Texas Winter 2010-2011

[Ntxw]

Nice hearing from you wall_cloud! Haven't had many pro mets ring a chime in lately. My question for you is what do you think of this weekend's storm from the SW? Models have swung just about every which way with it, strong/weak/warm/cold, it's been really hard to pinpoint.

[wall_cloud]

I think it is going to be colder than has been advertised thus far. Lots of low clouds and easterly flow picking up some of the cold airmass to our northeast. I'm still working on my forecast...I'll have to get back to you though.

[Ntxw]

Fair enough . I do hope there will be some wintry surprises. I know many of the pro mets on here don't like snow but hey! It's winter and if it's going to be cold it might as well. Thanks for taking a look, very much appreciative.

Edit: I don't know what it is about this system, I just seem to have deja vu when looking at the charts. Can't pinpoint it exactly from where...or why.

[srainhoutx]

There are some great analysis this morning from a couple of NWS offices across the region. Worth the read from some fine forecasters...

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
426 AM CST WED JAN 5 2011

.DISCUSSION...
AN ACTIVE SUBTROPICAL UPPER JET WAS CONTINUING OVER SE TX THIS
MORNING. THE UPPER CUT OFF LOW WEST OF SOUTHERN CA IS EXPECTED
TO PUSH EASTWARD LATER THIS WEEK AND SHEAR OFF AS AN UPPER TROUGH
AS IT MOVES ACROSS TEXAS. THIS SYSTEM WILL BE FOLLOWED BY A COLDER
AIR MASS EARLY NEXT WEEK. LIKED HOW THE NAM HANDLED THE FIRST
COUPLE OF DAYS AND THEN PREFERRED THE SLIGHTLY SLOWER ECMWF FOR
THE WEEKEND SYSTEM AND FOR THE COLD AIR OUTBREAK FOR EARLY NEXT
WEEK.

THE MAIN ITEM OF CONCERN FOR TODAY WILL BE THE FOG AND DRIZZLE
OCCURRING FROM THE DEPARTING SYSTEM. MAY NEED TO ISSUE A DENSE FOG
ADVISORY LATER THIS MORNING. FOR NOW THE FOG HAS BEEN PATCHY DENSE
IN ISOLATED SPOTS. AS NORTHERLY WINDS DEVELOP LATER...THE FOG AND
DRIZZLE IS EXPECTED TO END IN THE MID TO LATE MORNING PERIOD.

THURSDAY AND FRIDAY ARE EXPECTED TO BE NICE FAIR WEATHER DAYS. ON
FRIDAY SOUTHWESTERLY WINDS AT THE SURFACE SHOULD HELP WARM THE
DAYTIME HIGH TEMPERATURES TO NEAR 70.

OVER THE WEEKEND...THE STRONG UPPER TROUGH IS SETTING UP A PATTERN
FOR WIDESPREAD RAIN AND THUNDERSTORMS OVER SE TX. STILL NOT
CONFIDENT ON THE TIMING GIVEN THE DIFFERENT MODEL SOLUTIONS BUT
FOR NOW THINK THAT THE BEST RAIN CHANCES WILL BE LATE SATURDAY
AFTERNOON THROUGH SATURDAY NIGHT. THERE WILL POSSIBLY BE A SEVERE
WEATHER THREAT WITH A NEGATIVE TILTED UPPER TROUGH...STRONG
DIFFLUENCE COUPLED WITH A FAVORABLE REGION OF THE UPPER JET...AND
FAVORABLE LOW-LEVEL FLOW.

FOLLOWING THIS STORM SYSTEM...THE ECMWF MOVES AN ARCTIC AIR MASS
INTO THE PLAINS TUESDAY. SE TX LOOKS TO BE ON THE EDGE OF THE COLD
AIR WITH THE ECMWF COLDER THAN THE GFS. HOWEVER...THE MODEL HAS
BACKED OFF A BIT AND MODIFIED THE SYSTEM WARMER. FOR NOW WILL GO
WITH A BLEND OF THE ECMWF OUTPUT...THE MEX...AND THE ENSEMBLE
MEAN FOR TEMPERATURES MONDAY AND TUESDAY.

Dallas/Ft Worth:

.EXTENDED/COLD WX NEXT WEEK...
CONFIDENCE REMAINS HIGH THAT MUCH OF THE CONTINENTAL US WILL SEE
TEMPERATURES WELL BELOW NORMAL FOR MUCH OF NEXT WEEK AND THERE
HAS BEEN MUCH DISCUSSION AS TO WHETHER OR NOT IT WILL GET AS COLD AS
SOME OF THE MORE SEVERE ARCTIC INTRUSIONS OF YEARS PAST. LATEST
GLOBAL MODEL GUIDANCE CONTINUES TO SHOW EXPECTED OSCILLATIONS WITHIN
THE OVERALL UPPER AIR PATTERN BUT THE GENERAL CONSENSUS IS THAT
RIDGING OVER ALASKA WILL BUILD SUFFICIENTLY STRONG AND BECOME
PARTIALLY BLOCKED AS TO ALLOW A MASSIVE CHUNK OF COLD AIR TO HEAD
SOUTH INTO THE CONTINENTAL US. THE FIRST SHOT OF THIS COLD AIR WILL
MOVE RAPIDLY INTO NORTH TEXAS EARLY MONDAY WITH STRONG NORTHERLY
WINDS AND SHARPLY COLDER TEMPERATURES. AS WE HEAD THROUGH NEXT WEEK
HOWEVER...THERE ARE SOME CONCERNS AS TO WHETHER THE OVERALL PATTERN
WILL REMAIN FAVORABLE FOR CONTINUED SURGES OF COLD AIR.

EXTENSIVE ANALYSIS OF ARCHIVED UPPER AIR DATA FROM PREVIOUS RECORD
BREAKING COLD EVENTS INCLUDING THE SEVERE COLD SNAPS OF 1983 AND
1989 YIELD A COUPLE OF INTERESTING DETAILS. THE MOST SIGNIFICANT
ARE THE TEMPERATURES AT THE SOURCE OF BITTERLY COLD AIR.
GENERALLY... ARCTIC INTRUSIONS INTO NORTH TEXAS BEGIN WITH EXTREMELY
COLD AIR PARCELS WITHIN THE 800 TO 500MB LAYER LOCATED OVER
NORTHWEST/ NORTH-CENTRAL CANADA. THESE PARCELS WILL GRADUALLY
SUBSIDE AND WARM AS THEY HEAD SOUTH BUT ARE USUALLY STILL VERY COLD
BY THE TIME THEY REACH THE SURFACE. IN AT LEAST A HALF-DOZEN MAJOR
COLD SNAPS INCLUDING 1983/1989/1996...THE 500MB TEMPS ACROSS
NORTHWEST CANADA WERE TYPICALLY IN THE -45 TO -50C RANGE...AND 700MB
TEMPS WERE TYPICALLY IN THE -30 TO -35C RANGE. THE RECORD COLD OF
1983 HAD A SAMPLED 500MB TEMP OF -50C IN NORTHERN MONTANA. AS OF
NOW...NEITHER THE GFS NOR THE ECMWF HAS TEMPERATURES THAT COLD
ACROSS CANADA. PROGGED 850MB TEMPS ACROSS NORTH TEXAS ARE IN THE
-10 TO -15C RANGE WHICH DEFINITELY SUPPORTS COLD TEMPERATURES AT THE
SURFACE...HOWEVER IN THE EXTREME EVENTS...H85 TEMPS WERE IN THE -17
TO -20C RANGE WITH A FRIGID -24C AT OKC IN 1983. GIVEN THE FORECAST
TEMPERATURES THROUGH NEXT WEEK...CONFIDENCE IS INCREASING THAT THIS
WILL NOT BE HISTORICALLY COLD ACROSS NORTH TEXAS. OF COURSE THIS
ASSUMES A PERFECT PROG OF THE MODEL TEMPERATURES. THE OTHER CONCERN
IS THE POSITION OF THE UPPER RIDGE OVER ALASKA. THE LATEST RUNS
CONTINUE TO BUILD AN ANOMALOUSLY STRONG RIDGE OVER AK THEN HAVE HAD
SOME TROUBLE AS TO WHETHER IS WILL MOVE NORTH OR WEST INTO SIBERIA.
THIS RIDGE POSITION HAS IMPLICATIONS ON THE UPPER PATTERN OVER THE
WESTERN US. TYPICALLY WE LIKE TO SEE A STRONG TROF POSITIONED OVER
THE WEST/SW US WHICH DOES NOT MOVE TO KEEP THE COLD AIR FLOWING
SOUTHWARD. THESE MODEL DISCREPANCIES ARE EXPECTED IN THE 10-15 DAY
PERIOD AND WILL CONTINUE TO BE MONITORED.

AS OF NOW WE WILL CONTINUE TO SHOW THE STRONG FRONT ON MONDAY/END OF
THE CURRENT FORECAST PERIOD/ AND WILL INTRODUCE HIGH TEMPERATURES IN
THE UPPER 20S/LOWER 30S FOR TUESDAY THROUGH THE END OF NEXT WEEK.
OVERNIGHT LOWS WILL GENERALLY BE IN THE LOWER TEENS AND LOWER 20S.
IT SHOULD BE STRESSED THAT CONSIDERABLE DISCREPANCIES WITHIN THE
FINER DETAILS EXIST THIS FAR OUT AMONG NOT ONLY THE OPERATIONAL
GUIDANCE BUT AMONG THE INDIVIDUAL ENSEMBLE MEMBERS. SEVERAL
ENSEMBLE MEMBERS TO INDICATE A FAVORABLE RIDGE/TROF POSITION THROUGH
NEXT WEEK AND KEEP THE COLD AIR COMING SO IT WILL BE NECESSARY TO
FINE TUNE TEMPERATURE FORECASTS THROUGH NEXT WEEK. WHAT MAKES THIS
SYSTEM SIGNIFICANT IS THE POTENTIAL FOR THERE TO BE AN EXTENDED
PERIOD OF VERY COLD TEMPERATURES ACROSS THE REGION. IT IS THE
DURATION OF SUB-FREEZING AIR THAT CAN HAVE SERIOUS IMPACTS TO THE
REGION VERSUS JUST THE TEMPERATURES THEMSELVES.


CONCERNING PRECIPITATION POTENTIAL...LATEST 12Z ECMWF DOES SHOW AN
AREA OF QPF ALONG THE FRONT ON MONDAY LIKELY IN AN AREA OF STRONG
FRONTOGENETIC FORCING SQUEEZING OUT ANY AVAILABLE MOISTURE. TEMPS
ARE SUFFICIENTLY COLD FOR SNOW...BUT IT IS THE ONLY MODEL DOING SO
WITH SUCH VIGOR ATTM. BEING 7 DAYS OUT...WILL LEAVE THE 10 POPS IN
AND SEE IF THIS TREND CONTINUES. INTO NEXT WEEK...WITH TEMPS SO
COLD ANY MOISTURE COULD CREATE WINTRY PRECIPITATION BUT AS OF NOW IT
APPEARS THAT THINGS WILL BE VERY DRY. THESE DETAILS WILL BE WORKED
OUT OVER THE NEXT SEVERAL DAYS.



San Angelo:

.LONG TERM...
THE PRIMARY FOCUS IN THE LONG TERM PORTION OF THE FORECAST IS THE
TIMING AND INTENSITY OF THE COLD AIR THAT IS FORECAST TO IMPACT MUCH
OF THE CONUS EARLY NEXT WEEK. HOWEVER...THERE ARE A FEW INTERESTING
DAYS BETWEEN NOW AND THEN. TRANSIENT WAVES IN THE ACTIVE NORTHWEST
FLOW ALOFT WILL BRING WEAK SURFACE BOUNDARIES INTO WEST CENTRAL TX
THURSDAY AND FRIDAY YET WX CONDITIONS WILL REMAIN PLEASANT BOTH
DAYS. THURSDAY WILL BE THE COOLER OF THE TWO WITH HIGHS RANGING FROM
THE UPPER 50S ALONG THE I-20 CORRIDOR TO THE LOW/MID 60S TO THE
SOUTH. ON FRIDAY...MOST AREAS SHOULD CLIMB INTO THE MID 60S WITH A
FEW 70S POSSIBLE ALONG AND SOUTH OF THE CONCHO RIVER.

MID/HIGH CLOUDS WILL BE ON THE INCREASE BY THE END OF THE WORK WEEK
AS THE QUASI STATIONARY UPPER LOW SPINNING OF THE CA COAST
APPROACHES. THIS FEATURE WILL BE ACCOMPANIED BY STRONG LARGE SCALE
FORCING AS IT MOVES ACROSS TX. SOUTH WINDS FRIDAY NIGHT AND SATURDAY
WILL ADVECT LOW LEVEL MOISTURE INTO THE CWA SETTING THE STAGE FOR
DECENT RAIN CHANCES. THE STRONG QG FORCING APPEARS TO BE CENTERED
AROUND 00Z SUNDAY WITH THE STRONGEST LOW LEVEL CONVERGENCE ACROSS
THE EASTERN HALF OF THE AREA. THUS...POPS ARE HIGHEST HERE WITH
50/60 POPS ACROSS THE HEARTLAND. ABUNDANT CLOUD COVER AND COOL
EASTERLY WINDS WILL KEEP HIGHS RATHER COOL ON SATURDAY. MAX TEMPS
WERE LOWERED TO THE MID/UPPER 50S ACROSS MUCH OF THE CWA. PRECIP
CHANCES CONTINUE AREAWIDE THROUGH SATURDAY NIGHT AS THE LOW MOVES
ACROSS THE REGION. ON SUNDAY...POPS WERE INCLUDED NORTHEAST OF A
LINE FROM JAYTON...TO ABILENE...TO BROWNWOOD. THIS WOULD BE MORE A
STRATIFORM LIGHT RAIN ASSOCIATED WITH THE WRAP AROUND REGION OF THE
DEPARTING LOW. TEMPS ON SUNDAY HAVE ALSO BEEN LOWERED AS SURFACE
EAST TO NORTHEAST WINDS SHOULD KEEP CLOUDS IN PLACE IN CONJUNCTION
WITH LOW LEVEL COLD ADVECTION. NOW TO THE TOUGH PART OF THE
FORECAST...

THE MEDIUM RANGE MODELS HAVE BACKED OFF SLIGHTLY ON THE SPEED OF THE
INEVITABLE ARCTIC INTRUSION AND CONTINUE TO WAFFLE BACK AND FORTH ON
ITS INTENSITY. THE 05/00Z GFS NOW DELAYS THE COLD FRONT UNTIL MONDAY
NIGHT WHILE THE ECMWF IS ABOUT 12 HOURS FASTER...BRINGING THE FRONT
THROUGH MUCH OF THE AREA BY 18Z MONDAY. THE DGEX IS FASTER STILL BUT
IN MY OPINION REMAINS TOO SLOW. MY CONCERN IS THE UPPER LOW THAT IS
PROGGED TO TRAVERSE THE REGION OVER THE WEEKEND WILL ALLOW THE COLD
AIR TO RUSH SOUTH FASTER THAN EXPECTED. THE TRUE ARCTIC AIR MAY BE
SLIGHTLY DELAYED BUT COOLER TEMPS ARE ANTICIPATED EARLIER RATHER
THAN LATER. SURFACE PRESSURE FALLS AHEAD OF THE AFOREMENTIONED
UPPER JUXTAPOSED WITH THE BAROCLINICITY ALONG THE TX COAST ARE
EXPECTED TO PRODUCE A COASTAL TROF THIS WEEKEND WITH NORTHEAST
WINDS DEVELOPING ACROSS MUCH OF THE STATE. THE COLD AIR IS PROGGED
TO BE AS FAR SOUTH AS THE ARKLATEX REGION BY SUNDAY AFTERNOON. MY
THINKING IS AS THE NORTHEAST WINDS OVERSPREAD THE AREA...THE
EFFECTIVE COLD FRONT WILL BACKDOOR INTO THE AREA SUNDAY NIGHT WITH
EVEN COLDER AIR ARRIVING DURING THE DAY ON MONDAY. I ADDED A
SLIGHT CHANCE OF SNOW NORTH OF I-20 FOR MONDAY AS LARGE SCALE LIFT
SPREADS ACROSS THE SOUTHERN PLAINS BUT AT THIS TIME I DO NOT THINK
IT WILL AMOUNT TO MUCH. TEMPS ON MONDAY ARE EXPECTED TO TOP OUT IN
THE 30S ACROSS THE BIG COUNTRY WITH HIGHS NEAR 50 IN THE SOUTH. AS
MENTIONED YESTERDAY...THESE HIGHS TEMPS COULD BE RATHER GENEROUS
IF THE FRONT DOES INDEED ARRIVE EARLY. HIGHS TUESDAY IN THE WAKE
OF THIS FRONT MAY STRUGGLE TO REACH FREEZING ACROSS PORTIONS OF
THE AREA WITH THE SOUTHERN ZONES EXPECTED TO SEE MID/UPPER 30S
FOR HIGHS.

THE BLOCKING HIGH IS PROGGED TO REMAIN ENTRENCHED OVER AK THROUGH
MUCH OF NEXT WEEK. THIS MEANS THE PATTERN SHOULD CHANCE LITTLE WITH
MUCH COLDER THAN NORMAL CONDITIONS EXPECTED THROUGH MUCH OF THE
WEEK. THE GFS DEVELOPS A LEE CYCLONE BY MIDWEEK THAT SCOURS OUT THE
COLD DOME OVER WEST CENTRAL TX BY WEDNESDAY NIGHT AND THURSDAY BUT
THE WAVE ASSOCIATED WITH THIS CYCLONE LOOKS RATHER WEEK. IT WOULD
TAKE A QUITE STRONG SHORTWAVE TO ERODE THIS AIRMASS THAT QUICKLY.

Norman, OK:

SOME WINTRY
PRECIP WILL BE POSSIBLE SATURDAY NIGHT AS THE COLD AIR MOVES SETTLES
INTO THE REGION. MODELS THEN SHOW ANOTHER SHORTWAVE/DISTURBANCE
APPROACHING FROM THE NORTH MOVING ACROSS THE PLAINS LATE SUNDAY INTO
EARLY NEXT WEEK. THIS WILL BRING ANOTHER ROUND OF COLD ARCTIC AIR
INTO THE REGION. PRECIP CHANCES WILL CONT SUNDAY INTO EARLY NEXT
WEEK BUT THE BEST CHANCE FOR PRECIPITATION WITH THIS SECOND SYSTEM
WILL BE SUNDAY NIGHT INTO MONDAY NIGHT WITH MOST OF THE PRECIP
LIKELY FALLING IN THE FORM OF SNOW. THE COLD CONDITIONS WILL PERSIST
THROUGH AT LEAST WEDNESDAY. ANOTHER CHANGE IS THAT THE MODELS ARE
NOW SHOWING THAT THE SFC HIGH AND COLD AIR MAY BEGIN TO SHIFT EAST
CAUSING A SLIGHT WARM UP LATE NEXT WEEK. HOWEVER... BEFORE THAT
HAPPENS TEMPERATURES IN SOME LOCATIONS MAY NOT CLIMB ABOVE FREEZING
FOR SEVERAL DAYS NEXT WEEK.


Dodge City:

DAYS 3-7...

THE EXTENDED FORECAST IS A BIT MORE CHALLENGING AS THE MODELS, WHICH
HAVE BEEN REASONABLY CONSISTENT IN THE LAST FEW DAYS ARE NOW IN MORE
DISAGREEMENT. THE 00Z GFS SEEMS LIKE AN OUTLIER COMPARED TO THE 00Z
GEM AND 00Z ECWMF AS IT SLOWS THE ARCTIC FRONT PASSAGE CONSIDERABLY.
THIS RESULTS IN 5 TO 10 DEGREE TEMPERATURE CHANGE IN THE FORECAST.
CONSIDERED THIS IS A MODEL PERTURBATION AND DID NOT MAKE THIS
DRASTIC CHANGE. AS A RESULT, LEFT TEMPERATURES AS IS. I DID MAKE A
FEW CHANGES TO POPS TO GET US MORE IN COORDINATION WITH SURROUNDING
WFOS AND THE NEW GUIDANCE SUGGESTS THAT THE SOUTHERN SHORTWAVE
TROUGH WILL HAVE LESS OF AN IMPACT TO KANSAS AND WILL REMAIN SOUTH
INTO OKLAHOMA AND TEXAS ON SATURDAY. WHAT WILL GIVE US A FAIRLY GOOD
CHANCE AT PRECIPITATION IS THE SHORTWAVE TROUGH DIVING ACROSS THE
ROCKIES SUNDAY. HAVE LOW BALLED QPF AND SNOW AMOUNTS IN THE GRIDS
SINCE THIS IS FAR OFF IN THE EXTENDED, HOWEVER, THIS COULD BE A SNOW
ADVISORY AMOUNT EVENT AS BOTH THE GFS AND ECMWF INDICATE DECENT SNOW
AMOUNTS. WE WILL BE IN THE LEFT EXIT REGION OF A 250 HPA JET SO
THERE WILL BE PLENTY OF DYNAMICS AND LIFT TO GENERATE SIGNIFICANT
PRECIPITATION AMOUNTS. THIS IS SOMETHING THAT WILL HAVE TO BE
WATCHED. BREEZY NORTHERLY WINDS WILL ALSO PRODUCE NEGATIVE WIND
CHILLS IN THE EXTENDED, AND PROBABLY WILL NEED A WIND CHILL ADVISORY AT
SOME POINT AS WELL.

Lubbock:

.LONG TERM...
LITTLE CHANGES WERE MADE TO THE LONG TERM FORECAST AS ARCTIC AIR
BLAST CONFIDENCE IS INCREASING FOR NEXT WEEK. A WEAK SHORT WAVE WILL
TRANSVERSE THE AREA TOMORROW AFTERNOON AND EVENING.
HOWEVER...MOISTURE IS VERY LIMITED AND THERE IS LITTLE TO NO LIFT
BEING GENERATED FROM THIS DISTURBANCE. THERE WILL BE A BRIEF PERIOD
OF SHORT WAVE RIDGING ON FRIDAY BEFORE THE NEXT DISTURBANCE BEGINS
TO AFFECT THE AREA. A CLOSED LOW THAT HAS BEEN PARKED OFF THE
CALIFORNIA COAST WILL MOVE ON SHORE FRIDAY AND MOVE ACROSS THE
DESERT SOUTHWEST. ALL MODELS GENERALLY DEPICT THIS SYSTEM OPENING UP
BEFORE IT MOVES OVER THE AREA THOUGH THERE IS STILL SOME DEGREE OF
UNCERTAINTY OF HOW STRONG THE WAVE WILL BE ONCE IT REACHES WEST
TEXAS. MODELS RANGE FROM THE NAM BEING THE LEAST OPTIMISTIC FOR QPF
WHILE THE LATEST ECM RUN DEPICTS A STRONGER AND SHARPER WAVE.
PRECIPITATION TYPE IS EXPECTED TO BE MOSTLY IN LIQUID FORM ON
SATURDAY. HOWEVER...IF PRECIPITATION WERE TO PERSIST LONG ENOUGH
INTO THE EVENING THERE COULD BE A CHANGE OVER TO SNOW OR A WINTRY
MIX WITH COLDER AIR FILTERING INTO THE REGION. ANOTHER SYSTEM IS
EXPECTED TO DIVE DOWN FROM THE PACIFIC NORTHWEST WITH LIFT
SKIRTING OUR NORTHERN AREAS. STILL BELIEVE A SLIGHT CHANCE IS
WARRANTED FROM THIS SYSTEM ON MONDAY.

SURFACE RIDGING IS NOW PROGGED TO BEGIN BUILDING INTO THE AREA ON
SATURDAY WITH GENERALLY EASTERLY UPSLOPE FLOW PERSISTING ALL OF
NEXT WEEK. THE STRONGER COLD AIR PUSH WILL BE FROM A FRONTAL
PASSAGE ON SUNDAY EVENING. A 1040MB SURFACE HIGH WILL SPREAD
ACROSS THE CENTRAL PLAINS INTO AT LEAST THE MIDDLE OF NEXT WEEK
ALLOWING FOR A PERIOD OF SIGNIFICANT COLDER TEMPERATURES.
ADDITIONALLY...LOW LEVEL MOISTURE WILL BE ABUNDANT IN THE UPSLOPE
FLOW KEEPING CONDITIONS CLOUDY FOR SEVERAL DAYS.

Shreveport:

THE EXTENDED PACKAGE HAS DONE A SIGNIFICANT COOL DONE AS WE MOVE
INTO THE WEEKEND AND EARLY NEXT WEEK. MODELS ARE STILL BOLD ON
RAIN FORECAST THIS WEEKEND...WITH THE HEAVIEST RAIN FALLING
SATURDAY NIGHT. I DID NOT PLACE THIS IN THE FORECAST...BUT I
WOULD NOT BE SURPRISED IF WE SEE SOME SLEET MIXED IN WITH THE RAIN
SATURDAY NIGHT...ESPECIALLY IN THE I30 CORRIDOR AND NORTHWARD
WHERE WE WILL SEE TEMPS FALL INTO THE MID 30S OVERNIGHT.

AS WE MOVE INTO THE NEXT WORK WEEK TEMPS WILL BE VERY COLD...AS A
STRONG ARCTIC RIDGE SURGES INTO THE HEART OF THE COUNTRY. AND
DEPENDING ON MOISTURE WE COULD SEE SOME SNOW IN THE TUESDAY/WEDNESDAY
TIME FRAME. GUIDANCE POP NUMBERS ARE STILL LOW ATTM...SO HELD OFF
ON MENTIONING IN THE FORECAST PACKAGE UNTIL I SEE MORE CONFIDENT
NUMBERS

Midland/Odessa:

MONDAY...ANOTHER SHORTWAVE WILL DIVE INTO THE CENTRAL
PLAINS...DROPPING A MODIFIED ARCTIC FRONT INTO THE REGION MONDAY
NIGHT...FOR WELL-BELOW NORMAL TEMPS INTO THE EXTENDED. LONG RANGE
MODELS ADVERTISE GOOD ISENTROPIC UPGLIDE AS THE FRONT MOVES
THRU...KEEPING THE AREA SOCKED IN THRU WEDNESDAY. GUIDANCE LOOKS
TOO WARM FOR THIS SCENARIO...SO WE/LL STAY WELL BELOW MACHINE
NUMBERS FROM MONDAY ONWARD.



Austin/San Antonio:

AN ARCTIC OUTBREAK IS EXPECTED EARLY NEXT WEEK FOR SOUTH CENTRAL TEXAS.
A DENSE ARCTIC AIRMASS WILL MOVE SOUTHWARD AND ENTER TEXAS ON MONDAY.
THIS AIRMASS WILL OVERSPREAD SOUTH CENTRAL TEXAS MONDAY NIGHT AND WILL
REMAIN ENTRENCHED ACROSS OUR REGION THROUGH WEDNESDAY OF NEXT WEEK.
THIS WILL BE A DRY SYSTEM. THE GFS MOS GUIDANCE FOR MONDAY NIGHT
THROUGH TUESDAY NIGHT IS AROUND 10 DEGREES TOO WARM. THE GFS
TRADITIONALLY HAS A HARD TIME WILL SHALLOW ARCTIC OUTBREAKS ACROSS
TEXAS DUE TO THE MODELS POOR RESOLUTION IN THE LOWER LEVELS.


Corpus Christi:

LATEST MEDIUM RANGE MODELS SHOW MORE IN THE WAY OF
COOLING BEHIND THE FRONT THAT MOVES THROUGH BEHIND THIS SYSTEM AND
DROPPED EXPECTED MAX TEMPS QUITE A BIT FOR SUNDAY AS HIGH PRESSURE
NOSES INTO THE REGION. MODELS ALSO SHOW THAT HIGH PRESSURE WILL
BE BUILDING INTO THE AREA AS A PIECE OF THE ARCTIC AIRMASS COULD
BE INTO THE REGION BY MONDAY. SHOWED A TREND FOR SLIGHT COOLING
FROM SUNDAY. THEN THE ARCTIC AIRMASS ARRIVES MONDAY NIGHT ALONG
WITH POST FRONTAL CLOUDINESS. COULD SEE SOME THINNING OF THE
CLOUDS OVER THE COASTAL AREAS TUESDAY BUT IT WILL STILL BE COLD
FOR THE AREA WITH READINGS NOT EXPECTED TO MAKE IT OUT OF THE 40S.



Brownsville:

.LONG TERM...6 PM THURSDAY THROUGH TUESDAY...A WEST COAST MID
LEVEL CLOSED LOW WILL OPEN UP AND WILL MOVE ACROSS TX ON SAT AND
SAT NIGHT INCREASING POPS A BIT. MOST OF THE DEEPER MOISTURE WILL
REMAIN POOLED TO THE NORTH OF DEEP SOUTH TX AND WILL ACCORDINGLY
MAINTAIN ONLY SOME 20 TO 30 % POPS FOR SAT AND SAT NIGHT WITH THE
PASSAGE OF THE TROUGH AXIS. AFTER THIS TROUGH EXITS THE REGION
BROAD MID LEVEL TROFFING WILL PREVAIL OVER THE NORTH CENTRAL AND
NORTHEASTERN PORTIONS OF THE LOWER 48 STATES. THIS WILL USHER
THROUGH A FAIRLY COLD CANADIAN AIRMASS LATE IN THE FORECAST
PERIOD RESULTING IN A PRETTY DRASTIC DROP IN TEMPS NEXT TUES.
MODEL TO MODEL AGREEMENT BETWEEN THE GFS AND THE ECMWF IN THE 3 TO
7 DAY RANGE LOOKS REASAONABLE AT THE 500 MB LEVEL. RUN TO RUN
CONSISTENCY WITH THE GFS MEX MOS LOOKS GOOD AND WILL GO CLOSE TO
THE LATEST MEX RUN THROUGH MON AND WILL GO BELOW MEX GUIDANCE ON
TUES AFTER THE FRONT.

[Portastorm]

GFS = Lucy.

You see, gang ... she yanked the football from ya last night, didn't she?!

[benrayrog]

Just curious, is this weather system starting fizzle out?

[Portastorm]

Just curious, is this weather system starting fizzle out?

FWIW, thoughts from a longtime winter weather enthusiast in Texas:

1) The GFS typically suggests an event in the longer term, loses it in the intermediate term, and then re-latches onto the idea in the short term (3-4 days). This seems especially true in winter. Last night's 0z run backed off some on the severity of the cold outbreak as well as timing. Case in point.

2) In actuality, there was only several model runs over the past few days which suggested a potentially historic cold outbreak. A number of folks got very excited about that prospect/potential and seemed to think it was a lock. There's a difference in confidence with the likelihood of a very strong Arctic front versus historically cold temps. The majority of the model runs over the last 72 hours have favored the former and not the latter.

3) Just like in hurricane season, many of us seem to live and die on each model run (i.e. wobble). The pro mets don't.

4) We probably won't know what we are really dealing with until tomorrow or Friday as the computer models get a better handle on the developing features. But the potential still exists as does the likelihood of some very cold air heading down into Texas.

[benrayrog]

Just curious, is this weather system starting fizzle out?

FWIW, thoughts from a longtime winter weather enthusiast in Texas:

1) The GFS typically suggests an event in the longer term, loses it in the intermediate term, and then re-latches onto the idea in the short term (3-4 days). This seems especially true in winter. Last night's 0z run backed off some on the severity of the cold outbreak as well as timing. Case in point.

2) In actuality, there was only several model runs over the past few days which suggested a potentially historic cold outbreak. A number of folks got very excited about that prospect/potential and seemed to think it was a lock. There's a difference in confidence with the likelihood of a very strong Arctic front versus historically cold temps. The majority of the model runs over the last 72 hours have favored the former and not the latter.

3) Just like in hurricane season, many of us seem to live and die on each model run (i.e. wobble). The pro mets don't.

4) We probably won't know what we are really dealing with until tomorrow or Friday as the computer models get a better handle on the developing features. But the potential still exists as does the likelihood of some very cold air heading down into Texas.

Thank you very much for your explanation. At the very least, may be time to tap the brakes with our anticipation.

[srainhoutx]

HPC seems to think it's just a blip with their Morning Update Headline...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
756 AM EST WED JAN 05 2011

VALID 12Z SUN JAN 09 2011 - 12Z WED JAN 12 2011

...A COLD PATTERN FOR THE NATION WITH STORM POTENITAL OVER THE US
SRN TIER AND UP THE EAST COAST...

STILL EXPECT MOST OF THE CONUS TO REMAIN UNDER BELOW NORMAL
HEIGHTS ALOFT FOR MOST OF THE MEDIUM RANGE PERIOD...CORRESPONDING
TO RIDGING/ABOVE NORMAL HEIGHTS AT HIGHER LATITUDE. GUIDANCE IS
SHOWING SOME SHIFTING IN EMPHASIS WITH THE HIGH LATITUDE
RIDGING...WITH A WEAKENING TREND OVER CANADA AND A STRENGTHENING
TREND OVER/NEAR ALASKA. THIS TRANSITION SHOULD EVENTUALLY LEAD TO
SOMEWHAT MORE PACIFIC FLOW REACHING THE WRN CONUS. LATEST AND
RECENT MODEL/ENSEMBLE GUIDANCE SHOWS GOOD AGREEMENT WITH THE LARGE
SCALE SCENARIO THRU THE PERIOD. HOWEVER THERE ARE PERSISTENT
DETAIL DIFFERENCES AND RUN TO RUN CONTINUITY CHANGES WITH THE
AMPLITUDE/TIMING OF DAY 3 SAT NWRN CONUS/SWRN CANADA ENERGY
AMPLIFYING INTO THE WEST/PLAINS SUN/MON...WHICH IN TURN AFFECT A
TROF/CLOSED LOW ENTERING THE SWRN CONUS/NWRN MEXICO UNDERNEATH
FRI/SAT LEADING INTO THE MEDIUM RANGE.

AFTER GUIDANCE GENERALLY TRENDED FASTER/MORE AMPLIFIED WITH
W-CENTRAL CONUS FLOW IN THE PRIOR 24 HOURS...SOLUTIONS NOW REFLECT
SOME MODERATION AWAY FROM THAT IDEA AND AS A RESULT THE LEADING
SRN STREAM SHORTWAVE IS MORE SUPPRESSED AS REFLECTED IN MOST
GUIDANCE FROM BEFORE YESTERDAY. THE 00Z GFS/CMC ARE THE LEAST
AMPLIFIED BY EARLY NEXT WEEK...BUT THE CMC HAS AN OUTLIER
EVOLUTION OVER THE ERN PAC WHICH ARGUES FOR DISCOUNTING ITS
SOLUTION. GIVEN THE DEVELOPMENT OF DAILY OSCILLATION IN
GUIDANCE...AN INTERMEDIATE SOLUTION COMPOSED OF THE 00Z ECMWF AND
12Z ECMWF ENSEMBLE MEAN APPEARS TO BE THE BEST OPTION THRU AT
LEAST THE WEEKEND. LATER IN THE PERIOD THE 00Z GEFS MEAN JOINED
THE ECMWF MEAN ALOFT AND IN SHOWING ORGANIZED WRN ATLANTIC SURFACE
CYCLOGENSIS CLOSER TO THE COAST THAN THE 00Z GFS/ECMWF. TYPICAL
DIFFICULTY THAT GUIDANCE HAS WITH IMPORTANT DETAILS BEYOND 2-3
DAYS WOULD RECOMMEND A COMPROMISE BETWEEN THESE TWO CLUSTERS AS A
STARTING POINT...BUT THE UPDATED HPC PROGS DID ADJUST THE LOW
SLIGHTLY BACK TOWARD THE COAST CONSIDERING TRENDS FROM THE 06Z
GFS/DGEX AND THE 06Z GEFS MEAN AS PER POTENTIAL MID-UPPER LEVEL
DYNAMIC SUPPORT ALOFT. HOWEVER...THE 06Z GEFS/YESTERDAYS 12Z
ECMWF ENSEMBLE MEANS THAT WERE USED WITH THE 00Z ECMWF TO DERIVE
THE HPC BLENDED SOLUTION FOLLOW THIS TREND BETTER THAN THE 00Z
GEFS/ECMWF ENSEMBLE MEANS...LEAVING LINGERING UNCERTAINTY FOR WHAT
COULD BE A ANOTHER SIGNIFICANT WINTER COASTAL STORM.

AS FOR OTHER FEATURES...THERE IS GRADUAL IMPROVEMENT IN AGREEMENT
WITH EVOLUTION OVER THE NE CONUS INTO THE ATLANTIC DURING THE
WEEKEND. THE 00Z GFS IS A LITTLE STRONGER/SHARPER THAN CONSENSUS
WITH ITS SURFACE TROF OVER THE NORTHEAST AS OF EARLY DAY 3 SAT.
THE INITIAL 00Z ECMWF/12Z ECMWF MEAN BLEND ACCOUNTS WELL FOR THE
NON-00Z GFS PREFERENCE HERE. MEANWHILE ALONG THE WEST COAST THE
CANADIAN IS AN OUTLIER WITH ITS DEEP SYSTEM NEARING THE PAC NW
COAST BY EARLY DAY 7 WED. ASIDE FROM TYPICAL TIMING DIFFERENCES
THERE IS DECENT AGREEMENT IN PRINCIPLE ON A MERE WARM FRONT
NEARING THE WEST COAST LATE IN THE FCST. A COMPROMISE AMONG THE
ENSEMBLE MEANS AND SLOWER ECMWF PROVIDES TIMING NEAR THE MIDDLE OF
THE FULL ENVELOPE OF MODEL AND ENSEMBLE SOLUTIONS.

RAUSCH/SCHICHTEL

[wxman57]

I'd add to Portastorm's post above the fact that there is currently no significant cold air or big high pressure center in northern Canada or eastern Alaska. Models are predicting the high pressure to build there as cold air moves across the Polar region over the next 2-3 days. Let's see if that actually happens first. If it does, then we'll have a better idea what we might expect across the U.S.

Keep your eyes on the source region for this outbreak for clues.

[Snowluvr]

Since it may not get as cold as we had previously thought, would that increase the potential for a winter storm over east Texas and the Southeast since the air won't be as dry? I'm hoping that's the case.

[TeamPlayersBlue]

I'd add to Portastorm's post above the fact that there is currently no significant cold air or big high pressure center in northern Canada or eastern Alaska. Models are predicting the high pressure to build there as cold air moves across the Polar region over the next 2-3 days. Let's see if that actually happens first. If it does, then we'll have a better idea what we might expect across the U.S.

Keep your eyes on the source region for this outbreak for clues.

When you say check the source region, do you mean check the temps there? The 500MB flow? Explain a bit Frank said in Siberia it was -79 yesterday. Sucks to be the guy at that station!

[WacoWx]

All I want to do is wake up and see 10 pages added to this thread and its just not happening...yet. I'm still holding out for that second super intense blast from Siberia to come down late next week so all hell can break loose precipitation-wise.

[TeamPlayersBlue]

I keep seeing moisture rolling into the picture for friday - sunday for us Houston folk. That means we will need another reinforcing shot of cold air to come down for it to be any kind of event. I think this is the time frame pro mets were talking about when they said we may expect ice here in SE Tx. I think if a large high comes down originally like we expect, then a second will come down behind it that will be just as bad if not a bit colder. Maybe our friendly daytime models will help us out

Again, im no Pro met, just a weather nut.

[txagwxman]

Model Consensus Day 5

Model Consensus Day 7...

Clearly not as deep as previously advertised...

[wxman57]

When you say check the source region, do you mean check the temps there? The 500MB flow? Explain a bit Frank said in Siberia it was -79 yesterday. Sucks to be the guy at that station!

I mean watch NW Canada. We KNOW it's cold in Siberia. The question is whether the cold air will actually build in NW Canada. Has to do that before it moves south into the U.S. Here's a current surface plot of the region:

[northtxboy]

I know some of you are wanting to put the brakes on what is going to happen next week,,but,,I think we are in for it here in North Texas. I think we are going to be super cold highs in the 20s and teens and lows in the single digits. As far as snow/ice goes I think we will see some mix sunday night and snow monday, I think this cold air will come down just alittle bit early than what most mets are saying. If you live near the red river like I do you really need to keep an eye on this cause I think its going to get nasty.

[TeamPlayersBlue]

When you say check the source region, do you mean check the temps there? The 500MB flow? Explain a bit Frank said in Siberia it was -79 yesterday. Sucks to be the guy at that station!

I mean watch NW Canada. We KNOW it's cold in Siberia. The question is whether the cold air will actually build in NW Canada. Has to do that before it moves south into the U.S. Here's a current surface plot of the region:

i see, we expect the HP to begin building in around Saturday correct? I did some reading on the Mac Farland theory last night to brush up on the ingredients for EXTREME polar air

[txagwxman]

Expect mid 20s for IAH next week, that is it. The true Siberian air will be moving into Canada day 10.

[WacoWx]

^^^So youre tellin me theres a chance.