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

[Ed Mahmoud]

18Z WRF looks like the 12Z globals, front staying close, no winter wx here in SE Texas. But, like the 12Z GFS, a low moving along/just inland/just offshore Texas, so there could be a narrow band of potentially tornadic storms along the coast.

I see any potential for winter weather as suggested a few days ago by random model runs has passed by. I had yesterday off, and after a soup spilling accident, don't have my laptop for about a week.


I hope we don't have tornadic storms tomorrow, without the computer, I will be dependent on either TWC or the local TV stations, and I was planning to watch some sports on cable if tomorrow was a rainout.


BTW, that reminds me, it might not be a bad thing if Comcast scrolled tornado warnings across the bottom of all the cable channels it carries, for those not watching a local channel or TWC.

[Ed Mahmoud]

New WRF for tomorrow late afternoon



Forecast sounding- not super high surface based instability, but strong wind fields/helicity.

[r22weiss]

GFS sounding for KSGR, Sugerland TX at 18Z on 2/16.
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=GFS&fcsthr=030&STATIONID=KSGR

[Ed Mahmoud]

GFS sounding for KSGR, Sugerland TX at 18Z on 2/16.
http://beta.wxcaster.com/cgi-bin/parse_skewt_trace.cgi?model=GFS&fcsthr=030&STATIONID=KSGR

I live about equidistant between Hooks and Intercontintal. This is a scary sounding, but the forecast still shows some inhibition, although certainly not a cap of forged steel.

[JenBayles]

The "cap of forged steel" would be the Bear Creek Dome... Although in this case, I don't mind it a bit and hope it holds. Saturday is looking downright freaky.

[r22weiss]

Agreed it's looking crazy for tomorrow. I'm hoping the "Katy affect" as we call it out here where storms split and go around Katy happens tomorrow afternoon. The 12Z run of the GFS backed off some from the 00Z run where the LI was near -7 at 00Z on Sunday and as you mentions a slightly stronger Cap. Now showing near -4 to -5. But the EHI is still over 2. Not ideal chasing situation too with fast moving storms and low bases likely.

[Ed Mahmoud]

Agreed it's looking crazy for tomorrow. I'm hoping the "Katy affect" as we call it out here where storms split and go around Katy happens tomorrow afternoon. The 12Z run of the GFS backed off some from the 00Z run where the LI was near -7 at 00Z on Sunday and as you mentions a slightly stronger Cap. Now showing near -4 to -5. But the EHI is still over 2. Not ideal chasing situation too with fast moving storms and low bases likely.

HOU is rarely a good place to chase, I'd guess. Not a chaser, but I'd guess a lot of storms have low bases, and a lot are rain wrapped. Plus trees, buildings and traffic would seem to make chasing storms difficult.

[KatDaddy]

Excerpt from the recently posted SPC Day 2 Outlook:

ATTENTION WILL THEN TURN DOWNSTREAM IN THE DESTABILIZING WARM SECTOR
DURING THE AFTN...AS THE CAP ERODES AND ADDITIONAL STORMS DEVELOP.
CONVECTIVE MODE WILL PROBABLY REMAIN DISCRETE AHEAD OF THE APCHG
COLD FRONT ACROSS PORTIONS OF CNTRL/ECNTRL TX SWD TO THE MIDDLE TX
COAST.

BULK SHEAR VALUES WILL BE MORE THAN SUFFICIENT FOR SUPERCELLS AND
GIVEN MAGNITUDE OF LAPSE RATES...VERY LARGE HAIL MAY RESULT.
CONCERN FOR STRONG TORNADOES WILL EXIST...ESPECIALLY WITH THE
DISCRETE STORMS. FCST HODOGRAPHS SUGGEST THAT 0-1KM EFFECTIVE STORM
RELATIVE SHEAR VALUES WILL BE IN EXCESS OF 400 M2/S2.
AS STRONG FORCING FOR ASCENT BEGINS TO ACCELERATE EWD DURING THE
EVENING...ACTIVITY WILL LIKELY EVOLVE INTO A LINEAR MCS WITH DMGG
WIND GUSTS/HAIL BECOMING MORE OF A THREAT ALONG THE SABINE RVR
VLY/UPR TX COAST.

[jasons2k]

The best place to chase, by far, is the TX South Plains centered near Lubbock. No trees, griddle-flat terrain, a perfect grid of well-maintained roads, LP supercells which are much easier to see, and an almost daily dryline show in May, right on time from 5-7PM. Oh, and an Allsup's and a DQ in every town.

Here it's a nightmare - too many trees, a "web" of roads, traffic, and HP supercells that are rain-wrapped, plus we get only one or two decent chase days a year during the daytime, if that.

[Garnetcat5]

Ok...could someone interpret those soundings for those of us that can't read them... I'm in between Sugarland and Katy.....so you've peaked my interest...praying for BC Dome....

[Ed Mahmoud]

I can think of no scientific reason why any place in Houston area should be at substantially lower risk for tornadoes than any other.


The only place I can think of that actually did seem semi-protected compared to nearby areas when I was growing up was Long Island, NY (and to a lesser extent Eastern New England). The usual Southerly/Southwesterly winds ahead of a severe weather producing front would carry in cooler, stable, marine air off the Atlantic.


I don't know how many times, when living in Massapequa as a wee lad, ominous looking squall lines would fizzle about the time they reached NYC. I also saw it when visiting my grandmother who lived just South of Boston.

[r22weiss]

The best place to chase, by far, is the TX South Plains centered near Lubbock. No trees, griddle-flat terrain, a perfect grid of well-maintained roads, LP supercells which are much easier to see, and an almost daily dryline show in May, right on time from 5-7PM. Oh, and an Allsup's and a DQ in every town.

Here it's a nightmare - too many trees, a "web" of roads, traffic, and HP supercells that are rain-wrapped, plus we get only one or two decent chase days a year during the daytime, if that.

Agreed, the best place in TX to chase is out in the Panhandle. Have done some chasing mainly west of Katy where the trees are abit less and the view is better. But the conditions are hardly ideal for chasing in SE TX.

Ok...could someone interpret those soundings for those of us that can't read them

The soundings show a verticle picture of the atmopshere from a particular point, in this case Sugarland. It shows the wind direction and speed with height on the right side(the wind barbs). The rest of the sounding shows moisture in the atmopshere and the different parameters that come with that. In this case, the forecast sounding shows that there is enough lift, engergy, spin from the wind change in speed and direction with height, and moisture in place to cause storms that could rotate (supercells) or cause hail and damaging winds over much of South East Texas.
I hope this helps!

[JenBayles]

We tend to get smaller twisters than the midwest in the SE TX area. Instead of one huge mile-wide tornado, we'll get a dozen small ones skipping all over the place. The last major outbreak I remember in town was November of 1992 (or was it 1991?!). I looked out the back window and froze like a deer in the headlights when I saw a funnel coming straight for us about a block away. Luckily it veered off at the last moment, but it sucked about half our roof shingles off. As I recall, there were dozens of tornadoes around Katy and the entire Houston area that afternoon.

As for today, I'm seeing more sun peeking through in the past hour. Will it be enough to bust the cap?

[jasons2k]

Dewpoints are in the up to 68-69F now in the coastal bend - even up to 70F now at Corpus. First time I've seen a 70F dewpoint this season and will add plenty of fuel.

[Ptarmigan]

We tend to get smaller twisters than the midwest in the SE TX area. Instead of one huge mile-wide tornado, we'll get a dozen small ones skipping all over the place. The last major outbreak I remember in town was November of 1992 (or was it 1991?!). I looked out the back window and froze like a deer in the headlights when I saw a funnel coming straight for us about a block away. Luckily it veered off at the last moment, but it sucked about half our roof shingles off. As I recall, there were dozens of tornadoes around Katy and the entire Houston area that afternoon.

As for today, I'm seeing more sun peeking through in the past hour. Will it be enough to bust the cap?

The tornado outbreak happened on November 21, 1992. The last tornado outbreak was on November 17, 2003.

[Ed Mahmoud]

Relevant snip of NWS HGX AFD

FOR TOMORROW THE THREAT OF SEVERE WEATHER REMAINS SIGNIFICANT FOR
ALL OF SE TX. THE APPROACHING UPPER LEVEL LOW/TROF TO HAVE A GOOD
DEAL TO WORK WITH AS THE AIRMASS OVER SE TX IS PROGGED TO BE VERY
MOIST AND UNSTABLE. MODEL SOUNDINGS INDICATING HIGH PWS (AOA 1.6-
1.8") AND HELICITIES (+400M2/SEC2)...AND VERY LOW LI (-6/-8). NAM
ALSO HAS EHI NUMBERS PEAKING NEAR 3 OVER THE WRN PARTS OF OUR CWA
AROUND NOON. SO THE EXPECTED SCENARIO HAS SCATTERED/DISCRETE TSRA
DEVELOPING OVER THE CWA FROM LATE MORNING THROUGH THE AFTN HOURS.
WE WILL THEN SEE A SQUALL LINE ASSOCIATED WITH THE UPPER LOW/PAC-
IFIC FRONT DEVELOP OUT WEST AND SWEEP ACROSS THE STATE DURING THE
LATE AFTN/EARLY EVENING. TSRAS DURING THE AFTN HAVE THE POTENTIAL
TO PRODUCE TORNADOES ALONG WITH HAIL...STRONG WINDS AND HVY RAIN.
HVY RAINS AND DAMAGING WINDS TO ACCOMPANY THE SQUALL LINE. THREAT
OF FLOODING NOT QUITE AS ELEVATED AS THE SEVERE WX THREAT ATTM AS
PROGGED STORM MOTIONS ARE DECENT. ADDITIONAL DETAILS CAN BE FOUND
VIA SPC OUTLOOKS FOR DAY 1 AND DAY 2.

[southerngale]

I don't like seeing a moderate risk. I'm hoping something will change later tonight and it will be downgraded to only a slight risk.

Although I enjoy thunderstorms (except I need NO rain these days to get some outside work done), severe storms are an entirely different ballgame. It's hard to enjoy the sound of rain hitting your house, thunder booming and a good lightning show when either your house or someone else's in the area is being ripped apart by straightline winds or a tornado. Hopefully, this won't be an event worth talking about on Sunday.

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAKE CHARLES LA
313 PM CST FRI FEB 15 2008

LAZ027>033-041>045-051>055-TXZ180>182-201-215-216-161000-
VERNON-RAPIDES-AVOYELLES-BEAUREGARD-ALLEN-EVANGELINE-ST. LANDRY-
CALCASIEU-JEFFERSON DAVIS-ACADIA-LAFAYETTE-UPPER ST. MARTIN-
CAMERON-VERMILION-IBERIA-ST. MARY-LOWER ST. MARTIN-TYLER-JASPER-
NEWTON-HARDIN-JEFFERSON-ORANGE-
INCLUDING THE CITIES OF...LEESVILLE...ALEXANDRIA...MARKSVILLE...
DERIDDER...OAKDALE...VILLE PLATTE...OPELOUSAS...LAKE CHARLES...
JENNINGS...CROWLEY...LAFAYETTE...ST. MARTINVILLE...CAMERON...
ABBEVILLE...NEW IBERIA...MORGAN CITY...WOODVILLE...JASPER...
NEWTON...LUMBERTON...BEAUMONT/PORT ARTHUR...ORANGE
313 PM CST FRI FEB 15 2008

...SEVERE THUNDERSTORMS POSSIBLE SATURDAY NIGHT...

THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR EASTERN
TEXAS...AND A SLIGHT RISK FOR CENTRAL AND SOUTHERN LOUISIANA.

THUNDERSTORMS ARE EXPECTED TO INITIALLY DEVELOP SATURDAY AFTERNOON
ACROSS SOUTHEAST AND SOUTH CENTRAL TEXAS...GENERALLY NORTH AND
WEST OF THE HOUSTON AREA. AS A STRONG COLD FRONT MOVES INTO THE
AREA...THESE THUNDERSTORMS ARE EXPECTED TO ORGANIZE INTO A SQUALL
LINE THAT WILL MOVE EAST INTO EASTERN TEXAS SATURDAY EVENING...AND
CONTINUE THROUGH SOUTHERN AND CENTRAL LOUISIANA THE REMAINDER OF
SATURDAY NIGHT.

DAMAGING STRAIGHT LINE WINDS AND LARGE HAIL WILL BE THE PRIMARY
HAZARDS...THOUGH TORNADOES WILL ALSO BE POSSIBLE...ESPECIALLY OVER
EASTERN TEXAS EARLY SATURDAY EVENING.

IN ADDITION...DUE TO THE HIGH MOISTURE CONTENT OF THE
ATMOSPHERE...THUNDERSTORMS WILL BE CAPABLE OF VERY HIGH RAINFALL
RATES...WHICH COULD LEAD TO LOCALIZED OR URBAN FLOODING.

RESIDENTS ARE ENCOURAGED TO KEEP UP WITH THE LATEST FORECASTS AND
OUTLOOKS CONCERNING THIS POTENTIAL SEVERE WEATHER SITUATION.

[JenBayles]

Translation needed: NAM ALSO HAS EHI NUMBERS PEAKING NEAR 3. What is "EHI"? Sorry, just an amateur enthusiast.

Ugh... I gotta move, my dog just blew a gas bomb in my general DY-rection...

[southerngale]

Translation needed: NAM ALSO HAS EHI NUMBERS PEAKING NEAR 3. What is "EHI"? Sorry, just an amateur enthusiast.

Ugh... I gotta move, my dog just blew a gas bomb in my general DY-rection...

Energy Helicity Index

I found this article about it... http://www.stormtrack.org/library/forecast/ehi.htm

[RL3AO]

I don't like seeing a moderate risk. I'm hoping something will change later tonight and it will be downgraded to only a slight risk.

Personally I think you should hope that it won't be upgraded to a high risk as that seems very possible right now.