December: New Years Eve Outlook

[Paul Robison]

Worse than Wilma? Oh Paul...sigh. Let's not go overboard. I lived through Hurricane Wilma while living in the Florida Keys in 2005. This will not be anything like the widespread damage that left well over a million folks with damage in S Florida. Let's not hype. Thanks.

On the other hand:

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
507 PM CST THU DEC 19 2013

TXZ163-164-176>179-195>200-210>213-226-227-201300-
AUSTIN-BRAZOS-BURLESON-COLORADO-FORT BEND-GRIMES-HARRIS-HOUSTON-
LIBERTY-MADISON-MONTGOMERY-POLK-SAN JACINTO-TRINITY-WALKER-WALLER-
WASHINGTON-WHARTON-
507 PM CST THU DEC 19 2013

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHEAST TEXAS.

.DAY ONE...TONIGHT

NO HAZARDOUS WEATHER IS EXPECTED.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

ON SATURDAY...A STRONG UPPER LEVEL STORM SYSTEM WILL PUSH INTO TEXAS.
SOME SHOWERS AND THUNDERSTORMS ARE ANTICIPATED TO DEVELOP ACROSS SOUTHEAST
TEXAS ON SATURDAY...BUT THERE IS ALSO A RISK FOR SEVERE STORMS TO DEVELOP
MAINLY FROM THE COLLEGE STATION AREA THROUGH LUFKIN. THE MAIN THREAT
AT THIS POINT LOOKS TO BE STRONG DAMAGING WINDS WITH HAIL AND BRIEF
TORNADOES AS THE SECONDARY THREAT. WE WILL CONTINUE TO MONITOR
THIS SEVERE WEATHER THREAT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED SATURDAY.


Bear in mind that any power outages that do occur will probably drag on through XMas day. Hope y'all put Coleman lanterns on your Xmas wish list!

[Ptarmigan]

I knew I'd be sorry for clicking that 'Read Post Anyway' tab.


Yup, I think we could be looking at damage as severe as Hurricane Wilma caused in Houston in 2005.

Worse than Wilma? Oh Paul...sigh. Let's not go overboard. I lived through Hurricane Wilma while living in the Florida Keys in 2005. This will not be anything like the widespread damage that left well over a million folks with damage in S Florida. Let's not hype. Thanks.

Severe thunderstorms are bad, but they are nothing like a hurricane, like Wilma. Wilma was horrible for Mexico and Florida.

[Paul Robison]

I knew I'd be sorry for clicking that 'Read Post Anyway' tab.


Yup, I think we could be looking at damage as severe as Hurricane Wilma caused in Houston in 2005.

Worse than Wilma? Oh Paul...sigh. Let's not go overboard. I lived through Hurricane Wilma while living in the Florida Keys in 2005. This will not be anything like the widespread damage that left well over a million folks with damage in S Florida. Let's not hype. Thanks.

Severe thunderstorms are bad, but they are nothing like a hurricane, like Wilma. Wilma was horrible for Mexico and Florida.

I don't want either one! One is as bad as the other, IMHO. I pray for that cap that HGX has been talking about will hold. Face it folks, we do not want to spend our Christmas day in the dark, do we?

P.S. I'm over my fear of the governor looking over any possible damage in a helicopter, Ed Mahmoud. But I wouldn't want THIS person to have to come out here to help out. She's got enough to do already:

http://www.youtube.com/watch?v=WxKqhOdh86I

[Andrew]

Looks like the NAM is coming in faster and farther north but the gfs is coming in slower and farther south. Considering the NAM had a large amount of difference compared to the previous 12z run I am going to side with the GFS on this one.

[Paul Robison]

Looks like the NAM is coming in faster and farther north but the gfs is coming in slower and farther south. Considering the NAM had a large amount of difference compared to the previous 12z run I am going to side with the GFS on this one.

I assume that means the cap that HGX thinks will protect us from the big bad severe thunderstorms will break?

BTW: this is a graphic from the 00z run---12/20/13. What is it saying?

[TxJohn]

Hopefully we don't get any severe weather or anything. A nice rain event would be great...but keep all the severe weather threat.

Sigh...will it ever get cold again? A low of 67 tonight...a low of 70 tomorrow....we hit freezing next week but warm up to the lower 60s Christmas.....

It's so easy for us to set record HIGHS...we set new record highs year round...each year.... but we can't seem to set record lows or reach challenging territory.

Hopefully the models start trending colder.....MUCH colder.

[Paul Robison]

Hopefully we don't get any severe weather or anything. A nice rain event would be great...but keep all the severe weather threat.

Sigh...will it ever get cold again? A low of 67 tonight...a low of 70 tomorrow....we hit freezing next week but warm up to the lower 60s Christmas.....

It's so easy for us to set record HIGHS...we set new record highs year round...each year.... but we can't seem to set record lows or reach challenging territory.

Hopefully the models start trending colder.....MUCH colder.

I just saw the latest GFS mesoscale precipitation model. If I read it right, it still sees best chances for severe to be to the north and east of the Houston metro. Anybody else see it?

[Paul Robison]

Looks like the NAM is coming in faster and farther north but the gfs is coming in slower and farther south. Considering the NAM had a large amount of difference compared to the previous 12z run I am going to side with the GFS on this one.

1) Nobody got that I mentioned damage from Wilma in Houston...


Just me, but if I am going to pick a random big hurricane that didn't hit Houston to hyperventilate about, I'd pick Katrina.


And NAM is finally starting to head toward GFS solution, but GFS has been more consistent, and just based on precip amounts, GFS, instead of I-10, seems to be suggesting US 59, or areas a bit NE of it, as the highway of cap breakage. If 12Z models don't improve, assuming 0Z Euro doesn't feature a miracle, FUN-derstorm chances drop below one quarter glass full tomorrow.

Posted on another board.

New GFS, based on just rainfall totals, suggests it is close, but cap breaks North and East of metro Houston, favoring happy FUNderstorms mainly in the NE suburbs. Forecast soundings at 42 hours on GFS show barely a cap at LFK, a strong warm nose at GFS. NAM timing starting to sync up with GFS, as expected, as Saturday approaches. GFS seems to have better instability. Still, personal preference, GFS, as NAM solution is still changing.





Glass fullness unchanged for SETX. May actually drop after 12Z models tomorrow, especially if 0Z Euro also suggests cap doesn't break locally. TWC Houston TorCon of 4 (equivalent to an SPC 10% risk) and East TX TorCon of 5 (>10%, less than 15%) may be a touch overdone. But looks like extreme NE Texas, Arkansas, and Maybe Mississippi may be the action spot Saturday. Unrelated to severe, GFS suggests heavy rain threat along and just North of the surface low. And maybe an overnight late Saturday/early Sunday severe threat Kentucky/Tennessee on the Northern edge of the warm sector. But best instability may coincide with strongest capping. And highest bulk shear may not coincide with remaining good instability. (Using TwisterData.com for a lot of big picture stuff, especially with 3 hour intervals on GFS)

Dear Ed:

Thank you for posting. I feel better now.

[srainhoutx]

The cold front is pushing S across the Texas Panhandle and Oklahoma where 6mb per hour pressure rises are noted behind the front suggesting a sharp temperature gradient with the shallow/dense cold air behind that front. The cold front should begin to stall across portions of SW Texas intending NE or just S of the Dallas/Ft Worth area as the potent upper low begins its trek eastward across Northern Mexico today into Saturday

Showers and storms should start to develop tonight across portions of Central Texas in the warm sector and race NE with storm motion in the 45kt-55kt Range limiting heavy rainfall expect for portions of NE Texas where Flash Flood Watches may be needed later today. Saturday could be very stormy as a 140kt jet streak associated with the upper low turns more negative tilted, but capping issues still looks rather healthy which would tend to limit a widespread severe potential for Texas. The SPC has issued a Slight Risk for today across potions of Central/NE Texas/NW Louisiana and Arkansas. The Day 2 SPC Outlook places SE Texas in a Slight Risk with portions of the Lower Mississippi Valley from Monroe, Louisiana to Memphis, Tennessee in a Moderate Risk later on Saturday. The overnight guidance has trended a bit faster with the arrival of the cold front, so improving conditions may begin earlier Saturday afternoon//evening across the area. A light freeze still looks likely early Christmas Eve.

Christmas Day appears to start out cool, but increasing clouds and rain chances enter the forecast as a short wave (upper air disturbance) approaches. A re enforcing shot of 'colder air' should arrive next Thursday.

[srainhoutx]

Morning Update from Jeff:

A powerful storm system will bring a threat for severe weather to the region late tonight into Saturday.

A strong upper level storm system over the SW US is progressing toward TX this morning and in response impressive warm air advection over the past 24-36 hours has led to a rapid increase in moisture over the region with dewpoints in the upper 60’s areawide. These warm dewpoints over the colder nearshore waters has fostered the development of dense sea fog which extends along the entire upper and middle TX coast this morning and has spread inland along a line from Victoria to Beaumont. This fog will continue to plague the coastal locations until a front passes on Saturday.

Severe Threat:

Strong winter storm system with lots of wind energy will be crossing the state late tonight into Saturday. Soundings from Thursday evening across eastern TX showed a moist surface layer capped off by warm air in the mid levels and this will continue today and likely into tonight. Could see a few scattered fast moving showers under the cap today across the region.

Strong lift begins to approach after midnight tonight and this will help in eroding the capping inversion. Wind profiles really ramp up with a powerful low level jet of 45-55kts just above the surface tonight with winds veering to SW at the mid levels and WSW at the upper levels. A 140kt jet stream will be carving into the area by early Saturday morning as the base of the upper trough pulls into W TX and turns NE. A surface cold front will approach our northern counties this evening and likely stall as surface low pressure forms over central TX. While wind profiles look impressive, instability is really lacking. Best instability values I could find on any of the model guidance was around 1500 J/kg with most of the values between 800-1000 J/kg. When dealing with such strong wind speeds, you need good instability to force the updrafts or there is the potential for the strong winds to quickly tilt a weaker updraft…a balance is needed. The incoming upper forcing Saturday morning could help with sustaining updrafts and if that happens and updrafts can utilize the veering wind profiles supercells would be possible with a damaging wind and tornado threat.

I would typically be worried about a low level boundary (ie the stalling cold front) helping to enhance the low level shear and promoting a better tornado threat, but again it is not the shear in question but the needed surface energy…still will need to keep a close eye over our northern counties to see exactly where the shallow cold front begins to stall this evening as this area will be closest to the strongest lift and best low level shear environment.

Expect showers and thunderstorms to begin to increase in the 300am-600am time period from WSW to ENE across the area. Best severe weather window appears to be from about sunrise to just after noon on Saturday which is not an overly favorable severe weather time of day….however when dealing with winter severe weather outbreaks you don’t need much heating when such strong dynamics are at play aloft. Think we may see a broken line of thunderstorms form over central TX and move quickly across the region with wind damaging being the primary threat. Models have at times attempted to develop storms (supercells) ahead of the main line with a tornado threat, but this appears very conditional at the moment and highly dependent on the capping inversion weakening enough. Would not rule out a tornado with any sustained supercell structure either ahead or within the line given the forecasted wind profiles. SPC Day 2 outlook has the entire area include in a slight risk….but think the best severe chances are generally NE of a line from Columbus to Freeport where capping is weakest and lift strongest. Storm motions will be extremely fast on the order of 40-50kts so the forward motions alone could generate some wind damage…this will also limit warning lead times and weather conditions will change very quickly.

System should exit the region by late Saturday afternoon with a dryline punching across the region. Actual cold front will arrive on Sunday bringing cooler temperatures for the first of next week with low falling into the 30’s and highs in the 50’s under mainly sunny skies.

Christmas:

Looks like Christmas may feature increasing clouds as wind turn back to the south ahead of the next storm system. Temperatures look to be in the 40’s for lows and upper 50’s for highs with the potential for some slight rain chances by late afternoon and evening.

SPC Day 2 (Saturday) Outlook:

12202013 SPC DAY 2 day2otlk_0700.gif

[srainhoutx]

A brief update regarding the pattern beyond Christmas before we focus on the severe weather potential tonight into tomorrow...there are growing indication via the deterministic and ensemble Global guidance that a pattern change may be ahead as we head toward the end of December. The EPO is now being forecast to drop to around -3 while the PNA goes slight positive. Also of note are the indications on the long lasting positive AO may drop to a more neutral or slightly negative regime which favors a return of colder air into the Lower 48. There are also indications that the sub tropical jet may become rather active. If the cold air arrives and is deep enough, some interesting wintry mischief may be possible around the New Year time frame. We will see.

[skidog40]

so if the front doesn't stall? then what? this front was forecasted 10 days ago to bring us cold temps so, far it hasn't stalled.

[srainhoutx]

It appears that the guidance has under estimated the surface temps behind the cold front. NWS Tulsa has issued an Ice Storm Warning as temperatures across Oklahoma and the Texas Panhandle fall well below freezing.

[srainhoutx]

Updated SPC Day Outlook has been issued. Cities included in the Slight Risk are Austin, TX...Shreveport, LA...Little Rock, AR...Killeen, TX...Waco, TX...

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1014 AM CST FRI DEC 20 2013

VALID 201630Z - 211200Z

...THERE IS A SLGT RISK OF SVR TSTMS FROM CNTRL TX INTO CNTRL AR...

...SYNOPSIS...

THE LARGE-SCALE PATTERN WILL REMAIN CHARACTERIZED AS AMPLIFIED AND
MULTI-STREAM WITH THE PRIMARY FEATURE OF INTEREST BEING A
SUB-TROPICAL BRANCH SHORT-WAVE TROUGH WHICH WILL PROGRESS EWD ACROSS
THE SRN ROCKIES AND NRN MEXICO INTO THE SRN HIGH PLAINS BY 21/12Z.
IN THE LOW LEVELS...A COLD FRONT CURRENTLY FROM LOW PRESSURE OVER
THE MID MS VALLEY SWWD THROUGH W-CNTRL TX INTO SRN PARTS OF NM/AZ
WILL DECELERATE AND EVENTUALLY STALL BY TONIGHT. CYCLOGENESIS WILL
OCCUR LATER TONIGHT OVER THE LOWER RIO GRANDE VALLEY WITH THIS
FEATURE TRACKING NEWD ALONG THE STALLED SURFACE FRONT INTO CNTRL TX
BY THE END OF THE D1 PERIOD.

...TX/AR/LA THIS EVENING INTO EARLY SATURDAY...

12Z OBSERVED SOUNDINGS AHEAD OF THE COLD FRONT SHOW THE PRESENCE OF
A SEASONABLY MOIST BOUNDARY LAYER /I.E. LOWEST 100-MB MEAN-MIXING
RATIOS OF 12-14 G PER KG/ SURMOUNTED BY A WELL-DEFINED EML AND
ATTENDANT CAP. ASIDE FROM UPLIFT ALONG THE FRONT AND MODEST
LOW-LEVEL WAA...THIS CAP COUPLED WITH WIDESPREAD CLOUDS AND
NEGLIGIBLE HEIGHT FALLS/DCVA WILL LIKELY LIMIT TSTM COVERAGE THROUGH
THE PEAK OF THE DIURNAL HEATING CYCLE.

BY THIS EVENING...THE LEADING EDGE OF WEAK HEIGHT FALLS WILL BEGIN
TO OVERSPREAD A STRENGTHENING WAA REGIME ASSOCIATED WITH A
NOCTURNALLY INTENSIFYING LLJ TO SUPPORT AN INCREASE IN TSTMS FROM
NERN TX INTO AR AND NWRN LA. CONTINUED BOUNDARY LAYER MOISTENING
ALONG THE STALLING FRONT MAY ALLOW SOME OF THIS ACTIVITY TO BECOME
ROOTED WITHIN A MARGINALLY UNSTABLE /I.E. MLCAPE OF 500-750 J PER
JG/ BOUNDARY LAYER. GIVEN THE STRENGTHENING LLJ AND RESULTANT
ENHANCEMENT OF VERTICAL SHEAR...A LOW-PROBABILITY RISK FOR LOCALLY
DAMAGING WINDS AND/OR TORNADOES WILL EXIST WITH ANY SUSTAINED
STORMS.

MORE ROBUST TSTM DEVELOPMENT AND AN INCREASED SEVERE WEATHER RISK
WILL MATERIALIZE LATER TONIGHT INTO EARLY SATURDAY ALONG THE FRONT
FROM CNTRL TX INTO CNTRL AR AS DEEP-LAYER ASCENT INCREASES MARKEDLY
AHEAD OF THE MIGRATORY SHORT-WAVE TROUGH AND DEVELOPING SURFACE LOW.
WHILE INSTABILITY WILL REMAIN WEAK WITH MLCAPE LESS THAN 1000
J/KG...STRONG LOW-LEVEL AND DEEP-LAYER SHEAR WILL BE SUPPORTIVE OF
EMBEDDED SUPERCELL AND LEWP STRUCTURES CAPABLE OF DAMAGING WINDS AND
PERHAPS A COUPLE TORNADOES.

..MEAD/BUNTING.. 12/20/2013

[srainhoutx]

Winter Storm Warnings coming for the NWS Oklahoma City Region...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORMAN OK
1043 AM CST FRI DEC 20 2013

.UPDATE...
WE WILL LIKELY BE UPGRADING TO A WARNING THIS MORNING. SYNOPTIC
MODELS LOOK TO BE TOO AGGRESSIVE IN WARMING LOW-LEVEL TEMPERATURES
THIS AFTERNOON GIVEN THE MOSTLY CLOUDY SKIES AND CONTINUED COLD
AIR ADVECTION. NOW THAT THE FRONT HAS MOVED THROUGH AND WE SEE
HOW MUCH COOL AIR HAS ENTERED THE AREA... WE CAN MORE CONFIDENTLY
SEE THE AREA OF CONCERN FOR POTENTIAL ICE ACCUMULATIONS...
ESPECIALLY NEAR AND JUST WEST AND NORTH OF THE OKLAHOMA CITY
METRO. LATEST MODELS ALSO SUGGEST THAT 4 INCH SNOW ACCUMULATIONS
WILL BE POSSIBLE ACROSS NORTHWEST OKLAHOMA AS WELL. WE ARE
COORDINATING THE DETAILS WITH WPC AND OTHERS RIGHT NOW TO
DETERMINE THE SPECIFIC AREAS TO UPGRADE.

[Ptarmigan]

A brief update regarding the pattern beyond Christmas before we focus on the severe weather potential tonight into tomorrow...there are growing indication via the deterministic and ensemble Global guidance that a pattern change may be ahead as we head toward the end of December. The EPO is now being forecast to drop to around -3 while the PNA goes slight positive. Also of note are the indications on the long lasting positive AO may drop to a more neutral or slightly negative regime which favors a return of colder air into the Lower 48. There are also indications that the sub tropical jet may become rather active. If the cold air arrives and is deep enough, some interesting wintry mischief may be possible around the New Year time frame. We will see.

Negative EPO, Positive PNA, and Negative AO is more favorable for cold blasts. I have seen big cold blasts where there the AO and EPO were negative like in January 1940 (Hobby saw low of 5°F). EPO is going to be a bigger factor than AO.

[Ptarmigan]

Morning Update from Jeff:

A powerful storm system will bring a threat for severe weather to the region late tonight into Saturday.

A strong upper level storm system over the SW US is progressing toward TX this morning and in response impressive warm air advection over the past 24-36 hours has led to a rapid increase in moisture over the region with dewpoints in the upper 60’s areawide. These warm dewpoints over the colder nearshore waters has fostered the development of dense sea fog which extends along the entire upper and middle TX coast this morning and has spread inland along a line from Victoria to Beaumont. This fog will continue to plague the coastal locations until a front passes on Saturday.

Severe Threat:

Strong winter storm system with lots of wind energy will be crossing the state late tonight into Saturday. Soundings from Thursday evening across eastern TX showed a moist surface layer capped off by warm air in the mid levels and this will continue today and likely into tonight. Could see a few scattered fast moving showers under the cap today across the region.

Strong lift begins to approach after midnight tonight and this will help in eroding the capping inversion. Wind profiles really ramp up with a powerful low level jet of 45-55kts just above the surface tonight with winds veering to SW at the mid levels and WSW at the upper levels. A 140kt jet stream will be carving into the area by early Saturday morning as the base of the upper trough pulls into W TX and turns NE. A surface cold front will approach our northern counties this evening and likely stall as surface low pressure forms over central TX. While wind profiles look impressive, instability is really lacking. Best instability values I could find on any of the model guidance was around 1500 J/kg with most of the values between 800-1000 J/kg. When dealing with such strong wind speeds, you need good instability to force the updrafts or there is the potential for the strong winds to quickly tilt a weaker updraft…a balance is needed. The incoming upper forcing Saturday morning could help with sustaining updrafts and if that happens and updrafts can utilize the veering wind profiles supercells would be possible with a damaging wind and tornado threat.

I would typically be worried about a low level boundary (ie the stalling cold front) helping to enhance the low level shear and promoting a better tornado threat, but again it is not the shear in question but the needed surface energy…still will need to keep a close eye over our northern counties to see exactly where the shallow cold front begins to stall this evening as this area will be closest to the strongest lift and best low level shear environment.

Expect showers and thunderstorms to begin to increase in the 300am-600am time period from WSW to ENE across the area. Best severe weather window appears to be from about sunrise to just after noon on Saturday which is not an overly favorable severe weather time of day….however when dealing with winter severe weather outbreaks you don’t need much heating when such strong dynamics are at play aloft. Think we may see a broken line of thunderstorms form over central TX and move quickly across the region with wind damaging being the primary threat. Models have at times attempted to develop storms (supercells) ahead of the main line with a tornado threat, but this appears very conditional at the moment and highly dependent on the capping inversion weakening enough. Would not rule out a tornado with any sustained supercell structure either ahead or within the line given the forecasted wind profiles. SPC Day 2 outlook has the entire area include in a slight risk….but think the best severe chances are generally NE of a line from Columbus to Freeport where capping is weakest and lift strongest. Storm motions will be extremely fast on the order of 40-50kts so the forward motions alone could generate some wind damage…this will also limit warning lead times and weather conditions will change very quickly.

System should exit the region by late Saturday afternoon with a dryline punching across the region. Actual cold front will arrive on Sunday bringing cooler temperatures for the first of next week with low falling into the 30’s and highs in the 50’s under mainly sunny skies.

Christmas:

Looks like Christmas may feature increasing clouds as wind turn back to the south ahead of the next storm system. Temperatures look to be in the 40’s for lows and upper 50’s for highs with the potential for some slight rain chances by late afternoon and evening.

SPC Day 2 (Saturday) Outlook:

12202013 SPC DAY 2 day2otlk_0700.gif

Looks like the storm should be here by early Saturday morning.

[srainhoutx]

The 1730Z Day 2 SPC Outlook expands the Slight/Moderate Risk a bit further S and W...

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1112 AM CST FRI DEC 20 2013

VALID 211200Z - 221200Z

...THERE IS A MDT RISK OF SVR TSTMS FROM EAST TEXAS ACROSS MUCH OF
LOUISIANA...SOUTHEAST ARKANSAS...WESTERN TENNESSEE AND ALL OF
WESTERN MISSISSIPPI...

...THERE IS A SLGT RISK OF SVR TSTMS SURROUNDING THE MDT RISK AREA
FROM EAST TX THE UPPER TX GULF COAST NORTHEAST TO THE OH RIVER
VALLEY...TN VALLEY AND NORTHERN GULF COAST...

...SEVERE WEATHER OUTBREAK POSSIBLE ACROSS PARTS OF THE LOWER
MISSISSIPPI RIVER VALLEY ON SATURDAY...

...SYNOPSIS...
STRONG TO VERY STRONG MID AND UPPER LEVEL FLOW DOMINATES THE
PRONOUNCED SPLIT FLOW UPPER AIR REGIME ACROSS THE CONUS. A POTENT
SHORT WAVE TROUGH...CURRENTLY OVER THE NRN GULF OF CA...WAS PIVOTING
THROUGH THE BASE OF A POSITIVE-TILT LARGER SCALE TROUGH ORIENTED SW
TO NE FROM THE LOWER CO RIVER VALLEY TO THE NRN PLAINS. THIS
DISTURBANCE IS FORECAST TO EJECT OUT OF THE LARGER SCALE TROUGH
TOWARD DOWNSTREAM CONFLUENT FLOW ACROSS THE MIDWEST. AS THE
MID-LEVEL WAVE ACCELERATES NEWD FROM WEST TX TOWARD THE MS VALLEY ON
SATURDAY...500MB FLOW WILL STRENGTHEN TO AROUND 100KT ACROSS THE
ARKLATEX...WHILE SSWLY LOW LEVEL JET INTENSIFIES TO 60-70KT FROM
EAST TX TO THE OH VALLEY.

AT THE SFC...A SHARP QUASI-STATIONARY FRONT IS CURRENTLY BECOMING
DEFINED FROM CNTRL/NERN TX TO THE OH VALLEY. AS MID/UPPER TROUGH
APPROACHES LATER FRIDAY AND INTO SATURDAY LIFT ACROSS THIS BOUNDARY
WILL INTENSIFY SIGNIFICANTLY. ANOMALOUSLY HIGH PW AIRMASS ALONG AND
SOUTH OF THE BOUNDARY WILL CONTRIBUTE TO WIDESPREAD STRONG TO SEVERE
CONVECTION. IN FACT...SEVERE STORMS ARE LIKELY TO BE ONGOING AT THE
START OF THE DAY 2 PERIOD... ESPECIALLY ACROSS THE ARKLATEX. AS
AFOREMENTIONED MID/UPPER WIND FIELDS INTENSIFY...THE PROSPECT FOR
WIDESPREAD DAMAGING WINDS AND TORNADOES WILL INCREASE THROUGH THE
MORNING AND INTO LATE AFTERNOON/EVENING FROM EAST TX TO THE LOWER OH
VALLEY AND OVER THE LA/MS DELTA REGION.

...AKLATEX ACROSS LA/MS...
WHILE SBCAPE WILL BE LIMITED TO AOB 500 J/KG ACROSS THE WARM
SECTOR...FORECAST SOUNDINGS EXHIBIT ABUNDANT MOISTURE AND ADEQUATE
LAPSE RATES TO SUPPORT DEEP MOIST CONVECTION IN AN ENVIRONMENT
CHARACTERIZED BY INCREASINGLY STRONG ASCENT AND DEEP-LAYER SHEAR.
LATEST STORM SCALE GUIDANCE /WRF-ARW AND NAM4/ SHOW REMARKABLE
CONSISTENCY AND DEPICT THE EVOLUTION OF A STRONGLY FORCED
PRE-FRONTAL SQUALL-LINE NEAR THE TX/LA BORDER BY LATE MORNING. WITH
CLOUD-BEARING MEAN WINDS AND BUNKERS STORM MOTIONS AROUND 60KT...AS
WELL AS ENLARGED HODOGRAPHS CONTRIBUTING TO EFFECTIVE SRH OF 300-500
M2/S2...SEVERE WINDS AND TORNADOES APPEAR LIKELY WITH LEWP/BOW
STRUCTURES EMBEDDED WITHIN THE LARGER QLCS. MESOSCALE LOWS/WAVES
RIPPLING ALONG THE LINE MAY SUPPORT LOCALLY ENHANCED STRONG TORNADO
POTENTIAL THROUGH THE AFTERNOON ACROSS NRN LA.

THE BROKEN LINE OF SEVERE CONVECTION WILL ADVANCE EAST ACROSS NRN LA
AND THE MS RIVER THROUGH EARLY EVENING. TRAILING PORTION OF THE
CONVECTIVE LINE WILL MAKE SLOWER PROGRESS EAST ACROSS SRN LA AND MAY
NOT ARRIVE ACROSS THE LA/MS DELTA REGION UNTIL AFTER DARK SATURDAY
EVENING. NONETHELESS...EXPECT SEVERE WIND/TORNADO THREAT TO PERSIST
AFTER DARK OVER THESE AREAS.

....AR/TN TO OH VALLEY...
CONVECTIVE INSTABILITY WILL REMAIN WEAK ACROSS THESE AREAS BUT
MESOSCALE FORCING FOR ASCENT WILL BE PRONOUNCED ALONG THE
QUASI-STATIONARY FRONT...AND ESPECIALLY NEAR FRONTAL WAVES FORECAST
TO FORM AND RIPPLE ENEWD ALONG THE FRONT THROUGH THE DAY. THIS WILL
RESULT IN BOUTS OF STRONG TO SEVERE STORMS SPREADING NEWD FROM AR TO
SRN IL/IND AND PERHAPS AS FAR NORTHEAST AS SWRN OH INTO THE EVENING.
STORM MOTIONS IN EXCESS OF 50KT AND RELATIVELY MOIST ADIABATIC
PROFILE...ALONG WITH ORGANIZING INFLUENCE FROM FRONTAL
WAVES/LOWS...SHOULD SUPPORT BOWING STRUCTURES CAPABLE OF PRODUCING
DAMAGING WINDS. ISOLATED/BRIEF TORNADOES MAY ALSO OCCUR COINCIDENT
WITH ANY PERSISTENT FRONTAL WAVE.

..CARBIN.. 12/20/2013

[Katdaddy]

So much for the 80F weather in League City. Temp dropped 20F just N of Corsicana and now its setting at 38F in Roanoke N of Ft Worth. Its back to Winter for NTX. WXman57 would not like this weather

Severe weather potential still looking possible for SE TX tomorrow.

[skidog40]

stalled yet? what if it doesn't stall and keeps coming?