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

[Andrew]

Finally before logging off, want to see the biggest difference in the world from the GFS and Euro? Look below.

[vci_guy2003]

What the heck?! That phallic shaped euro looks utterly inconceivable!
I don't believe it

[srainhoutx]

Early thoughts from the HPC:

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
246 AM EST WED JAN 26 2011

VALID 12Z SUN JAN 30 2011 - 12Z WED FEB 02 2011

A NARROW RIDGE IS EXPECTED TO AMPLIFY ALONG THE WEST COAST OF
NORTH AMERICA...WHICH SHOULD LEAD TO A POSITIVELY TILTED TROUGH
EXTENDING FROM THE POLAR VORTEX IN NORTHWEST QUEBEC SOUTHWEST INTO
THE SOUTHERN ROCKIES. ENERGY TO AMPLIFY THE TROUGH SHOULD CUT
THROUGH THE PACIFIC NORTHWEST JUST PRIOR TO THE WEST COAST RIDGE
BECOMING FULL LATITUDE IN EXTENT ON MONDAY. THE 00Z GEFS MEAN/12Z
ECMWF ENSEMBLE MEAN/00Z ECMWF AGREE ON THIS SCENARIO. BOTH THE
00Z GFS AND 00Z CANADIAN OUTPACE THE REMAINDER OF THE GUIDANCE
WITH THE TROUGHING EAST OF THE ROCKIES AND WERE NOT USED. WHILE
THIS CHOICE LED TO REASONABLE CONTINUITY AT THE 500 HPA
LEVEL...THE SURFACE PRESSURES COULD NOT MAINTAIN CONTINUITY BEYOND
MONDAY MORNING. USED A 00Z ECMWF/12Z ECMWF ENSEMBLE MEAN THROUGH
THE PERIOD.

ROTH


GFS and Euro Ensembles are not that different regarding the temps at 850mb...

[srainhoutx]

It looks like most of the NWS offices this morning are going with a Euro(temps)/GFS(moisture) split. The moisture appears to be the biggest question mark right now other than just how low those temps will be. Interesting...

[wxman57]

Actually, I think that the Euro surface charts for next week seem to fit the projected 500mb pattern the best. Arctic front moves through early Tuesday morning. It drives straight south, lee of the Rockies. Euro 2m temps here are in the lower 20s by Thursday morning with highs near freezing. No sign of post-frontal moisture, though. If you remember, this is what I said was one of the 3 possibilities which could happen next week - a very cold but dry frontal passage. This option is looking more likely, though I'm not confident in the post-frontal moisture/disturbance situation yet.

[wxman666]

Wow!!! So much can change overnight!

[wxman57]

My "best guess" is that Texas will see the coldest air of the season as Canadian/Arctic air races southward lee of the Rockies starting Sunday morning. The Canadian/Arctic air reaches the Red River around mid afternoon on Monday and the upper TX coast before sunrise Tuesday. I think that the Euro and Canadian are most likely correct with the upper air pattern, which is a very sharp upper trof across the eastern Rockies next week. This would limit (or possibly eliminate) the possibility of post-frontal precipitation across Texas.

How cold? A good guess might be low 20s in Houston, low teens in Dallas. Way too early to be very confident in temps. Could be colder, could be "warmer". Would I actually put low 20s in the forecast for our Houston clients yet? Probably not. I'd indicate mid to upper 20s for now, waiting for the weekend to see what the airmass up north looks like.

[srainhoutx]

With rain in the forecast for the weekend and the 'coldest air of the season' expected around Tuesday, I suspect folks are wondering will they need to make some preparations prior to the foul weather. How long of duration (24/48 hours) are you thinking wxman57 regarding below freezing temps, should that senario play out?

[srainhoutx]

HPC Morning Update paints a very cold pattern ahead...

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
829 AM EST WED JAN 26 2011

VALID 12Z SUN JAN 30 2011 - 12Z WED FEB 02 2011

A NARROW RIDGE IS EXPECTED TO AMPLIFY ALONG THE WEST COAST OF
NORTH AMERICA...WHICH SHOULD LEAD TO A POSITIVELY TILTED TROUGH
EXTENDING FROM THE POLAR VORTEX IN NORTHWEST QUEBEC SOUTHWESTWARD
INTO THE SOUTHERN ROCKIES. ENERGY THAT SHOULD AMPLIFY THE TROUGH
SHOULD CUT THROUGH THE PACIFIC NORTHWEST JUST PRIOR TO THE WEST
COAST RIDGE BECOMING FULL LATITUDE IN EXTENT ON MONDAY. THE 06Z
GEFS MEAN AND 00Z ECMWF ENSEMBLE MEAN AGREE ON THIS SCENARIO
THOUGH THAT TIME. THEREAFTER... THE 00-06Z GFS/GEFS MEAN SEPARATE
ENERGY OVER THE SOUTHWESTERN US AND PUSH BROAD TROUGHING THROUGH
THE NORTHEAST BY TUE/D6 WHILE THE ECMWF SOLUTION FAVORS DIGGING A
SHARPER TROUGH THROUGH THE MIDWEST /OPERATIONAL RUN IS QUITE
ROBUST WITH A CLOSED LOW THOUGH MN AND WI/. CANADIAN ENSEMBLE MEAN
AND NAEFS MEAN SIDE CLOSER TO THE ECMWF ENSEMBLE MEAN. IN
ADDITION... ECMWF ENSEMBLE SPREAD /NORMALIZED STANDARD DEVIATION/
ACTUALLY SHOWS COMPARABLY LOWER THAN RECENT SPREAD OVER THE
SOUTHEAST AT 500MB WITH RIDGING AHEAD OF THE DIGGING CENTRAL CONUS
TROUGH WHILE THE GEFS MEMBERS WERE BASICALLY FLAT/ZONAL. CURRENT
RELATIVE MEASURE OF PREDICTABILITY MAPS WERE NOT AVAILABLE FOR THE
GEFS MEMBERS. THE FORECAST WAS BASED ON A 00Z ECMWF/ECMWF ENSEMBLE
MEAN BLEND THROUGH THE PERIOD... WITH AN INCREASED ENSEMBLE WEIGHT
BY TUE-WED/D6-7.

THE 06Z GFS/GEFS MEAN OUTPACED THE REMAINDER OF THE GUIDANCE WITH
A CLIPPER SYSTEM MOVING THROUGH THE GREAT LAKES SAT/D3. A
RELATIVELY QUIET PATTERN SHOULD ENSUE EARLY NEXT WEEK EAST OF THE
ROCKIES AS SFC HIGH PRESSURE PUSHES SOUTHWARD EAST OF THE TERRAIN.
A FAIR AMOUNT OF UNCERTAINTY EXISTS AS TO THE EVOLUTION OF LOW
PRESSURE DEVELOPING OUT OF THE SOUTHERN PLAINS EARLY IN THE WEEK.
OPERATIONAL ECMWF HAS NOT BEEN TOO CONSISTENT ON TIMING BUT ITS
ENSEMBLE MEAN HAS STAYED THE COURSE.


FRACASSO/ROTH

[wxman57]

With rain in the forecast for the weekend and the 'coldest air of the season' expected around Tuesday, I suspect folks are wondering will they need to make some preparations prior to the foul weather. How long of duration (24/48 hours) are you thinking wxman57 regarding below freezing temps, should that scenario play out?

We could see below-freezing temps for 16-18 hours Wednesday night/Thursday morning. Probably no precip, just cold. I'm going to add extra insulation over my pipes in the attic this week. They're on the floor of the attic so I can just spread a couple rolls of fiberglass insulation over the top of the pipes.

[srainhoutx]

NCEP Update regarding the 12Z NCEP suite...

NCEP Operational Status Message
Wed Jan 26 13:37:26 2011 GMT
NOUS42 KWNO 261337
ADMNFD

SENIOR DUTY METEOROLOGIST NWS ADMINISTRATIVE MESSAGE
NWS NCEP CENTRAL OPERATIONS CAMP SPRINGS MD
1335Z WED JAN 26 2011
THE 12Z NAM STARTED ON TIME WITH 31 CANADIAN...13 MEXICAN
AND 8 CARIBBEAN STATIONS AVBL FOR INGEST.
THERE WERE 8 DROPSONDE REPORTS ALONG THE MID-ATLANTIC
SEABOARD IN SUPPORT OF WINTER STORM RECON...ALTHOUGH ONLY 3
WERE INGESTED BY THE NAM. THERE WERE ALSO 3 FLIGHT LEVEL
REPORTS AROUND 300 MB.
12Z NAM RAOB RECAP...
WAL/72402 - LATE FOR NAM.
CRITICAL WEATHER DAY STATUS...
NCEP DOES NOT ANTICIPATE A CWD DURING THE NEXT 3 DAYS.
CARR/SDM/NCO/NCEP

[ronyan]

We dropped to 34.3 F here last night. It wasn't supposed to be that cold I don't think.

[tireman4]

32 in the burbs of Humble....

[redneckweather]

I was coming here to post the same thing. I knew it was going to get colder than what was forecasted with the way the north wind was blowing yesterday. We were forecasted to get down to 35 but ended up at 28. I've lost count on how many times I've dipped into the 20's here at my house. It seems that is was more than last year by a good margin?

I sure hope some energy is held back for us here next week. I don't think the cold air will be a problem. Fingers crossed on some moisture to work with!

[Cuda17]

28°F in Bellville...

[Cuda17]

28°F in Bellville...

Wow... I just noticed that the other weather station here in Bellville recorded a reading of 25.8 at 7:22 this morning...

[srainhoutx]

Imapct Weather has just released an updated video. Enjoy...

http://www.youtube.com/impactweather

[biggerbyte]

With rain in the forecast for the weekend and the 'coldest air of the season' expected around Tuesday, I suspect folks are wondering will they need to make some preparations prior to the foul weather. How long of duration (24/48 hours) are you thinking wxman57 regarding below freezing temps, should that scenario play out?

We could see below-freezing temps for 16-18 hours Wednesday night/Thursday morning. Probably no precip, just cold. I'm going to add extra insulation over my pipes in the attic this week. They're on the floor of the attic so I can just spread a couple rolls of fiberglass insulation over the top of the pipes.

Wxman, will you clarify something for us? You said 16-18 hours below freezing Wednesday night/Thursday morning. You meant to say 6-8 hours instead?

[srainhoutx]

The 12Z GFS paints an interesting picture for Monday with a robust Upper Air Disturbance to our W poised to track across TX after the Arctic front has entered the Lone Star State...

01262011 12Z GFS f126.gif

01262011 12Z GFS f138.gif

01262011 12Z GFS f168.gif

01262011 12Z GFS f174.gif

01262011 12Z GFS f180.gif

[biggerbyte]

Guys, let me be the voice of reason this round. We still do not know how much of this cold air is coming to our part of Texas. Even the video from impact that srain posted a link for mentions there is uncertainty. I caution again to prepare for the extreme, do not assume, and have no expectations. Everything still looks dry with this event, but even that is not 100% yet. It will be in a couple of days. Whatever does come down, it looks to be fairly short lived. It will modify and slide off to east. Right now, I am expecting nothing more than what many of us have already seen, temp. wise. We have plenty of time to get excited. Today is NOT the day.