I’m probably preaching to the choir, but ... a reminder to those who don’t know: It is scientifically impossible to make a 100% accurate/specific forecast for acute flooding. On a day like this you may see 1” or you could see 10+”. That’s wet roads vs inundated. Chaos theory still rules tropical forecasts. Some will feel shorted, other surprised. No win. Instead of blaming someone for a bad forecast (when it’s never been represented that we are certain of the actual intensity of the rain, but only certain of its potential to be heavy at times), keep your eyes open for changing conditions and act accordingly. We do know today won’t be quiet and sunny, but instead quite wet.
That said, I feel these wild HRRR runs can’t be dismissed as, over doing it. By nature, this is a mesoscale event with banding rains setting up near the coast in undetermined locations. This would mean a widespread 1-3 inches with pockets getting 4X that.
JUNE 2018: Drying Trend & Summer Heat Returns
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brooksgarner
- Global Moderator
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- Location: Houston, TX
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Broadcast Met
http://BrooksGarner.com
http://twitter.com/BrooksWeather
http://BrooksGarner.com
http://twitter.com/BrooksWeather
- '17 Harvey
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- '91 Bob
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stormlover
- Posts: 439
- Joined: Wed Dec 04, 2013 10:21 am
- Location: Lumberton TX
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Hrr nailed harvey
To slightly echo what Brooks said...
The 06z 3km NAM got my attention this morning. It isn't initializing too bad at all right now for what is inland and out over the Gulf. However, this particular model run takes the heavy rain squall currently sitting to the south off the upper TX coast and pushes it more to the NE of Houston.
However, it shows an intense rain-band coming from the west moving east towards Houston tomorrow afternoon, similar to a rain-band that dumped 5-6 inch per hour rainfall rates that caused the severe flooding during Harvey east of I-45.
This particular run shows that rain-band moving and interacting with another rain-band coming from the south, and stalling over Houston for a good 3-5 hours dumping about 8-10 inches of rain over us during that time. However, I've learned over the years, in a tropical airmass like this with PWATS so high, you can sometimes double those rainfall totals.
Certainly something to keep an eye on!
The 06z 3km NAM got my attention this morning. It isn't initializing too bad at all right now for what is inland and out over the Gulf. However, this particular model run takes the heavy rain squall currently sitting to the south off the upper TX coast and pushes it more to the NE of Houston.
However, it shows an intense rain-band coming from the west moving east towards Houston tomorrow afternoon, similar to a rain-band that dumped 5-6 inch per hour rainfall rates that caused the severe flooding during Harvey east of I-45.
This particular run shows that rain-band moving and interacting with another rain-band coming from the south, and stalling over Houston for a good 3-5 hours dumping about 8-10 inches of rain over us during that time. However, I've learned over the years, in a tropical airmass like this with PWATS so high, you can sometimes double those rainfall totals.
Certainly something to keep an eye on!
Blake
Boomer Sooner
Boomer Sooner
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tireman4
- Global Moderator
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- Location: Humble, Texas
- Contact:
YES! YES! Absolutely. Ladies and gentlemen, our pro mets come in here on their own time. They graciously do this to inform and help us. A HUGE thanks to all our pro mets ( Andrew, Brooks, David, Steve, Wxman 57, Belmer, Blake and McCheer) and amateurs that help with us on our board. This will be an this ever changing situation.brooksgarner wrote:I’m probably preaching to the choir, but ... a reminder to those who don’t know: It is scientifically impossible to make a 100% accurate/specific forecast for acute flooding. On a day like this you may see 1” or you could see 10+”. That’s wet roads vs inundated. Chaos theory still rules tropical forecasts. Some will feel shorted, other surprised. No win. Instead of blaming someone for a bad forecast (when it’s never been represented that we are certain of the actual intensity of the rain, but only certain of its potential to be heavy at times), keep your eyes open for changing conditions and act accordingly. We do know today won’t be quiet and sunny, but instead quite wet.
That said, I feel these wild HRRR runs can’t be dismissed as, “over doing it.” By nature, this is a mesoscale event with banding rains setting up near the coast in undetermined locations. This would mean a widespread 1-3 inches with pockets getting 4X that.
With the mid-level rotation, exact predictions for locations become even more difficult. It's likely a steeper gradient will be seen today with very heavy rain in Houston, especially south of I-10. Be prepared for heavy showers, possible entraining near the coast. Rain will spread inland, with thick bands more prevalent. Rain expected to be more widespread and heavier tomorrow.
Area Forecast Discussion
National Weather Service Houston/Galveston TX
645 AM CDT Mon Jun 18 2018
.AVIATION [12Z TAF Issuance]...
Broad picture of today`s weather is fairly straight-forward.
Periods of showers, with isolated thunder offshore this morning
developing more over land this afternoon. MVFR ceilings expected
area wide, with breezy/gusty ESE winds today. Showers and storms
don`t really leave the picture through the forecast period.
The details for individual sites on a day like today, however, are
quite tricky. Have tried to flesh out the best chances for
thunderstorms, as well as the times where winds should be
breeziest. This seems likely to see amendments/updates through the
day to best reflect the evolution of today`s weather.
A final note - there is a bit of a VFR moat impacting the Houston
metro terminals early this morning. It probably would have been
fair to start the TAF with prevailing VFR and TEMPO MVFR, but did
not want to make an already long TAF even longer for an hour or
two on the top line. Expecting MVFR to settle in across the area
early enough.
Luchs
&&
.PREV DISCUSSION /Issued 425 AM CDT Mon Jun 18 2018/...
.DISCUSSION...
Early morning satellite imagery shows convection blossoming over
the central Gulf. This development is associated with a tropical
wave and parent upper low approaching the Texas coast from the
east. Ahead of these feature, tropical moisture is still very
much in place early this morning with GOES Total Precipitable
Water satellite imagery showing precipitable water values of
1.9-2.2 inches across Southeast Texas. Aircraft soundings out of
Houston show that the mid-levels of the atmosphere are not quite
as saturated as previously advertised by forecast soundings
(observed dew point depression at 750 MB about 7 C versus forecast
dew point depressions 2-3 C).
While additional atmospheric moistening is expected through the
day, this somewhat drier mid-level air combined with observed
storm motions around 20-25 MPH will help limit rain coverage and
accumulations to under 0.5 inches near and south of the
Interstate 10 corridor through the morning commute. The potential
for higher rain totals will increase during the day, however, as
convective temperatures in the mid 80s today will allow for
scattered to numerous showers and thunderstorms to develop by mid
to late morning. Speed convergence is expected to result in the
greatest coverage over the Gulf waters and south of the Highway 59
corridor today, short term guidance continues to advertise
highest rain totals occurring as a result of diurnal heating with
isolated cells capable of producing localized 1-3 inch amounts in
a short period of time. This locally heavy rain may result in
localized/minor urban flood issues this afternoon, but expect most
of the region to be able to handle the anticipated areal average
of anywhere from 0.25-1.5 inches of rainfall today. Cloud cover
and rain should help limit temperatures into the lower to mid 80s
today.
Loss of heating should allow for a downward trend in shower and
thunderstorm coverage over the northern counties by this evening,
but the increasing lift associated with the approach of the upper
low over the central Gulf will result in periods of rain
persisting through the overnight hours across the region. Best
coverage is still anticipated to remain along the coast with
anywhere from 1-2 inches possible south of Interstate 10 during
the overnight hours. Lows Tuesday morning are forecast to range
from the 70s inland to low 80s along the coast.
The upper low over the central Gulf this morning is expected to
near or move over the middle/lower Texas coast on Tuesday. Lobes
of energy rotating around the low are expected to result in waves
or bands of rainfall moving across the region during the day and
highest rain chances are expected to occur across the southwestern
counties, closer to the center of the upper low. Precipitable
water values peak near 2.2-2.4 inches during the day tomorrow and
this, combined with long, skinny CAPE profiles on forecast
soundings, will only serve to enhance the potential for high rain
rates. Low level winds still appear to promote fairly fast storm
motions, but their nearly unidirectional profile will keep the
potential for training storms high. Forecast rain amounts for
Tuesday range from roughly 1-3 inches south of Interstate 10 (and
less than that north), but training may promote locally enhanced
totals. At least a minor flooding risk will continue to exist on
Tuesday from locally heavy rain, but the actual flooding risk is
going to be highly dependent on what happens today. The region
should be able to handle 3-4 inches of rain over the course of an
afternoon and if we see that today, concerns will be heightened
for tomorrow. Conversely... if we don`t, concerns will be lowered.
Periods of rain will continue Tuesday night into Thursday as the
upper low wobbles along the middle/lower Texas coast. The threat
for locally heavy rain will persist through these periods with the
deep tropical moisture in place, but given the highly uncertain
nature of what the region`s sensitivity to additional rainfall
will be as a result of its dependence on what happens today and
tomorrow... only highlighting the potential for localized flooding
concerns. Rain chances will begin to taper off sometime Thursday
night or Friday as a passing upper trough over the Central Plains
shunts the low/inverted trough over south Texas into Mexico, with
broad mid-level ridging becoming established across the region by
this weekend. This should result in gradually warming temperatures
and low, mainly seabreeze driven rain chances this weekend.
Huffman
National Weather Service Houston/Galveston TX
645 AM CDT Mon Jun 18 2018
.AVIATION [12Z TAF Issuance]...
Broad picture of today`s weather is fairly straight-forward.
Periods of showers, with isolated thunder offshore this morning
developing more over land this afternoon. MVFR ceilings expected
area wide, with breezy/gusty ESE winds today. Showers and storms
don`t really leave the picture through the forecast period.
The details for individual sites on a day like today, however, are
quite tricky. Have tried to flesh out the best chances for
thunderstorms, as well as the times where winds should be
breeziest. This seems likely to see amendments/updates through the
day to best reflect the evolution of today`s weather.
A final note - there is a bit of a VFR moat impacting the Houston
metro terminals early this morning. It probably would have been
fair to start the TAF with prevailing VFR and TEMPO MVFR, but did
not want to make an already long TAF even longer for an hour or
two on the top line. Expecting MVFR to settle in across the area
early enough.
Luchs
&&
.PREV DISCUSSION /Issued 425 AM CDT Mon Jun 18 2018/...
.DISCUSSION...
Early morning satellite imagery shows convection blossoming over
the central Gulf. This development is associated with a tropical
wave and parent upper low approaching the Texas coast from the
east. Ahead of these feature, tropical moisture is still very
much in place early this morning with GOES Total Precipitable
Water satellite imagery showing precipitable water values of
1.9-2.2 inches across Southeast Texas. Aircraft soundings out of
Houston show that the mid-levels of the atmosphere are not quite
as saturated as previously advertised by forecast soundings
(observed dew point depression at 750 MB about 7 C versus forecast
dew point depressions 2-3 C).
While additional atmospheric moistening is expected through the
day, this somewhat drier mid-level air combined with observed
storm motions around 20-25 MPH will help limit rain coverage and
accumulations to under 0.5 inches near and south of the
Interstate 10 corridor through the morning commute. The potential
for higher rain totals will increase during the day, however, as
convective temperatures in the mid 80s today will allow for
scattered to numerous showers and thunderstorms to develop by mid
to late morning. Speed convergence is expected to result in the
greatest coverage over the Gulf waters and south of the Highway 59
corridor today, short term guidance continues to advertise
highest rain totals occurring as a result of diurnal heating with
isolated cells capable of producing localized 1-3 inch amounts in
a short period of time. This locally heavy rain may result in
localized/minor urban flood issues this afternoon, but expect most
of the region to be able to handle the anticipated areal average
of anywhere from 0.25-1.5 inches of rainfall today. Cloud cover
and rain should help limit temperatures into the lower to mid 80s
today.
Loss of heating should allow for a downward trend in shower and
thunderstorm coverage over the northern counties by this evening,
but the increasing lift associated with the approach of the upper
low over the central Gulf will result in periods of rain
persisting through the overnight hours across the region. Best
coverage is still anticipated to remain along the coast with
anywhere from 1-2 inches possible south of Interstate 10 during
the overnight hours. Lows Tuesday morning are forecast to range
from the 70s inland to low 80s along the coast.
The upper low over the central Gulf this morning is expected to
near or move over the middle/lower Texas coast on Tuesday. Lobes
of energy rotating around the low are expected to result in waves
or bands of rainfall moving across the region during the day and
highest rain chances are expected to occur across the southwestern
counties, closer to the center of the upper low. Precipitable
water values peak near 2.2-2.4 inches during the day tomorrow and
this, combined with long, skinny CAPE profiles on forecast
soundings, will only serve to enhance the potential for high rain
rates. Low level winds still appear to promote fairly fast storm
motions, but their nearly unidirectional profile will keep the
potential for training storms high. Forecast rain amounts for
Tuesday range from roughly 1-3 inches south of Interstate 10 (and
less than that north), but training may promote locally enhanced
totals. At least a minor flooding risk will continue to exist on
Tuesday from locally heavy rain, but the actual flooding risk is
going to be highly dependent on what happens today. The region
should be able to handle 3-4 inches of rain over the course of an
afternoon and if we see that today, concerns will be heightened
for tomorrow. Conversely... if we don`t, concerns will be lowered.
Periods of rain will continue Tuesday night into Thursday as the
upper low wobbles along the middle/lower Texas coast. The threat
for locally heavy rain will persist through these periods with the
deep tropical moisture in place, but given the highly uncertain
nature of what the region`s sensitivity to additional rainfall
will be as a result of its dependence on what happens today and
tomorrow... only highlighting the potential for localized flooding
concerns. Rain chances will begin to taper off sometime Thursday
night or Friday as a passing upper trough over the Central Plains
shunts the low/inverted trough over south Texas into Mexico, with
broad mid-level ridging becoming established across the region by
this weekend. This should result in gradually warming temperatures
and low, mainly seabreeze driven rain chances this weekend.
Huffman
The 12z 3k NAM even looks more aggressive with qpf amounts, showing training feeder bands over the area. This system is starting to remind me of the August 2016 inland "Tropical depression" that stalled in Louisiana and caused major flooding.
Can you post a pic of the 06z NAM?Belmer wrote:To slightly echo what Brooks said...
The 06z 3km NAM got my attention this morning. It isn't initializing too bad at all right now for what is inland and out over the Gulf. However, this particular model run takes the heavy rain squall currently sitting to the south off the upper TX coast and pushes it more to the NE of Houston.
However, it shows an intense rain-band coming from the west moving east towards Houston tomorrow afternoon, similar to a rain-band that dumped 5-6 inch per hour rainfall rates that caused the severe flooding during Harvey east of I-45.
This particular run shows that rain-band moving and interacting with another rain-band coming from the south, and stalling over Houston for a good 3-5 hours dumping about 8-10 inches of rain over us during that time. However, I've learned over the years, in a tropical airmass like this with PWATS so high, you can sometimes double those rainfall totals.
Certainly something to keep an eye on!
Mike
Beaumont, TX
(IH-10 & College Street)
Beaumont, TX
(IH-10 & College Street)
The fact that no Flood Watches have been issued yet anywhere in Texas is a real testament to the growing drought conditions.
CAn you post this graphic? Whats it say for the Beaumont area?don wrote:The 12z 3k NAM even looks more aggressive with qpf amounts, showing training feeder bands over the area. This system is starting to remind me of the August 2016 inland "Tropical depression" that stalled in Louisiana and caused major flooding.
Mike
Beaumont, TX
(IH-10 & College Street)
Beaumont, TX
(IH-10 & College Street)
Flash flooding should be a concern because dry hard clay doesn't absorb moisture very well. Heavy downpours will cause a lot of runoff until things get a chance to loosen up.sau27 wrote:The fact that no Flood Watches have been issued yet anywhere in Texas is a real testament to the growing drought conditions.
Apparently, the NWS is considering issuing a Flash Flood watch maybe as early as today...Here is the 12z NAM QPF:
Last edited by don on Mon Jun 18, 2018 10:05 am, edited 1 time in total.
Is this thing even moving?
-
FreeportTX35
- Posts: 17
- Joined: Mon Jun 11, 2018 1:35 pm
- Contact:
I was thinking the same thing it looks like it stalled
Layer 3 radar picking up an eye feature south of Freeport. I'm sure it's just a dry slot but it is rotating.
Last edited by Cromagnum on Mon Jun 18, 2018 11:34 am, edited 1 time in total.
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srainhoutx
- Site Admin
- Posts: 19616
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- Location: Maggie Valley, NC
- Contact:
NWS HoustonVerified account @NWSHouston · 2h2 hours ago
Periods of rain, some locally heavy, are possible today thru Thursday. Intense rainfall in a short period of time could lead to flooding issues. However if rainfall is spread out over time w/ lower rain rates, it would be well handled. Stay tuned for updates #houwx #glswx #bcswx
Periods of rain, some locally heavy, are possible today thru Thursday. Intense rainfall in a short period of time could lead to flooding issues. However if rainfall is spread out over time w/ lower rain rates, it would be well handled. Stay tuned for updates #houwx #glswx #bcswx
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srainhoutx
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Baytown reporting 2 inch per hour rainfall rates with the training storms rotating through. Humble/Kingwood and IAH likely next in line.
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Just had a line pass over Beaumont and I hadn't heard rain THAT heavy in a long time! Everyone got up to go see because it sounded like hail! Lasted about 5min then back to all light rain. Looks like another line passing shortly. When they say these small tropical cells can be heavy at times, boy do they ever mean it! So far Beaumont has been hammered all day and plenty more headed right for us according to radar! Seems most of the concentration so far has been on the ESE side of Houston towards LA!
Mike
Beaumont, TX
(IH-10 & College Street)
Beaumont, TX
(IH-10 & College Street)
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srainhoutx
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NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1244 PM EDT MON JUN 18 2018
AREAS AFFECTED...SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 181643Z - 182243Z
SUMMARY...LOCALLY HEAVY DOWNPOURS ARE EXPECTED THIS AFTERNOON
ACROSS THE NORTHERN GULF COAST OF TEXAS AND ADJACENT COASTAL PLAIN
AND EXTENDING EASTWARD ACROSS MUCH OF SOUTH CENTRAL LOUISIANA.
RAINFALL RATES OF 2+ INCHES PER HOUR ARE POSSIBLE WITH THE
HEAVIEST CONVECTION.
DISCUSSION...A MID TO UPPER LEVEL LOW SLOWLY MEANDERING OVER THE
WESTERN GULF OF MEXICO IS CAUSING ENHANCED LOW LEVEL MOISTURE
CONVERGENCE OVER THE COASTAL WATERS AND ADJACENT COASTAL PLAINS OF
TEXAS AND LOUISIANA. MULTIPLE BANDS OF HEAVY CONVECTION MOVING
TOWARDS THE NORTHWEST ARE EXPECTED TO TRAIN OVER SOME AREAS
REPEATEDLY THROUGH THE EARLY TO MID AFTERNOON HOURS.
FACTORS SUPPORTING THIS HEAVY RAINFALL EVENT ARE THE HIGHLY
ANOMALOUS PWS NEAR 2.5 INCHES, 30 TO 40 KNOTS OF SUSTAINED 850MB
MOISTURE TRANSPORT, 1000-1500 J/KG OF MLCAPE, AND VERY SLOW
MOVEMENT OF THE MAIN DISTURBANCE OVER THE GULF. ONE OF THE
MITIGATING FACTORS IS THE RELATIVELY HIGH FLASH FLOOD GUIDANCE
OWING TO RECENT DRY CONDITIONS OVER THIS REGION, SO FLASH FLOODING
IS CONSIDERED POSSIBLE IN THOSE AREAS THAT HAVE VERY HIGH RAINFALL
RATES.
THE MAJORITY OF THE HIGH RES MODEL GUIDANCE IS INDICATING
SCATTERED RAINFALL TOTALS ON THE ORDER OF 1 TO 3 INCHES, WITH
ISOLATED TOTALS OF 4 INCHES OR MORE POSSIBLE THROUGH 23Z. THE
HRRR IS INDICATING THE HEAVIEST RAINFALL NEAR AND JUST WEST OF THE
GREATER HOUSTON AREA, WITH SOME DIFFERENCES IN THE GUIDANCE ON HOW
FAR INLAND THESE RAIN BANDS GO THIS AFTERNOON.
D. HAMRICK
ATTN...WFO...CRP...HGX...LCH...LIX...
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ccbluewater
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12z NAM really painting some rain from San Luis Pass / Galveston up the 45 Corridor.