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

[srainhoutx]

HPC already has areas E of Hwy 59 under a Slight Risk for Excessive Rainfall. ~Sigh~



SPC has us under a Slight Risk as well...



DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0214 AM CDT TUE OCT 27 2009

VALID 291200Z - 301200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM CNTRL TX TO SRN MO...

...CNTRL TX...NEWD TO SRN MO...

UPPER TROUGH OVER THE SRN/CNTRL ROCKIES IS EXPECTED TO SHIFT EAST
INTO THE PLAINS DURING THE DAY3 PERIOD...THOUGH NOT AS A UNIFIED
LONG WAVE TROUGH BUT RATHER IN SEVERAL PIECES. ONE
SIGNIFICANT...AND LIKELY PRIMARY...UPPER CIRCULATION CENTER WILL
EJECT NEWD ACROSS CO INTO SD WITH SOME VARIANCE NOTED AMONG THE
LATEST SHORT RANGE MODEL GUIDANCE. A SECONDARY PIECE OF ENERGY WILL
EMERGE OVER FAR WEST TX LATE WITHIN THE BASE OF THE LONGER WAVE.
THIS SECONDARY SHORTWAVE WILL TRY TO INDUCE A WAVE ALONG SRN
PORTIONS OF THE COLD FRONT...MOST LIKELY ALONG THE LOWER RIO GRANDE
VALLEY BEFORE SHIFTING OFFSHORE. GIVEN THE BI-MODAL STRUCTURE OF
THIS EJECTING SYSTEM THERE ARE SOME NUANCES THAT WILL BE IMPOSSIBLE
TO ASCERTAIN THREE DAYS IN ADVANCE...NAMELY CONVECTIVE INFLUENCES
FROM DAY2 ACTIVITY AND ULTIMATE STORM MODE. OF PARTICULAR CONCERN
IS THE OVERALL MOISTURE INCREASE EXPECTED AHEAD OF COLD FRONT.
MODELS ARE IN GENERAL AGREEMENT THAT A LARGE SWATH OF 60+ SFC DEW
POINTS...70+ ACROSS PARTS OF TX/LA...WILL BE OBSERVED ACROSS THE
WARM SECTOR WHERE STRONGER H5 FLOW WILL OVERSPREAD A
MARGINAL-MODESTLY UNSTABLE AIRMASS. GIVEN THAT DEEP LAYER SHEAR IS
FORECAST TO BE STRONG...ANY STORMS THAT MANAGE TO DEVELOP EITHER
ALONG THE COLD FRONT...OR PERHAPS IMMEDIATELY AHEAD OF WIND
SHIFT...COULD PRODUCE SEVERE DAMAGING WIND GUSTS OR PERHAPS EVEN
ISOLATED TORNADOES. NWD EXTENT OF SEVERE RISK WILL BE LIMITED BY
MOISTURE RETURN NEEDED FOR SFC-BASED BUOYANCY.

..DARROW.. 10/27/2009

Morning e-mail from Jeff...

Small break before area is under the gun again Wed PM-Fri

Upper storm system from yesterday is clearing the area this morning with gusty NW winds and low clouds left behind. Clouds should erode quickly this morning leaving sunny skies and pleasant conditions. It will be very short lived as big changes return on Wed.

Powerful upper trough develops over the 4 corners over the next 24 hours resulting in impressive surface low pressure formation over the plains. Strong jet stream dynamics develop over TX with 40-50kt low level jet developing Wed afternoon below a nearly 140kt southern branch jet arching out of the SW US. Tremendous wind energy will come to bear over the state and this system…in addition to excessive rainfall looks to have a fairly high severe weather threat as well.

Moisture will make a rapid return Wed PM as the low level jet cranks up over the W Gulf. PWS near .4-.6 inches this morning rebound toward another 2.0 inch event by late Wed. Given aggressive moisture return Wed PM we will not be able to keep convection in check as lift begins to overspread the region from the approaching upper trough and very favorable upper air dynamics. Expect to see scattered thunderstorms develop by Wed late afternoon/evening and move inland off the western Gulf within low level warm air advection regime. This will continue all day Thursday with rounds of thunderstorms moving inland within the warm sector. Given low level wind shear profiles expected to be in place Thursday across the warm sector some of these cells may develop supercell structures and low level mesocyclones resulting in tornado formation.

Cold front slams into this very moist warm sector Thursday night with another slow moving squall line episode likely. GFS continues to slow this boundary over the area and produces some concerning rainfall amounts Thursday night/Friday morning. Pattern supports the slowing of the boundary and cell training in a near saturated air mass. Threat for excessive flooding rainfall will be high and with grounds now completely saturated significant run-off will be generated into already swollen and flooding creeks and rivers.

May see the boundary slip off the coast early Friday morning as convective outflows move it Gulfward. Upper trough lags back to the west with moisture being pulled up and over the cool dome at the surface with rain continuing into at least midday Friday and possibly Friday evening under increasing cold air advection at the surface.

Flash Flood Watch will likely be issued Wed or early Thursday for this next event. Widespread 1-3 inches is likely with isolated amounts of 4-6 inches. Would not be surprised if a few 8 inch amounts occurred given the longer duration of the event and tremendous moisture in place. All severe modes will be possible with this system also given the strong wind energy that will be in place. Tornado threat will be increasing across the returning warm sector Wed PM into Thursday with hail/wind threat along the squall line Thursday night/Friday morning.

Hydro:

Rainfall yesterday on top of downstream moving flood waves is resulting in additional rises on area rivers bringing them closer to flood stage. Upstream flood gate operations on the Brazos and Trinity basins will result in downstream rises along with non-flood control lakes passing through the run-off from the rains of the past several weeks.

Trinity River:

Minor flooding is in progress both above and below Lake Livingston as upstream run-off moves downstream. Operations at Lake Livingston will send more water downstream toward Liberty toward the end of the week with minor to moderate flooding to continue.

Brazos River:

Inflows from the Navasota River and Little River will result in rises on the middle and lower Brazos basin this week. While rises are expected the river is forecast to remain below flood stage at all forecast points.

Navasota River:

The river is rising and will rise to near flood stage late this week into this weekend and hold.

Tres Palacios River:

River is near flood stage this morning, but should crest and begin to fall today.

Lavaca/Navidad Rivers:

Rises are in progress on these rivers, but should remain below flood stage

Colorado River:

Upstream heavy rains above the Highland Lakes should be contained into the flood control pool at Lake Travis. Run-off below Lake Travis will result in a rise on the lower Colorado River, but the river should remain below flood stage.

Guadalupe River:

Rises on the middle part of the basin will translate downstream. Bloomington is already above flood stage and is forecast to fall and then rise back above flood stage toward the end of the week. The forecast at Victoria is are a rise to above action stage, but not flood stage toward the end of the week, but there is a good amount of water coming downstream and given the QPF for the end of the week flooding on the lower Guadalupe River looks likely.

Rainfall Thursday-Friday will be widespread with high basin wide averages leading to additional run-off and likely additional river increases.

[southerngale]

Well, I've got over 1/2" of standing water in my garage and praying it doesn't rise anymore or it will be in my livingroom. We have flood warnings in effect now. Our roadways are completely covered over as I was coming home from work around 8:30pm. We have huge ditches and they have exceeded their banks and the water is up to peoples front doors. I'm so thankful that I built on piers and the only thing remaining on a slab is my livingroom and garage with outdoor kitchen. The flooring is all scored and stained concrete so the cleanup is much easier than it would be with wood or carpet. I hope everyone stays safe on those wet roadways.

Oh no, Jagno. I wasn't watching radar when you posted this, but I'm thinking/hoping the rain was subsiding by then and the water didn't rise any more. Let us know & praying all is well.

I only ended up dumping about 1.75" out with this event... not nearly as much as last week's event. Everything is so saturated though, so there's a lot of water standing around.

[southerngale]

I wish it was going to be a little cooler for Halloween as it looks quite warm. It'll be quite toasty in costumes. We have outdoor activities tomorrow evening and Saturday afternoon/night, but oh well. What can ya do? At least it isn't supposed to rain Saturday. I'm hoping the rain holds off until late tomorrow night. Last night, for Wednesday night, it said after 1am. It doesn't say that anymore and just says 40%
Then 70% for Thursday and Friday.


Here's a portion of the early morning Lake Charles NWS discussion concerning the heavy rain threat Thursday and Friday.

NO REST FOR THE WEARY AS MAJOR CHANGES TO TAKE PLACE ON WEDNESDAY.
GLOBAL MODELS AGREE ON A LARGE AND POWERFUL UPPER LEVEL TROUGH
TAKING SHAPE OVER THE WESTERN CONUS...WHICH WILL IN TURN CAUSE
A DEEP SURFACE LOW PRESSURE TO DEVELOP IN THE HIGH PLAINS. IN
RESPONSE A 40-50 KNOT LLJ WILL DEVELOP WEDNESDAY AFTERNOON INTO
WEDNESDAY NIGHT OVER THE FORECAST AREA...WITH A WARM FRONT MOVING
QUICKLY INLAND FROM THE WESTERN GULF DURING THE EVENING AND
OVERNIGHT HOURS. THUS LOW TEMPS FOR WEDNESDAY NIGHT WILL LIKELY BE
REACHED DURING THE EVENING HOURS...WITH TEMPERATURES RISING DURING
THE NIGHT. A DRAMATIC RISE IN PRECIPITABLE WATER VALUES IS ALSO
FORECAST WITH LEVELS AT 12Z WEDNESDAY ONLY AT 0.50 INCHES BUT
RISING ABOVE 2 INCHES BY 6Z THURSDAY. LIFT ASSOCIATED WITH THE
WARM FRONT AND LLJ WILL PROMOTE SCATTERED SHOWERS AND
THUNDERSTORMS BEGINNING AS EARLY AS WEDNESDAY EVENING AND
CONTINUING THROUGH THE NIGHT.

AS TROUGH BEGINS TO EJECT INTO THE PLAINS STATES THE MODELS BEGIN
TO DIFFER ON TIMING OF A COLD FRONT...WITH ECMWF BRINGING THE
FRONT QUICKLY INTO THE AREA THURSDAY AFTERNOON BUT GFS DELAYING
UNTIL THURSDAY NIGHT. BOTH MODELS SHOW A CONCERNING STALL OF THE
FRONT IN THE CWA...WITH HIGH QPF NUMBERS ONCE AGAIN...BEFORE UPPER
TROUGH FINALLY EJECTS TO THE EAST ON FRIDAY AND FORCES THE FRONT
EASTWARD OUT OF OUR REGION. THUS ANOTHER HEAVY RAINFALL AND FLOOD
EVENT APPEARS LIKELY FOR THURSDAY AND FRIDAY...AND A FLASH FLOOD
WATCH WILL PROBABLY BE NEEDED. HAVE RAISED POPS TO THE HIGH
LIKELY CATEGORY ALTHOUGH CATEGORICAL POPS SEEM AN ALMOST
CERTAINTY. IN ADDITION TO THE FLOOD THREAT...FORECAST SOUNDINGS
SHOW HIGH INSTABILITY LEVELS AND STRONG DEEP LAYER AND DIRECTIONAL
SHEAR WHICH SUGGEST SEVERE WEATHER WILL ALSO BE A THREAT MUCH OF
THURSDAY INTO FRIDAY...WITH ALL MODES OF SEVERE WEATHER POSSIBLE.

AFTER THIS NEXT SYSTEM...MODELS NOW ARE SUGGESTING AN EXTENDED
PERIOD OF NEAR NORMAL TEMPERATURES AND DRY CONDITIONS AS WE MOVE
INTO NOVEMBER.

It's been a while since we've needed to say this, but dry conditions will be nice for a while. We need to dry out. lol - what a difference from summer.

[JenBayles]

Langham Creek is out of its banks at Clay Road outside Bear Creek Park. Makes me nervous about another heavy rain event in a couple days. It's a Spring redux: one-two-three punches of heavy rains and... flood. Welcome back El Nino.

[southerngale]

Well, not too sure about tomorrow night. Now it's 70%.
Wed. night/Thurs./Thurs. night/Fri./Fri. night look like 70%/70%/80%/70%/70% - geesh. Of course that could change, or just not come to fruition. If it holds off until later in the night, I'll be happy.

[JenBayles]

Seems like every time I check the forecast it looks worse - more rain lasting longer. I know we'll flood again one of these days, but sure hope it's in the daylight hours next time.

[Ptarmigan]

I don't want to sound bullish. I think we could see up to 12-15 inches of rain by the time this rain is over.

[JenBayles]

I don't want to sound bullish. I think we could see up to 12-15 inches of rain by the time this rain is over.

Who is "we"?

[vbhoutex]

I don't want to sound bullish. I think we could see up to 12-15 inches of rain by the time this rain is over.

Who is "we"?

Yes, who is we and where are you getting figures that high from. Please back it up with more than I think!! No one else is coming up with figures anywhere near that. Also what time frame are you talking about?

[vbhoutex]

This is what Larry Cosgrove is saying we will see in SE TX for the next few days.

http://www.examiner.com/x-3775-Houston-%20...%20iner-email

[Ptarmigan]

Yes, who is we and where are you getting figures that high from. Please back it up with more than I think!! No one else is coming up with figures anywhere near that. Also what time frame are you talking about?

"We" is SE Texas and SW Louisiana. I am thinking between Wednesday night to Friday morning. I should of put a disclaimer at the end.

[Ptarmigan]

This is what Larry Cosgrove is saying we will see in SE TX for the next few days.

http://www.examiner.com/x-3775-Houston-%20...%20iner-email

When I access it, I get:

Forbidden

You don't have permission to access http://www.examiner.com/x-3775-Houston- ... iner-email on this server.

[southerngale]

This is what Larry Cosgrove is saying we will see in SE TX for the next few days.

http://www.examiner.com/x-3775-Houston-%20...%20iner-email

When I access it, I get:

Forbidden

You don't have permission to access http://www.examiner.com/x-3775-Houston- ... iner-email on this server.

Try this link: http://www.examiner.com/x-3775-Houston-Weather-Examiner~y2009m10d27-Weather-Forecast-For-Houston-TX-And-Vicinity-Wednesday-October-28-2009

[Jagno]

We ended up with 5 1/2" of rain at my home when the water came into the garage. Thankfully it stopped there. I'm not so sure it will stop this time. The local weather guys are prediciting in excess of 7" this time and possibly more in localized areas. The road crews were out clearing ditches yesterday so hopefully this will help somewhat. For today I've got to go get the produce out of the garden before this next round of liquid sunshine.

[srainhoutx]

Morning e-mail from Jeff...

NWS has issued a Flash Flood Watch effective Thursday morning for all of SE TX.

Next powerful storm system to affect the area late tonight through early Saturday…threat for severe weather and flooding.

Big changes in store for the area as cool/dry air mass gives way to rapid influx of tropical moisture by late this afternoon. Deep upper level trough over the SW US will eject toward W TX tonight with strong pressure falls in the lee of the Rockies helping develop an impressive 40-50kt low level jet. PWS will rapidly increase to near 2.0 inches yet again by late this evening as southern Gulf of Mexico air mass pulls northward over the region.

Warm front moves northward this evening with lift starting to overspread the region from the west. Given the returning boundary and lift showers and thunderstorms may develop on this boundary and track northward. Shear profiles greatly increase this evening as low level SE winds veer to SW in the mid levels. Threat will increase for rotating mesocyclones along and north of the returning warm front.

Entire area will be warm sectored by Thursday AM with impressive low level shear in place and very moist air mass. GFS/NAM both show a decent vort rotating around the upper trough across SE TX Thursday morning igniting the warm sector. Will likely see numerous supercells develop and train from SW to NE across the area Thursday. All severe modes will be possible given high amounts of wind shear in place. Instability may be lacking for a significant tornado outbreak, but with all the wind aloft wind damage and isolated tornadoes are possible. Main threat will be excessive rainfall especially in any training locations.

Strong cold front arrives Thursday night with a large linear MCS along the boundary. Bad news is that the front greatly slows over the region as strong SW flow aloft becomes parallel to the boundary. Threat is high for training of excessive rainfall across the area nearly all night Thursday….with the front not clearing the coast until early Friday.

Rains will not end after frontal passage as the trough hangs back to the west allowing moisture to run up and over the cold dome building in at the surface. Will keep moderate rains all day Friday into Friday evening before the trough axis shifts eastward Saturday allowing the rains to end.

Flood:

GFS/NAM QPF numbers are of concern given the already saturated grounds and ongoing river flooding (See Hydro section). Given PWS over 200% above normal, threat for long duration cell training, and high hourly rainfall rates flooding seems likely. Widespread amounts of 2-4 inches with isolated amounts of 5-7 inches appear likely. In fact HPC QPF has a 4.9 in bullseye over SE TX from Thursday AM to Friday AM. Would not be surprised if a few locations netted 8-10 inches with this event. With low FFG and already flooding rivers…this rainfall is only going to make conditions worse.

Severe:

Thursday is shaping up to be active severe wise with a highly sheared warm sector air mass. Feel HP supercells are possible with a tornado threat given the strong low level shear in place. Lots of wind energy aloft with 120-140kt jet over the region and nearly 50kt low level jet just above the surface. Storms will move quick off toward the NE and this fast forward motion may produce damaging winds along the leading edge. Severe threat will lessen Thursday evening to isolated wind damage along the SE moving squall line and end by Friday morning as the area is cold sectored behind the front.

Hydro:

River Flood Warnings: Trinity River, lower Brazos River

Trinity River:

Minor flooding is in progress from above Liberty to below Moss Bluff. Several lakes are operating flood gates

Lake Lewisville: releasing 2191 cfs
Lake Ray Hubbard: releasing 5031 cfs
Cedar Creek: releasing 10,738 cfs
Richland Chambers: releasing 9501 cfs

At Liberty
Current stage is 26.69 ft.

Forecast: upstream releases from Lake Livingston will result in a rise to around 27.5 ft. Moderate flooding begins at 27.0ft. At 27.0 ft flooding of outlying communities around Liberty begins with several locations cut-off.

Brazos River:

Flood Warning is issued from below Richmond to below Rosharon. Middle Brazos lakes have begun flood gate operations:

Lake Granbury: releasing 2200 cfs
Lake Waco: releasing 12,732 cfs
Lake Limestone: releasing 7350cfs into the Navasota River

At Richmond

Current Stage: 29.38 ft
Flood Stage: 48.0ft

Forecast: Upstream flood wave from inflows on the Navasota and Little Rivers will reach the lower Brazos by the end of the week. The river is forecast to rise to near 42.0 ft at Richmond…below flood stage. At levels above 45.0 ft flow escapes locations below US 59 and floods portions of the US 59 turn-arounds. Water reaches to the toe of the levee protection at Greatwood, New Territory, Telfair, Richmond and Rosenberg. At 46.1 ft flow downstream of the gage results in backwater up Flat Bank Creek threatening homes in Missouri City.

At Rosharon:
Current Stage: 31.38 ft
Flood Stage: 43.0 ft

Forecast: river will hold and then begin a steep rise to above flood stage by the end of the week. River will crest around 48.0 ft this week. At 43.0 ft flow escapes the channel inundating portions of the floodplain. At 50.7ft minor flow passes into Oyster Creek.

Guadalupe River:

At Victoria
Current Stage: 13.31 ft
Flood Stage: 21.0 ft

Forecast: River will rise to near 20.0ft late Friday…just below flood stage. At 21.0 ft minor low land flooding develops as flow exceeds the left bank.

At Bloomington

Current Stage: 17.82ft
Flood Stage: 20.0ft

Forecast: River will begin rises today and crest near 25.0ft this weekend. Moderate flooding begins at 24.0ft. At levels above 24.0ft the river inundates the flood plain with secondary roads near the river flooded.

Rains over the next 48 hours will only worsen the ongoing river flooding and likely result in additional rises and delayed recessions.

[JenBayles]

Good luck with the produce Jagno. Nothing like washing mud, slugs and snails off all your garden gleanings.

I gave up on my veggie garden this year. Too much to do trying to put the house back together, and way too hot too early. I had surviving jalapeno and bell pepper plants from the year before that set on bumper crops, so all was not lost.

The heat wasn't entirely unwelcome in one respect: it finally did a number on the chocolate mint that was invading everything both inside and outside the raised bed.

[srainhoutx]

Just an FYI: HPC has mentioned that a wave of low pressure "may form" along the very slow moving CF. Like last Monday, the front may not move too far E and hang up again for a bit as the Upper Low slowly moves by on Saturday. HPC is discounting this feature for now, as it was the first time it showed up on guidance. The severe nature of this threat is concerning as it is a much stroger system than what we experienced on Monday with some impressive dynamics. We Shall See.

[JenBayles]

This article by Mike Snyder appeared in today's City & State section of the Houston Chronicle. Mike did a superb job of covering the April floods in western Harris County as well as other issues surrounding the disaster itself and ongoing recovery and mitigation efforts.

http://www.chron.com/disp/story.mpl/met ... 89777.html

Houston mayor's race
Flooding is an issue with no cheap solution
By MIKE SNYDER Copyright 2009 Houston Chronicle
Oct. 28, 2009, 12:13AM

The drumbeat of rainfall on roofs this week focused Houstonians' attention on an issue that has received only intermittent attention in this year's mayoral campaign: flooding.

Monday's rains did not cause significant flooding, but water entered hundreds of Houston homes during intense downpours last April. And the city's tolerance for flooding is diminishing even as its aging drainage system makes the problem more acute, said Wayne Klotz of Houston, president of the American Society of Civil Engineers.

“It's not OK to have water in your house,” City Controller Annise Parker frequently observes on the campaign trail. Parker and Councilman Peter Brown have posted detailed flood control policy statements on their campaign Web sites. Former City Attorney Gene Locke and Harris County Board of Education Trustee Roy Morales also have proposed steps to deal with the problem.

But all the measures that work — increasing drainage capacity, purchasing large tracts of land for flood detention, buying out homes that flood repeatedly — are costly, and the candidates agree on the need for fiscal restraint amid a recession. In this environment, can any candidate credibly promise to protect all homes from flooding?

“I think that ought to be your goal,” said Locke, who said he would emphasize cooperation among the city, the Harris County Flood Control District and other agencies to find the best solutions.

The three candidates with experience in city government — Brown, Parker and Locke — agreed that Houston's current system for planning drainage upgrades and other capital improvements relies too much on a desire to spread money evenly among nine council districts.

Instead, the city should undertake an analysis of drainage needs in each watershed and develop a list of projects to meet those needs, Parker said.

7 percent of tax base
She has offered the most specific plan for paying for drainage and other infrastructure improvements. She said revenues from tax increment reinvestment zones that are not needed to retire their debt should be funneled into a dedicated infrastructure fund, and certain zones should not be allowed to take on debt for new projects.

While the zones are carrying out their project plans, revenues from increased property values are used for improvements within their boundaries. Parker said Houston's 22 zones account for 7 percent of its tax base, which could supply substantial funds for infrastructure improvements over time.

Klotz said flooding should be seen as a public safety issue, citing the hypothetical example of a single mother who cannot get home to care for her child in the evening because flooding has made her route impassable. The next mayor, Klotz said, must decide whether getting that mother home is as important as some of the city's other spending priorities.

Enforce standards
One of the most effective steps Houston's mayor can take is to enforce the city's runoff standards in its extraterritorial jurisdiction, or ETJ, said Jim Blackburn, an attorney who has sued governmental agencies on behalf of flooded homeowners. The ETJ is a five-mile-wide buffer surrounding the city that is subject to annexation.This could be done through the city Planning Commission's authority to review subdivision plats in the ETJ, Blackburn said.

Brown agreed that the city does not exercise all its authority to regulate stormwater standards in the ETJ and said it would exercise greater oversight if he were elected. He also advocates building regional detention areas adjacent to expanded watersheds, developing tools such as interactive online maps to help residents track flood control work, and hold city government accountable.

Morales, in an interview, emphasized the need for creating additional large detention areas to hold floodwaters and for increasing elevation standards for properties subject to coastal storm surge.

mike.snyder@chron.com

[JenBayles]

This is what Larry Cosgrove is saying we will see in SE TX for the next few days.

http://www.examiner.com/x-3775-Houston-%20...%20iner-email

Here's the text from David's link. Nice discussion for laypeeps like me.

Discussion

I bet when you were tiring of the summer heat and drought you never thought that flooding rain threats were just a month or two away. Truth of the matter is, the El Nino episode is on full blast, showing a unique subtropical jet stream that takes dead aim for Texas rather than the usual first visit to California. When the southern branch windfield merges with an oncoming storm and full -latitude trough, huge amounts of precipitation will unfold. And as (bad) luck would have it, just such a scenario awaits residents of the Houston metro from late Wednesday through Friday morning.

The attendant cold front will slow as it approaches Texas on early Thursday morning. As a result, the core of 500MB vorticity will approach from the northwest, triggering a training echo thunderstorm generation pattern. A strong heat ridge over Florida will lock in the thermal boundary, most likely along a line from Matagorda TX to Shreveport LA. For some living to the north and west of Houston (say parts of Austin, Waller, and Montgomery Counties), the rain will be minimal after sunset of Thursday. But those of you living along and to the right of the US Highway 59 axis (from Wharton all the way to Marshall and the Sabine River headwaters), the frontal structure will continue to trigger torrential rains, locally strong thunderstorms, and flash flooding. If the NAM, ECMWF, and RGEM solutions verify, more than 5 inches of rain will inundate parts of the metro area before the system slowly pulls away on Friday afternoon. This excessive precipitation will be accompanied by wind and severe thunderstorms in much of the Corn Belt and Mid-South, with near-blizzard conditions in parts of CO....NE Panhandle....E WY....W SD....and ND. So if you are doing any air travel the next 48 hours, you can count on multiple delays.

As was the case with the most recent storm, beautiful cool weather will envelop Texas for the weekend. Temperatures may actually get into the mid/upper 40s (F) in downtown Houston on Sunday morning. And while it might warm up a bit heading into early next week, the numerical models suggest that another, longer extent and duration polar air mass will affect the entire eastern two-thirds of the nation through at least November 5.

[srainhoutx]

HPC now has us under a Moderate Risk for Excessive Rainfall...