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

[Extremeweatherguy]

After this current cold snap, it looks like severe weather could be our next concern...



DAY 4-8 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0350 AM CST MON DEC 17 2007

VALID 201200Z - 251200Z

...DISCUSSION...
TWO PRIMARY SHORTWAVE TROUGHS STILL ARE PROGGED TO CROSS
S-CENTRAL/SERN CONUS DURING PERIOD. REF DAY-3 OUTLOOK FOR DETAILS
ON LEAD WAVE...WHICH SHOULD MOVE EWD ACROSS SRN APPALACHIANS AND
OFFSHORE ATLANTIC COAST DAYS 4-5/20TH-21ST...AND MAY OUTPACE
DESTABILIZING/MODIFYING LOW-LEVEL TRAJECTORIES ACROSS N-CENTRAL/NERN
GULF. RESULTING DAY-4/20TH-21ST SVR POTENTIAL WOULD BE EWD
EXTENSION OF DAY-3 THREAT...WHICH APPEARS TOO MRGL/CONDITIONAL TO
ASSIGN 30 PERCENT CATEGORICAL THRESHOLD LINE ATTM. MREF
CONSENSUS...ECMWF AND UKMET SFC PATTERNS STRONGLY INDICATE THAT
ASSOCIATED FROPA SHOULD NOT PRECLUDE MORE FULL MODIFICATION OF GULF
AIR MASS IN ADVANCE OF MUCH STRONGER TROUGH PROGGED FROM
SRN/CENTRAL PLAINS TO LOWER/MID MS VALLEY DAY-6/22ND-23RD.
THEREFORE CONFIDENCE IS INCREASING ENOUGH FOR CATEGORICAL OUTLOOK
FOR SVR POTENTIAL AHEAD OF SECOND SYSTEM...THOUGH LACK OF RESOLUTION
OF DETAILS PRECLUDES MORE THAN BROAD/OVERLAPPING DAY 5-6 AREAS ATTM.

..EDWARDS.. 12/17/2007

[jasons2k]

From Jeff Lindner:

Zonal upper pattern develops across the US with multiple storm systems to affect TX through the next 7 days leading up to Christmas. Southerly flow will return this afternoon as cold polar high moves off to the east. Moisture will rapidly return with PWS forecasted to reach at least 1.0 inch along the coast by early Tuesday AM. Approaching disturbance will induce lift and combined with returning moisture may produce a few showers Tuesday. Next much stronger system arrives Wednesday afternoon and evening. Increasing low level jet feeding developing surface low pressure over NC TX will bring moist and unstable air northward from the Gulf of Mexico. Main question at this time is degree and quality of Gulf return flow as the last front has blasted deep into the Gulf and position of surface high by Wed AM is not all that favorable for direct return of high dewpoint air mass. After reviewing SPC’s Day 3 discussion it appears at least possible that a low end severe threat will be found over the region Wed PM ahead of a dry line. Expect storms to be tied to lift along the dry line and intensity tied to degree and quality of return flow.

Dry Thursday before the next even stronger storm system arrives Friday night. Return flow becomes established once again early Friday with good transport of moisture into the area during the day Friday. May see some warm air advection streamers develop as low level jet cranks up. Cold front comes across early Sat AM much like this past Saturday with a chance of showers and thunderstorms and gusty NW winds following. Air mass behind the Saturday front will be of more polar origin so a good cool down is in store. May once again see freezing temps next Sun AM and Christmas Eve.

Long range extended shows next storm affecting the region Christmas Day with a chance of rain…followed by a potential arctic air intrusion the week between Christmas and New Years.

[Dthomas104]

Oh you guys just made my Christmas!!!!!!

[Extremeweatherguy]

Well the Sunday night freeze no longer looks likely, but there does seem to be quite a nice cool down in the offing. Sunday through Christmas day (Tuesday) will struggle to make 60F under somewhat cloudy skies and a north breeze...

Saturday Night: Partly cloudy, with a low around 44.

Sunday: Partly sunny, with a high near 59.

Sunday Night: Mostly cloudy, with a low around 43.

Monday: Mostly cloudy, with a high near 56.

Monday Night: Mostly cloudy, with a low around 41.

Christmas Day: Mostly sunny, with a high near 60.

[JenBayles]

Cold is great; cold and cloudy and gloomy is even better. Guess I can't have everything I want for Christmas!

[jasons2k]

Showers with some thunder mixed-in is really starting to pop now.

[srainhoutx]

MESOSCALE DISCUSSION 2242
NWS STORM PREDICTION CENTER NORMAN OK
1012 PM CST WED DEC 19 2007

AREAS AFFECTED...SERN TX INTO SWRN LA

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 200412Z - 200545Z

A CONTINUED INCREASE IN STORM COVERAGE AND INTENSITY IS EXPECTED
THROUGH 06Z. ISOLATED HAIL AND/OR LOCALLY DAMAGING WINDS WILL BE
THE PRIMARY SEVERE WEATHER HAZARDS...THOUGH A TORNADO OR TWO IS
POSSIBLE. CONVECTIVE TRENDS ARE BEING MONITORED FOR A POSSIBLE WW.

A RAPID INCREASE IN TSTM DEVELOPMENT HAS OCCURRED OVER THE PAST HALF
HOUR OVER SERN TX FROM NEAR TO UTS TO N OF LFK. WATER VAPOR
IMAGERY...RUC DIAGNOSTIC FIELDS AND REGIONAL VWP/PROFILER DATA ALL
SUGGEST THAT DEEP LAYER FORCING FOR ASCENT IS RAPIDLY STRENGTHENING
ACROSS AREA...LIKELY CONTRIBUTING TO THIS INCREASE IN CONVECTIVE
DEVELOPMENT. THESE STORMS APPEAR TO BE DEVELOPING ALONG THE ERN
EDGE OF STRONGER CAPPING OBSERVED BY 00Z S TX SOUNDINGS WITHIN A
MOIST LOW-LEVEL ENVIRONMENT CHARACTERIZED BY DEWPOINTS IN THE
LOW/MID 60S AND MLCAPES OF 300-800 J/KG.

CURRENTLY...IT APPEARS THE MARGINAL INSTABILITY IS INHIBITING STORM
ORGANIZATION WITH MAJORITY OF ACTIVITY LIKELY SLIGHTLY ELEVATED.
HOWEVER WITH TIME...A FEW OF THE MORE INTENSE STORMS MAY BECOME
SURFACE-BASED WITHIN A RATHER STRONGLY SHEARED KINEMATIC ENVIRONMENT
WITH EFFECTIVE BULK SHEARS OF 45-55 KT AND EFFECTIVE SRH VALUES OF
250-350 M2/S2. LOCALLY DAMAGING WINDS AND SEVERE HAIL WILL BE THE
PRIMARY HAZARDS...THOUGH A TORNADO OR TWO WILL BE POSSIBLE WITH ANY
SUSTAINED SUPERCELLS.
..MEAD.. 12/20/2007


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



http://www.spc.noaa.gov/products/md/md2242.html

[Extremeweatherguy]

The temperature differences between the local airports tonight is quite extreme. As of 9pm Hooks airport in Tomball is sitting at 50F, while IAH is sitting at 60F. That is a 10 degree difference within a small distance! It is quite unusual too see such a great difference between these two airports. A 2-4 degree difference is not usual, but a 10 degree difference definitely is.

BTW, here are some other 9pm airport reports:

Conroe - 47F
Hobby - 65F
Sugar Land - 58F
Brenham - 48F
Galveston - 64F
My thermometer - 49F

Quite an odd night out there!

[Extremeweatherguy]

The huge temperature difference continues at 10pm. Hooks is now at 48F while IAH is at 57F.

Update: As of midnight, the difference has finally diminished. Hooks is now at 46F and IAH at 50F (only a 4 degree difference). This is much more normal.

[JenBayles]

I'm just glad I don't have to run the AC tonite. This back-and-forth stuff is driving me nuts! The lastest forecast for Christmas Day is making me very happy though. Bring on the cold, rain and gloomy weather!

[Diva]

It's thundering and showers just beginning.....

[Extremeweatherguy]

Dewpoints are dropping like a rock out there today! At 10am, Hooks airport had a dewpoint of 63F, but now, as of 1pm, their dewpoint is all the way down to 33F. That equates to a 30 degree drop in dewpoints in just three hours. Amazing!

[srainhoutx]

RED FLAG WARNING
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
1234 PM CST SAT DEC 22 2007

...RED FLAG WARNING THIS AFTERNOON FOR MOST OF SOUTHEAST TEXAS...

.THE RED FLAG WARNING HAS BEEN EXPANDED FURTHER SOUTH AND EAST TO
INCLUDE MOST OF SOUTHEAST TEXAS.

TXZ163-176-177-195>199-210>212-226-235-236-230000-
/O.CON.KHGX.FW.W.0007.000000T0000Z-071223T0000Z/
AUSTIN-BRAZOS-BURLESON-COLORADO-GRIMES-HOUSTON-JACKSON-MADISON-
MATAGORDA-MONTGOMERY-WALKER-WALLER-WASHINGTON-WHARTON-
1234 PM CST SAT DEC 22 2007

...RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM CST THIS
AFTERNOON...

A RED FLAG WARNING REMAINS IN EFFECT UNTIL 6 PM CST THIS
AFTERNOON.

A COLD FRONT HAS CLEARED THE AREA. CLEAR SKIES WITH NORTHWEST
WINDS OF 15 TO 25 MPH WITH GUSTS TO 30 MPH CAN BE EXPECTED THIS
AFTERNOON. RELATIVE HUMIDITIES WILL BOTTOM OUT AT 15 TO 25
PERCENT...NOT RECOVERING UNTIL AROUND SUNSET.
A RED FLAG WARNING MEANS THAT CRITICAL FIRE WEATHER CONDITIONS
ARE EITHER OCCURRING NOW...OR WILL SHORTLY. A COMBINATION OF
STRONG WINDS...LOW RELATIVE HUMIDITY...AND WARM TEMPERATURES WILL
CREATE EXPLOSIVE FIRE GROWTH POTENTIAL.

$$

http://forecast.weather.gov/wwamap/wwat ... %20warning

[southerngale]

Red flag warning? The ground is too saturated here for any kind of fire threat. Have the recent rains missed those areas?

[vbhoutex]

The winds are still way up in our area. At the site nearest me they are blowing 17 mph sustained with gusts to 36 mph. I thought they should have died down by now.

[Extremeweatherguy]

It is pretty miserable to be outside right now. Gusts are still whipping by at over 30mph and temperatures are falling like a rock. I am currently sitting at 47.1F up here in Spring, but the wind chill with the gusts makes it feel like it is in the upper 30s.

With dewpoints still very lower and CAA continuing, I see no reason why many will not reach the lower to middle 30s tonight north of I-10. Bundle up!

[Extremeweatherguy]

10pm reports..

College Station - 40F (dewpoint of 23F)
Huntsville - 40F (dewpoint of 23F)
Conroe - 43F (dewpoint of 25F)
Hooks - 43F (dewpoint of 23F)
IAH - 45F (dewpoint of 25F)
Hobby - 49F (dewpoint of 26F)
Galveston - 52F (dewpoint of 32F)

[Extremeweatherguy]

The GFS operational and MOS have warmed up significantly for the 00z output in the longer range and now show highs reaching the upper 60s to lower 70s for Thursday through Saturday. This scenario is in question however. The reason they show this warming is because they push a warm front north through our region by early Thursday and stall a surface low over south Texas. This does not really seem too likely, IMO, but none the less it is something to watch. If this does happen, then it will mean significantly higher rain chances off the Gulf for late in the week with dewpoints approaching the sticky near-60F range. We could even see a few thunderstorms. One thing is for sure, this would definitely put a dent in our continued cool weather streak were it to happen! :? I have a feeling we will see this scenario disappear in future runs though. At the moment, I am still planning on a cool, cloudy week and will not take this warmer, wetter scenario seriously until it begins to appear on multiple back-to-back runs. For now, this warm front scenario is just a bit too questionable for me. I will re-examine the possibility once the 12z data comes out.

update: Did anyone catch this morning's NWS forecast update? lol. They have decided to warm things up considerably and are obviously now jumping on these new developments. They are calling for mid 60s on Christmas day and they continue with highs in the 60s through the weekend. It will sure be funny if the 12z runs now decide to switch back to a colder look though, then they would have to scramble to lower the numbers again.

update #2 (12/23/07 10:20am): the 12z Operational GFS run now looks much cooler for Wednesday and Thursday than the 00z did and once again shows highs likely only staying in the 50s to near 60F during that timeframe. If the 12z GFS MOS follows suit, then expect the NWS to once again lower temperatures for the long range.

[Extremeweatherguy]

It's official...Houston has now had it's 2nd freeze of the season!

IAH is sitting at 32F as of 7am.

BTW - - At 7:06am, I fell to 28.6F on my thermometer, thus making this now my coldest morning of the season. Brr! (update: Now down to 27.9F at 7:16am)

[Extremeweatherguy]

Here is a list of the official morning lows here in SE Texas (12/23/07)...

IAH - 31F
Hooks - 29F
Conroe - 26F
Hobby - 34F
Galveston - 38F
Brenham - 23F
College Station - 27F
Huntsville - 26F