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

[Mr. Weather]

according to accuweather its suppose to rain/snow here in Houston on the night of the 3rd and morning of the 4th but im not putting that much confidence in it still to far out most likely it will change and just be rain if that

[srainhoutx]

Perhaps it's just me, but when guidance has been suggesting and now the HPC mentioning a phasing of the Polar Jet (northern stream) and the Southern Stream, an eyebrow is raised. The Euro looks down right cold. I'd be cautious regarding the short wave (500mb) pattern at this range. What I do see is the ensembles suggesting an interesting situation with lots of potential, but many finer details are yet to be determined. All in all at this range, we still have at lot to work out...


PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
352 AM EST TUE JAN 25 2011

VALID 12Z SAT JAN 29 2011 - 12Z TUE FEB 01 2011


THE LONGWAVE PATTERN IS EXPECTED TO UNDERGO A TRANSITION AS
FOLLOWING THE PROGRESSION OF A WEAK WAVE FROM THE GREAT LAKES
ACROSS THE NORTHEAST DAYS 3-4...THE ECMWF/ECMWF ENSEMBLE
MEAN/GFS/GEFS MEAN 500 MB HEIGHTS SHOW A LOWER AMPLITUDE/LONGER
WAVELENGTH TROUGH ACROSS THE CENTRAL TO EASTERN US. A CLOSED LOW
IN THE SOUTHERN STREAM EMERGES OUT OF BAJA CA AND GRADUALLY
WEAKENS/SHEARS EAST ACROSS THE SOUTHERN PLAINS SUN 30 JAN TO MON
31 JAN.

THE AMPLIFICATION OF THE 500 MB RIDGE ALONG THE WEST
COAST/NORTHEAST PACIFIC FAVORS AMPLIFICATION OF A WAVE TRAVELING
NORTH-SOUTH ACROSS THE SOUTHWEST US MON AND POSSIBLY INTO THE
SOUTHERN PLAINS TUE 01 FEB. THE PHASING OF THE NORTHERN AND
SOUTHERN STREAM WAVES LEAD TO SIGNIFICANT DIFFERENCES IN THE SFC
PRESSURE PATTERN. A BLEND OF THE 12Z-00Z ECMWF AND 12Z ECMWF
ENSEMBLE MEANS WAS USED TO MITIGATE DIFFERENCES IN THE SURFACE
FRONTAL POSITION.

THE CONFLUENT FLOW ALOFT MAY LEAD TO AN INCREASING UPPER LEVEL JET
AND PRECIP BREAKING OUT ALONG THE FRONTAL BOUNDARY. THE 00Z GFS
WAS ALONE IN AMPLIFYING PRIMARILY THE NORTHERN STREAM...PRODUCING
AN AREA OF LOW PRESSURE MOVING FROM MN TO THE UPPER LAKES ON TUE
01 FEB. THE GEFS MEAN SHOWED A MUCH LOWER AMPLITUDE 500 MB WAVE
AND CONSEQUENTLY MUCH HIGHER SFC PRESSURES.

THE 00Z GFS/00Z AGREE THE NEXT PACIFIC SHORTWV WEAKENS AS IT COMES
ASHORE IN VANCOUVER ISLAND FRI EVENING 29 JAN. THE 00Z GFS IS ON
THE SOUTHERN EDGE OF THE CLUSTER OF LOW SOLUTIONS OVER THE
NORTHEAST PACIFIC 00Z SAT-00Z SUN...WHERE THE WEAKER/FURTHER NORTH
GEFS MEAN MATCHES BETTER WITH THE ECMWF/12Z ECMWF ENSEMBLE MEAN.
THE MAJORITY MODELS/ENSEMBLE MEANS TAKE THIS WAVE AND PROPAGATE
DOWNSTREAM AND HELP TO FROM THE SOUTHWEST US TROUGH ON MON
NIGHT-TUE. THE DEEP LAYER RIDGE BECOMES REINFORCED OVER THE
NORTHEAST PACIFIC/ADJACENT PACIFIC NORTHWEST THEREAFTER THROUGH AT
LEAST TUE 01 FEB.

PETERSEN

[djmike]

according to accuweather its suppose to rain/snow here in Houston on the night of the 3rd and morning of the 4th but im not putting that much confidence in it still to far out most likely it will change and just be rain if that

Yup, I checked this morning and Accuweather has rain/snow forecasted for the Beaumont area on the 4th. I know it will likley change later today, but all in all intresting that these sites are now starting to forecast snow/rain for areas of SETX. Lastnight, they had ice for our area. Hmmm.

[Mr. Weather]

Does anyone know how often accuweather updates their website ?

[srainhoutx]

Morning Update from the HPC:

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
903 AM EST TUE JAN 25 2011

VALID 12Z SAT JAN 29 2011 - 12Z TUE FEB 01 2011

THE LONGWAVE PATTERN IS EXPECTED TO GRADUALLY TRANSITION FROM A
MEAN RIDGE OVER THE WEST/TROUGH OVER THE EAST ON DAY 3 TOWARD A
MEAN TROUGH OVER THE ROCKIES/RIDGE OVER THE SOUTHEAST BY DAY 7.
THE MANNER IN WHICH INDIVIDUAL MODELS ACTUALLY ARRIVE AT THEIR
PREDICTIONS VARIES CONSIDERABLY HOWEVER...WHICH IS CONFIRMED BY
THE UNUSUALLY LARGE DETERMINISTIC SOLUTION SPREAD ENTERING DAY
3...LAGGED-AVERAGE FORECASTS FROM THE GFS/ECMWF...AND THE TOTAL
ENSEMBLE SPREAD. THUS...THE FORECAST PHILOSOPHY WILL EMPHASIZE
MODEL CONSENSUS AND CONTINUITY TO THE FULL EXTENT POSSIBLE...WITH
GLOBAL ENSEMBLE MEANS USED TO CONSTRUCT THE PRELIMINARY
PRESSURES/FRONTS FOR DAYS 3/7...INCLUDING THE ECMWF ENSEMBLE
MEAN/GEFS MEAN/NAEFS BCMEAN.

THE MAIN DIFFERENCE WITH THE MEANS INVOLVES THE ORIENTATION AND
STRENGTH OF THE MEAN RIDGE OVER THE SOUTHEAST BY DAY 7...WITH THE
ECMWF ENSEMBLE MEAN MORE AMPLIFIED AND STRONGER THAN THE
GEFS/NAEFS. WOULD NORMALLY PLACE GREATER EMPHASIS ON THE ECMWF
ENSEMBLE MEAN IN SUCH A CASE DUE TO ITS HIGHER RESOLUTION AND
GREATER NUMBER OF MEMBERS CONSTITUTING ITS MEAN.
HOWEVER...TELECONNECTIONS WITH THE LARGE NEGATIVE HEIGHT ANOMALY
NEAR HUDSON BAY SHOWS BETTER AGREEMENT WITH THE GEFS/NAEFS.
THUS...REDUCED THE ECMWF ENSEMBLE MEAN CONTRIBUTION TO ABOUT 50
PERCENT. ALSO MANUALLY INCORPORATED DETERMINISTIC DETAIL IN THE
PROGS WHERE CLUSTERING OF SOLUTIONS EXISTED. HOWEVER...THIS WAS
MINIMAL...WITH CONFIDENCE BELOW AVERAGE FOR THE ENTIRE PERIOD.

JAMES

[tireman4]

Does anyone know how often accuweather updates their website ?

I believe, and someone can correct me on this, that they are tied with the models. There is no human interaction with the Accuweather forecasts at all. That is why I do not even look at them. You are better served to go with the National Weather Service or here...

[Mr. Weather]

Does anyone know how often accuweather updates their website ?

I believe, and someone can correct me on this, that they are tied with the models. There is no human interaction with the Accuweather forecasts at all. That is why I do not even look at them. You are better served to go with the National Weather Service or here...

thanks i did not know that

[Andrew]

Does anyone know how often accuweather updates their website ?

I believe, and someone can correct me on this, that they are tied with the models. There is no human interaction with the Accuweather forecasts at all. That is why I do not even look at them. You are better served to go with the National Weather Service or here...

thanks i did not know that

Don't trust any forecast over 7 days. There is almost never any human interaction.

[harpman]

The latest GFS?

[srainhoutx]

The latest GFS?

Running...

[redneckweather]

I know it's hard to do but I would not get DRAWN in to every single model run over the next few days. They are going to jump around all over the darn place and give y'all a freakin migraine. They are fun to look at but do not take every model run seriously right now. I'm even seeing some pro mets dancing around from model to model and you would think they would know better.


The fact is, we got some cold air that WILL be coming down and I believe it will be cold enough to produce wintry precip IF their is any precip around at the time, which will be possible.


Until then, enjoy the model mayhem.

[cristina99]

I thought Channel 2 used Accuweather for their forecasts. I have been keeping a co-worker apprised of all this "winter event" talk and she wanted to know why none of the weather people on the news have yet to say anything. Usually they start talking about stuff like this at least a week out. Have the models changed from earlier this morning?

[jasons2k]

I thought Channel 2 used Accuweather for their forecasts. I have been keeping a co-worker apprised of all this "winter event" talk and she wanted to know why none of the weather people on the news have yet to say anything. Usually they start talking about stuff like this at least a week out. Have the models changed from earlier this morning?

You have to keep in mind the actual forecasts that Accuweather (and others) provides to paying clients such as TV stations is very different than the FREE computer-generated forecasts on the .com sites.

[tireman4]

I thought Channel 2 used Accuweather for their forecasts. I have been keeping a co-worker apprised of all this "winter event" talk and she wanted to know why none of the weather people on the news have yet to say anything. Usually they start talking about stuff like this at least a week out. Have the models changed from earlier this morning?

You have to keep in mind the actual forecasts that Accuweather (and others) provides to paying clients such as TV stations is very different than the FREE computer-generated forecasts on the .com sites.

Agreed 1000 percent. Most of us do not get to see those sites...LOL. In reference to why no one is talking about it, I refer you to our esteemed resident meteorologist:

Wxman57:
It'll be another 5-6 days before we have much confidence in next week's weather. This is the time period prior to an event that the models tend to struggle, so I wouldn't put too much stock in any model runs for the next 3-5 days. And don't expect the local NWS office to mention any winter precip next week. They'll only do so when they're confident that such precip is more likely than not, and that's not going to happen this week.

[tireman4]

I thought Channel 2 used Accuweather for their forecasts. I have been keeping a co-worker apprised of all this "winter event" talk and she wanted to know why none of the weather people on the news have yet to say anything. Usually they start talking about stuff like this at least a week out. Have the models changed from earlier this morning?

You have to keep in mind the actual forecasts that Accuweather (and others) provides to paying clients such as TV stations is very different than the FREE computer-generated forecasts on the .com sites.

Agreed 1000 percent. Most of us do not get to see those sites...LOL. In reference to why no one is talking about it, I refer you to our esteemed resident meteorologist ( to take nothing away from Txagwxman or Candy Cane or others):

Wxman57:
It'll be another 5-6 days before we have much confidence in next week's weather. This is the time period prior to an event that the models tend to struggle, so I wouldn't put too much stock in any model runs for the next 3-5 days. And don't expect the local NWS office to mention any winter precip next week. They'll only do so when they're confident that such precip is more likely than not, and that's not going to happen this week.

[srainhoutx]

For what it's worth, the 12Z suggests some wintry weather in the TX Panhandle and perhaps N TX/OK early next week. Nothing but rain here and then the front arrives in Operational GFS world.

[srainhoutx]

Impact Weather has a new updated video that is well worth watching...

http://www.youtube.com/impactweather

[wxman57]

12Z GFS is a bit colder for our area next week, but still keeps the snow well to the north from the TX Panhandle to Oklahoma. It IS seeing more Arctic air coming down, though. We won't really have much confidence in just what kind of airmass will move south until the weekend, most likely.

[srainhoutx]

The 12Z Canadian (GEM) is colder as well and does suggest an Upper Air disturbance heading into that colder air...

[srainhoutx]

The 12Z Euro is looking mighty cold...Brrr...

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