Texas/New Mexico/Louisiana/Mexico Obs And Discussion Thread Part 3

[Ed Lizard]

Unfortunately, (fortunately?) I don't have acess to any other models that far out. 2009 (DFW)/2004 (Coast) anybody?

http://wxmaps.org/pix/dfwgfsb.png says you don't have that much to get excited about, really...

[Ed Lizard]

Good bye to forecaster #35...

THIS WILL BE MY LAST FORECAST AFTER 13 YEARS AT WFO HGX. THANKS TO

THE STAFF HERE FOR MAKING THIS A GREAT OFFICE TO WORK IN. I HAVE

LEARNED A LOT HERE. LOTS OF MEMORIES OF THE MAJOR EVENTS WE HAVE

WORKED TOGETHER TOO. LOOKING FORWARD TO WORKING TOGETHER AGAIN

AND CROSSING PATHS DOWN THE ROAD.

[Srain]

A quiet couple of days are ahead before things get interesting on Monday. A potent Winter Storm will cross Southern New Mexico and track between Lubbock and Amarillo bringing heavy snows and possible blizzard conditions across the Panhandles of TX/OK in SW Kansas. In the warm sector, a negative tilted trough/strong cold front sets the stage for severe weather chances developing from Central Texas on E. The morning Day 3 update from the SPC mentions the possibility of a Slight Risk for mainly damaging winds being introduced in future convective outlooks. Chilly weather will follow the storm for Tuesday into Wednesday. Clouds begin to increase late Wednesday as over running conditions begin as a Coastal Trough sets up along the Texas Coastal waters. Rains may be likely on Thursday. Much colder air sweeps into the area and yet another upper low develops in the Desert SW during the Christmas Holiday period.

DAY 3 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

0153 AM CST SAT DEC 17 2011

VALID 191200Z - 201200Z

...SYNOPSIS...

CUTOFF UPPER LOW NOW SITUATED OVER NRN BAJA THAT IS PART OF A WRN

U.S. REX BLOCK WILL BEGIN TO EJECT EWD SUNDAY AND CONTINUE THROUGH

THE SRN PLAINS MONDAY. ATTENDANT SFC LOW WILL LIKELY MOVE ACROSS NRN

TX OR OK WITH TRAILING PACIFIC FRONT ADVANCING THROUGH THE REMAINDER

OF TX.

...CNTRL THROUGH ERN TX AND WRN LA...

STRONG 50-60 KT SLY LLJ ASSOCIATED WITH THE EJECTING UPPER LOW WILL

TRANSPORT PARTIALLY MODIFIED GULF AIR INTO THE SRN PLAINS MONDAY

WITH SFC DEWPOINTS FROM THE LOW-MID 60S ACROSS SRN-SERN TX TO MID

50S OVER N-NCNTRL TX. WRN EXTENSION OF SERN U.S. SFC RIDGE IS

FORECAST TO BE IN PLACE EARLY MONDAY OVER CNTRL/ERN TX. INCREASING

SLY FLOW AND ISENTROPIC ASCENT ABOVE THIS COOL...STABLE LAYER WILL

LIKELY RESULT IN WIDESPREAD LOW CLOUDS EARLY IN PERIOD...LIMITING

DESTABILIZATION POTENTIAL SOMEWHAT. NEVERTHELESS...LOW LEVEL THETA-E

ADVECTION AND POTENTIAL FOR SOME OF THE LOW CLOUDS MIXING OUT FROM

THE SOUTH DURING THE AFTERNOON MAY SUPPORT AN AXIS OF MARGINAL

INSTABILITY WITH MLCAPE GENERALLY AOB 500 J/KG.

A BAND OF STORMS WILL LIKELY BE IN PROGRESS WITHIN ZONE OF DEEPER

ASCENT ALONG WARM CONVEYOR BELT ACROSS WRN TX MONDAY MORNING. SOME

OF THE STORMS MAY INTENSIFY AND BECOME SURFACE BASED AS THEY BEGIN

TO INTERACT WITH THE MOISTENING AND DESTABILIZING BOUNDARY LAYER

FARTHER EAST. GIVEN DEGREE OF FORCING...PRIMARY CONVECTIVE MODE IS

EXPECTED TO BE LINEAR. HOWEVER...ACTIVITY WILL REMAIN EMBEDDED

WITHIN STRONG LOW-LEVEL AND DEEP SHEAR ACCOMPANYING THE SHORTWAVE

TROUGH AS IT PROGRESSES EWD...SUPPORTING POTENTIAL FOR EMBEDDED

ORGANIZED STRUCTURES. PRIMARY THREAT IS EXPECTED TO BE ISOLATED

DAMAGING WIND...BUT A COUPLE OF TORNADOES CANNOT BE RULED OUT.

THREAT WILL SHIFT INTO THE LOWER MS VALLEY OVERNIGHT. DUE TO

POTENTIAL LIMITING FACTORS WITHIN THERMODYNAMIC ENVIRONMENT...5%

PROBABILITIES WILL BE INTRODUCED AT THIS TIME...BUT A PORTION OF

THIS AREA MAY NEED TO BE UPGRADED TO A SLIGHT RISK IN LATER

OUTLOOKS.

[Ed Lizard]

Limited time, I feel like a snow weenie model hugging, but through 54 hours I'm liking the 500 mb pattern from the NAM for potential fun locally (see SWODY3 above) Monday afternoon/evening.

I will not thumb my nose at a forced line of storms with 30 knot wind gusts or pea to marble hail. Beggars can't be choosers.

[Ed Lizard]

Poor low level lapse rates and poor instability. On the bright side, tremendous shear/helicity.

[Srain]

The 12Z GFS suggests an early Tuesday morning arrival of the storms/front. The bigger threat of anything of the severe nature would tend to be E of the I-35 corridor...

[Srain]

The 12Z Euro has joined the GFS/Canadian solution suggesting a coastal trough/low forming mid week. That model is also suggesting a bit strong upper air disturbance sweeping from W to E bringing down some chilly air for the Christmas Weekend...

[wxmx]

Guidance is getting mighty interesting...CMC and Euro are cold enough for some wintry precipitation if we get decent shortwave energy at the base of the long wave trough. No access to 500mb vorticity/700 and 850 mb RH/precipitation for the Euro past day 7, but the fact that it cut offs at day 10 and it's a very positive trough argues for some decent s/w energy riding the trough base....on the downside, the surface high pressures drops down very far south, so it's possible near surface layer might be very dry...I like the trends, though.

I'll pay a visit to the Houston area (Rosenberg) from the 22nd-27th, BTW

[Srain]

Winter Storm Warnings are now in effect for SW New Mexico with Winter Storm Watches extending NE into NE Kansas. Blizzard Watches have been hoisted from E N MX, the NW TX/OK Panhandles and SW/S Central Kansas for up to 12-14 inches of snow.

In the warm sector, The SPC has as Slight Risk of severe weather for parts of Eastern TX including areas just S of Dallas/FT Worth and including the Houston/Galveston region, mainly N of I-10. This storm looks eerily similar to the December 29, 2006 storm that brought numerous tornadoes across N TX and the Dallas/ Fort Worth area, but is not as strong at the 5H level and not as far S as that event. Severe Weather events, while not uncommon in December, have a history of catching folks off guard so it is prudent to at least mention the severe side of the very dynamic Winter Storm with the busy Holiday period approaching.

The squall line should get going Monday afternoon across Central Texas and march E during the overnight hours into early Tuesday morning before clearing the area. Damaging winds with some hail are the most likely threat, but an isolated tornado or two cannot be ruled out.

Cloudy skies and breezy conditions can be expected Tuesday into Wednesday. The fly in the ointment appears on Thursday. The guidance is all over the place concerning a possible coastal trough and over running rains along southern areas, or no precip chances at all. The same can be said for the Christmas Holiday Weekend. Guidance suggests light rains/drizzle with over running rains on Christmas Eve into Christmas Day. Temps will remain cool with increasing thick clouds.

There is much uncertainty with the week ahead, so expect changes in the very active un La Nina pattern with upper lows dropping S into the S CA/Baja Regions all week creating model mayhem and some forecasting challenges.

[Ed Lizard]

SWODY2 mentions limited instability, but, like me, it seems to be glass half full for SE Texas for 'fun-derstorms'. That is MUCape, but I actually don't want a tornado, hail or 50 knot winds will be fine.

[Srain]

SPC Day 2 Update suggests a bit of increased opportunity for severe weather chances in the warm sector mainly E of the I-35 Corridor and even a mention of an isolated possible tornado or two...

DAY 2 CONVECTIVE OUTLOOK

NWS STORM PREDICTION CENTER NORMAN OK

1130 AM CST SUN DEC 18 2011

VALID 191200Z - 201200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS CENTRAL/SOUTHEAST TX TO

FAR WESTERN LA...

...SYNOPSIS...

WHILE THE PRIMARY WESTERLIES PERSIST OVER CANADA/CONUS NORTHERN

TIER...THE CLOSED/SLOW-MOVING UPPER LOW CURRENTLY CENTERED OVER

NORTHERN BAJA/FAR NORTHWEST MEXICO WILL BEGIN TO MODESTLY ACCELERATE

EAST-NORTHEASTWARD AS IT REACHES THE SOUTHERN PLAINS BY MONDAY

AFTERNOON/NIGHT.

...CENTRAL/EAST TX TO WESTERN LA...

AS THE AFOREMENTIONED UPPER LOW EMERGES FROM NORTHWEST MEXICO/DESERT

SOUTHWEST...A PERSISTENTLY STRONG 50-60 KT SOUTHERLY LOW LEVEL JET

WILL AID IN THE NORTHWARD TRANSPORT OF A PARTIALLY MODIFIED GULF

AIRMASS INTO THE SOUTHERN PLAINS ON MONDAY. EAST OF A GRADUALLY

DEEPENING SOUTHERN HIGH PLAINS SURFACE LOW AND A

DRYLINE/EASTWARD-MOVING PACIFIC FRONT...THIS WILL GENERALLY RESULT

IN SURFACE DEWPOINTS IN THE LOWER TO MIDDLE 60S ACROSS

CENTRAL/SOUTHEAST TX BY AFTERNOON...WITH MIDDLE TO UPPER 50S F

DEWPOINTS INTO NORTH-CENTRAL TX/FAR SOUTHERN OK.

WITH SHOWERS/TSTMS LIKELY TO BE ONGOING EARLY MONDAY ACROSS WEST TX

INTO PARTS OF NORTH/CENTRAL TX AND OK...WIDESPREAD LOW CLOUDS MAY

LIMIT APPRECIABLE DESTABILIZATION INTO EARLY AFTERNOON.

NONETHELESS...CONTINUED THETA-E ADVECTION AND DIURNAL HEATING/MIXING

SHOULD YIELD A WEAKLY CAPPED BOUNDARY LAYER WITH A CORRIDOR OF

MLCAPE OF 500-800 J/KG ACROSS CENTRAL/SOUTHEAST TX BY MID/LATE

AFTERNOON TO THE EAST OF THE DRYLINE/PACIFIC FRONT. ALONG WITH

ARRIVAL OF MORE APPRECIABLE FORCING FOR ASCENT...THIS SHOULD RESULT

IN AN AFTERNOON/EVENING INCREASE OF SURFACE BASED TSTMS.

GIVEN THE DEGREE OF FORCING...EXPECTED EASTWARD PROGRESSION OF THE

PACIFIC FRONT ACROSS TX...AND CURRENTLY FORECAST VEER-BACK-VEER LOW

TO MID-LEVEL WIND PROFILES...THE PRIMARY CONVECTIVE MODE IS EXPECTED

TO BE LINEAR ESPECIALLY ACROSS CENTRAL INTO NORTH TX.

NONETHELESS...ASIDE FROM DAMAGING WINDS...AT LEAST SOME TORNADO

THREAT WILL EXIST GIVEN THE DEGREE OF LOW LEVEL SHEAR/SRH. SUCH A

TORNADO THREAT COULD BE THE CASE WITH INITIAL WARM SECTOR STORMS

EAST OF THE PACIFIC FRONT...ANY QLCS-EMBEDDED CIRCULATIONS THAT

EVOLVE...AND/OR WITH QLCS-SOUTH PERIPHERAL STORMS THAT SHOULD BE OF

A MORE DISCRETE NATURE /FORCING FOR ASCENT WILL BE A BIT MORE

SUBTLE/ WITHIN A HIGHER MOISTURE CONTENT AIRMASS ACROSS SOUTHEAST

TX. AT LEAST AN ISOLATED/MARGINAL DAMAGING WIND/TORNADO THREAT

SHOULD CONTINUE THROUGH MONDAY NIGHT AND INTO EARLY TUESDAY ACROSS

SOUTHEAST/EAST TX INTO WESTERN/SOUTHWEST LA.

...NORTHWEST TX/SOUTHWEST OK...

EVEN WITH A COOL/MARGINALLY MOIST BOUNDARY LAYER...LOW-TOPPED TSTMS

CAPABLE OF HAIL TO AROUND SEVERE LEVELS AND/OR PERHAPS A TORNADO

COULD DEVELOP EARLY/MID AFTERNOON MONDAY IN CLOSE PROXIMITY TO THE

NEARLY STACKED SOUTHERN HIGH PLAINS CYCLONE. SHOULD

MODEST/SUFFICIENT HEATING OCCUR...THIS COULD INITIALLY BE THE CASE

ACROSS NORTHWEST TX INCLUDING THE TX SOUTH PLAINS/SOUTHERN TX

PANHANDLE VICINITIES. GIVEN THE LIMITED NATURE OF THE

MOISTURE/BUOYANCY AND EXPECTED COLD FRONTAL PROGRESSIONS...ANY

STRONG/SEVERE TSTM THREAT SHOULD REMAIN MARGINAL AND OF A RELATIVELY

LIMITED DURATION.

[David Reimer]

Morning AFD from FWD

LARGE UPPER LEVEL LOW NEAR SAN DIEGO WILL BEGIN TO HEAD EAST

DURING THE DAY AND WILL TRACK ACROSS THE TEXAS PANHANDLE MONDAY

EVENING BEFORE CURLING NORTH INTO THE CENTRAL PLAINS ON TUESDAY.

THIS WILL BE A POWERFUL STORM SYSTEM...BRINGING HEAVY SNOW FROM

THE PANHANDLE INTO KANSAS...AND A ROUND OF POSSIBLY SEVERE

THUNDERSTORMS WITH THE POTENTIAL FOR TORNADOES IN OUR AREA.

FOR TODAY...MID LEVEL CLOUDS WILL BE INCREASING ACROSS THE REGION

FROM THE SOUTHWEST AS ISENTROPIC LIFT BEGINS TO ORGANIZE. HIGHS

WILL BE NEAR 60 DESPITE THE LACK OF SUNSHINE AS SOUTHERLY WINDS

BRING WARMER AIR NORTHWARD. SATURATION OF THE LOW LEVELS OCCURS

TONIGHT...WITH SOME WEAK SHOWERS BY DAYBREAK MAINLY WEST OF I-35.

WIND SPEEDS THROUGH THE ENTIRE COLUMN INCREASE DRAMATICALLY ON

MONDAY AS THE UPPER LOW EDGES CLOSER. VERY HIGH VALUES OF SHEAR

ARE EXPECTED WITH 0-6KM SHEAR OF 55KT...0-1KM SHEAR OF 35KT AND

0-3KM HELICITY EXCEEDING 500M2/S2. 850MB WINDS ARE ALSO DUE

SOUTHERLY...WHICH IS MORE BACKED THAN NORMAL. THIS SHOULD ALLOW

FOR EXCELLENT TRANSPORT OF MOISTURE/WARM AIR NORTHWARD AND A RAPID

MODIFICATION OF OUR AIR MASS DURING THE DAY. THE NAM/HI-RES WRF

ARE FAVORED FOR INSTABILITY FORECASTS AS THEIR SURFACE TEMPS

APPEAR MOST REASONABLE. ALTHOUGH CAPE LIKELY WILL NOT EXCEED 1000

J/KG...IT SHOULD BE NOTED THAT 100-300J/KG OF THE TOTAL CAPE IS

LOCATED BELOW 3KM DUE TO LFC OCCURRING WITHIN 1KM OF THE GROUND.

THIS SYSTEM HAS SOME SIMILARITIES TO THE DECEMBER 29 2006 SYSTEM

THAT PRODUCED 2 DOZEN TORNADOES OVER OUR AREA. THE 2006 SYSTEM WAS

A LITTLE BIT STRONGER AT 500 MB...TRACKED FARTHER SOUTH...AND THE

SURFACE LOW AND WARM FRONT WERE ALSO FARTHER SOUTH. I DONT EXPECT

A SEVERE WEATHER EVENT OF THAT CALIBER THIS TIME AROUND...BUT

THERE ARE ENOUGH SIMILARITIES THAT IT RAISES THE CONCERN FOR

TORNADOES DESPITE MANY MODEL FORECASTS SAYING THE INSTABILITY WILL

BE LIMITED. THE MODELS IN 2006 ALSO UNDERPLAYED THE INSTABILITY

AND THIS TIME WE WILL BE A LITTLE MORE WARY. SINCE IT IS DECEMBER

AND SEVERE WEATHER IS NOT USUALLY ON PEOPLES MIND...WE ARE GOING

TO ADVERTISE THE THREAT NOW DESPITE LOWER THAN NORMAL CONFIDENCE.

THE 2006 CASE HAD NUMEROUS DISCRETE SUPERCELLS AHEAD OF THE COLD

FRONT...AND I DONT EXPECT THAT THIS TIME AROUND. EXPECT MOST OF

THE CONVECTION TO DEVELOP ALONG A NORTH-SOUTH ORIENTED COLD FRONT

WHICH SHOULD MOVE INTO THE WESTERN CWA BY 3 PM. A SOLID SQUALL

LINE SHOULD DEVELOP ALONG THE FRONT...AND REACH THE I-35 CORRIDOR

AROUND 6PM MONDAY. STORM MOTION AT 45KT MEANS ANY STORM WILL HAVE

THE POTENTIAL FOR WIND DAMAGE DUE TO DOWNWARD MOMENTUM TRANSPORT

OF 55KT 850MB WINDS. TORNADO THREAT WILL BE LIMITED BY THE STORM

MODE BEING MAINLY LINEAR...BUT WILL BE POSSIBLE DUE TO THE HIGH

LOW LEVEL SHEAR AND CAPE. TORNADO THREAT IS HIGHEST SOUTH OF A

GOLDTHWAITE...HILLSBORO...ATHENS LINE WHERE INSTABILITY PARAMETERS

ARE GREATEST. SQUALL LINE SHOULD CLEAR THE CWA BY 2 AM TUESDAY.

[Ed Lizard]

The gold standard of Houston cool season low instability tornado outbreaks, November 1992.

Of course, that is probably something like 1900, 1915 and Carla, oft spoken of, rarely repeated.

F-4 damage...

[Srain]

Some interesting trends today regarding the Christmas timeframe. As posted in the Medium range thread on the main page, the 12Z Euro was suggesting the possiblity of potential wintry mischief fairly far S in Texas. The 00Z GFS and Canadian seem to like that idea as well...

00_054_G1_north@america@zoomout_I_4PAN_CLASSIC@012_144.jpg[/email]]

[JoMo]

Have to see what the Euro has to say about that, it's typically been slower. Looks interesting for you all though.

[Ed Lizard]

Steve, as you may know, GFS forecast soundings suggest snow in NW Harris County Christmas Night.

Which would be four miracles in seven years...

[Srain]

Have to see what the Euro has to say about that, it's typically been slower. Looks interesting for you all though.

Yeah, JoMo. Jorge and I have been chattting about this for a few days now. It will be interesting to see how it plays out.

Steve, as you may know, GFS forecast soundings suggest snow in NW Harris County Christmas Night.

Which would be four miracles in seven years...

I checked the soundings before posting here and on KHOU to make absolutely sure, Ed. Still a week away, but seeing some areement does begin to raise an eyebrow...clown map...

[wxmx]

At least the GFS is colder, like the Euro, with the 0C isotherm down to near Tampico. The difference lies in how the Polar Jet and Subtropical jet interact...if there's a full or partial phase, like what the Euro is implying, it will probably be in old MX, that is, farther SW, and probably a slow mover and with lower mid level heights... so add that to the increased vorticity, and you get someone with some unusual precip ammounts, but closer to S TX or N/NE MX. A compromise between the 12z Euro and 0z GFS solutions would be ideal for SE TX, IMO.

[Srain]

At least the GFS is colder, like the Euro, with the 0C isotherm down to near Tampico. The difference lies in how the Polar Jet and Subtropical jet interact...if there's a full or partial phase, like what the Euro is implying, it will probably be in old MX, that is, farther SW, and probably a slow mover and with lower mid level heights... so add that to the increased vorticity, and you get someone with some unusual precip ammounts, but closer to S TX or N/NE MX. A compromise between the 12z Euro and 0z GFS solutions would be ideal for SE TX, IMO.

I agree, Jorge. I do like the trends and the GFS ensembles agree as well. Just perhaps we can offer a little magic for you and the family while you're in the SE TX area for the Holidays...

[wxmx]

Analog pattern of the 12z Euro

1894

[wxmx]

I agree, Jorge. I do like the trends and the GFS ensembles agree as well. Just perhaps we can offer a little magic for you and the family while you're in the SE TX area for the Holidays...

Wouldn't that be something? Kids would be thrilled...those kids include me.

[wxmx]

0z Euro has little of the northern stream s/w, with a more progressive trough and a lot less colder setup...

[Flexo]

0z Euro has little of the northern stream s/w, with a more progressive trough and a lot less colder setup...

aka the reality solution

[Srain]

The theme for today will be warming temps and increasing winds. Pressure is falling at a rate of 3-5 mb every 3 hours in W TX and moisture levels will increase throughout the day. The atmosphere appears to be capped in the SW areas, but rain and storm chances should increase in the Western areas throughout the day into this evening. There may be some streamer showers late afternoon in the Metro Houston area as strengthening S/SE winds bring moisture N from the Gulf. Areas N of I-10 appear to have the greatest threat for severe weather with damaging winds and some hail chances being the primary threat. An isolated tornado or two cannot be ruled out with stronger storms along and just ahead of the squall line late tonight into early on Tuesday. There have been past cold weather Winter Storms that have caught many by surprise with the December 29, 2006 storm as an analog event that produced 22 tornadoes near Dallas/Ft Worth. This storm appears to be a bit further N, but severe weather chances remain rather high with a Slight Risk for parts of Central/N TX and all of SE TX. We'll need to monitor short range meso guidance for any further 'fine tuning' on this active weather day. Stay Tuned!

[Ed Lizard]

aka the reality solution

Glass half full on the winter weather in a week, and ditto strong storms towards the end of ESPN's Monday Night Football. Early SWODY 1 includes SETX in a SLIGHT RISK, and I don't expect a change in 25 minutes.

[Srain]

Morning e-mail from Jeff:

Highly active weather pattern continues this week with multiple weather systems to impact the area.

Powerful upper level storm system over AZ this morning will move ENE across NM into KS on Tuesday resulting in full blown blizzard conditions across the TX and OK panhandles. While southward over the rest of TX a potential for strong to severe thunderstorms this afternoon-early Tuesday.

Highly dynamic weather event for the region tonight as the potent SW US upper storm moves into the plains. Low level jet of 40kts extending from KBRO to near KFWD this morning will increase to 50kts this afternoon and shift eastward to our western counties (Matagorda Bay to College Station). Surface to 925mb flow remains backed out of the south into this evening with 60-80kt mid level flow out of the southwest and 100-120kt upper level jet carving into the area this evening. Tremendous wind energy will be in place along with favorable backing of the low level wind fields and turning with height to produce strong wind shear across the region this afternoon into tonight. Low level jet will bring a rapid influx of moisture from the western Gulf with dewpoints rising into the low to mid 60’s by this afternoon and PWS increasing from .8 to 1.5 inches this evening. SPC has outlooked the entire area with a slight risk for severe thunderstorms this afternoon/tonight and this seems reasonable. Only current drawback to a widespread severe event appears to be a general lack of instability with CAPE values of 800-1200 J/kg across most of the area late this afternoon. Tremendous shearing environment may not be utilized if instability is low and updrafts are modest.

With all that said, expect thunderstorms to develop quickly along I-35 early this afternoon as strong forcing overspreads the western edge of the low level jet. Initial storm mode looks supercellular with the best chances for any tornadoes and large hail near/along I-35 this afternoon. Linear forcing along developing cold pool/pre-frontal trough should result in isolated cells growing upscale into a large squall line/MCS by late afternoon as it approaches our western counties. Strong mid level winds digging into the backside of this activity will likely result in bowing line segments and the threat for corridors of damaging winds increasing early this evening as the line moves across SE TX. Feel the best threat for damaging winds will be north of I-10 where the best dynamics and lift will be located. Strong low level shear may also produce a few rotating updrafts either in cells that develop ahead of the line or along the line itself producing a few brief tornadoes. Feel the best tornado threat is just north of our area in the region from NE of Austin to near Centerville. Based on the large amounts of wind energy feel the main threat will be wind damage along the leading edge of the main line with winds of 55-65mph possible.

Strong storm system will move into the Midwest Tuesday with rapid clearing and drying over TX. Dry period will be short lived however in our fast active flow with the next storm already digging into the SW US Tuesday. This storm will move across N MX late Tuesday and toward TX Wednesday. Downstream forcing will generate a lower TX coastal trough with moisture quickly flow northward over a surface cool dome. Surface low will form over the Gulf waters and move NE up the coast late Wednesday into early Thursday. Strong sub-tropical jet aloft on the order of 100kts+ will work with the developing coastal system to produce widespread rains late Wednesday into Thursday. While rains may be widespread amounts will be on the lower side as most of what falls will be light to moderate and confined closer to the coast or offshore. This system will be fast moving and expect rainfall to end by midday Thursday.

May see a brief period of clearing Thursday afternoon/Friday before yet another system arrives toward the weekend. Models are nearly completely different in the handling of this system and its potential to produce precipitation in the cold air mass over the region. One thing looks fairly certain….its looks cold Saturday-Monday with highs possibly only in the 40’s and lows in the 30’s and may be below freezing for some areas under mainly cloudy skies. For now until some kind of agreement forms in the models will go with cloudy and cold conditions with highs near 50 and lows in the 30 with a 20-30% chance of light rainfall both Saturday and Sunday. Forecast for this weekend is extremely low confidence and expect some changes in the coming days.

[Ed Lizard]

MESOSCALE DISCUSSION 2378

NWS STORM PREDICTION CENTER NORMAN OK

1243 PM CST MON DEC 19 2011

AREAS AFFECTED...NERN NM / NWRN TX PANHANDLE / WRN OK PANHANDLE /

SERN CO / SWRN KS

CONCERNING...HEAVY SNOW

VALID 191843Z - 192315Z

INITIALLY LIGHT TO MODERATE SNOWFALL RATES WILL TRANSITION TO HEAVY

SNOWFALL RATES THIS AFTERNOON. SNOWFALL RATES AOA 1 INCH/HR WILL

BECOME LIKELY FIRST W OF 102 DEG LONGITUDE /I.E. CO/KS BORDER/ AND

THEN SPREAD INTO SWRN KS. LOCALIZED BLIZZARD CONDITIONS WILL TEND

TO INCREASE IN COVERAGE BY LATE AFTERNOON.

SURFACE MESOANALYSIS SHOWS A SURFACE LOW OVER E-CNTRL NM WITH A SW

TO NE ORIENTED BAROCLINIC ZONE FROM THE LOW NEWD AND BISECTING THE

TX PANHANDLE AND EXTENDING INTO SWRN KS. APPRECIABLE SURFACE

PRESSURE RISES --NOTED EARLIER THIS MORNING-- BEHIND THE FRONT AND A

STRENGTHENING LOW LEVEL PRESSURE GRADIENT WILL LEAD TO INCREASING

NLY WINDS AND COINCIDE WITH INCREASING LOW LEVEL COLD AIR ADVECTION

ON THE POLEWARD/BACKSIDE SIDE OF THE EWD MIGRATING SURFACE CYCLONE.

THIS WILL ALLOW THE COLUMN TO GRADUALLY COOL AND SUPPORT A PHASE

CHANGE TO ALL SNOW ACROSS PARTS OF THE TX-OK PANHANDLES.

DEEP LAYER ASCENT WILL BECOME MAXIMIZED OVER THE REGION LATER THIS

AFTERNOON AS STRONG UPPER FORCING FOR ASCENT OVERSPREADS THE

STRENGTHENING BAROCLINIC ZONE AND IN TURN LEADS TO HEAVIER SNOWFALL

RATES /21-00Z/. THE POSSIBILITY OF CONVECTIVE ENHANCEMENT

/THUNDERSNOW/ APPEARS TO INCREASE TOWARDS 00Z INVOF THE NRN TX

PANHANDLE/OK PANHANDLE. IT IS HERE...THAT FORECAST SOUNDINGS SHOW

MID-LEVEL LAPSE RATES STEEPENING AS THE NOSE OF THE MID-LEVEL DRY

SLOT MOVES N FROM THE TX S PLAINS AND ENCROACHES UPON THE TX-OK

PANHANDLES THIS AFTERNOON. THE LATEST SREF PROBABILITY GUIDANCE AND

EXPERIMENTAL CONVECTION-ALLOWING ENSEMBLE /SSEO/ SHOW A SWATH OF 1

INCH/HR RATES FROM NE NM INTO SWRN KS /LOCALLY HEAVIEST NEAR THE 5

STATE BORDER REGION/. A SUBSTANTIAL REDUCTION IN VISIBILITIES AND

INCREASINGLY STRONG WIND GUSTS WITH TIME MAY YIELD INCREASING

COVERAGE OF LOCALIZED BLIZZARD CONDITIONS BY LATE THIS AFTERNOON.

..SMITH.. 12/19/2011

ATTN...WFO...DDC...GLD...AMA...PUB...ABQ...

LAT...LON 35100313 35320489 36510460 37790449 38410155 37260133

35100313

[DoctorMu]

Another day, another dud in Aggieland. Maybe 0.1 in. Perhaps a few drops when the front slips through, but the energy is far, far north.

[wxmx]

0z Euro is back with the farther S and W energy...temps are not as cold as 2 days ago, but precip is abundant...Mexican plateau receives considerable snowfall in this run...around 1-1.5 feet for Zacatecas!

[Srain]

0z Euro is back with the farther S and W energy...temps are not as cold as 2 days ago, but precip is abundant...Mexican plateau receives considerable snowfall in this run...around 1-1.5 feet for Zacatecas!

LOL

What an interesting pattern ahead for the long Christmas Holiday Weekend. Potential freezing temps and over running precip to boot. Wintry mischief for Texas as well? I tend to think the GFS was a bit too progressive. The ensembles suggest a slower progression of the trough and cut off vorts. Fun times ahead...