hone in - your zip code will differ
https://www.weather.gov/hgx/
keep an eye on radar, especially wind velocity https://radar.weather.gov/lite/N0S/HGX_loop.gif
I'll be keeping an eye on GOES-16, hopefully mesoscale floaters will be covering our area as it draws near http://weather.cod.edu/satrad/exper/
https://www.weather.gov/hgx/
keep an eye on radar, especially wind velocity https://radar.weather.gov/lite/N0S/HGX_loop.gif
I'll be keeping an eye on GOES-16, hopefully mesoscale floaters will be covering our area as it draws near http://weather.cod.edu/satrad/exper/
Any confidence in how capped we are going to be come Wednesday or Thursday down here?
Interesting that the latest discussion from the SPC mentions that an upgrade to the severe risk may be needed...
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Tue Mar 27 2018
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
ARKANSAS AND WESTERN MISSISSIPPI SOUTHWESTWARD ACROSS SOUTHERN AND
EASTERN TEXAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA...
...SUMMARY...
Severe thunderstorms are possible Wednesday from portions of south
and east Texas into the lower Mississippi Valley region.
...Synopsis...
Very slow progression of the larger-scale upper flow field over the
U.S. is expected, with ridging prevailing over both eastern and
western portions of the country, and a large trough expanding over
the central states. At smaller scales, a southern-stream trough is
forecast to advance into/across the southern Plains through the
period.
At the surface, a cold front -- likely augmented locally by
convective outflow -- is forecast to extend northeast-to-southwest
across central Texas. With time, frontal cyclogenesis is expected
in the Arklatex vicinity, in response to the advance of the upper
system. The low should then continue shifting northeast across the
Ozarks toward the lower Ohio Valley through the overnight hours.
...Southern and eastern Texas into the lower Mississippi Valley
area...
Showers and thunderstorms -- potentially widespread in coverage --
should be ongoing at the start of the period from the mid
Mississippi/lower Ohio Valleys southwestward into portions of the
eastern half of Texas. This convection should diminish through the
day across Texas, though uncertainty prevails with regards to how
much ongoing convection and associated cloud cover will persist --
and thus the degree to which afternoon heating/destabilization can
occur.
As the upper trough advances steadily eastward through the afternoon
and into the evening, an increase in thunderstorms will likely occur
-- particularly across southeast Texas. With an amply moist
boundary layer beneath steepening lapse rates aloft, and wind
profiles veering/increasing with height ahead of the surface front
and associated upper system, organized/rotating storms are expected
to evolve. As such, risk for all severe hazards is apparent, though
the degree -- and spatial extent -- of the risk remains uncertain,
largely due to prior (Day 1) cloud cover/convection and associated
outflow boundary locations. While potential for
greater-than-slight-risk severe potential could evolve, will
maintain only 15% severe risk at this time, though a northwestward
expansion into the Arklatex, and westward to include a bit more of
east Texas, is being included. An upgrade in probabilistic risk
level will be deferred until later outlooks, once the likely
evolution of Day 1 convection becomes more certain.
Overnight, upscale growth of afternoon Texas convection may occur,
with some severe risk -- to possibly include all hazards -- likely
to spread across Louisiana into the lower Mississippi Valley area
late.
Day 2 Convective Outlook
NWS Storm Prediction Center Norman OK
1226 PM CDT Tue Mar 27 2018
Valid 281200Z - 291200Z
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHERN
ARKANSAS AND WESTERN MISSISSIPPI SOUTHWESTWARD ACROSS SOUTHERN AND
EASTERN TEXAS...
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE
SLIGHT RISK AREA...
...SUMMARY...
Severe thunderstorms are possible Wednesday from portions of south
and east Texas into the lower Mississippi Valley region.
...Synopsis...
Very slow progression of the larger-scale upper flow field over the
U.S. is expected, with ridging prevailing over both eastern and
western portions of the country, and a large trough expanding over
the central states. At smaller scales, a southern-stream trough is
forecast to advance into/across the southern Plains through the
period.
At the surface, a cold front -- likely augmented locally by
convective outflow -- is forecast to extend northeast-to-southwest
across central Texas. With time, frontal cyclogenesis is expected
in the Arklatex vicinity, in response to the advance of the upper
system. The low should then continue shifting northeast across the
Ozarks toward the lower Ohio Valley through the overnight hours.
...Southern and eastern Texas into the lower Mississippi Valley
area...
Showers and thunderstorms -- potentially widespread in coverage --
should be ongoing at the start of the period from the mid
Mississippi/lower Ohio Valleys southwestward into portions of the
eastern half of Texas. This convection should diminish through the
day across Texas, though uncertainty prevails with regards to how
much ongoing convection and associated cloud cover will persist --
and thus the degree to which afternoon heating/destabilization can
occur.
As the upper trough advances steadily eastward through the afternoon
and into the evening, an increase in thunderstorms will likely occur
-- particularly across southeast Texas. With an amply moist
boundary layer beneath steepening lapse rates aloft, and wind
profiles veering/increasing with height ahead of the surface front
and associated upper system, organized/rotating storms are expected
to evolve. As such, risk for all severe hazards is apparent, though
the degree -- and spatial extent -- of the risk remains uncertain,
largely due to prior (Day 1) cloud cover/convection and associated
outflow boundary locations. While potential for
greater-than-slight-risk severe potential could evolve, will
maintain only 15% severe risk at this time, though a northwestward
expansion into the Arklatex, and westward to include a bit more of
east Texas, is being included. An upgrade in probabilistic risk
level will be deferred until later outlooks, once the likely
evolution of Day 1 convection becomes more certain.
Overnight, upscale growth of afternoon Texas convection may occur,
with some severe risk -- to possibly include all hazards -- likely
to spread across Louisiana into the lower Mississippi Valley area
late.
-
Katdaddy
- Global Moderator
- Posts: 2517
- Joined: Thu Feb 04, 2010 8:18 am
- Location: League City, Tx
- Contact:
Flash Flood Watch just issued for much of SE TX including the Houston-Galveston areas:
Flood Watch
National Weather Service Houston/Galveston TX
201 PM CDT Tue Mar 27 2018
Austin-Brazos-Burleson-Grimes-Houston-Madison-Montgomery-Polk-
San Jacinto-Trinity-Walker-Waller-Washington-
Including the cities of Bellville, Brenham, Brookshire, Bryan,
Caldwell, Coldspring, College Station, Conroe, Corrigan,
Crockett, Groveton, Hempstead, Huntsville, Lake Somerville,
Livingston, Madisonville, Navasota, Onalaska, Prairie View,
Sealy, Shepherd, The Woodlands, Trinity, and Willis
201 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM 1 AM CDT WEDNESDAY THROUGH
LATE WEDNESDAY NIGHT...
The National Weather Service in Houston/Galveston has issued a
* Flash Flood Watch for a portion of southeast Texas...including
the following counties...Austin...Brazos...Burleson...Grimes...
Houston...Madison...Montgomery...Polk...San Jacinto...
Trinity...Walker...Waller and Washington.
* From 1 AM CDT Wednesday through late Wednesday night
* A band of showers and thunderstorms moving slowly southeastward
through the region. Heavy rainfall from training of storms could
lead to 1 to 3 inches with isolated totals of 4 to 5 inches. The
heaviest rainfall should fall between 3 am and 9 pm.
* Area small creeks will respond with rises from the heavy
rainfall and persons near these small creeks should monitor the
weather closely.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
Flood Watch
National Weather Service Houston/Galveston TX
201 PM CDT Tue Mar 27 2018
Austin-Brazos-Burleson-Grimes-Houston-Madison-Montgomery-Polk-
San Jacinto-Trinity-Walker-Waller-Washington-
Including the cities of Bellville, Brenham, Brookshire, Bryan,
Caldwell, Coldspring, College Station, Conroe, Corrigan,
Crockett, Groveton, Hempstead, Huntsville, Lake Somerville,
Livingston, Madisonville, Navasota, Onalaska, Prairie View,
Sealy, Shepherd, The Woodlands, Trinity, and Willis
201 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM 1 AM CDT WEDNESDAY THROUGH
LATE WEDNESDAY NIGHT...
The National Weather Service in Houston/Galveston has issued a
* Flash Flood Watch for a portion of southeast Texas...including
the following counties...Austin...Brazos...Burleson...Grimes...
Houston...Madison...Montgomery...Polk...San Jacinto...
Trinity...Walker...Waller and Washington.
* From 1 AM CDT Wednesday through late Wednesday night
* A band of showers and thunderstorms moving slowly southeastward
through the region. Heavy rainfall from training of storms could
lead to 1 to 3 inches with isolated totals of 4 to 5 inches. The
heaviest rainfall should fall between 3 am and 9 pm.
* Area small creeks will respond with rises from the heavy
rainfall and persons near these small creeks should monitor the
weather closely.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
You do not have the required permissions to view the files attached to this post.
Here's the watch for the bottom part of SE Texas not covered in Katdaddy's post.
Flood Watch
National Weather Service Houston/Galveston TX
201 PM CDT Tue Mar 27 2018
TXZ200-213-214-227-237-238-280315-
/O.NEW.KHGX.FF.A.0002.180328T1200Z-180329T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Brazoria-Chambers-Fort Bend-Galveston-Harris-Liberty-
Including the cities of Alvin, Anahuac, Angleton, Cleveland,
Dayton, Freeport, Friendswood, Galveston, Houston, Humble, Katy,
Lake Jackson, League City, Liberty, Missouri City, Mont Belvieu,
Pasadena, Pearland, Richmond, Rosenberg, Sugar Land, Texas City,
Tomball, and Winnie
201 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM WEDNESDAY MORNING THROUGH
THURSDAY MORNING...
The National Weather Service in Houston/Galveston has issued a
* Flash Flood Watch for a portion of southeast Texas...including
the following counties...Brazoria...Chambers...Fort Bend...
Galveston...Harris and Liberty.
* From Wednesday morning through Thursday morning
* A band of showers and thunderstorms will slowly expand
southeastward into the watch area Wednesday morning. In addition
the band may slow as it moves into the watch area with
individual storms moving northeast through the band. Rainfall of
1 to 3 inches should be common with isolated bands of 4 to 5
inches. The most intense rainfall should occur Wednesday after
noon through midnight.
* With the heavy rainfall expect area small creeks and bayous to
rise and persons near these creeks and bayous should monitor
the weather closely Wednesday.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
&&
$$
Flood Watch
National Weather Service Houston/Galveston TX
201 PM CDT Tue Mar 27 2018
TXZ200-213-214-227-237-238-280315-
/O.NEW.KHGX.FF.A.0002.180328T1200Z-180329T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Brazoria-Chambers-Fort Bend-Galveston-Harris-Liberty-
Including the cities of Alvin, Anahuac, Angleton, Cleveland,
Dayton, Freeport, Friendswood, Galveston, Houston, Humble, Katy,
Lake Jackson, League City, Liberty, Missouri City, Mont Belvieu,
Pasadena, Pearland, Richmond, Rosenberg, Sugar Land, Texas City,
Tomball, and Winnie
201 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM WEDNESDAY MORNING THROUGH
THURSDAY MORNING...
The National Weather Service in Houston/Galveston has issued a
* Flash Flood Watch for a portion of southeast Texas...including
the following counties...Brazoria...Chambers...Fort Bend...
Galveston...Harris and Liberty.
* From Wednesday morning through Thursday morning
* A band of showers and thunderstorms will slowly expand
southeastward into the watch area Wednesday morning. In addition
the band may slow as it moves into the watch area with
individual storms moving northeast through the band. Rainfall of
1 to 3 inches should be common with isolated bands of 4 to 5
inches. The most intense rainfall should occur Wednesday after
noon through midnight.
* With the heavy rainfall expect area small creeks and bayous to
rise and persons near these creeks and bayous should monitor
the weather closely Wednesday.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
&&
$$
-
srainhoutx
- Site Admin
- Posts: 19685
- Joined: Tue Feb 02, 2010 2:32 pm
- Location: Maggie Valley, NC
- Contact:
Just to relay what the current thinking is at HGX about the Flood Watch, no major flooding issues are expected as the ground is extremely dry. Jeff is indicating that in the Cypress Creek area soil moisture is completely dry down to 8 inches. The concern is for street flooding and roadway ponding in the typical known areas across SE Texas. Of course there is some uncertainty regarding if/where any training of thunderstorms may occur. That is frankly something that forecasters cannot pinpoint at this range and will likely not know the full extent of the severe weather potential until early tomorrow morning. We will be watching things very closely...particularly very early tomorrow morning. I know that the KHOU Weather Team is gearing up for early morning coverage as we will on the Weather Forum.
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Member: National Weather Association
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So no worries for SE Louisiana? I told hubby we would probably be heading away from the storms, should they happen. We will be leaving tomorrow afternoon about 3pm heading east on I10.
Sure has been overcast today, have had some light drizzle here in Stafford.
Sure has been overcast today, have had some light drizzle here in Stafford.
it is incredibly dry in Cypress area, I can't wait for some rain - just hope everyone stays safe & we don't get severe/tornado stuffsrainhoutx wrote:Just to relay what the current thinking is at HGX about the Flood Watch, no major flooding issues are expected as the ground is extremely dry. Jeff is indicating that in the Cypress Creek area soil moisture is completely dry down to 8 inches. The concern is for street flooding and roadway ponding in the typical known areas across SE Texas. Of course there is some uncertainty regarding if/where any training of thunderstorms may occur. That is frankly something that forecasters cannot pinpoint at this range and will likely not know the full extent of the severe weather potential until early tomorrow morning. We will be watching things very closely...particularly very early tomorrow morning. I know that the KHOU Weather Team is gearing up for early morning coverage as we will on the Weather Forum.
I second that. Hopefully some generous,watering rains for everyone over the next couple of days and not all at once with ice bombs falling from the sky.unome wrote:it is incredibly dry in Cypress area, I can't wait for some rain - just hope everyone stays safe & we don't get severe/tornado stuff
-
srainhoutx
- Site Admin
- Posts: 19685
- Joined: Tue Feb 02, 2010 2:32 pm
- Location: Maggie Valley, NC
- Contact:
Tuesday evening briefing from Jeff:
Flash Flood Watch issued by NWS for Wednesday across the region.
A strong upper level storm system and slow moving cold front will move into SE TX late tonight and slowly move across the region into early Thursday morning. Ingredients are coming together to produce a period of heavy rainfall on Wednesday into Wednesday evening with high moisture levels and potential for training storm cells. Main corridor of potential cell training will be along and south of the US 59 corridor Wednesday evening. Hourly rainfall rates may approach 1.5-2.0 inches which certainly can cause street flooding.
Widespread storm totals of 1-3 inches looks likely with isolated totals upward of 4-5 inches. HCFCD soil moisture sensor at Cypress Creek and Sharp Rd indicates fairly dry near surface soil conditions down to roughly 8 inches suggesting at least some of the incoming rainfall will be able to be absorbed into the dry top soil layers as long as rainfall rates due to greatly exceed infiltration rates. Additionally spring green up over the region will help to reduce surface run-off compared to similar rainfall amounts/rates in late February.
Overall main concern remains street flooding with high hourly rates especially under any areas of sustained cell training. While rises on creeks and bayous are likely, they should easily handle widespread 1-3 inches of rainfall and most will handle even 4-5 inches without any significant problems. Only concern would be if any sustained training develops that produces a rapid 3-4 inches in an hour of greater than 5 inches in a couple of hours which would result in maximum run-off conditions simply due to the amount of volume falling in such a short period of time.
Severe threat also remains with large hail and damaging winds possible Wednesday afternoon and an isolated tornado threat especially SE of US 59.
HCFCD will be monitoring the situation closely on Wednesday, but at this time will remain in normal operations.
Flash Flood Watch issued by NWS for Wednesday across the region.
A strong upper level storm system and slow moving cold front will move into SE TX late tonight and slowly move across the region into early Thursday morning. Ingredients are coming together to produce a period of heavy rainfall on Wednesday into Wednesday evening with high moisture levels and potential for training storm cells. Main corridor of potential cell training will be along and south of the US 59 corridor Wednesday evening. Hourly rainfall rates may approach 1.5-2.0 inches which certainly can cause street flooding.
Widespread storm totals of 1-3 inches looks likely with isolated totals upward of 4-5 inches. HCFCD soil moisture sensor at Cypress Creek and Sharp Rd indicates fairly dry near surface soil conditions down to roughly 8 inches suggesting at least some of the incoming rainfall will be able to be absorbed into the dry top soil layers as long as rainfall rates due to greatly exceed infiltration rates. Additionally spring green up over the region will help to reduce surface run-off compared to similar rainfall amounts/rates in late February.
Overall main concern remains street flooding with high hourly rates especially under any areas of sustained cell training. While rises on creeks and bayous are likely, they should easily handle widespread 1-3 inches of rainfall and most will handle even 4-5 inches without any significant problems. Only concern would be if any sustained training develops that produces a rapid 3-4 inches in an hour of greater than 5 inches in a couple of hours which would result in maximum run-off conditions simply due to the amount of volume falling in such a short period of time.
Severe threat also remains with large hail and damaging winds possible Wednesday afternoon and an isolated tornado threat especially SE of US 59.
HCFCD will be monitoring the situation closely on Wednesday, but at this time will remain in normal operations.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey
Member: National Weather Association
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Katdaddy
- Global Moderator
- Posts: 2517
- Joined: Thu Feb 04, 2010 8:18 am
- Location: League City, Tx
- Contact:
Time to be weather aware across SE TX the next 24 hours. The Flash Flood Watch has been extended SW to cover all of SE TX and the SPC still has SE TX and Upper TX Coast in a slight risk area for severe weather. An active weather ahead.
Flood Watch
National Weather Service Houston/Galveston TX
814 PM CDT Tue Mar 27 2018
TXZ226-236-281200-
/O.EXA.KHGX.FF.A.0002.180328T1200Z-180329T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Matagorda-Wharton-
Including the cities of Bay City, El Campo, Palacios, Pierce,
and Wharton
814 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM 7 AM CDT WEDNESDAY THROUGH
THURSDAY MORNING...
The National Weather Service in Houston/Galveston has expanded
the
* Flash Flood Watch to include a portion of southeast Texas...
including the following counties...Matagorda and Wharton.
* From 7 AM CDT Wednesday through Thursday morning
* A band of showers and thunderstorms will slowly expand
southeastward into the watch area Wednesday morning. In addition
the band may slow as it moves into the watch area with
individual storms moving northeast through the band. Rainfall of
1 to 3 inches should be common with isolated bands of 4 to 5
inches. The most intense rainfall should occur Wednesday afternoon
through midnight.
* With the heavy rainfall expect area small creeks and bayous to
rise and persons near these creeks and bayous should monitor
the weather closely Wednesday.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
Flood Watch
National Weather Service Houston/Galveston TX
814 PM CDT Tue Mar 27 2018
TXZ226-236-281200-
/O.EXA.KHGX.FF.A.0002.180328T1200Z-180329T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Matagorda-Wharton-
Including the cities of Bay City, El Campo, Palacios, Pierce,
and Wharton
814 PM CDT Tue Mar 27 2018
...FLASH FLOOD WATCH IN EFFECT FROM 7 AM CDT WEDNESDAY THROUGH
THURSDAY MORNING...
The National Weather Service in Houston/Galveston has expanded
the
* Flash Flood Watch to include a portion of southeast Texas...
including the following counties...Matagorda and Wharton.
* From 7 AM CDT Wednesday through Thursday morning
* A band of showers and thunderstorms will slowly expand
southeastward into the watch area Wednesday morning. In addition
the band may slow as it moves into the watch area with
individual storms moving northeast through the band. Rainfall of
1 to 3 inches should be common with isolated bands of 4 to 5
inches. The most intense rainfall should occur Wednesday afternoon
through midnight.
* With the heavy rainfall expect area small creeks and bayous to
rise and persons near these creeks and bayous should monitor
the weather closely Wednesday.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
A Flash Flood Watch means that conditions may develop that lead
to flash flooding. Flash flooding is a very dangerous situation.
You should monitor later forecasts and be prepared to take action
should Flash Flood Warnings be issued.
latest from hgx https://twitter.com/iembot_hgx
Area Forecast Discussion
National Weather Service Houston/Galveston TX
859 PM CDT Tue Mar 27 2018
.DISCUSSION...
At 800 PM, a cold front extended from just north of Shreveport to Centerville to north of San Antonio. A pre-frontal trough extended just south of the front and this feature is helping to generate scattered to numerous showers and thunderstorms over the northern third of the region. Some of the short term guidance is bullish with rainfall totals overnight and if the HRRR is correct, some spots north of a Brenham to Trinity line could receive between 4 and 6 inches of rain overnight. Have expanded the FFA to include Wharton and Colorado counties tonight and started the Watch at 03z (1000 PM). WPC has expanded the moderate risk for flash flooding into the CWA and slight risk for flash flooding now extends north of a Columbus to New Waverly to Livingston line. GOES-R derived PW values show PWATs near 1.80 inches over the the NW corner of SE TX. 300 MB winds are broadly divergent over East Texas. 850 MB moisture is is present with 850 mb Tds between 13-15 C. Moisture flux convergence is targeting areas north of a Brenham to Trinity line as well so all the ingredients are in place for a heavy rain event tonight as storms train along the weak front tonight. Have bumped PoPs up over the north and sped up the onset but the previous forecast was on the right track. 43
Area Forecast Discussion
National Weather Service Houston/Galveston TX
859 PM CDT Tue Mar 27 2018
.DISCUSSION...
At 800 PM, a cold front extended from just north of Shreveport to Centerville to north of San Antonio. A pre-frontal trough extended just south of the front and this feature is helping to generate scattered to numerous showers and thunderstorms over the northern third of the region. Some of the short term guidance is bullish with rainfall totals overnight and if the HRRR is correct, some spots north of a Brenham to Trinity line could receive between 4 and 6 inches of rain overnight. Have expanded the FFA to include Wharton and Colorado counties tonight and started the Watch at 03z (1000 PM). WPC has expanded the moderate risk for flash flooding into the CWA and slight risk for flash flooding now extends north of a Columbus to New Waverly to Livingston line. GOES-R derived PW values show PWATs near 1.80 inches over the the NW corner of SE TX. 300 MB winds are broadly divergent over East Texas. 850 MB moisture is is present with 850 mb Tds between 13-15 C. Moisture flux convergence is targeting areas north of a Brenham to Trinity line as well so all the ingredients are in place for a heavy rain event tonight as storms train along the weak front tonight. Have bumped PoPs up over the north and sped up the onset but the previous forecast was on the right track. 43
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Mesoscale Discussion 0184
NWS Storm Prediction Center Norman OK
1158 PM CDT Tue Mar 27 2018
Areas affected...South Central Texas
Concerning...Severe Thunderstorm Watch 21...
Valid 280458Z - 280700Z
The severe weather threat for Severe Thunderstorm Watch 21
continues.
SUMMARY...The severe-weather threat for large hail and damaging
winds continues across WW 21.
DISCUSSION...Trends in mosaic radar imagery showed the strongest
storm expected to affect WW 21 was approaching the Rio Grande River
near the borders of southern Maverick and northwest Webb Counties).
MESH per NWS MRMS data indicated severe hail is possible with this
storm as it reaches the U.S. side of the international border.
Additional storms were observed in radar imagery in Mexico tracking
to the northeast, where the environment remains moderately unstable
with steep midlevel lapse rates and strong effective bulk shear for
storm organization. Models suggest a couple of midlevel impulses
embedded within southwesterly flow aloft will track to the northeast
across WW 21 during the night, supporting additional storm
development. The storms with the strongest, sustained updrafts have
been located near and south of an outflow boundary which extended
northeast from northwest Webb County to East TX. The presence of
strong surface-based inhibition north of this boundary suggests
storms should tend to weaken as they track north of that boundary.
The stronger instability resides south of this boundary, posing the
greatest potential for a severe threat and longer lived storms.
..Peters.. 03/28/2018
...Please see http://www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...CRP...EWX...BRO...
Mesoscale Discussion 0185
NWS Storm Prediction Center Norman OK
0505 AM CDT Wed Mar 28 2018
Areas affected...Portions of central/southeast Texas
Concerning...Severe potential...Watch possible
Valid 281005Z - 281130Z
Probability of Watch Issuance...40 percent
SUMMARY...A few damaging gusts and a brief tornado or two are
possible this morning. Watch issuance is possible.
DISCUSSION...A QLCS has evolved across central Texas early this
morning and is advancing east/northeast around 30 kt. Meanwhile, a
stationary boundary extends from just north of T20 to GYB and points
northeast. Where this QLCS intersects the boundary, a narrow
corridor of enhanced streamwise vorticity may continue to yield
upticks in low-level rotation and a possible brief tornado or two
(as well as a few damaging gusts) over the next several hours.
Therefore, a watch may be considered within this narrow corridor
ahead of the line/boundary intersection.
..Picca/Thompson.. 03/28/2018
...Please see http://www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...EWX...
Mesoscale Discussion 0184
NWS Storm Prediction Center Norman OK
1158 PM CDT Tue Mar 27 2018
Areas affected...South Central Texas
Concerning...Severe Thunderstorm Watch 21...
Valid 280458Z - 280700Z
The severe weather threat for Severe Thunderstorm Watch 21
continues.
SUMMARY...The severe-weather threat for large hail and damaging
winds continues across WW 21.
DISCUSSION...Trends in mosaic radar imagery showed the strongest
storm expected to affect WW 21 was approaching the Rio Grande River
near the borders of southern Maverick and northwest Webb Counties).
MESH per NWS MRMS data indicated severe hail is possible with this
storm as it reaches the U.S. side of the international border.
Additional storms were observed in radar imagery in Mexico tracking
to the northeast, where the environment remains moderately unstable
with steep midlevel lapse rates and strong effective bulk shear for
storm organization. Models suggest a couple of midlevel impulses
embedded within southwesterly flow aloft will track to the northeast
across WW 21 during the night, supporting additional storm
development. The storms with the strongest, sustained updrafts have
been located near and south of an outflow boundary which extended
northeast from northwest Webb County to East TX. The presence of
strong surface-based inhibition north of this boundary suggests
storms should tend to weaken as they track north of that boundary.
The stronger instability resides south of this boundary, posing the
greatest potential for a severe threat and longer lived storms.
..Peters.. 03/28/2018
...Please see http://www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...CRP...EWX...BRO...
Mesoscale Discussion 0185
NWS Storm Prediction Center Norman OK
0505 AM CDT Wed Mar 28 2018
Areas affected...Portions of central/southeast Texas
Concerning...Severe potential...Watch possible
Valid 281005Z - 281130Z
Probability of Watch Issuance...40 percent
SUMMARY...A few damaging gusts and a brief tornado or two are
possible this morning. Watch issuance is possible.
DISCUSSION...A QLCS has evolved across central Texas early this
morning and is advancing east/northeast around 30 kt. Meanwhile, a
stationary boundary extends from just north of T20 to GYB and points
northeast. Where this QLCS intersects the boundary, a narrow
corridor of enhanced streamwise vorticity may continue to yield
upticks in low-level rotation and a possible brief tornado or two
(as well as a few damaging gusts) over the next several hours.
Therefore, a watch may be considered within this narrow corridor
ahead of the line/boundary intersection.
..Picca/Thompson.. 03/28/2018
...Please see http://www.spc.noaa.gov for graphic product...
ATTN...WFO...HGX...EWX...
Last edited by unome on Wed Mar 28, 2018 5:30 am, edited 1 time in total.
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srainhoutx
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A Moderate Risk for Excessive Rainfall has been extended a bit SW from yesterday's Day 2 Excessive Rainfall Outlook to include portions of Metro Houston.
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Katdaddy
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A Flash Flood Watch for SE TX will be in effect from 7AM this morning until 7AM Thursday morning. In addition, the SPC continues the slight risk area for S, S Central, E, and SE TX. An area of strong thunderstorms are moving into western portions of SE TX this morning. Currently it looks like the morning Houston-Galveston rush hour will not be effected much however it will likely be different this evening with flash flooding and strong to severe thunderstorms. Remain weather aware today and do not drive through high water.
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srainhoutx
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A quick update this morning on what we may see as the day progresses. The first batch of showers and thunderstorms have produced some flooding issues near San Antonio to Georgetown in S Central Texas early this morning. This batch of heavy rainfall has dropped about 3.5 inches in Grimes County and I expect this batch of rain and embedded storms to weaken some as it slowly creeps ESE this morning.
Inspecting Water Vapor Imagery and our High Resolution Rapid Refresh guidance including the Experimental HRRRX, a shortwave currently dropping S out of Southern California into the Baja looks to round the bottom of the base of our Upper Trough still well to our West in Arizona/New Mexico/Northern Mexico. The shorter range meso guidance is suggesting a rather robust mid/upper level jet streak to energize the atmosphere with additional lift. I am a bit concerned that for most of us in SE Texas, destabilization may begin rather quickly late this morning/early afternoon to our W and SW where some sunshine may occur. Some areas around our Region may see some sunshine which tends to further destabilize our atmosphere if that rain to our NW weakens this morning. The shortwave mentioned to our W and SW could be the "trigger" that fires off an impressive line of thunderstorms, some possibly severe this afternoon into tonight. The HRRR/HRRRX suites update hourly and there is a trend for a slow moving line of storms arriving near our afternoon/evening rush hour. We should get an update from the SPC at 13Z regarding the Convective Outlook and any potential Upgrade to an Enhanced Risk. Stay weather aware today as this will be a rapidly changing weather day into tonight and early tomorrow morning.
Inspecting Water Vapor Imagery and our High Resolution Rapid Refresh guidance including the Experimental HRRRX, a shortwave currently dropping S out of Southern California into the Baja looks to round the bottom of the base of our Upper Trough still well to our West in Arizona/New Mexico/Northern Mexico. The shorter range meso guidance is suggesting a rather robust mid/upper level jet streak to energize the atmosphere with additional lift. I am a bit concerned that for most of us in SE Texas, destabilization may begin rather quickly late this morning/early afternoon to our W and SW where some sunshine may occur. Some areas around our Region may see some sunshine which tends to further destabilize our atmosphere if that rain to our NW weakens this morning. The shortwave mentioned to our W and SW could be the "trigger" that fires off an impressive line of thunderstorms, some possibly severe this afternoon into tonight. The HRRR/HRRRX suites update hourly and there is a trend for a slow moving line of storms arriving near our afternoon/evening rush hour. We should get an update from the SPC at 13Z regarding the Convective Outlook and any potential Upgrade to an Enhanced Risk. Stay weather aware today as this will be a rapidly changing weather day into tonight and early tomorrow morning.
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srainhoutx
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Wednesday morning briefing from Jeff:
Slight risk of severe thunderstorms with damaging winds, large hail, and isolated tornadoes
Heavy rainfall likely with street flooding the main concern
Overnight strong to severe thunderstorms have erupted along the I-35 corridor producing flash flooding from San Antonio to Austin. These storms have since moved eastward and will be approaching the western portions of SE TX this morning. The Texas TECH WRF model weakens this activity leaving a boundary in place that results in storms redeveloping this afternoon while the HRRR brings this line through much of the region before slowing if not stalling near the coast. Both models show a period of time this afternoon and evening where a line of storms may slow over a portion of the region including Harris County. Based on the recent radar trends…will lean toward the Texas Tech some as the line is not as organized as earlier and there is a general downward trend in intensity over the last few hours.
Will maintain the widespread 1-3 inches across the area with isolated totals of 4-5 inches. Think these higher isolated totals will be across the central and coastal portions of the area where some of the short range guidance is indicating a line of storms to slow. Very high moisture levels do support excessive hourly rainfall rates of 1-3 inches so this is certainly a situation where things can go bad fast if sustained training develops for a period of time.
Overall hydrologic setting is better than late Feb with generally dry surface layers, a green up in vegetation, and near normal flow levels on at least the creeks and bayous. There will certainly be rises on creeks and bayous today with the forecasted rainfall amounts, but the main threat will be street flooding. The biggest concern areas for any type of minor channel flooding would be our usual areas that see rapid rises during such rains:
South Mayde Creek near Greenhouse
Upper Little Cypress Creek
Upper Spring Creek
The widespread nature of the rainfall may result in rises on the San Jacinto River basin, but we would need widespread 4-5 inches to likely result in minor flooding on the West Fork of the San Jacinto at Humble and at this time this looks unlikely.
Severe weather threat may increase later this morning as the air mass slowly destabilizes over the area. Main threat today will be large hail and damaging winds. An isolated tornado is possible and the line out west did produce a fairly strong radar signature for a tornado earlier this morning east of San Antonio.
Slight risk of severe thunderstorms with damaging winds, large hail, and isolated tornadoes
Heavy rainfall likely with street flooding the main concern
Overnight strong to severe thunderstorms have erupted along the I-35 corridor producing flash flooding from San Antonio to Austin. These storms have since moved eastward and will be approaching the western portions of SE TX this morning. The Texas TECH WRF model weakens this activity leaving a boundary in place that results in storms redeveloping this afternoon while the HRRR brings this line through much of the region before slowing if not stalling near the coast. Both models show a period of time this afternoon and evening where a line of storms may slow over a portion of the region including Harris County. Based on the recent radar trends…will lean toward the Texas Tech some as the line is not as organized as earlier and there is a general downward trend in intensity over the last few hours.
Will maintain the widespread 1-3 inches across the area with isolated totals of 4-5 inches. Think these higher isolated totals will be across the central and coastal portions of the area where some of the short range guidance is indicating a line of storms to slow. Very high moisture levels do support excessive hourly rainfall rates of 1-3 inches so this is certainly a situation where things can go bad fast if sustained training develops for a period of time.
Overall hydrologic setting is better than late Feb with generally dry surface layers, a green up in vegetation, and near normal flow levels on at least the creeks and bayous. There will certainly be rises on creeks and bayous today with the forecasted rainfall amounts, but the main threat will be street flooding. The biggest concern areas for any type of minor channel flooding would be our usual areas that see rapid rises during such rains:
South Mayde Creek near Greenhouse
Upper Little Cypress Creek
Upper Spring Creek
The widespread nature of the rainfall may result in rises on the San Jacinto River basin, but we would need widespread 4-5 inches to likely result in minor flooding on the West Fork of the San Jacinto at Humble and at this time this looks unlikely.
Severe weather threat may increase later this morning as the air mass slowly destabilizes over the area. Main threat today will be large hail and damaging winds. An isolated tornado is possible and the line out west did produce a fairly strong radar signature for a tornado earlier this morning east of San Antonio.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey
Member: National Weather Association
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