SE TX/SW LA weather: Much cooler and WET after Tuesday

[srainhoutx]

MESOSCALE DISCUSSION 2153
NWS STORM PREDICTION CENTER NORMAN OK
0519 AM CDT THU OCT 29 2009

AREAS AFFECTED...SERN TX

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 291019Z - 291145Z

TSTMS MAY GRADUALLY DEVELOP FROM ONGOING SHOWER ACTIVITY THIS
MORNING. SHOULD THIS OCCUR...ENVIRONMENT WILL FAVOR SUPERCELLS WITH
THE THREAT FOR A TORNADO OR TWO. CONVECTIVE TRENDS ARE BEING
MONITORED FOR A POSSIBLE WW.

TRENDS IN REGIONAL RADAR IMAGERY INDICATE DEEPENING/INCREASING
SHOWER ACTIVITY FROM AUS EWD THROUGH CLL TO NEAR OR JUST S OF UTS.
BASED ON MODEL GUIDANCE AND SATELLITE IMAGERY...IT APPEARS THAT THE
SLOW EWD MIGRATION OF LARGE-SCALE TROUGH MAY BE PROVIDING SUFFICIENT
BACKGROUND ASCENT TO OVERCOME LINGERING CONVECTIVE INHIBITION. THIS
TREND SHOULD CONTINUE THROUGH THE MORNING. AMBIENT AIR MASS IS
QUITE MOIST WITH DEWPOINTS IN THE MID 70S...CONTRIBUTING TO MLCAPE
OF 1000-1500 J/KG BASED ON RUC PROXIMITY SOUNDINGS.

AREA VWP/PROFILER DATA INDICATE NOTABLE DIRECTIONAL/SPEED SHEAR IN
THE LOWEST 0.5 KM...WITH A GRADUAL INCREASE IN SPEED SHEAR ABOVE
THAT LAYER. THIS IS RESULTING IN RELATIVELY STRONG NEAR-GROUND
SHEAR /I.E. 30-35 KT THROUGH THE LOWEST KM/...WHICH IS MORE THAN
SUFFICIENT FOR UPDRAFT ROTATION. GIVEN THE MOIST/LOW LCL AIR MASS
IN PLACE...THE THREAT WILL EXIST FOR TORNADOES WITH ANY SUPERCELLS
THAT CAN BECOME ESTABLISHED.

..MEAD.. 10/29/2009


ATTN...WFO...LCH...SHV...HGX...FWD...EWX...

[KatDaddy]

A long weather day is just beginning. I will be posting updates from downtown Houston through out the day.

[srainhoutx]

Hot off the press with Jeff's e-mail...

Active 36 hours for SE TX as strong storm system across the state.



Flash Flood Watch extended until 700am Friday morning



Discussion:

Powerful upper level trough moving into New Mexico this morning while strong cold front and upper level jet arrive over TX. 140kt jet rounds the base of this trough with sub-tropical jet stream over S TX placing SE TX in a favorable diffluent upper air pattern. Moisture has rapidly increased with PWS now pushing 2.0 inches and continuing to increase. Numerous training streamers have developed mainly E of I-45 and this pattern will continue today while coverage and intensity increases.



Main event comes tonight as cold front plows into 50kt low level jet and tremendous moisture advection. Expect the current W TX squall line to continue to develop and intensify as it moves eastward this afternoon reaching SE TX toward sunset. Line will slow while crossing SE TX overnight given upper level flow becoming parallel to the frontal boundary. Threat for cell training and excessive rainfall will be high along with flash flooding.



Front will push off the coast early Friday with widespread rains continuing into Friday evening as the upper trough lags behind the surface cold front. Expect strong cold air advection with gusty north winds of 15-25mph and falling temps under moderate to at times heavy rainfall. Rain should clear the area late Friday evening with sunny but cool conditions expected on Halloween.



Rainfall:

Widespread rainfall amounts of 2-4 inches with isolated amounts of 5-8 inches will be possible through Friday evening. Given saturated grounds, excessive moisture levels, and high potential for cell training flooding is likely. Ongoing river issues will only be worsened by rainfall of this magnitude. Urban flash flooding/ponding is likely given 2-3 inch per hour rainfall rates. If heavy rains focus over Harris County with widespread amounts of 4-5” flooding of area bayous will be possible.



Severe:

Threat looks marginal and is conditional on the degree of surface heating. Low level shear is strong however lacking instability is resulting in only weak to moderate updrafts and shallow streamer type convection. Given daytime heating and moist low level air mass instability may approach 1500-2000 J/kg this afternoon helping o support deep convection. Storms rooted in the near surface layer with begin to rotate with wind shear in place and may produce a tornado. Wind damage threat will increase this evening as main line approaches from the west. Linear nature of the line supports a straight line wind threat as 120kt jet streak plows into the base of the upper trough.



Tides:

Very strong SE winds overnight have resulted in water level rise along the upper TX coast. Water levels are currently running 1.0-1.8 feet above predicted levels from Brazoria County into SW LA. Large swells over the NW Gulf have brought high water to the beaches trapping the last high tide near the shoreline. Winds should veer more to the S and SSW this afternoon which is a less favorable water piling direction along the upper coast. Tides will remain elevated until the front passes and strong offshore flow develops early morning.



Hyrdo:

Flood Warnings continue for the lower Brazos River, lower Trinity River, and lower Guadelupe River, and Navasota River. Additional rainfall today into Friday will result in additional rises and delayed recessions on these watersheds and may push some of these channels into major flood over the weekend.

[JenBayles]

Thanks srain. You must have been reading my mind - I checked in specifically to see what our Jeff had to say this morning.

[srainhoutx]

Your welcome Jen. E-mail was a bit later than normal. WV Imagery is suggesting that things will pick up a bit later in the day as forcing and warming take place. I am concerned with the sunshine we're seeing in our area at the moment. Storm should sart firing as the atmosphere becomes more destabilized around the lunch hour. There is some fairly strong energy approaching from S TX at this time...

http://adds.aviationweather.noaa.gov/sa ... g&itype=wv

Edit to add keep an eye to our SW near Victoria. This will likely be the first area to see the strongest storms form and progress slowy E throughout the day.

[srainhoutx]

HPC Excessive Rainfall Update keeps SE TX in a High Risk...



Edit to add Discussion from HPC...

TOTAL RAINFALL AMOUNTS OF FIVE INCHES WILL BE POSSIBLE TO THE
RIGHT OF A LINE FROM 15 W DWH 20 ENE UTS 15 WSW LFK 25 S GGG
20 ESE TXK 35 NNW ELD 30 WSW ELD 20 S BAD 40 WSW IER 25 W POE
25 SSE JAS 25 W BPT 10 SSW LVJ 10 SE 5R5 5R5 25 W SGR 15 W DWH.


LITTLE CHANGE FROM PREVIOUS OUTLOOK OR REASONING. LARGE SCALE MID
LVL TROF OVR THE WRN U.S. WILL ADVANCE SLOWLY EWD AS ADNL SHRTWV
ENERGY CONTINUES TO DIG INTO THE BACKSIDE OF THE SYSTEM. THIS
WILL ALLOW FOR DEEP-LAYERED MSTR TO STREAM NWD FM THE WRN GULF
AHEAD OF IT SETTING THE STAGE FOR SGFNT CNVCTV RAINS ACROSS THE
OUTLOOK AREA. THE OVERALL VERY SLOW MOVEMENT OF THE UPPER SYSTEM
AND THE PARALLELING OF THE UPPER FLOW TO THE LLVL CNVGNC ZONE
WOULD ARGUE FOR CNVCTN TO REPEAT OVER LOCALIZED AREAS..POSSIBLY
FOR UP TO 24HRS. GIVEN THE HI PWS PRESENT AND THE STRONG
LIKELIHOOD OF REPEATING CELLS..AMTS OF 1.50 INCHES PER HOUR ARE
POSSIBLE WITHIN THE OUTLOOK AREA WITH WIDESPREAD 2.00 TO 4.00 INCH
RNFL TOTALS AND LOCALIZED AMTS IN EXCESS OF 5.00 INCHES
PARTICULARLY INVOF ERN TX BY THE END OF THE PD.

FINALLY..STORM TOTALS IN EXCESS OF 7.00 OR MORE ARE POSSIBLE GIVEN
THAT SGFNT RAINS WILL CONTINUE BEYOND THE END OF THE FCST PD.

KORTY

[srainhoutx]

HGX Updates with a great explantion of what we are seeing right now...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
949 AM CDT THU OCT 29 2009

.DISCUSSION...
12Z SOUNDINGS SHOW A BIT OF A CAP BETWEEN 850-750 MB AT CRP WITH
PW VALUES NEAR 1.6 INCHES. MOISTURE LEVELS ARE CONSIDERABLY
HIGHER...EXCEEDING 2 INCHES AT LCH. LOW LEVEL JET BETWEEN 50-60
KNOTS IS RIGHT OVER HEAD. THE AREA SHOULD CONTINUE TO GET SHOWERS
ON THE EDGE OF THE CAPPING INVERSION (OVER SOUTHERN ZONES) WITH
THE STORMS INCREASING AS THEY MOVE NORTH AT A RATHER BRISK 30 TO
40 MPH. RAINFALL AMOUNTS DURING THE DAY LOOK TO REMAIN A BIT
BENIGN THIS AFTERNOON DUE TO THE FAST STORM MOTION TODAY. HEAVIER
TOTALS SHOULD FALL OVER THE NORTHERN HALF OF THE REGION DUE TO THE
WEAKER CAP AND HIGHER MOISTURE LEVELS. AT THE SURFACE...WEAK LOW
PRESSURE WAS LOCATED NEAR DFW WITH A WEAK TROF EXTENDING SOUTH
TOWARD ANOTHER WEAK LOW NEAR COT. A COLD FRONT LAGS A BIT BEHIND
THE PRE-FRONTAL TROUGH AND AT 13Z EXTENDS FROM OKC TO JCT TO DRT.
THE FRONT WILL CONTINUE TO PUSH EAST AT A SLOW BUT STEADY PACE. AM
EXPECTING THE FRONT TO ARRIVE TONIGHT AND SLOW FURTHER AS THE
FRONT BECOMES PARALLEL TO THE UPPER FLOW.

SPC STILL HAS THE AREA OUTLOOKED FOR A SLIGHT CHC OF SEVERE
STORMS. LOW LEVEL SHEAR IS IMPRESSIVE BUT WEAK CAP AND LIMITED
CAPE MAKES THE SEVERE THREAT SOMEWHAT CONDITIONAL. IF BREAKS IN
THE EXTENSIVE CLOUD COVER OCCUR...SEVERE THREAT WILL INCREASE QUICKLY.
BREEZY TO STRONG SOUTHERLY WINDS WILL ALSO PERSIST TODAY AND
RESIDENTS MIGHT WANT TO SECURE LIGHT WEIGHT ITEMS THIS AFTERNOON.

PROBLEMS BEGIN TONIGHT. MOISTURE LEVELS EXCEED 2.00 INCHES AS THE
FRONT ENTERS THE CWA. A STRONG 160 KNOT SPEED MAX DEVELOPS AND SE
TX WILL LIE IN A RIGHT REAR QUAD. THIS FEATURE COUPLED WITH THE
SURFACE BOUNDARY WILL ENHANCE RAINFALL POTENTIAL. BEST CHANCE FOR
FLOODING RAINS WILL DEVELOP BETWEEN 06-12Z. CURRENT RAINFALL
TOTALS STILL LOOK ON THE MARK. RAIN WILL LINGER FRIDAY MORNING
UNTIL THE 850 MB FRONT CLEARS THE COAST. 43

[JenBayles]

Seeing occasional breaks in the clouds here in Bear Creek along with increasing breezes. Looks like we need to take down the pool umbrellas today unless we want to fish them out of the pool tomorrow.

Can someone 'splain to me what I'm seeing on the water vapor loop? Looks like East TX is in a pretty dry slot. Does WV primarily show moisture in upper levels or all levels? (Never quite understood that.)

And another question! Our liveoak tree has produced the largest crop of acorns in 18 years. It's been over 6 weeks and no end in sight. Acorns are 3" deep under the tree and we shovel out a good 50 pounds a day from the pool. I'm guessing the tree was stressed from the summer drought and is trying to reproduce rapidly. Anyone else experience this?

[srainhoutx]

MESOSCALE DISCUSSION 2156
NWS STORM PREDICTION CENTER NORMAN OK
1048 AM CDT THU OCT 29 2009

AREAS AFFECTED...E TX/WRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 291548Z - 291745Z

STORMS ARE PROGGED TO SLOWLY INCREASE IN INTENSITY OVER THE NEXT FEW
HOURS ACROSS THIS REGION...WITH WW POSSIBLE BY EARLY AFTERNOON.

LATEST RADAR/VISIBLE IMAGERY AS WELL AS LIGHTNING DATA SHOW A
SLOW/STEADY INCREASE IN THUNDERSTORM COVERAGE AND INTENSITY OVER THE
PAST HOUR OR SO...BOTH INVOF THE COLD FRONT MOVING ACROSS CENTRAL TX
AS WELL AS WITHIN A ZONE OF PRE-FRONTAL WARM ADVECTION EXTENDING AS
FAR E AS WRN LA. WHILE HEATING REMAINS LIMITED BY ABUNDANT CLOUD
COVER...EVEN MODEST HEATING OF THE VERY MOIST /LOW TO MID 70S
DEWPOINTS/ BOUNDARY LAYER WILL RESULT IN ADDITIONAL DESTABILIZATION
OF THE PRE-FRONTAL WARM SECTOR. THIS -- COMBINED WITH WEAK HEIGHT
FALLS AHEAD OF THE APPROACHING UPPER SYSTEM SHOULD RESULT IN A
CONTINUED/STEADY INCREASE IN STORMS THROUGH THE AFTERNOON.

ALONG WITH THE THREAT FOR DAMAGING WINDS...SURFACE SELYS ACROSS TX
INCREASING/VEERING RAPIDLY TO SLY AT 50-PLUS KT AT 1/2 TO 1 KM IS
YIELDING LOW-LEVEL SHEAR SUPPORTIVE OF ROTATION/ISOLATED TORNADOES.
EXPECT SEVERE/TORNADO POTENTIAL TO INCREASE INTO THIS AFTERNOON IN
CONJUNCTION WITH THE STEADY INCREASE IN STORM
ORGANIZATION/INTENSITY.

..GOSS.. 10/29/2009


ATTN...WFO...LCH...SHV...HGX...FWD...OUN...EWX...SJT...

[vbhoutex]

Definite yes on the acorns. sounds like someone is shooting at the house all day long as they come down.

Rains have started here at the house with occasional bursts of torrential rain. Radar indicates that it is training in nature, but hopefully won't be long lasting. Methinks I will be watching radar a lot today and tonight!!

[srainhoutx]

Jen, water vapor imagery shows moisture in the Mid and Upper levels mostly. The area of drier air has filled in considerably since earlier this morning. Yesterday you could actually see mountain waves on WV and VIS imagery in the Davis and Guadalupe Mountains of W TX from the 140 kt Jet Streak winds passing over the higher terrain. We are seeing acorns in our area as well for the first time since the neighborhood was built in the late 90's. My grandmother used to say it was a sign of a bad winter.

[Diva]

The wind is howling in Orange County today. Gusts to 30+mph. No rain yet though, not that I'm complaining.

Just saw this on KOGT.com....

Persons having interests in the Sabine River Basin below the reservoir are hereby advised that at 6:30 A.M. on Thursday, October 29, 2009, the reservoir elevation was 172.14' m.s.l. Currently, one generator is out of service for repairs and the other generator is operating 24 hours per day, 7 days per week. Based on the National Weather Service forecast, the reservoir will continue to rise and spillway gates will have to be opened.

Interested persons should monitor current river and reservoir levels and reservoir release amounts since the river could reach flood stage and evacuation of persons, animals and property may become necessary.

Releases through the spillway gates, depending on upstream and downstream conditions, will be made in accordance with the Guide for Spillway Gate Operation for Toledo Bend Reservoir dated March 1994, as Revised June 27, 2001. The first step will be to open five gates one foot each.

Once spillway releases begin, the local sheriff's offices, as well as the Toledo Bend Project offices at the dam will be able to give the latest reported river stages and river forecasts from the National Weather Service, River Forecast Center.

Up-to-date reservoir elevations and releases may be obtained from the Toledo Bend Project offices on a 24 hour per day basis at 337/286-5253 and 409/565-2273.

Toledo Bend Reservoir is not a flood control reservoir and can experience significant rises in elevation in a short time span, as much as one to two feet in a 24 to 36 hour period.

Information on specific river gages can be obtained from the National Weather Service at the following web site: http://www.srh.noaa.gov/wgrfc

Also, from the USGS at the following website: http://tx.waterdata.usgs.gov

[srainhoutx]

Yikes...

URGENT - WEATHER MESSAGE
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1119 AM CDT THU OCT 29 2009

...WIND ADVISORY FOR THIS AFTERNOON...

.STRONG WINDS ALOFT MIXING TO THE SURFACE WILL PRODUCE STRONG
SOUTHERLY SURFACE WINDS OF 20 TO 25 MPH WITH GUSTS EXCEEDING 45
MPH AT TIMES. THE WINDS WILL BEGING TO TAPER OFF BY EARLY EVENING
AS A COLD FRONT APPROACHES THE REGION AND THE PRESSURE GRADIENT
BEGINS TO RELAX.

TXZ163-164-176>179-195>200-210>214-226-227-235>238-292300-
/O.NEW.KHGX.WI.Y.0011.091029T1619Z-091029T2300Z/
AUSTIN-BRAZORIA-BRAZOS-BURLESON-CHAMBERS-COLORADO-FORT BEND-
GALVESTON-GRIMES-HARRIS-HOUSTON-JACKSON-LIBERTY-MADISON-MATAGORDA-
MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-WASHINGTON-
WHARTON-
INCLUDING THE CITIES OF...ALVIN...ANAHUAC...ANGLETON...BAY CITY...
BELLVILLE...BRENHAM...BROOKSHIRE...BRYAN...CALDWELL...CLEVELAND...
COLDSPRING...COLLEGE STATION...COLUMBUS...CONROE...CORRIGAN...
CROCKETT...DAYTON...EAGLE LAKE...EDNA...EL CAMPO...FREEPORT...
FRIENDSWOOD...GALVESTON...GROVETON...HEMPSTEAD...HOUSTON...
HUMBLE...HUNTSVILLE...KATY...LAKE JACKSON...LAKE SOMERVILLE...
LEAGUE CITY...LIBERTY...LIVINGSTON...MADISONVILLE...
MISSOURI CITY...MONT BELVIEU...NAVASOTA...ONALASKA...PALACIOS...
PASADENA...PEARLAND...PIERCE...PRAIRIE VIEW...RICHMOND...
ROSENBERG...SEALY...SHEPHERD...SUGAR LAND...TEXAS CITY...
THE WOODLANDS...TOMBALL...TRINITY...WEIMAR...WHARTON...WILLIS...
WINNIE
1119 AM CDT THU OCT 29 2009

...WIND ADVISORY IN EFFECT UNTIL 6 PM CDT THIS EVENING...

THE NATIONAL WEATHER SERVICE IN HOUSTON/GALVESTON HAS ISSUED A
WIND ADVISORY...WHICH IS IN EFFECT UNTIL 6 PM CDT THIS EVENING.

STRONG WINDS ALOFT MIXING TO THE SURFACE WILL PRODUCE STRONG
SOUTHERLY SURFACE WINDS OF 20 TO 25 MPH WITH GUSTS EXCEEDING 45
MPH AT TIMES. THE WINDS WILL BEGING TO TAPER OFF BY EARLY EVENING
AS A COLD FRONT APPROACHES THE REGION AND THE PRESSURE GRADIENT
BEGINS TO RELAX.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DRIVERS OF VANS...CAMPERS...TRAILERS...AND OTHER HIGH-PROFILE
VEHICLES SHOULD BE ALERT TO THE DANGER OF THESE WINDS...
ESPECIALLY WHEN DRIVING ALONG EAST TO WEST ORIENTED ROADS.

[Ptarmigan]

Looks like the bad stuff will be here starting this afternoon to early Friday morning. First, severe weather and than heavy rains.

[srainhoutx]

I wonder what role the moisture from newly designated 95E off Acapulco will play in this event if any? Hmmm...

http://www.srh.noaa.gov/tropical/satpix ... v_loop.php

[jasons2k]

Already a tornado watch to our north.

Looks like a very busy evening/night across SE Texas:


Shot at 2009-10-29

[vbhoutex]

I wonder what role the moisture from newly designated 95E off Acapulco will play in this event if any? Hmmm...

http://www.srh.noaa.gov/tropical/satpix ... v_loop.php

You had to bring that up didn't you? May be something to watch.

[srainhoutx]

Impressive moisture plume setting up from Matagorda County eastward. We have been getting some heavy fast moving tropical downpours in NW Harris County for about an hour.

Edit to add we are getting rumbles of thunder now as well.

[srainhoutx]

Mid day update from Jeff...

Carefully watching radar trends early this afternoon.



Increasingly organizing line of shower/thunderstorms producing heavy rainfall trying to line up from Humble to downtown Houston to Wharton County. Within the last hour storms have rapidly organized and intensified over Montgomery County and show organizing trends over Fort Bend and western Harris counties.



Strong SSW low level flow continues to foster a very favorable training environment and as this lines continues to organize rainfall trends will need close watch through the afternoon hours.



Everything still on track for heavy rains overnight as the surface cold front moves into the area. Still hard to pin point where the heaviest rains will fall, but cannot deny the model agreement of the axis along the US 59 corridor from near Wharton through Harris County to Lake Livingston. Would not put this area in concrete as shifts in this potentially narrow line could move the heaviest axis west or east of Harris County.



Next update will be around 430pm

[vbhoutex]

We have been getting the same here Steve without the thunder. I just heard it in the distance though as I was finishing this post. Have picked up a quick .25" in the last 45 minutes. What Jeff states is what I am seeing happening in real time here as we have had training showers for the last hour minimum. Not liking the trend at all, especially if the worst is to come tonight. Pouring again!!