August 2017: Looking Back at Harvey 5 Year Later

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srainhoutx
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Monday morning briefing from Jeff:

Large scale heavy rainfall event underway across much of central TX this morning.

Overnight rainfall has been excessive over portions of central TX with 4-6 inches since midnight NW of Austin around Llano, TX resulting in flash flooding. An LCRA gage at the Llano River at Llano recorded 6.03 inches since midnight. Decaying thunderstorm complex has moved deep into SE TX this morning…currently approaching the I-45 corridor N of I-10. This complex of storms has generated a well defined cold pool at the surface which is working its way SE across the area. Another, much more intense, band of thunderstorms is moving SE across the I-35 corridor and will be nearing our W/NW counties later this morning. Rainfall has already averaged 1-2 inches NW of a line from Columbus to Huntsville and an additional inch will be possible over this are in the next hour. Since this outflow along the leading edge of the cold pool has pushed well ahead of the main rain of rainfall weakening of this complex is likely over the next few hours before surface heating across the central and southern portions of the area leads to new development by mid to late morning.

As seen overnight in C TX, the main threat continues to be with slow moving or training cells which will be very capable of producing 2-3 inches of rainfall in an hour.

Slow moving short wave and front will remain overhead tonight into Tuesday with additional rounds of showers and thunderstorms likely. Heavy rainfall will continue to be the main threat with favorable moist low level feed off the Gulf and a nearly saturated air mass. Additional rainfall totals of 2-4 inches will be possible with isolated amounts upwards of 5 inches.
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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srainhoutx
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Tropical Storm Franklin strengthening with sustained winds of 50 MPH. Early morning first Visible Imagery suggests there main be some rapid intensification possible before reaching the Yucatan Peninsula.
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08072017_1145Z_goes13_x_vis2km_07LSEVEN_30kts-1008mb-149N-807W_100pc.jpg
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srainhoutx
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For our Neighbors in S Central Texas...
08072017 mcd0642.gif
MESOSCALE PRECIPITATION DISCUSSION 0642
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
735 AM EDT MON AUG 07 2017

AREAS AFFECTED...SOUTH CENTRAL TX

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 071135Z - 071435Z

SUMMARY...MERGER OF COMPLEXES POSE VERY HIGH BURST OF RAINFALL
WITH CONTINUED SHOWERS POSING FLASH FLOODING RISK

DISCUSSION...EXPERIMENTAL GOES-16 10.3 IR SHOWS AN EXPLOSIVE
DEVELOPMENT OF GROWING COMPLEX OF VERY COLD CLOUD TOPS (AS LOW AS
-84C) THUNDERSTORMS OVER BANDARA AND MEDINA COUNTY OVER THE LAST
HOUR OR SO. THIS IS IN RESPONSE TO INCREASED CONVERGENCE ALONG A
MID-LEVEL BOUNDARY/EFFECTIVE COLD FRONT MCV/SHORTWAVE LOCATED IN
THE THE SOUTHERN TX HILL COUNTRY WHERE LOW LEVEL FLOW HAD BACKED
IN RESPONSE TO ITS DEEPENING.

ADDITIONALLY...COLD POOL DRIVEN SQUALL LINE FROM CENTRAL TX
CONTINUES TO DRIVE SOUTH ON SOUTHERLY INFLOW...WITH THE WESTERN
EDGE OF THE LINE STALLING UNDER WEAKER FORWARD PROPAGTION (DUE TO
INFLUENCE OF SHORTWAVE TO ITS NORTHWEST) AND CURRENTLY
INTERSECTING/MERGING WITH THE NEW RAPID DEVELOPMENT.

STRONG MOISTURE FLUX AND AMPLE DEEP MOIST PROFILES SUPPORT TPWS
AOA 2.25" AND LIKELY TO SUPPORT RATES UP TO 3"/HR GIVEN THE
MERGERS. THIS MERGER/INTERSECTION SHOULD EXHAUST THE LOCAL
INSTABILITY AND SUPPORT FURTHER SOUTHERN PROPAGATION OVER THE NEXT
TWO HOURS...BUT WITH THE INCREASE IN LATENT HEAT RELEASE...FURTHER
FOCUSING/DEVELOPMENT OF AN MCV/MESO LOW WILL ALLOW FOR MODERATE TO
HEAVY RAIN SHOWERS TO REMAIN IN THE VICINTIY WITH RATES UP TO
1"/HR FURTHER COMPOUNDING ANY FLOODING CONDITIONS. AS SUCH
LOCALIZED TOTALS TO 2-3" ARE LIKELY WITH POSSIBLE 4 OR 5" HIGHLY
LOCALIZED MAXIMA POSSIBLE.

OF GREATER CONCERN...IS ANY EASTWARD SHIFT OF THE MID-LEVEL
EFFECTIVE COLD FRONT OF THE DEVELOPING MCV (WHICH GIVEN TRENDS
APPEARS LIKELY) WILL POSE A THREAT TO METRO SAN ANTONIO INCREASING
THE LIKELIHOOD FOR FLASH FLOODING CONDTIONS KNOWNING TO THE PRONE
AREA/URBAN SETTING. AS SUCH FLASH FLOODING IS CONSIDERED LIKELY.

GALLINA

ATTN...WFO...CRP...EWX...
Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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DoctorMu
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Yes, that's an impressive meso west of her over Austin - San Antonio. A couple of bands/outflows are swinging east towards College Station and Houston. About 1/2 inch about 4 am last night IMBY

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FYI --> My blog based on this WPC outlook -->
http://www.khou.com/news/local/flooding ... /462535009


SUMMARY...VERY HEAVY SHOWERS AND THUNDERSTORMS MOVING THROUGH

SOUTHEAST TX AND PARTS OF SOUTHWEST LA WITH INTENSE RAINFALL RATES

OF UP TO 2.5 INCHES/HR. SOME FLASH FLOODING IS POSSIBLE.



DISCUSSION...THE LATEST RADAR IMAGERY SHOWS A BAND OF VERY HEAVY

SHOWERS AND THUNDERSTORMS MOVING ACROSS THE SOUTHEAST TX COASTAL

PLAIN WHICH WILL BE IMPACTING THE HOUSTON METROPOLITAN AREA OVER

THE NEXT COUPLE OF HOURS. THE ACTIVITY IS FOCUSING IN A VERY

MOIST/TROPICAL AIRMASS AND WITHIN A STRONG INSTABILITY GRADIENT

ALONG THE IMMEDIATE MIDDLE/UPPER TX COASTLINE.



OVER THE NEXT FEW HOURS...EXPECT VERY INTENSE RAINFALL RATES WITH

CONVECTION LIKELY BECOMING A BIT FURTHER ORGANIZED OUT AHEAD OF A

WEAK AREA OF LOW PRESSURE AND AN ASSOCIATED MCV OVER SOUTH-CENTRAL

TX. THE CONVECTION WILL LIFT NORTHEAST ACROSS SOUTHEAST TX AND

GRADUALLY GET INTO SOUTHWEST LA. THE RAINFALL RATES MAY REACH 2.5

INCHES/HR GIVEN PWATS OF 2.2 TO 2.4 INCHES WHICH WILL YIELD HIGHLY

EFFICIENT RAINFALL PROCESSES.



THE LATEST SATELLITE AND RADAR TRENDS SUPPORT AS MUCH AS MUCH AS 3

TO 5 INCHES OF RAIN LOCALLY THROUGH 22Z...AND CONSIDERING THE

URBANIZED ENVIRONMENT AND SUCH HEAVY RAINFALL RATES...FLASH

FLOODING WILL BE A CONCERN GOING THROUGH THE AFTERNOON HOURS.



ORRISON
Broadcast Met
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What is used to ascertain if the sky is too worked over to rain, this afternoon? Thanks.
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srainhoutx
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Tropical Storm Franklin Discussion Number 5
NWS National Hurricane Center Miami FL AL072017
400 PM CDT Mon Aug 07 2017

Visible satellite imagery continues to show a fairly well-organized
tropical cyclone, although infrared images indicate some warming of
the convective cloud tops. Observations from an Air Force Hurricane
Hunter aircraft show that the storm has a fairly broad inner core,
which is consistent with the ragged eye-like feature noted on the
visible imagery. The current intensity is kept at 50 kt based on a
blend of SFMR and flight-level observations from the aircraft along
with sampling considerations. Franklin has a well-defined,
symmetric upper-level outflow pattern, and some strengthening is
still expected prior to landfall. Although the cyclone could be near
hurricane strength at landfall on the east coast of the Yucatan
peninsula, the broad inner core of the system would argue against
rapid intensification during the next 12 hours. Weakening will occur
due to the passage over the Yucatan peninsula, and restrengthening
over the very warm waters of the Bay of Campeche is forecast.
Although northerly shear could inhibit strengthening somewhat,
Franklin is predicted to become a hurricane before making
landfall in mainland Mexico. The official intensity forecast is
similar to the latest HFIP Corrected Consensus forecast.

Based on center fixes from the aircraft along with geostationary
and microwave imagery, the initial motion is northwestward or
310/11 kt. The track forecast reasoning remains basically
unchanged. A mid-level high pressure area near the northwestern
Gulf of Mexico coast should force Franklin to take a
west-northwestward to westward course for the next several days.


FORECAST POSITIONS AND MAX WINDS

INIT 07/2100Z 18.6N 85.9W 50 KT 60 MPH
12H 08/0600Z 19.1N 87.6W 60 KT 70 MPH...INLAND
24H 08/1800Z 19.9N 89.9W 40 KT 45 MPH...INLAND
36H 09/0600Z 20.3N 91.9W 50 KT 60 MPH...OVER WATER
48H 09/1800Z 20.5N 94.0W 65 KT 75 MPH...OVER WATER
72H 10/1800Z 20.5N 98.5W 55 KT 65 MPH...INLAND
96H 11/1800Z...DISSIPATED

$$
Forecaster Pasch
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I'm tracking the shortwave/meso low to our northwest near Hearne, to see if new convection will get going around it and to its SE flank tonight. I think some folks will get some heavy rain overnight, so it's something that should be monitored.
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Looks like showers popping around the remnant vortex currently around College/Bryan area...
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srainhoutx
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I emptied .70 of an inch from Friday until Sunday evening last night. Emptied another 1.82 from the gauge tonight. My yard is happy.
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Always keep an eye on an MVC in 2.0+ inch PW air mass with light winds aloft. Lack of good low level inflow may keep things from organizing much...although coastal outflow boundary from earlier is starting to wash out and return of southerly 10-15kt inflow is likely around midnight over the area. HRRR from earlier was hinting at convergent zone along US 59 on SE flank of MVC circulation and returning juicy air mass from the south.
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DoctorMu
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TexasBreeze wrote:Looks like showers popping around the remnant vortex currently around College/Bryan area...
Yes indeed. It's been a bit of a ride. Another 1 inch of rain IMBY. So nice to turn the sprinklers OFF.

The vortex is swirling down toward Houston.

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Last edited by DoctorMu on Mon Aug 07, 2017 11:21 pm, edited 1 time in total.
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I have been trying (and failing) to see if the MCV is moving or just sitting stationary over college stattion. Anyone have a better idea if it is moving?
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It is stationary it appears and getting more organized training storms around it.
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srainhoutx
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Heavy rainfall Update from Jeff:

NWS has issued an Urban Flood Advisory for NW Harris County, Waller County, and SW Montgomery County until 130am.

Training band of heavy rainfall is developing from near Magnolia to just north of Sealy. While cell motions have been quick, training of the rainfall is yielding nearly .75 to 1.0 of an inch in 30 minutes over NW Harris and portions of Waller County as recorded by HCFCD gages near Waller recently.

Influx of deep tropical moisture and unstable air mass spreading inland over the coastal counties will eventually collide with this increasing line at some point around midnight. Hourly rainfall rates may increase into the 2-3 inch range with isolated storm totals potential pushing 4-5 inches in a couple of hours. Thus far rainfall rates have been manageable, but trends point to more sustained and organized banding features overnight which may yield high rates and approach/exceed flash flood guidance over portions of the area resulting in rapid rises on area watersheds.

Amounts greater than 3.0 inches in an hour or two across NW Harris County would be of concern given already saturated conditions.

Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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Looks like heavy rain is moving in. Be safe everyone.
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HRRR runs concern me. However, I do think the worst should be out of the metro by morning commute time, so hopefully that gives any street flooding time to drain.

Pro tip: If water gets into your tailpipe and into the engine, your car will break and will be impossible to fix. Think about that next time you drive into flood waters!
A transplant from Houston to Lincoln, Nebraska.
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djjordan
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Flood Advisory
National Weather Service Houston/Galveston TX
1138 PM CDT MON AUG 7 2017

TXC157-201-339-473-080730-
/O.NEW.KHGX.FA.Y.0205.170808T0438Z-170808T0730Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery TX-Fort Bend TX-Waller TX-Harris TX-
1138 PM CDT MON AUG 7 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
South central Montgomery County in southeastern Texas...
Northwestern Fort Bend County in southeastern Texas...
Southeastern Waller County in southeastern Texas...
Northwestern Harris County in southeastern Texas...

* Until 230 AM CDT.

* At 1135 PM CDT, Doppler radar and automated rain gauges indicated
heavy rain due to thunderstorms. This can cause minor flooding in
the advisory area. A gauge at Katy has reported two inches of rain
in the past hour, and an inch in the past 15 minutes. Other
locations in Harris County have reported in excess of an inch of
rain in the past hour.

* Some locations that will experience heavy rain include...
Katy, Tomball, Jersey Village, Brookshire, The Woodlands, western
Addicks Park Ten, Oak Ridge North, Fulshear, Pattison, The
Woodlands Pavillion, Hooks Airport, Cinco Ranch, Willowbrook,
Cypress and northern Weston Lakes.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don`t drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

&&
~~~When Thunder Roars Go Indoors~~~
~~~Turn Around Don't Drown~~~
~~~Run From The Water, Hide From The Wind~~~
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srainhoutx
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Urban Flood Advisory Update from Jeff:

Urban Flood Advisory issued for portions of Fort Bend, western Harris, Waller, and southern Montgomery Counties until 230am.

Band of heavy rainfall producing rainfall rates of 1-2 inches an hour extends from Conroe to Tomball to Katy moving ENE at 20mph while cells along the line move NNE at 20-25mph. Fast forward motions have kept rainfall totals thus far in the 1-2 inch range over a 1-2 hour period which can be handled. Brief periods of cell training has resulted in a quick 1-1.5 inches in 30 minutes or less under the most intense cells. Recent cells over Katy have produce 1 inch of rainfall in 15 minutes.

Overall cell motions should limit rainfall amounts to 1-3 inches over the next several hours. Will have to watch influx of deep moisture now approaching US 59 for more enhanced cell mergers and potential for backbuilding of the main band across portions of Fort Bend and Austin Counties which could result in a period of cell training.

Position of mid level low pressure center just north of Brenham continues to favor the SE flank of the circulation for the heavy rainfall production which is generally along or about 30 miles either side of US 59 currently.

Carla/Alicia/Jerry(In The Eye)/Michelle/Charley/Ivan/Dennis/Katrina/Rita/Wilma/Humberto/Ike/Harvey

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djjordan
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Flood Advisory
National Weather Service Houston/Galveston TX
1218 AM CDT TUE AUG 8 2017

TXC157-201-339-080815-
/O.NEW.KHGX.FA.Y.0206.170808T0518Z-170808T0815Z/
/00000.N.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Montgomery TX-Fort Bend TX-Harris TX-
1218 AM CDT TUE AUG 8 2017

The National Weather Service in League City has issued a

* Flood Advisory for...
Southeastern Montgomery County in southeastern Texas...
North central Fort Bend County in southeastern Texas...
Central Harris County in southeastern Texas...

* Until 315 AM CDT.

* At 1218 AM CDT, Doppler radar and automated rain gauges indicated
heavy rain due to thunderstorms. This will cause minor flooding in
the advisory area. Up to two inches of rain have already fallen.

* Some locations that will experience flooding include...
Northeastern Sugar Land, Bellaire, Humble, West University Place,
Jacinto City, Jersey Village, Hunters Creek Village, Bunker Hill
Village, Piney Point Village, Downtown Houston, Greenway / Upper
Kirby Area, Kingwood, Spring Branch North, Second Ward, Greater
Greenspoint, Spring, Greater Heights, Mission Bend, Neartown /
Montrose and Memorial Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don`t drown when encountering flooded roads. Most flood
deaths occur in vehicles.
~~~When Thunder Roars Go Indoors~~~
~~~Turn Around Don't Drown~~~
~~~Run From The Water, Hide From The Wind~~~
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