Texas Winter 2011-2012...

[Texas Snowman]

BTW, somebody may have posted on an earlier page, but if not, here's an interesting post by Cory Mottice on how the AO, NAO, and PNA affect winter weather patterns across North America.


http://www.corymottice.com/2011/12/26/h ... -patterns/

[Portastorm]

BTW, somebody may have posted on an earlier page, but if not, here's an interesting post by Cory Mottice on how the AO, NAO, and PNA affect winter weather patterns across North America.


http://www.corymottice.com/2011/12/26/h ... -patterns/

This is a very good educational piece and I highly encourage folks here to read it! Nice link, Texas Snowman ... thanks!

Meanwhile, it looks like NWSFO Austin/San Antonio is on board with the 12z Euro and Canadian:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE AUSTIN/SAN ANTONIO TX
257 PM CST TUE DEC 27 2011

.DISCUSSION...
A DRY NWLY FLOW TO PREVAIL THE REMAINDER OF THE WEEK WITH A
GRADUAL WARMING TREND. A SHORT WAVE WILL DIVE SEWD ACROSS TX
WEDNESDAY...HOWEVER MAIN EFFECTS WILL BE A FEW MID LEVEL CLOUDS
ACROSS S TX AND A WEAK SURFACE TROUGH THAT WILL SHIFT WINDS TO SW-
WLY MAINLY ACROSS THE WESTERN HALF OF THE CWA. THE MID LEVEL FLOW
BECOMES WESTERLY BY THE WEEKEND WITH S-SWLY LOW LEVEL FLOW
PREVAILING WHICH WILL ALLOW FOR RETURN OF SHALLOW MOISTURE BY
SATURDAY MORNING...AND DEEPER MOISTURE SATURDAY NIGHT INTO SUNDAY
MORNING. WILL CONTINUE SLIGHT CHANCE SHOWERS FOR SUNDAY MORNING
INTO SUNDAY EVENING MAINLY FOR THE S CENTRAL AND SERN COUNTIES
AHEAD OF THE NEXT COLD FRONT. TIMING OF THE COLD FRONT LATE NEXT
WEEKEND VARIES FROM THE GFS EARLY SUNDAY MORNING TO LATE SUNDAY
AFTERNOON/EVENING FOR THE ECMWF & CMC. PREFER THE SLOWER BUT MUCH
COLDER ECWMF/CMC SOLUTIONS. HAVE USED THE COLD ECWMF TEMPERATURES
WITH SOME SLIGHT ADJUSTMENT UPWARD AS DONT WANT TO BE ALL IN JUST
YET. APPEARS A COLD START TO THE NEW YEAR YEAR EARLY NEXT WEEK.
WITH THE DEEP TROF DEVELOP TO OUR EAST...SHOULD ALSO BE DRY SO NO
WINTER PRECIPITATION CONCERNS AT THIS POINT.

[Rgv20]

NWS in Brownsville not ready to jump in on the ECMWF solution for now....

FROM NEW YEAR`S AND BEYOND THE FORECAST GETS TRICKY. DESPITE
GFS/ECMWF COMING DIFFERENCE...THE SENSIBLE WEATHER LOOKS ABOUT THE
SAME. THIS MEANS THICKENING CLOUDS AND AN INCREASING CHANCE FOR
SHOWERS ACROSS THE REGION...THOUGH HAVE UNDERCUT THE LONG RANGE
GFS GUIDANCE BY 20 PERCENT GIVEN UNCERTAINTY AND LACK OF SOLID
FORCING FROM THE WEAK WAVE OVERTOPPING THE RIDGE POKING NORTH FROM
MEXICO. WITH WINDS VEERING TO EAST/NORTHEAST HAVE A SMALLER
DIURNAL RANGE DESPITE THE MILD START...WITH TEMPERATURES ONLY
MOVING A FEW DEGREES FROM MORNING LOWS BACK INTO THE UPPER 60S
RANCHES TO LOWER 70S VALLEY.

BEYOND NEW YEAR`S DAY THE FORECAST IS SUBJECT TO CHANGE. THE GFS
AND ITS ENSEMBLES REMAIN CONSISTENT ON A RELATIVELY FLAT MID/UPPER
FLOW ACROSS THE LOWER 48 WITH GENERAL RIDGING ACROSS TEXAS AND
NORTHERN MEXICO AND DEEPENING BUT INITIALLY PROGRESSIVE CYCLONE
SETTING UP SHOP BY NEXT TUESDAY ACROSS THE CANADIAN MARITIMES. THE
ECMWF AND ITS ENSEMBLES ON THE OTHER HAND DIVE THE ENERGY STRAIGHT
FROM THE CANADIAN PRAIRIES INTO THE SOUTHEAST U.S. BY LATE
TUESDAY...ULTIMATELY CUTTING OFF A PRODIGIOUS EASTERN SEABOARD
CYCLONE AND PUNCHING VERY DRY...WINDY...AND CHILLY AIR DEEP INTO
NORTHERN MEXICO BEGINNING NEXT TUESDAY. LOW LEVEL DIFFERENCES
BETWEEN THE MODELS ARE PRETTY STARK. 850 MB TEMPERATURES ON THE
GFS ARE ABOVE +10C NEXT TUESDAY IN DEEP SOUTH TEXAS WHILE FALLING
BELOW -5C ON THE ECMWF!

SO...WHICH MODEL TO CHOOSE? `GUT` TELLS ME THAT THE ECMWF MAY BE
OVERPLAYING THIS SYSTEM. WOULD PREFER TO SEE A NEUTRAL TO
NEGATIVE PHASE ARCTIC/NORTH ATLANTIC OSCILLATION WHICH WOULD TEND
TO FAVOR A STRONGER AND FARTHER SOUTH EASTERN CYCLONE. IN 2009 (EL
NINO PLUS NEGATIVE AO/NAO) AND 2010 (LA NINA PLUS NEGATIVE AO/NAO)
THERE WERE LATE DECEMBER SNOW EVENTS ON THE ATLANTIC COAST. BUT
WITH ENSEMBLE FORECASTS AND CURRENT CONDITIONS OF THE AO/NAO STILL
ON THE POSITIVE SIDE INTO THE WEEKEND...THE PROGRESSIVE PATTERN IS
MORE LOGICAL. WILL BE INTERESTING TO SEE HOW THINGS ULTIMATELY
INTERACT...BUT FOR NOW PREFER TO PLAY IT CLOSE TO THE VEST AND
HOLD UP THE SHARP TRANSITION UNTIL MODELS SHOW BETTER CONSENSUS.

THIS MEANS A LEAN TOWARD THE GFS WITH A SLIGHTLY COOLER MONDAY
WITH STILL SOME RAIN CHANCES BEFORE PRECIPITATION ENDS MONDAY
NIGHT OR EARLY TUESDAY. HAVE KEPT TEMPERATURES ONLY A SHADE BELOW
SEASONAL AVERAGES...WHICH ARE HIGHS AROUND 70 AND LOWS IN THE
UPPER 40S TO LOWER 50S...FOR NOW.

[Rgv20]

Looks like the NWS in Corpus is leaning toward the ECMWF/CMC solution..

FORECAST ISSUE IN THE LONG TERM IS THE TIMING OF THE NEXT COLD
FRONT. THERE IS CONSIDERABLE SPREAD AMONG MODELS WITH AMPLITUDE OF
TROUGH DIGGING INTO THE CENTRAL CONUS SATURDAY THROUGH MONDAY.
DETERMINISTIC GFS SOLUTIONS HAVE BEEN THE MOST PROGRESSIVE FROM RUN
TO RUN WITH THE LEAST AMPLITUDE RESULTING IN A WEAKER FRONT ON NEW
YEARS DAY...WHILE THE ECMWF HAS BEEN MUCH MORE BULLISH IN SHOWING A
SLOWER AND MUCH DEEP TROUGH...THUS A STRONGER COLD FRONT THROUGH THE
AREA SUNDAY NIGHT INTO MONDAY. THE CANADIAN HAS TRENDED TOWARDS THE
LATTER AS WELL. THE KEY SEEMS TO BE HOW MUCH AMPLIFICATION OF AN
EASTERN PACIFIC TROUGH ALONG 140W OCCURS AROUND DAY 5...WITH
SUBSEQUENT AMPLIFICATION DOWNSTREAM OVER THE CONUS. THERE IS STRONG
ECMWF ENSEMBLE SUPPORT FOR A DEEPER...BUT LESS DRASTIC THAN
DETERMINISTIC ECMWF...FULL LATITUDE TROUGH TRANSLATING ACROSS THE
CENTRAL AND EASTERN CONUS. HAVE TRENDED TOWARDS A STRONGER FRONTAL
PASSAGE SUNDAY NIGHT THAN THE GFS BUT NOT QUITE AS STRONG AS THE 12Z
ECMWF. SHOULD BE STRESSED THE FORECAST CONFIDENCE IS LOW FOR SUNDAY
THROUGH TUESDAY ON TEMPS AND TIMING OF FRONTAL PASSAGE. REGARDLESS
OF FRONTAL STRENGTH AND TIMING...THERE SHOULD BE SUFFICIENT MOISTURE
BY SUNDAY OR SUNDAY NIGHT FOR ISOLATED TO SCATTERED SHOWERS ALONG
THE FRONT.

[Texas Snowman]

KXII-TV met Steve LaNore (Denison/Sherman) is buying into the European lock-stock-and-barrell, or so it sounds.

Here's a snippet from his Tuesday afternoon weather blog: "The next big potential weather change takes place this weekend. A shot of arctic air is indicated to move southward as a trough digs down from Alaska and deepens Sat-Sun. Some of the models show this and some do not, but the European version tends to be the most reliable for these very cold systems. It has been consistent in showing a “big” chill” moving in this weekend probably on New Year’s Day. As for snow or ice, it’s too early to say, but anything would probably be very light as stiff northerly winds drive the low-level moisture well out ahead of the coldest air."

FYI, he's forecasting a high of 40 on Monday and a high of 38 on Tuesday.

http://www.kxii.com/weather

[Ntxw]

18z GFS has the scenario but instead of early week it delays the same thing for late week.

[iorange55]

Man that looks violent




And we thought it was going to be boring for a few weeks...pfft.

[Rgv20]

It's going to be an interesting war in the model world as the 12zGFS and CMC Ensembles (First two pics below) are fairly similar with the 500mb pattern by next Tuesday morning. They are forecasting a more progressive and weaker trough for the early part of next week. In contrast the 12zECMWF Ensembles (Third pic below) are slower and stronger with the trough in the eastern part of the country resulting in a colder forecast for us in Texas.


12zGFS Ensembles



12zCMC Ensembles



12zECMWF Ensembles

[vbhoutex]

I know it is TOTAL LALA LAND, but take a look at the GFS run on the Twisterdata model site and pick the snow depth for the 300+ hour range. http://www.twisterdata.com/index.php?prog=forecast&model=GFS&grid=3&model_yyyy=2011&model_mm=12&model_dd=27&model_init_hh=18&fhour=00&parameter=SNOWIN&level=SURFACE&unit=none&maximize=n&mode=singlemap&sounding=n&output=image&view=large&archive=false Make that the 264hr+ range.

[Ntxw]

So 12z was the flip switch. 0z will be telling regarding trends, if we can get the GFS to even come close, I'd be happy to say next week will be cold . The european op and ensembles have been very aggressive with the +PNA compared to the GFS. I guess this explains the difference between a brief cold shot and an outbreak.

http://raleighwx.americanwx.com/models/teleconnections.html

[Ntxw]

Well, 0z GFS isn't the euro but it's not zonal anymore. Just places the ridge/troughs a bit different (more east). Small differences out in the Pacific can mean big changes down the line.

[Turtle]

Hey, look at this! Shreveport Discussion:

CONTINUED TO FOLLOW PREVIOUS FCST PACKAGES IN THE EXTENDED PERIODS
BY TRENDING CLOSER TO THE EURO SOLUTION..BUT DID NOT FEEL
COMFORTABLE BUYING INTO A MAJOR COLD AIR SCENARIO BASED ON ONLY
ONE MODEL RUN.

[cycloneye]

The Houston/Galveston folks go with ECMWF/CMC scenario in their early morning discussion.

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HOUSTON/GALVESTON TX
328 AM CST WED DEC 28 2011


IN THE EXTENDED...MODEL GUIDANCE CONTINUES TO BE SOMEWHAT SPLIT
WITH THE TIMING AND STRENGTH OF OUR NEXT COLD FRONT. THE ECMWF
CONTINUES TO ADVERTISE A VERY AMPLIFIED UPPER LEVEL PATTERN WITH A
LARGE TROUGH ACROSS THE EASTERN UNITED STATES BY EARLY NEXT
WEEK...ALTHOUGH IT NOW DEEPENS THIS TROUGH FURTHER EAST THAN
PREVIOUS RUNS. THE CANADIAN MODEL IS VERY SIMILAR TO THIS SOLUTION
WHILE THE GFS REMAINS WEAKER AND MORE PROGRESSIVE WITH THIS
SYSTEM ALTHOUGH NOT AS MUCH AS PREVIOUS RUNS. HAVE DECIDED TO
TREND THE FORECAST CLOSER TO THE ECMWF/CANADIAN SOLUTION AND BRING
THE COLD FRONT THROUGH SOUTHEAST TEXAS ON SUNDAY AFTERNOON. WILL
KEEP SLIGHT CHANCE POPS IN THE FORECAST FOR SATURDAY AND SUNDAY
AHEAD OF THE FRONT. COLDER AIR MOVES IN BEHIND THE FRONT WITH
TEMPERATURES FOR THE FIRST WEEK OF 2012 LOOKING TO BE ABOUT 5
DEGREES BELOW NORMAL ACROSS THE REGION. 38

[wxman57]

Sunday's cold front is coming into better focus now. The 00Z Euro has made a major shift toward less cold air. Yesterday's 12Z Euro had 850mb temps down to -13C along the upper TX coast next Tue/Wed. Last night's run bumped those 850mb temps up to +1C to +2C along the upper TX coast, which is MUCH more reasonable given the Euro's 12Z Tuesday prediction of only a light freeze in that region next Tue-Thu. Given that the source region of the cold air is in southwestern Canada where temps are currently 20-30F above normal, the 00Z Euro is much more believable. Most likely a few light freezes along the upper TX coast next week.

As the Euro trends warmer, the GFS is trending colder for Sunday's front, and it's also backed off on the "12Z oozer" in favor of a stronger front arriving later on Sunday (18Z). Not as late as the Euro (21Z Sun)/Canadian (06Z Mon), but later than yesterday's runs. It forecasts lows in SE TX down to the upper 30s next week. That's probably still too warm, as I think we have a good shot of a Gulf Coast freeze out of this. Nothing colder than we've already seen, just typical January cold.

So it looks like a moderately strong cold front moving through Texas on Sunday, reaching the coast Sunday late afternoon/evening. No bitter cold, as the source region is not that cold. No post-frontal precip, just gusty northerly winds in its wake.

In addition, the Euro has completely backed off on its prediction (from 12Z yesterday) of a major East Coast storm next week in favor of a more progressive upper trof and no storm. This is in line with the Canadian and GFS.

[Texas Snowman]

Joe B thinks that the MJO is heading in the right direction. Here's a tweet of his from last night:

(@BigJoeBastardi) "Another MJO driven winter.. have been in blow torch phases 4,5 but heading into igloo, perhaps even to colder 8,1,2"

[Texas Snowman]

Norman NWS seems to be leaning toward Euro solution, or at least hinting in that direction:

THEN WE REACH THE CHALLENGING PART OF THE FORECAST. MODELS AGREE
THAT THE FLOW WILL AMPLIFY AND DRIVE A MORE SUBSTANTIAL COLD FRONT
THROUGH OUR REGION SATURDAY NIGHT AND SUNDAY. EXACT TIMING IS
STILL UNCERTAIN...AND ANY NEW YEARS EVE FIREWORKS DISPLAYS IN
NORTHWEST OKLAHOMA MAY HAVE TO CONTEND WITH AN INCREASE OF BREEZY
NORTHWEST WINDS. THERE IS ALSO UNCERTAINTY AS TO HOW COLD THE POST
FRONTAL AIR WILL BE. WHILE THE SUDDEN DEVELOPMENT OF A 1050 MB
HIGH WITHIN A PACIFIC AIR MASS MOVING OVER THE ROCKIES...VIA THE
ECMWF MODEL...DOES NOT EXACTLY FIT WITH EXPERIENCE...THERE ARE
SOME FACTORS FAVORING THAT MODEL. THE ECMWF HAS BEEN CONSISTENT
FOR 3 RUNS...THE SURFACE PRESSURES RISE MOST MARKEDLY OVERNIGHT...
AND THE GFS MODEL HAS TRENDED A LITTLE BIT IN THAT DIRECTION. THE
GFS IS TRENDING COLDER...AND A COUPLE OF ITS ENSEMBLE MEMBERS...
PERTURBATIONS 3 AND 5...ARE EQUALLY COLD AS THE ECMWF. IN
COLLABORATION WITH SURROUNDING OFFICES WE COOLED OFF THE FORECAST
QUITE A BIT FOR SUNDAY THROUGH TUESDAY. THE FORECAST COULD STILL
GO COLDER...WITH HIGHS PERHAPS NEAR THE FREEZING MARK ON
MONDAY...IF THE ECMWF SOLUTION WINS OUT.

AT LEAST WE DO NOT HAVE THE COMPLICATING FACTOR OF PRECIPITATION.
THERE IS VERY LITTLE CHANCE OF ANYTHING MEASURABLE...ALTHOUGH THE
STRONG HEIGHT FALLS AND MID LEVEL FRONT IN THE ECMWF SUGGEST THAT
SNOW FLURRIES WOULD BE POSSIBLE BY SUNDAY MORNING IN NORTHERN
OKLAHOMA.

BEYOND MONDAY UNCERTAINTY INCREASES FURTHER...BUT THERE ARE FEW
SCENARIOS THAT WOULD BRING ANY PRECIPITATION EVENTS IN THE NEXT 7
DAYS.

[Texas Snowman]

And Fort Worth's take:

OUR NEXT SIGNIFICANT FRONT WILL ARRIVE ON SUNDAY WITH AN UPPER
LEVEL TROUGH DIGGING SOUTH THROUGH THE PLAINS AT THE SAME TIME.
HOWEVER...THE MODELS TONIGHT ARE NOT AS FAR SOUTH WITH THE TRACK
OF THE UPPER LEVEL TROUGH...KEEPING THE BASE OF THE TROUGH JUST
NORTHEAST OF THE REGION. THE GFS CONTINUES TO BE THE OUTLIER
KEEPING THE TROUGH WELL NORTH AND NORTHEAST OF THE REGION AND
HAVE CONTINUED TO BLEND THE CANADIAN AND ECMWF MODELS FOR SUNDAY
THROUGH TUESDAY. EVEN WITH THE BASE OF THE TROUGH BARELY GRAZING
OUR NORTHEASTERN COUNTIES...THE MODELS CONTINUE TO SHOW COLD DRY
CANADIAN AIR REACHING NORTH TEXAS WITH THE COLDEST AIR REMAINING
NORTH OF INTERSTATE 20. FOR THIS PACKAGE...HAVE STUCK FAIRLY CLOSE
TO THE ECMWF AND CANADIAN MODEL TEMPERATURES WHICH ARE WARMER THAN
THE PREVIOUS FORECAST PACKAGE DUE TO THE MORE NORTHERN TRACK OF
THE UPPER LEVEL SYSTEM. HOWEVER...THE BEGINNING OF NEXT WEEK STILL
LOOKS PRETTY CHILLY WITH HIGHS IN THE 40S AND LOWS IN THE 20S AND
30S. IT IS INTERESTING TO NOTE THAT BOTH THE CANADIAN AND GFS
ENSEMBLE MEMBERS SHOW A WIDE SPREAD OF SOLUTIONS WITH THIS SYSTEM
BUT NEITHER ENSEMBLE GROUP HAS STRONG SUPPORT FOR ITS LATEST
OPERATIONAL RUN. THIS SYSTEM WILL BE CLOSELY MONITORED WITH EACH
UPCOMING MODEL RUN.

[Portastorm]

Sunday's cold front is coming into better focus now. The 00Z Euro has made a major shift toward less cold air. Yesterday's 12Z Euro had 850mb temps down to -13C along the upper TX coast next Tue/Wed. Last night's run bumped those 850mb temps up to +1C to +2C along the upper TX coast, which is MUCH more reasonable given the Euro's 12Z Tuesday prediction of only a light freeze in that region next Tue-Thu. Given that the source region of the cold air is in southwestern Canada where temps are currently 20-30F above normal, the 00Z Euro is much more believable. Most likely a few light freezes along the upper TX coast next week.

As the Euro trends warmer, the GFS is trending colder for Sunday's front, and it's also backed off on the "12Z oozer" in favor of a stronger front arriving later on Sunday (18Z). Not as late as the Euro (21Z Sun)/Canadian (06Z Mon), but later than yesterday's runs. It forecasts lows in SE TX down to the upper 30s next week. That's probably still too warm, as I think we have a good shot of a Gulf Coast freeze out of this. Nothing colder than we've already seen, just typical January cold.

So it looks like a moderately strong cold front moving through Texas on Sunday, reaching the coast Sunday late afternoon/evening. No bitter cold, as the source region is not that cold. No post-frontal precip, just gusty northerly winds in its wake.

In addition, the Euro has completely backed off on its prediction (from 12Z yesterday) of a major East Coast storm next week in favor of a more progressive upper trof and no storm. This is in line with the Canadian and GFS.

Well written summary, sir. I would concur. Seems like the medium-range op runs are converging on a similar solution.

I thought one of the Texas NWSFO discussions from yesterday -- think it was Brownsville actually -- hit the nail on the head when they basically said "not sure about an Arctic outbreak since the AO and NAO have been and continue to be positive." Your point wxman57 about source regions (something you try to drill into our thick skulls every winter! ) is also something of which we should pay attention.

[Ntxw]

Wxman has been great as usual sticking to his guns! Quite a set of ammo there!

Speaking of Arctic outbreaks and Brownsville, this is not going to happen, but I wanted to ask a pro if we were to draw up a cross polar flow/mcfarland signature is what the lalaland GFS showing what it would look like? Or is it just extreme Alaskan blocking?



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[wxman57]

Wxman has been great as usual sticking to his guns! Quite a set of ammo there!

Speaking of Arctic outbreaks and Brownsville, this is not going to happen, but I wanted to ask a pro if we were to draw up a cross polar flow/mcfarland signature is what the lalaland GFS showing what it would look like? Or is it just extreme Alaskan blocking?

[http://img43.imageshack.us/img43/9245/gfsh.gif

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http://img818.imageshack.us/img818/4083/gfs2.gif

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Doesn't look like a great setup for cross-Polar flow on the 384hr GFS. Note that there is some flow across the Pole but it's shunted west into the Gulf of Alaska. Of course, the GFS probably doesn't have a great handle on the weather 3-4 days from now much less 15-16 days out.