February 1-5, 2011 Arctic Blast/Winter Storm Discussion

[srainhoutx]

I'm a bit busy, but if someone has the time there are some interesting and informative discussions coming out from Corpus and DFW and other NWS offices as well that might be worth the read.

[Andrew]

I'm a bit busy, but if someone has the time there are some interesting and informative discussions coming out from Corpus and DFW and other NWS offices as well that might be worth the read.

Corpus:

.LONG TERM (SUNDAY THROUGH FRIDAY)...APPEARS THAT THE RAIN SHOWERS
AND/OR THUNDER SHOULD BE TAPERING OFF BY SUNDAY MORNING...UNLESS
MODELS PROVE TO BE TOO FAST. JUST HAVE SOME LOW CHANCE/SLIGHT CHANCE
POPS OVER THE EASTERN AREAS SUNDAY MORNING...THEN DRIER AIR PUSHES
IN. IF THINGS GO AS PLANNED...MOST OF SUNDAY SHOULD SHAPE UP TO BE A
NICE DAY DURING THE AFTERNOON...WITH WARM AFTERNOON TEMPERATURES AND
CLEARING SKIES. RETURN OF LIGHT SOUTHEAST WINDS OVERNIGHT AND
MOISTURE ADVECTION SHOULD RESULT IN FOG FORMATION BY MONDAY
MORNING...INCLUDING THE SEA FOG. MOISTURE ADVECTION IS PRETTY GOOD
AS THE NEXT UPPER TROUGH APPROACHES...SO DO EXPECT SOME CONVECTION
MONDAY NIGHT AND TUESDAY MORNING (KEPT THE SLIGHT CHANCE FOR SHOWERS
MONDAY) GIVEN AFOREMENTIONED ADVECTION...ALTHOUGH RAINFALL SHOULD BE
LIGHT IF RECEIVED. BEST SHOT OF RAIN (AS USUAL) WILL BE NORTHEAST AS
AREA BECOMES DRY-SLOTTED BY TUESDAY AFTERNOON. TUESDAY AFTERNOON
LOOKS TO BE THE LAST OF THE WARM WEATHER FOR A WHILE (I.E. GENERALLY
ABOVE NORMAL TEMPERATURES SUNDAY - TUESDAY)...THEN ARCTIC BLAST
COMES DOWN TUESDAY NIGHT. DO NOT THINK MUCH OF THE RAIN CHANCE WITH
THE ARCTIC FRONT AS MOISTURE GETS PRETTY SCOURED OUT AND PUSHED
SOUTH WITH THE WESTERLY WINDS IN THE BOUNDARY LAYER AND MID LEVELS.
MODELS PRETTY MUCH AGREE (AS MUCH AS MODELS CAN) WITH A FROPA IN
KCRP AROUND MIDNIGHT...GIVE OR TAKE A COUPLE OF HOURS. AFTER
FROPA... TEMPERATURES WILL REMAIN WELL BELOW NORMAL FOR THE NEXT FEW
DAYS. GFS HAS BACKED OFF ON ITS COLDER SCENARIO WHILE ECMWF AND
CANADIAN KEEPING IT COLD (GFS FETCH IN THE MID LEVELS PUSHING
COLDEST AIR FARTHER NORTHEAST THAN BEFORE). FOR NOW...WILL RELY MORE
ON THE ECMWF/CANADIAN SOLUTION AND KEEP SIMILAR TEMPERATURES AS
FORECAST. GFS IS ALSO WETTER THAN ECMWF (CANADIAN HINTS AT WETTER
TOO) AND FOR NOW WILL CONTINUE MORE WITH THE DRIER AND COLDER ECMWF
AND SEE WHAT TRANSPIRES (KEEP PREVIOUS FORECAST CONSISTENCY AND ISC
SIMILARITIES). HOWEVER...IF GFS IS RIGHT ON THE MOISTURE AND ECMWF
IS RIGHT ON THE TEMPERATURES...COULD NOT RULE OUT SOME WINTRY PRECIP
(ALBEIT LIGHT) THURSDAY OR FRIDAY MAINLY WESTERN AREAS. TOO MUCH
UNCERTAINTY TO GO WITH THIS SOLUTION BLEND AT THIS TIME.

DFW:

OVERALL THERE IS BETTER AGREEMENT AMONG THE 12Z MEDIUM RANGE
MODELS THAN WE HAVE SEEN IN SEVERAL DAYS. HOWEVER THERE HAS BEEN
A PRETTY DRAMATIC SHIFT FROM PREVIOUS RUNS IN HOW THE MODELS ARE
HANDLING THE PRIMARY UPPER LEVEL FEATURES. OF NOTE...THEY HAVE ALL
INITIALIZED THE SHORTWAVE TROUGH OVER NORTHERN BRITISH COLUMBIA
MUCH STRONGER THAN BEFORE. THE MODELS NOW SIMULATE AN INTERACTION
WITH THIS SHORTWAVE AND AN UPPER LOW NOW ABOUT 1000 MILES OFF THE
OREGON COAST. IN ESSENCE...THE TWO SYSTEMS WILL ROTATE/DUMBBELL
AROUND EACH OTHER OVER THE WESTERN US. THE BC SHORTWAVE SHOULD
CONTINUE TO INTENSIFY THIS WEEKEND AND IS EXPECTED TO BECOME THE
DOMINANT SYSTEM. THIS SHOULD CAUSE THE PACIFIC UPPER LOW TO SWING
THROUGH OUR REGION FAIRLY QUICKLY...LIKELY EARLY TUESDAY...WITH
WIDESPREAD RAIN ACROSS THE AREA. YESTERDAY THE GFS/ECMWF MODELS
WERE FORECASTING A MUCH SLOWER PASSAGE AND INDICATING A THREAT
FOR WINTRY WEATHER OVER THE AREA. WITH THE FASTER MOVEMENT THERE
WILL BE LESS OPPORTUNITY FOR PRECIPITATION INTO SUB-FREEZING AIR.

THE MODELS ARE ALL FORECASTING THE ARCTIC AIR MASS TO WAIT UNTIL
THE PASSAGE OF THE UPPER TROUGH BEFORE ENTERING THE
REGION...SOMETIME DURING THE DAY ON TUESDAY. IN FACT...NO MODEL
TODAY SUGGESTS MUCH CHANCE FOR ANY WINTRY PRECIPITATION AS THE
RAIN ENDS BEFORE SUB FREEZING AIR ARRIVES. HOWEVER THERE REMAINS A
PROVERBIAL FLY IN THE OINTMENT. OUR SUNDAY FRONT IS FORECAST TO
HANG AROUND THE REGION INTO MONDAY NIGHT BY ONLY THE NAM...WITH
ALL OF THE OTHER MODELS INDICATING EROSION OF THIS SHALLOW LAYER
OF COLD AIR. THE NAM ONLY GOES OUT 84 HOURS...AND IT IS SHOWING
SUB FREEZING TEMPERATURES IN SOUTHERN OKLAHOMA AT MIDNIGHT MONDAY.
THIS FRONTAL POSITION GIVES THE LEADING EDGE OF THE SUB FREEZING
AIR A BIG HEAD START OVER THE OTHER MODELS...AND CONFIRMS A
POSSIBILITY THAT THE ARCTIC AIR WILL BLEED INTO THE NORTHERN ZONES
BEFORE THE PRECIPITATION ENDS. THE NAM IS USUALLY SUPERIOR WITH
ITS HANDLING OF SHALLOW COLD AIR...AND THUS WE WILL BE LOOKING
FORWARD TO GETTING WITHIN ITS FORECAST TIME RANGE FOR THE TUESDAY
EVENT. GIVEN THE NAM/S HINT AT THIS POSSIBILITY AS WELL AS THE
USUAL CAVEAT THAT SHALLOW ARCTIC AIR ARRIVES A LITTLE FASTER THAN
THE MEDIUM RANGE GUIDANCE FORECASTS...WE WILL RETAIN A MENTION OF
FREEZING RAIN IN THE FORECAST NORTH OF A COMANCHE- WAXAHACHIE-
SULPHUR SPRINGS LINE TUESDAY. ARCTIC AIR MAY BE TOO SHALLOW FOR
SLEET ACROSS NORTH TEXAS...BUT DID KEEP THIS POSSIBILITY MENTIONED
ACROSS THE FAR NW. ALL PRECIP SHOULD CLEAR OUT TUESDAY AFTERNOON.

THE BIG STORY WILL BE THE COLD TEMPERATURES BEHIND THIS FRONT.
THE UPPER LEVEL PATTERN WILL BECOME AMPLIFIED INTO A SEMI-REX
BLOCK CONFIGURATION ACROSS THE WESTERN PART OF NORTH AMERICA NEXT
WEEK. PRESSURE RISES OCCURRING NORTH OF MONTANA SHOULD YIELD A
1050+ MB HIGH WHICH BUILDS SOUTH EARLY-MID WEEK AND BECOMES
CENTERED ACROSS THE TX PANHANDLE WED-THU. GFS/ECMWF/CANADIAN
FORECASTS ALL INDICATE UNUSUALLY COLD AIR AT 850 MB WITH TEMPS
ACROSS THE PLAINS RANGING FROM -15C TO -24C. THE 500 MB PATTERN
WILL REMAIN IN A FAVORABLE POSITIVE TILTED TROUGH PHASE FOR
LIMITED MODIFICATION OF THIS AIR MASS NEXT WEEK. EXPECT TEMPS TO
PLUMMET DURING THE DAY TUESDAY INTO THE TEENS AND 20S BY WEDNESDAY
MORNING. HIGHS WEDNESDAY MAY STRUGGLE TO REACH THE LOW 30S. BRISK
NORTH WINDS SHOULD CONTINUE FOR A COUPLE DAYS...WITH WIND CHILLS
IN THE SINGLE DIGITS AT TIMES. WILL TEMPER THE MODIFICATION OF
TEMPS INTO NEXT WEEKEND...GOING WELL BELOW MEX MOS...WITH THE GFS
SEEMINGLY OUT TO LUNCH WITH THE AMOUNT OF AIR MASS MODERATION IT
IS FORECASTING. ALTHOUGH COLD...MODELS SHOW LIMITED MOISTURE FOR
PRECIPITATION BUT THIS WILL NEED TO BE WATCHED AS AN UPPER LEVEL
TROUGH REMAINS TO OUR WEST.

[Andrew]

GFS 108 & 126 & 144 & 174(coming in colder):

GFS keeps the cold air with us MUCH MUCH longer and is colder.

[cristina99]

can someone please tell me what the colors mean? I think I know what they mean, but I'm new at this, so could you please give me a lesson.

[Andrew]

can someone please tell me what the colors mean? I think I know what they mean, but I'm new at this, so could you please give me a lesson.

On the maps I posted?

[BiggieSmalls]

Dallas mets (at least CBS) seem to still think the cold is all but a done deal (lows in the high teens, highs around freezing for 3 or so days)....but the timing of the cold air arriving in time to change the rain to freezing rain/sleet/snow on Tuesday is a little more in doubt than yesterday.

[srainhoutx]

A lot of features to watch this weekend. We have a disturbance near Baja that will be our weekend. Cold air is on the march, heading S in Central/Western Canada as noted on IR Imagery. The Pacific storm that will be the moisture maker next week is slowly progressing E and S offshore W of Seattle/Portland. We’ve been watching this pattern and event since the 17th. And now we wait…Oh, and those low 70's felt great today with plentiful sunshine...

[cisa]

Anyone wanna give a gut feeling about next wk?

[sleetstorm]

Perhaps two to three days with highs in the thirties, if not colder. Perhaps off & on light to maybe moderate sleet/snow on Webnesday/Thursday/Friday with perhaps a few nights in the twenties/teens? Those are simply my thoughts.

[cristina99]

Thought there would be a litle bit more action on here tonight.

[vci_guy2003]

Hey sleetstorm, wanna bet that won't happen?
Here's mine. Partly cloudy throughout. Highs mid to upper 40s. Lows upper 20s to mid 30s. No precip

[Andrew]

Thought there would be a litle bit more action on here tonight.

Waiting on 00z runs. Nam is coming in stronger (colder)

1056mb

[cristina99]

oooooh - good! Can't wait.

[ronyan]

A 1056 mb high in Montana seems pretty impressive.

[Andrew]

A 1056 mb high in Montana seems pretty impressive.

It is, especially for the NAM which is known for its warm bias. The cold air is filtering down faster also.

[biggerbyte]

I really hope this works out for you guys. It would be a dream come true for this Feb. 2 birthday boy.

[skidog38]

has it ever snowed more than 2 days in row in houston?

[skidog38]

A lot of features to watch this weekend. We have a disturbance near Baja that will be our weekend. Cold air is on the march, heading S in Central/Western Canada as noted on IR Imagery. The Pacific storm that will be the moisture maker next week is slowly progressing E and S offshore W of Seattle/Portland. We’ve been watching this pattern and event since the 17th. And now we wait…Oh, and those low 70's felt great today with plentiful sunshine...

is there something big setting up that has never been seen down here?

[Ptarmigan]

has it ever snowed more than 2 days in row in houston?

No, there are no records of snowing more than 2 days in a row. However, weather records from the past are missing, so it could be possible.

[Mr. Weather]

has it ever snowed more than 2 days in row in houston?

is this something that u are seeing may happen or is this just a question ? j/w