It looks as if we have a chance at a good ole' fashioned "Arctic Outbreak" (the same arctic outbreak that produced the huge snows and record lows temperatures on Thanksgiving 1990).
I will update this thread as more is posted about it and the latest models come out.
NEXT INTERESTING SYSTEM IS DUE SUNDAY OR MONDAY...MODELS COULD
EASILY BE OFF BY 24 HOURS OR SO. BUT IT LOOKS COLD WITH 512 DM
THICKNESS ON SUNDAY. GFS AND ESPECIALLY 00Z RUN HAS AN ARCTIC
OUTBREAK COMPLETE WITH PRECIPITATION. NOT GOING TO JUMP ON THIS
YET...9 OUT OF 10 ARCTICS SLIP BY EAST OF THE CASCADES OR EVEN EAST
OF THE ROCKIES...BUT BEARS WATCHING.
Arctic Outbreak Possible For Western Washington
Moderator: S2k Moderators
Forum rules
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K.
The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K.
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Matt-hurricanewatcher
Sounds good to me...The Gfs pulls the first shot of cold air into the Portland area around Sunday Morning. With a large area of really cold air over southwestern Canada. How much of that moves down or doe's it move southeast is the quastion. 5 Gfs at this time show this...Ecmwf with Cmc also support some what of a cool down. Just they are slower.
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This is exactly the reason I don't buy the GFS for the central plains next week-with arctic air out west, it usually spells a ridge for this area. Also, similar to cold air here that gets banked against the Rockies, that air should get banked in which would be hard for it to move. Only possible reason I can see for the GFS scenario is how transient everything has been this year so maybe the west will have a 2-3 day cold shot then it moves on. Good luck to you all out west-I hope you get the snow you wish for!!
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AccuWeather.com just updated, and it looks as if we will be getting multiple punches of cold, arctic air.
6-10 Day Forecast:http://wwwa.accuweather.com/adcbin/public/local_index_6to10day.asp?zipcode=98031&metric=0&partner=accuweather&traveler=0
11-15 Day Forecast: http://wwwa.accuweather.com/adcbin/public/local_index_11to15day.asp?zipcode=98031&metric=0&partner=accuweather&traveler=0
We are going to get cold, and it will be this weekend, but the big cold will be holding off until towards mid week next week. Then it looks like we will get reinforcing shots of arctic air constaintly.
Latest NWS Forecast Discussion: THE BIG QUESTION IN THE FORECAST IS WHEN THE NEXT FRONTAL SYSTEM
WILL ARRIVE. LONGER RANGE MODEL SOLUTIONS HAVE NOT HAD GREAT RUN TO
RUN CONSISTENCY OVER THE PAST SEVERAL DAYS...THOUGH IT LOOKED MOST
LIKELY THAT THE FRONT WOULD ARRIVE LATE IN THE WEEKEND. THE MOST
RECENT SOLUTIONS SHOW FASTER TIMING. THE GFS IS ESPECIALLY FAST...
WITH THE RECENTLY RECEIVED 06Z RUN SHOWING PCPN REACHING WRN WA BY
LATE FRI NIGHT. FOR NOW...IN COORDINATION WITH SURROUNDING OFFICES
...WE HAVE MOVED PCPN UP TO SAT NIGHT BUT THIS MAY NEED TO BE
REVISED BEFORE LONG. WHEN THIS SYSTEM DOES ARRIVE...IT WILL USHER IN
A COOL AIR MASS WILL RELATIVELY LOW SNOW LEVELS.[/url]
6-10 Day Forecast:http://wwwa.accuweather.com/adcbin/public/local_index_6to10day.asp?zipcode=98031&metric=0&partner=accuweather&traveler=0
11-15 Day Forecast: http://wwwa.accuweather.com/adcbin/public/local_index_11to15day.asp?zipcode=98031&metric=0&partner=accuweather&traveler=0
We are going to get cold, and it will be this weekend, but the big cold will be holding off until towards mid week next week. Then it looks like we will get reinforcing shots of arctic air constaintly.
Latest NWS Forecast Discussion: THE BIG QUESTION IN THE FORECAST IS WHEN THE NEXT FRONTAL SYSTEM
WILL ARRIVE. LONGER RANGE MODEL SOLUTIONS HAVE NOT HAD GREAT RUN TO
RUN CONSISTENCY OVER THE PAST SEVERAL DAYS...THOUGH IT LOOKED MOST
LIKELY THAT THE FRONT WOULD ARRIVE LATE IN THE WEEKEND. THE MOST
RECENT SOLUTIONS SHOW FASTER TIMING. THE GFS IS ESPECIALLY FAST...
WITH THE RECENTLY RECEIVED 06Z RUN SHOWING PCPN REACHING WRN WA BY
LATE FRI NIGHT. FOR NOW...IN COORDINATION WITH SURROUNDING OFFICES
...WE HAVE MOVED PCPN UP TO SAT NIGHT BUT THIS MAY NEED TO BE
REVISED BEFORE LONG. WHEN THIS SYSTEM DOES ARRIVE...IT WILL USHER IN
A COOL AIR MASS WILL RELATIVELY LOW SNOW LEVELS.[/url]
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Aslkahuna
- Professional-Met
- Posts: 4550
- Joined: Thu Feb 06, 2003 5:00 pm
- Location: Tucson, AZ
- Contact:
I don't know about WA, but here in AZ the GFS is about as useful as teats on a boar hog. This is especially true beyond Day 7. The ECMWF is a far superior model to the GFS in the medium range (and beyond Day 10 anything you use is worthless) so I wouldn't get too excited until you start to see a model consensus among several models.
Steve
Steve
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Aslkahuna wrote:I don't know about WA, but here in AZ the GFS is about as useful as teats on a boar hog. This is especially true beyond Day 7. The ECMWF is a far superior model to the GFS in the medium range (and beyond Day 10 anything you use is worthless) so I wouldn't get too excited until you start to see a model consensus among several models.
Steve
Well, I have been talking to some people on the Farmer's Almanac Weather Forums, and they seem to say that the models have been showing the same thing consistently (last 5 days), and most models are agreeing with each other.
I expect that we will have a really clear picture as what this first shot of Arctic air will bring and just how cold it will get (we are supposed to be getting several bouts of Arctic air, all the way through New Years).
I will update this thread with whatever NWS says when they update in a few hours.
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Latest NWS Weather Discussion: AFTERWARD IT IS A LITTLE MORE INTERESTING. COOLER AIR SUNDAY NIGHT
THROUGH TUESDAY...NOT BITTERLY COLD...AND REPEATED CHANCES OF
PRECIP. SO WILL WORD ZONES WITH MENTION OF 500 FOOT SNOW LEVEL. NOT
AN ARCTIC OUTBREAK AND NOT AN OVERRUNNING SNOW EVENT...BUT THE
CHANCE OF SNOW AT RELATIVELY LOW ELEVATIONS IS THERE.
THROUGH TUESDAY...NOT BITTERLY COLD...AND REPEATED CHANCES OF
PRECIP. SO WILL WORD ZONES WITH MENTION OF 500 FOOT SNOW LEVEL. NOT
AN ARCTIC OUTBREAK AND NOT AN OVERRUNNING SNOW EVENT...BUT THE
CHANCE OF SNOW AT RELATIVELY LOW ELEVATIONS IS THERE.
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Also what are your guys take on the CPC forecast....
PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST TUE DEC 21 2004
6 TO 10 DAY OUTLOOK FOR DECEMBER 27 - 31 2004 . . . . . . . FOR THE 6-10 DAY PERIOD THE ENSEMBLE MEANS ARE IN VERY GOOD AGREEMENT ON THE EXPECTED CIRCULATION PATTERN... AND ARE NOW IN GOOD AGREEMENT WITH SOLUTIONS FROM YESTERDAY... AS THE ECMWF ENSEMBLE MEAN HAS COME INTO BETTER AGREEMENT WITH THE GFS AND THE CANADIAN ENSEMBLE MEANS. ALL MODELS AGREE ON RETROGRESSION OF A RIDGE FROM THE EASTERN GULF OF ALASKA TO NEAR 160W. THIS FAVORS THE DEVELOPMENT OF TROUGHING OVER WESTERN NORTH AMERICA AND IS EVIDENT IN ALL ENSEMBLE SOLUTIONS. ALL MODELS ALSO HAVE ABOVE NORMAL HEIGHTS OVER THE NORTH ATLANTIC EXTENDING WESTWARD INTO THE MIDWEST AND SOUTHEAST. TELECONNECTIONS FROM THE NEGATIVE HEIGHT CENTER OVER THE PACIFIC NORTHWEST SUPPORT THE UPSTREAM RIDGE OVER THE NORTH PACIFIC AS WELL AS THE DOWNSTREAM RIDGE OVER EASTERN NORTH AMERICA. THE SPAGHETTI DIAGRAMS FROM THE GFS AND CANADIAN ENSEMBLES INDICATE A MODERATE AMOUNT OF SPREAD OVER THE NORTH PACIFIC AND NORTH ATLANTIC WITH LESS SPREAD OVER MOST OF NORTH AMERICA. AS USUAL THE ECMWF HAS RELATIVELY SMALL SPREAD OVER MUCH OF THE PACIFIC/NORTH AMERICAN DOMAIN. THE PNA INDEX WHICH RECENTLY HAS BEEN POSITIVE IS FORECAST TO BECOME NEGATIVE BY DAY 7 AND REMAIN NEGATIVE THROUGH DAY 14. THE NAO INDEX WHICH IS CURRENTLY STRONGLY POSITIVE IS FORECAST TO DECREASE IN VALUE BUT REMAIN WEAKLY POSITIVE THROUGH THE END OF WEEK 2. TEMPERATURES ARE LIKELY TO BE BELOW NORMAL OVER THE WESTERN PART OF THE CONUS UNDER THE INFLUENCE OF THE TROUGH FORECAST TO RESIDE ALONG THE WEST COAST. ABOVE NORMAL TEMPERATURES ARE LIKELY OVER THE EASTERN HALF OF THE COUNTRY DUE TO ANOMALOUS SOUTHWESTERLY FLOW AND ABOVE NORMAL HEIGHTS. WESTERN ALASKA SHOULD ALSO SEE ABOVE NORMAL TEMPERATURES UNDER THE INFLUENCE OF THE RIDGE FORECAST OVER THE ALEUTIANS. PRECIPITATION IS EXPECTED TO BE ABOVE NORMAL IN A SWATH FROM THE SOUTHWEST... ACROSS THE CENTRAL PLAINS STATES INTO THE OHIO VALLEY AND THE NORTHEAST AS THE STORM TRACK IS EXPECTED TO CROSS THE MIDDLE OF THE CONUS... WHILE THE SOUTHEAST COAST SHOULD REMAIN MOSTLY DRY UNDER BUILDING HEIGHTS. THE OFFICIAL D+8 HEIGHT PROG CONSISTS OF 30 PERCENT OF TODAYS ECMWF ENSEMBLE MEAN CENTERED ON DAY 7... 30 PERCENT OF THE GFS ENSEMBLE MEAN CENTERED ON DAY 8... 10 PERCENT OF THE LATEST OPERATIONAL ECMWF CENTERED ON DAY 7... 10 PERCENT EACH OF TODAYS HIGH RESOLUTION 0Z AND 6Z GFS CENTERED ON DAY 8 AND 10 PERCENT OF TODAYS DAVA CENTERED ON DAY 8. MODELS OF THE DAY: GFS ENSEMBLE MEAN AND ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE FOR THE 6 TO 10 DAY PERIOD IS ABOVE AVERAGE TODAY OVERALL...RATED 4 ON A SCALE FROM 1 TO 5 DUE TO EXCELLENT MODEL AGREEMENT AND GOOD CONTINUITY WITH RESPECT TO YESTERDAYS MODEL RUNS.
14 DAY OUTLOOK FOR DECEMBER 29 2004 - JANUARY 4 2005 DURING WEEK 2 THE GFS ENSEMBLE MEAN... THE 0Z AND 6Z GFS... AND THE DAVA ARE AGAIN IN VERY GOOD AGREEMENT WITH ALL SOLUTIONS HAVING A PATTERN FAIRLY SIMILAR TO THAT FORECAST DURING THE 6-10 PERIOD. THE MODELS DEPICT A STRONG RIDGE OVER THE ALEUTIANS... BELOW NORMAL HEIGHTS OVER WESTERN NORTH AMERICA AND ABOVE NORMAL HEIGHTS OVER THE EASTERN CONUS AND THE NORTH ATLANTIC. THE MAIN DIFFERENCE AMONG THE SOLUTIONS TODAY IS OVER THE NORTH ATLANTIC... WHERE THE ENSEMBLE MEAN AND THE 6Z GFS SHIFT THE CENTER OF THE ABOVE NORMAL HEIGHTS WESTWARD TO THE WESTERN ATLANTIC... WHILE THE 0Z GFS MAINTAINS THE RIDGE NEAR 50W. THE RUN TO RUN CONTINUITY AMONG THE MODELS IS QUITE GOOD TODAY FOR ALL SOLUTIONS. THE GFS ENSEMBLE SPAGHETTI DIAGRAMS INDICATE LOW TO MODERATE SPREAD OVER THE CONUS AND LARGER SPREAD OVER THE EASTERN PACIFIC AND THE WESTERN AND CENTRAL ATLANTIC.
6 to 10 day Outlook Table
OUTLOOK FOR DEC 27 - 31, 2004
STATE TEMP PCPN
WASHINGTON B N
8 to 14 day Outlook Table
OUTLOOK FOR DEC 29, 2004 - JAN 04, 2005
STATE TEMP PCPN
WASHINGTON B B
PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST TUE DEC 21 2004
6 TO 10 DAY OUTLOOK FOR DECEMBER 27 - 31 2004 . . . . . . . FOR THE 6-10 DAY PERIOD THE ENSEMBLE MEANS ARE IN VERY GOOD AGREEMENT ON THE EXPECTED CIRCULATION PATTERN... AND ARE NOW IN GOOD AGREEMENT WITH SOLUTIONS FROM YESTERDAY... AS THE ECMWF ENSEMBLE MEAN HAS COME INTO BETTER AGREEMENT WITH THE GFS AND THE CANADIAN ENSEMBLE MEANS. ALL MODELS AGREE ON RETROGRESSION OF A RIDGE FROM THE EASTERN GULF OF ALASKA TO NEAR 160W. THIS FAVORS THE DEVELOPMENT OF TROUGHING OVER WESTERN NORTH AMERICA AND IS EVIDENT IN ALL ENSEMBLE SOLUTIONS. ALL MODELS ALSO HAVE ABOVE NORMAL HEIGHTS OVER THE NORTH ATLANTIC EXTENDING WESTWARD INTO THE MIDWEST AND SOUTHEAST. TELECONNECTIONS FROM THE NEGATIVE HEIGHT CENTER OVER THE PACIFIC NORTHWEST SUPPORT THE UPSTREAM RIDGE OVER THE NORTH PACIFIC AS WELL AS THE DOWNSTREAM RIDGE OVER EASTERN NORTH AMERICA. THE SPAGHETTI DIAGRAMS FROM THE GFS AND CANADIAN ENSEMBLES INDICATE A MODERATE AMOUNT OF SPREAD OVER THE NORTH PACIFIC AND NORTH ATLANTIC WITH LESS SPREAD OVER MOST OF NORTH AMERICA. AS USUAL THE ECMWF HAS RELATIVELY SMALL SPREAD OVER MUCH OF THE PACIFIC/NORTH AMERICAN DOMAIN. THE PNA INDEX WHICH RECENTLY HAS BEEN POSITIVE IS FORECAST TO BECOME NEGATIVE BY DAY 7 AND REMAIN NEGATIVE THROUGH DAY 14. THE NAO INDEX WHICH IS CURRENTLY STRONGLY POSITIVE IS FORECAST TO DECREASE IN VALUE BUT REMAIN WEAKLY POSITIVE THROUGH THE END OF WEEK 2. TEMPERATURES ARE LIKELY TO BE BELOW NORMAL OVER THE WESTERN PART OF THE CONUS UNDER THE INFLUENCE OF THE TROUGH FORECAST TO RESIDE ALONG THE WEST COAST. ABOVE NORMAL TEMPERATURES ARE LIKELY OVER THE EASTERN HALF OF THE COUNTRY DUE TO ANOMALOUS SOUTHWESTERLY FLOW AND ABOVE NORMAL HEIGHTS. WESTERN ALASKA SHOULD ALSO SEE ABOVE NORMAL TEMPERATURES UNDER THE INFLUENCE OF THE RIDGE FORECAST OVER THE ALEUTIANS. PRECIPITATION IS EXPECTED TO BE ABOVE NORMAL IN A SWATH FROM THE SOUTHWEST... ACROSS THE CENTRAL PLAINS STATES INTO THE OHIO VALLEY AND THE NORTHEAST AS THE STORM TRACK IS EXPECTED TO CROSS THE MIDDLE OF THE CONUS... WHILE THE SOUTHEAST COAST SHOULD REMAIN MOSTLY DRY UNDER BUILDING HEIGHTS. THE OFFICIAL D+8 HEIGHT PROG CONSISTS OF 30 PERCENT OF TODAYS ECMWF ENSEMBLE MEAN CENTERED ON DAY 7... 30 PERCENT OF THE GFS ENSEMBLE MEAN CENTERED ON DAY 8... 10 PERCENT OF THE LATEST OPERATIONAL ECMWF CENTERED ON DAY 7... 10 PERCENT EACH OF TODAYS HIGH RESOLUTION 0Z AND 6Z GFS CENTERED ON DAY 8 AND 10 PERCENT OF TODAYS DAVA CENTERED ON DAY 8. MODELS OF THE DAY: GFS ENSEMBLE MEAN AND ECMWF ENSEMBLE MEAN FORECAST CONFIDENCE FOR THE 6 TO 10 DAY PERIOD IS ABOVE AVERAGE TODAY OVERALL...RATED 4 ON A SCALE FROM 1 TO 5 DUE TO EXCELLENT MODEL AGREEMENT AND GOOD CONTINUITY WITH RESPECT TO YESTERDAYS MODEL RUNS.
14 DAY OUTLOOK FOR DECEMBER 29 2004 - JANUARY 4 2005 DURING WEEK 2 THE GFS ENSEMBLE MEAN... THE 0Z AND 6Z GFS... AND THE DAVA ARE AGAIN IN VERY GOOD AGREEMENT WITH ALL SOLUTIONS HAVING A PATTERN FAIRLY SIMILAR TO THAT FORECAST DURING THE 6-10 PERIOD. THE MODELS DEPICT A STRONG RIDGE OVER THE ALEUTIANS... BELOW NORMAL HEIGHTS OVER WESTERN NORTH AMERICA AND ABOVE NORMAL HEIGHTS OVER THE EASTERN CONUS AND THE NORTH ATLANTIC. THE MAIN DIFFERENCE AMONG THE SOLUTIONS TODAY IS OVER THE NORTH ATLANTIC... WHERE THE ENSEMBLE MEAN AND THE 6Z GFS SHIFT THE CENTER OF THE ABOVE NORMAL HEIGHTS WESTWARD TO THE WESTERN ATLANTIC... WHILE THE 0Z GFS MAINTAINS THE RIDGE NEAR 50W. THE RUN TO RUN CONTINUITY AMONG THE MODELS IS QUITE GOOD TODAY FOR ALL SOLUTIONS. THE GFS ENSEMBLE SPAGHETTI DIAGRAMS INDICATE LOW TO MODERATE SPREAD OVER THE CONUS AND LARGER SPREAD OVER THE EASTERN PACIFIC AND THE WESTERN AND CENTRAL ATLANTIC.
6 to 10 day Outlook Table
OUTLOOK FOR DEC 27 - 31, 2004
STATE TEMP PCPN
WASHINGTON B N
8 to 14 day Outlook Table
OUTLOOK FOR DEC 29, 2004 - JAN 04, 2005
STATE TEMP PCPN
WASHINGTON B B
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Another one, this from Clearwest...
Discussion for Monday, Dec. 27 through Thursday Dec. 30: Now it gets interesting! The forecast models indicate very cold arctic air will move east from Siberia and Alaska into northern and central Canada Sunday and Monday. Some of this cold air is forecast to get caught up by the system off the coast and move south into our area by about Sunday or Monday. At this time, it doesn't appear that we will be hit by a serious outbreak, but readings in the +5 to +10F range will be possible in the coldest spots Monday and Tuesday mornings. By about Tuesday or Wednesday, the westerilies are forecast to strengthen over the eastern Pacific once again, bringing warmer, more moist air back into our area from off the Pacific at that time. Because the forecast models have been having considerable differences of opinion concerning this possible arctic outbreak, growers should check this page from time to time for revisions in the Forecast
Discussion for Monday, Dec. 27 through Thursday Dec. 30: Now it gets interesting! The forecast models indicate very cold arctic air will move east from Siberia and Alaska into northern and central Canada Sunday and Monday. Some of this cold air is forecast to get caught up by the system off the coast and move south into our area by about Sunday or Monday. At this time, it doesn't appear that we will be hit by a serious outbreak, but readings in the +5 to +10F range will be possible in the coldest spots Monday and Tuesday mornings. By about Tuesday or Wednesday, the westerilies are forecast to strengthen over the eastern Pacific once again, bringing warmer, more moist air back into our area from off the Pacific at that time. Because the forecast models have been having considerable differences of opinion concerning this possible arctic outbreak, growers should check this page from time to time for revisions in the Forecast
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Reading the discussions from the various options, Spokane had a lengthy but good explanation. Sounds like the GFS is the odd man out as far as these forecasts, but it is trending toward the ETA. "THE BIGGEST UNCERTAINTY IS THE EVOLUTION OF THE UPPER LEVEL WAVE MOVING SOUTHWARD OUT OF THE ARCTIC AND ITS IMPACT ON SENSIBLE WEATHER. THE GFS HAS BEEN THE ODD ONE OUT AS IT HAS MAINTAINED A MORE PROGRESSIVE OPEN WAVE PATTERN MOVING THROUGH THE REGION SATURDAY NIGHT THROUGH SUNDAY.THE UKMET...ECMWF...CANADIAN GEM...AND NOGAPS ALL DEVELOP A CLOSED LOW THAT DIGS SOUTHWARD OFF THE WEST COAST WITH THE NOGAPS KEEPING THE CLOSED CIRCULATION FURTHER WEST. HOWEVER...THE 18Z GFS DOES SEEM TO BE TRENDING MORE TOWARD THE ECMWF SOLUTION."
Also they say the ETA has initialized better then the GFS. Another excerpt: THE GFS...DESPITE GOOD RUN-TO-RUN CONSISTENCY...IS STILL THE OUTLIER. A LOOK AT ENSEMBLE MEMBERS OF THE GFS DO NOT INSPIRE ANY INCREASED CONFIDENCE. HALF OF THE MEMBERS PROPOSE A SOLUTION CLOSER TO THE OTHER PREVIOUSLY MENTIONED MODELS WHILE THE OTHER HALF SUPPORT
THE OPERATIONAL SOLUTION OF THE GFS. THE PREPONDERANCE OF THE EVIDENCE WOULD SUGGEST A SOLUTION CLOSER TO THE ETA"
But still subtle changes make a big difference in the forecasts: "THE NERVE WRACKING ASPECT THOUGH IS IF THE WAVE PROPAGATES FURTHER EASTWARD AND SLOWER THAN PROJECTED WE COULD SEE CONSIDERABLY MORE SNOWFALL AND COLDER TEMPERATURES...IF THE WAVE GOES FURTHER WESTWARD...LITTLE TO NO PRECIPITATION AND WARMER TEMPERATURES"
Of course this is the Eastern Washington outlook, but we get the idea.
Also they say the ETA has initialized better then the GFS. Another excerpt: THE GFS...DESPITE GOOD RUN-TO-RUN CONSISTENCY...IS STILL THE OUTLIER. A LOOK AT ENSEMBLE MEMBERS OF THE GFS DO NOT INSPIRE ANY INCREASED CONFIDENCE. HALF OF THE MEMBERS PROPOSE A SOLUTION CLOSER TO THE OTHER PREVIOUSLY MENTIONED MODELS WHILE THE OTHER HALF SUPPORT
THE OPERATIONAL SOLUTION OF THE GFS. THE PREPONDERANCE OF THE EVIDENCE WOULD SUGGEST A SOLUTION CLOSER TO THE ETA"
But still subtle changes make a big difference in the forecasts: "THE NERVE WRACKING ASPECT THOUGH IS IF THE WAVE PROPAGATES FURTHER EASTWARD AND SLOWER THAN PROJECTED WE COULD SEE CONSIDERABLY MORE SNOWFALL AND COLDER TEMPERATURES...IF THE WAVE GOES FURTHER WESTWARD...LITTLE TO NO PRECIPITATION AND WARMER TEMPERATURES"
Of course this is the Eastern Washington outlook, but we get the idea.
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Aslkahuna
- Professional-Met
- Posts: 4550
- Joined: Thu Feb 06, 2003 5:00 pm
- Location: Tucson, AZ
- Contact:
I stopped thinking that the 8-14 outlook was a credible source of information years ago. The important thing here is to not pin one's hopes on the GFS. In fact, this type of situation is one where local forecast studies rather than model runs are to be preferred. Those studies usually look at indicators that either models don't have or are not resolved by the model grids.
Steve
Steve
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Cumulonimbus
- Tropical Depression
- Posts: 70
- Joined: Sun Jun 22, 2003 9:03 am
- Location: Newcastle, WA
The GFS is usually first jumping on the bandwagen showing arctic air plunging south into the western US west of the Continental Divide. At 168 hours both on Sunday and Monday they had -33 850 mb temps in southern BC and -14 C over Seattle by Monday. Now just 24 hours later(but closer to the event) there is some cool air seeping south, west of the Cascades but most of it looks to be moving east across southern Canada.
In 1998 before the GFS existed and the MRF was the long range American Model it showed an arctic outbreak moving south southwest out of Canada. It showed this at least 1 week ahead of time and run after run after run showed the same thing CONSISTANTLY!! Too bad they had to mess with a good thing because the GFS is a JOKE! Yes it will show a pattern change but details are completely lost with every run. And so once again it forecast an arctic outbreak...until today. As the event draws closer I would not be surprised to see us in a SOUTHERLY flow aloft as the coldest air is west of the coast and return flow around the upper low brings warmer air in from the ocean.
The ECMWF is the superior model by far with changes and many forecasters always mention that it is the first model to show a distinct pattern change and the model of choice for details.
Cooler....yes but arctic cold and snow...not this time at least not yet. This looks more like last December minus the arctic front that did move south through western Washington on Jan 3rd.
It is tough for arctic air to move south here due to the mountains. It can happen and does once in awhile. Dec 1968-Jan 1969 was the winter to be here. Single digit lows on the 30th of Dec, followed by 15 inches of snow. Jan 69 saw 47 inches of snow in Seattle at the airport and a total of 65+ inches of snow fell here that winter.
I want snow but I don't see it happening....at least not yet.
In 1998 before the GFS existed and the MRF was the long range American Model it showed an arctic outbreak moving south southwest out of Canada. It showed this at least 1 week ahead of time and run after run after run showed the same thing CONSISTANTLY!! Too bad they had to mess with a good thing because the GFS is a JOKE! Yes it will show a pattern change but details are completely lost with every run. And so once again it forecast an arctic outbreak...until today. As the event draws closer I would not be surprised to see us in a SOUTHERLY flow aloft as the coldest air is west of the coast and return flow around the upper low brings warmer air in from the ocean.
The ECMWF is the superior model by far with changes and many forecasters always mention that it is the first model to show a distinct pattern change and the model of choice for details.
Cooler....yes but arctic cold and snow...not this time at least not yet. This looks more like last December minus the arctic front that did move south through western Washington on Jan 3rd.
It is tough for arctic air to move south here due to the mountains. It can happen and does once in awhile. Dec 1968-Jan 1969 was the winter to be here. Single digit lows on the 30th of Dec, followed by 15 inches of snow. Jan 69 saw 47 inches of snow in Seattle at the airport and a total of 65+ inches of snow fell here that winter.
I want snow but I don't see it happening....at least not yet.
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Cumulonimbus wrote:The GFS is usually first jumping on the bandwagen showing arctic air plunging south into the western US west of the Continental Divide. At 168 hours both on Sunday and Monday they had -33 850 mb temps in southern BC and -14 C over Seattle by Monday. Now just 24 hours later(but closer to the event) there is some cool air seeping south, west of the Cascades but most of it looks to be moving east across southern Canada.
In 1998 before the GFS existed and the MRF was the long range American Model it showed an arctic outbreak moving south southwest out of Canada. It showed this at least 1 week ahead of time and run after run after run showed the same thing CONSISTANTLY!! Too bad they had to mess with a good thing because the GFS is a JOKE! Yes it will show a pattern change but details are completely lost with every run. And so once again it forecast an arctic outbreak...until today. As the event draws closer I would not be surprised to see us in a SOUTHERLY flow aloft as the coldest air is west of the coast and return flow around the upper low brings warmer air in from the ocean.
The ECMWF is the superior model by far with changes and many forecasters always mention that it is the first model to show a distinct pattern change and the model of choice for details.
Cooler....yes but arctic cold and snow...not this time at least not yet. This looks more like last December minus the arctic front that did move south through western Washington on Jan 3rd.
It is tough for arctic air to move south here due to the mountains. It can happen and does once in awhile. Dec 1968-Jan 1969 was the winter to be here. Single digit lows on the 30th of Dec, followed by 15 inches of snow. Jan 69 saw 47 inches of snow in Seattle at the airport and a total of 65+ inches of snow fell here that winter.
I want snow but I don't see it happening....at least not yet.
I see where you are coming from, but it looks as if we are going to get several shot of very cold air. The second one that looks to be coming in around the 30th of December.
Anyone who knows more about these things, what is the ETA model? That seems to be the one that the NWS says has been more accurate and has initialized better. How far out does it go? It would be great if all the models showed that we will get major cold shots later.
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Latest NWS Forecast Discussion:
SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL PRODUCE DRY WEATHER
THROUGH THE END OF THE WEEK...WITH PATCHY NIGHT AND MORNING FOG. IT
WILL ALSO ALLOW COLD TEMPERATURES AT NIGHT...WITH MANY WESTERN
WASHINGTON LOCATIONS FALLING BELOW FREEZING. A FRONT WILL BRING RAIN
CHRISTMAS DAY...FOLLOWED BY A BLAST OF COLD AIR WHICH COULD BRING
LOW ELEVATION SNOW TO SOME AREAS SUNDAY AND EARLY NEXT WEEK.
&&
.DISCUSSION...NOT MUCH HAPPENING RIGHT NOW WITH MOSTLY CLOUDY SKIES
AND PATCHY FOG. LIGHT OFFSHORE GRADIENTS. COULD BE A LITTLE MORE
FOGGY THE NEXT TWO DAYS. THEN A FRONT ARRIVES FRI NIGHT. COLD AIR
BEHIND THE FRONT ARRIVES BY SAT AFTERNOON AND STAYS IN PLACE THROUGH
NEXT WEEK WITH JUST A GRADUAL WARMUP. BULK OF COLD AIR SLIPS INTO
EASTERN WA BUT STILL -15 C OR SO AT 850 MB OVER THE WEST ON SUNDAY.
NOT MUCH PCPN IN THE MODELS AFTER THE FRONT SATURDAY... MAINLY JUST
SHOWERS SUNDAY. BUT WHAT LITTLE THERE IS FROM SUNDAY ON WILL BE
DURING THE COLD. SO SNOW SHOWERS A POSSIBILITY SUNDAY ALONG WITH
GUSTY NE WINDS. NO PCPN MON OR TUE IN THE GFS. THEN A SYSTEM MOVES
INTO OREGON WED WITH COLD AIR STILL IN PLACE OVER WA. THAT IS A GOOD
PATTERN FOR A WARM OVERRUNNING SNOW EVENT. BUT NO NEED TO JUMP ON
THE 180 OUR PROG YET. COLD WEATHER SUN-TUE LOOKS LIKE THE MAIN
MESSAGE FOR NOW. BURKE[/quote]
SYNOPSIS...A RIDGE OF HIGH PRESSURE WILL PRODUCE DRY WEATHER
THROUGH THE END OF THE WEEK...WITH PATCHY NIGHT AND MORNING FOG. IT
WILL ALSO ALLOW COLD TEMPERATURES AT NIGHT...WITH MANY WESTERN
WASHINGTON LOCATIONS FALLING BELOW FREEZING. A FRONT WILL BRING RAIN
CHRISTMAS DAY...FOLLOWED BY A BLAST OF COLD AIR WHICH COULD BRING
LOW ELEVATION SNOW TO SOME AREAS SUNDAY AND EARLY NEXT WEEK.
&&
.DISCUSSION...NOT MUCH HAPPENING RIGHT NOW WITH MOSTLY CLOUDY SKIES
AND PATCHY FOG. LIGHT OFFSHORE GRADIENTS. COULD BE A LITTLE MORE
FOGGY THE NEXT TWO DAYS. THEN A FRONT ARRIVES FRI NIGHT. COLD AIR
BEHIND THE FRONT ARRIVES BY SAT AFTERNOON AND STAYS IN PLACE THROUGH
NEXT WEEK WITH JUST A GRADUAL WARMUP. BULK OF COLD AIR SLIPS INTO
EASTERN WA BUT STILL -15 C OR SO AT 850 MB OVER THE WEST ON SUNDAY.
NOT MUCH PCPN IN THE MODELS AFTER THE FRONT SATURDAY... MAINLY JUST
SHOWERS SUNDAY. BUT WHAT LITTLE THERE IS FROM SUNDAY ON WILL BE
DURING THE COLD. SO SNOW SHOWERS A POSSIBILITY SUNDAY ALONG WITH
GUSTY NE WINDS. NO PCPN MON OR TUE IN THE GFS. THEN A SYSTEM MOVES
INTO OREGON WED WITH COLD AIR STILL IN PLACE OVER WA. THAT IS A GOOD
PATTERN FOR A WARM OVERRUNNING SNOW EVENT. BUT NO NEED TO JUMP ON
THE 180 OUR PROG YET. COLD WEATHER SUN-TUE LOOKS LIKE THE MAIN
MESSAGE FOR NOW. BURKE[/quote]
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According to the CPC the pac northwest could remain in the upcoming pattern through at least Jan 5th. Trough in the west, and ridge in the east....Here are the highlights of that discussion........
PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST WED DEC 22 2004
6 TO 10 DAY OUTLOOK FOR DECEMBER 28 2004 - JANUARY 1 2005 . . . . . . . FOR THE 6-10 DAY PERIOD THE ENSEMBLE MEANS ARE AGAIN IN VERY GOOD AGREEMENT ON THE EXPECTED CIRCULATION PATTERN... CONTINUING THE PATTERN FIRST FORECAST EARLIER IN THE WEEK. ALL MODELS AGREE ON RETROGRESSION OF A RIDGE FROM THE EASTERN GULF OF ALASKA TO NEAR 155W... TROUGHING ALONG THE WEST COAST... AND STRONG RIDGING EXTENDING FROM THE EASTERN HALF OF THE U.S. TO THE NORTH CENTRAL ATLANTIC. THIS PATTERN CONTINUES TO TELECONNECTION WELL... ESPECIALLY FROM THE NEGATIVE HEIGHT CENTER OVER THE PACIFIC NORTHWEST. THE SPAGHETTI DIAGRAMS EXHIBIT RELATIVELY LITTLE SPREAD... WITH THE GFS HAVING THE MOST SPREAD OVER THE EASTERN PACIFIC OFF THE CALIFORNIA COAST AND OVER THE NORTH ATLANTIC. THE CANADIAN ENSEMBLES HAVE MODERATE SPREAD ACROSS THE PACIFIC AND THE ECWMF ENSEMBLES SHOW LITTLE SPREAD ANYWHERE IN THE PACIFIC/NORTH AMERICAN DOMAIN. THE PNA INDEX WHICH RECENTLY HAS RETURNED TO NEAR ZERO IS FORECAST TO BECOME STRONGLY NEGATIVE BY DAY 7 AND REMAIN NEGATIVE THROUGH DAY 14. THE NAO INDEX WHICH IS CURRENTLY POSITIVE IS FORECAST TO REMAIN POSITIVE THROUGH THE END OF WEEK 2. TEMPERATURES ARE LIKELY TO BE BELOW NORMAL OVER THE WESTERN PART OF THE CONUS UNDER THE INFLUENCE OF THE TROUGH FORECAST TO RESIDE ALONG THE WEST COAST. ABOVE NORMAL TEMPERATURES ARE LIKELY OVER THE EASTERN HALF OF THE COUNTRY DUE TO ANOMALOUS SOUTHWESTERLY FLOW AND ABOVE NORMAL HEIGHTS. WESTERN ALASKA SHOULD ALSO SEE ABOVE NORMAL TEMPERATURES UNDER THE INFLUENCE OF THE RIDGE FORECAST OVER THE ALEUTIANS... WHILE THE CENTRAL AND EASTERN PARTS OF ALASKA SHOULD BE BELOW NORMAL WITH ANOMALOUS NORTHERLY FLOW DOWNSTREAM OF THE RIDGE AXIS.
8 TO 14 DAY OUTLOOK FOR DECEMBER 30 2004 - JANUARY 5 2005 DURING WEEK 2 THE GFS ENSEMBLE MEAN... THE 0Z AND 6Z GFS... AND THE DAVA ARE AGAIN IN VERY GOOD AGREEMENT WITH ALL SOLUTIONS HAVING A PATTERN FAIRLY SIMILAR TO THAT FORECAST DURING THE 6-10 PERIOD. THE MODELS DEPICT A STRONG RIDGE OVER THE ALEUTIANS... BELOW NORMAL HEIGHTS OVER WESTERN NORTH AMERICA AND ABOVE NORMAL HEIGHTS OVER THE EASTERN CONUS AND THE NORTH ATLANTIC. THE MAIN DIFFERENCE AMONG THE SOLUTIONS TODAY IS OVER THE PACIFIC SECTOR AND ALASKA... WHERE BOTH THE 0Z AND 6Z GFS SOLUTIONS ARE FARTHER WEST WITH BOTH THE POSITIVE CENTER AND THE NEGATIVE CENTER THAN THE ENSEMBLE MEAN. THE HIGH RESOLUTION RUNS PLACE THE RIDGE CENTER NEAR THE DATE LINE AND THE NEGATIVE CENTER OVER ALASKA... WHILE THE ENSEMBLE MEAN HAS THE POSITIVE CENTER NEAR 160W AND THE NEGATIVE CENTER OVER WESTERN CANADA. THE DAVA HAS A WEAKER SOLUTION... ESPECIALLY OVER WESTERN NORTH AMERICA... WHERE THE DAVA SPLITS THE REGION OF BELOW NORMAL HEIGHTS OVER THE PACIFIC NORTHWEST.
Also looking at the 12z GFS things are looking great, and even though they don't show much moisture, that could easly change with this kind of a pattern change.
WOO HOO winter finally on the way!!
PROGNOSTIC DISCUSSIONS FOR 6 TO 10 AND 8 TO 14 DAY OUTLOOKS
NWS CLIMATE PREDICTION CENTER CAMP SPRINGS MD
300 PM EST WED DEC 22 2004
6 TO 10 DAY OUTLOOK FOR DECEMBER 28 2004 - JANUARY 1 2005 . . . . . . . FOR THE 6-10 DAY PERIOD THE ENSEMBLE MEANS ARE AGAIN IN VERY GOOD AGREEMENT ON THE EXPECTED CIRCULATION PATTERN... CONTINUING THE PATTERN FIRST FORECAST EARLIER IN THE WEEK. ALL MODELS AGREE ON RETROGRESSION OF A RIDGE FROM THE EASTERN GULF OF ALASKA TO NEAR 155W... TROUGHING ALONG THE WEST COAST... AND STRONG RIDGING EXTENDING FROM THE EASTERN HALF OF THE U.S. TO THE NORTH CENTRAL ATLANTIC. THIS PATTERN CONTINUES TO TELECONNECTION WELL... ESPECIALLY FROM THE NEGATIVE HEIGHT CENTER OVER THE PACIFIC NORTHWEST. THE SPAGHETTI DIAGRAMS EXHIBIT RELATIVELY LITTLE SPREAD... WITH THE GFS HAVING THE MOST SPREAD OVER THE EASTERN PACIFIC OFF THE CALIFORNIA COAST AND OVER THE NORTH ATLANTIC. THE CANADIAN ENSEMBLES HAVE MODERATE SPREAD ACROSS THE PACIFIC AND THE ECWMF ENSEMBLES SHOW LITTLE SPREAD ANYWHERE IN THE PACIFIC/NORTH AMERICAN DOMAIN. THE PNA INDEX WHICH RECENTLY HAS RETURNED TO NEAR ZERO IS FORECAST TO BECOME STRONGLY NEGATIVE BY DAY 7 AND REMAIN NEGATIVE THROUGH DAY 14. THE NAO INDEX WHICH IS CURRENTLY POSITIVE IS FORECAST TO REMAIN POSITIVE THROUGH THE END OF WEEK 2. TEMPERATURES ARE LIKELY TO BE BELOW NORMAL OVER THE WESTERN PART OF THE CONUS UNDER THE INFLUENCE OF THE TROUGH FORECAST TO RESIDE ALONG THE WEST COAST. ABOVE NORMAL TEMPERATURES ARE LIKELY OVER THE EASTERN HALF OF THE COUNTRY DUE TO ANOMALOUS SOUTHWESTERLY FLOW AND ABOVE NORMAL HEIGHTS. WESTERN ALASKA SHOULD ALSO SEE ABOVE NORMAL TEMPERATURES UNDER THE INFLUENCE OF THE RIDGE FORECAST OVER THE ALEUTIANS... WHILE THE CENTRAL AND EASTERN PARTS OF ALASKA SHOULD BE BELOW NORMAL WITH ANOMALOUS NORTHERLY FLOW DOWNSTREAM OF THE RIDGE AXIS.
8 TO 14 DAY OUTLOOK FOR DECEMBER 30 2004 - JANUARY 5 2005 DURING WEEK 2 THE GFS ENSEMBLE MEAN... THE 0Z AND 6Z GFS... AND THE DAVA ARE AGAIN IN VERY GOOD AGREEMENT WITH ALL SOLUTIONS HAVING A PATTERN FAIRLY SIMILAR TO THAT FORECAST DURING THE 6-10 PERIOD. THE MODELS DEPICT A STRONG RIDGE OVER THE ALEUTIANS... BELOW NORMAL HEIGHTS OVER WESTERN NORTH AMERICA AND ABOVE NORMAL HEIGHTS OVER THE EASTERN CONUS AND THE NORTH ATLANTIC. THE MAIN DIFFERENCE AMONG THE SOLUTIONS TODAY IS OVER THE PACIFIC SECTOR AND ALASKA... WHERE BOTH THE 0Z AND 6Z GFS SOLUTIONS ARE FARTHER WEST WITH BOTH THE POSITIVE CENTER AND THE NEGATIVE CENTER THAN THE ENSEMBLE MEAN. THE HIGH RESOLUTION RUNS PLACE THE RIDGE CENTER NEAR THE DATE LINE AND THE NEGATIVE CENTER OVER ALASKA... WHILE THE ENSEMBLE MEAN HAS THE POSITIVE CENTER NEAR 160W AND THE NEGATIVE CENTER OVER WESTERN CANADA. THE DAVA HAS A WEAKER SOLUTION... ESPECIALLY OVER WESTERN NORTH AMERICA... WHERE THE DAVA SPLITS THE REGION OF BELOW NORMAL HEIGHTS OVER THE PACIFIC NORTHWEST.
Also looking at the 12z GFS things are looking great, and even though they don't show much moisture, that could easly change with this kind of a pattern change.
WOO HOO winter finally on the way!!
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Latest NWS Forecast Discussion:
COLD AIR STARTS TO SEEP INTO REGION SAT NIGHT AND REALLY COMES
THROUGH ON SUNDAY. GFS HAS -15 C OR SO AT 850 MB. DEFINITELY COLD
ENOUGH FOR SNOW BUT THE GFS ALSO PUSHES ALL THE MOISTURE OUT OF THE
WAY. MIGHT GET SOME FLURRIES WITH THE MODIFIED ARCTIC FRONT PASSAGE
ON SUNDAY BUT FOR NOW WILL JUST SAY CHANCE OF SHOWERS. SUNDAY WILL
PROBABLY START WITH WARMEST TEMPS OF THE DAY AT MIDNIGHT AND COOL
THROUGH THE DAY...INTO THE 20S SUNDAY NIGHT.
TEMPS REMAIN ON THE COOL SIDE UNTIL WEDNESDAY AT LEAST. ACTUALLY
HAVE FORECAST A HIGH FOR SEATTLE ON MONDAY OF ONLY 37. BELOW
FREEZING AT NIGHT. ANY PRECIP IS LIKELY TO BE AT LEAST PARTLY IN THE
FORM OF SNOW...BUT MIGHT NOT AMOUNT TO MORE THAN FLURRIES. CHANCE
POPS. LATER IN THE WEEK A NEW SYSTEM DEVELOPS OFFSHORE AND DIVES
INTO OREGON...SOME POTENTIAL FOR SNOW WITH THAT ONE IN THE TUE OR
WED TIME FRAME. BUT NOT HIT THIS ONE TOO HARD YET. BURKE
COLD AIR STARTS TO SEEP INTO REGION SAT NIGHT AND REALLY COMES
THROUGH ON SUNDAY. GFS HAS -15 C OR SO AT 850 MB. DEFINITELY COLD
ENOUGH FOR SNOW BUT THE GFS ALSO PUSHES ALL THE MOISTURE OUT OF THE
WAY. MIGHT GET SOME FLURRIES WITH THE MODIFIED ARCTIC FRONT PASSAGE
ON SUNDAY BUT FOR NOW WILL JUST SAY CHANCE OF SHOWERS. SUNDAY WILL
PROBABLY START WITH WARMEST TEMPS OF THE DAY AT MIDNIGHT AND COOL
THROUGH THE DAY...INTO THE 20S SUNDAY NIGHT.
TEMPS REMAIN ON THE COOL SIDE UNTIL WEDNESDAY AT LEAST. ACTUALLY
HAVE FORECAST A HIGH FOR SEATTLE ON MONDAY OF ONLY 37. BELOW
FREEZING AT NIGHT. ANY PRECIP IS LIKELY TO BE AT LEAST PARTLY IN THE
FORM OF SNOW...BUT MIGHT NOT AMOUNT TO MORE THAN FLURRIES. CHANCE
POPS. LATER IN THE WEEK A NEW SYSTEM DEVELOPS OFFSHORE AND DIVES
INTO OREGON...SOME POTENTIAL FOR SNOW WITH THAT ONE IN THE TUE OR
WED TIME FRAME. BUT NOT HIT THIS ONE TOO HARD YET. BURKE
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Latest NWS Forecast Discussion:
FXUS66 KSEW 231040
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PST THU DEC 23 2004
.SYNOPSIS...AN UPPER RIDGE WILL PRODUCE DRY WEATHER TODAY AND FRIDAY
...BUT IT WILL ALLOW PATCHY NIGHT AND MORNING FOG. TEMPERATURES WILL
BE COLD AGAIN TONIGHT...WITH MANY SPOTS IN WESTERN WASHINGTON BELOW
FREEZING. A FRONT WILL BRING RAIN CHRISTMAS DAY...WITH SNOW IN THE
MOUNTAINS. A BLAST OF COLD AIR WILL FOLLOW THE FRONT...WITH LOW
ELEVATION SNOW POSSIBLE IN SOME AREAS SUNDAY AND EARLY NEXT WEEK.
&&
.DISCUSSION...AN UPPER RIDGE EXTENDS ACROSS THE YUKON FROM THE HIGH
CENTERED NEAR 38N/137W...PRODUCING NLY FLOW ALOFT ALONG MOST OF THE
W COAST OF N AMERICA. LOW LEVEL FLOW REMAINS WEAKLY OFFSHORE ACROSS
WRN WA...AND TEMPS HAVE FALLEN BELOW FREEZING OVER MUCH OF THE AREA
WITH PATCHY FOG.
THE UPPER RIDGE WILL LEAN POSITIVELY AND DROPPING SE ACROSS WRN WA
TONIGHT...OPENING THE DOOR TO THE NEXT FRONTAL SYSTEM UPSTREAM. THE
FRONT WILL MOVE SE ACROSS THE FORECAST AREA SAT MORNING...WITH A
MUCH COLDER AIR MASS PUSHING INTO THE AREA IN ITS WAKE. THE MOST
IMPORTANT WEATHER FEATURE SAT WILL LIKELY BE SNOW IN THE MOUNTAINS.
THE STRENGTH OF THE FRONT AND THE WLY FLOW JUST BEHIND IT SHOULD
EASILY GIVE US SNOW ADVISORY CRITERIA IN THE CASCADES...AND HEAVY
SNOW WARNING AMOUNTS -- 12+ INCHES IN 12 HOURS OR 18+ INCHES IN 24
HOURS -- ARE POSSIBLE.
THE UPPER TROUGH WILL DIG OVER WRN WA SAT NIGHT AND SUN MORNING...
WHILE THE GFS SHOWS A WEAK SURFACE LOW MOVING FROM THE S SIDE OF
VANCOUVER ISLAND INTO NW OREGON. THE EUROPEAN AND UK MODELS SHOW THE
TROUGH DIGGING MUCH MORE STRONGLY THAN THE GFS DOES...WHICH WOULD
PROBABLY BE A DRIER SCENARIO FOR WRN WA...AND THE CANADIAN SEEMS TO
BE BETWEEN THEM. THERE IS EVERY REASON TO BELIEVE THAT THE AIR MASS
WILL BE COLD ENOUGH TO SUPPORT LOW ELEVATION SNOW SAT NIGHT AND SUN
MORNING -- IT STILL LOOKS LIKE THE 1000-850 MB THICKNESS WILL BE
BELOW 1300 M WITH THE 850 MB TEMPS AROUND -7 C. THE LIMITING FACTOR
WILL PROBABLY BE PCPN. WHILE THE COLDEST AIR WILL BE IN THE N
INTERIOR...IT MAY BE ENTIRELY DRY THERE...AND I DON`T EXPECT A PUGET
SOUND CONVERGENCE ZONE. MOST OF THE PCPN WILL PROBABLY FALL ALONG
THE COAST AND IN THE S PART OF WRN WA. SO AT THIS TIME A WIDESPREAD
SIGNIFICANT SNOW EVENT IS UNLIKELY...BUT WE COULD SEE LOCAL AMOUNTS
OF 1 TO 3 INCHES.
I WILL ISSUE A SPECIAL WEATHER STATEMENT WITH THE MORNING PACKAGE TO
TALK ABOUT SNOW OVER THE HOLIDAY WEEKEND.
SUN NIGHT AND MON LOOK MOSTLY DRY AS AN UPPER RIDGE FOLLOWS THE
TROUGH. THE COLD AIR SHOULD STAY IN PLACE OVER WRN WA AS A SURFACE
HIGHS MOVES SE THROUGH BC AND INTO WRN MONTANA. ANOTHER FRONTAL
SYSTEM WILL PROBABLY SPREAD PCPN OVER THE COLD AIR AROUND TUE. THE
LONGER RANGE MODELS HAVE BEEN INCONSISTENT WITH REGARD TO HOW THIS
WILL PLAY OUT...BUT I THINK OUR CURRENT EXTENDED FORECAST COVERS IT
FINE FOR NOW.
MCDONNAL
FXUS66 KSEW 231040
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PST THU DEC 23 2004
.SYNOPSIS...AN UPPER RIDGE WILL PRODUCE DRY WEATHER TODAY AND FRIDAY
...BUT IT WILL ALLOW PATCHY NIGHT AND MORNING FOG. TEMPERATURES WILL
BE COLD AGAIN TONIGHT...WITH MANY SPOTS IN WESTERN WASHINGTON BELOW
FREEZING. A FRONT WILL BRING RAIN CHRISTMAS DAY...WITH SNOW IN THE
MOUNTAINS. A BLAST OF COLD AIR WILL FOLLOW THE FRONT...WITH LOW
ELEVATION SNOW POSSIBLE IN SOME AREAS SUNDAY AND EARLY NEXT WEEK.
&&
.DISCUSSION...AN UPPER RIDGE EXTENDS ACROSS THE YUKON FROM THE HIGH
CENTERED NEAR 38N/137W...PRODUCING NLY FLOW ALOFT ALONG MOST OF THE
W COAST OF N AMERICA. LOW LEVEL FLOW REMAINS WEAKLY OFFSHORE ACROSS
WRN WA...AND TEMPS HAVE FALLEN BELOW FREEZING OVER MUCH OF THE AREA
WITH PATCHY FOG.
THE UPPER RIDGE WILL LEAN POSITIVELY AND DROPPING SE ACROSS WRN WA
TONIGHT...OPENING THE DOOR TO THE NEXT FRONTAL SYSTEM UPSTREAM. THE
FRONT WILL MOVE SE ACROSS THE FORECAST AREA SAT MORNING...WITH A
MUCH COLDER AIR MASS PUSHING INTO THE AREA IN ITS WAKE. THE MOST
IMPORTANT WEATHER FEATURE SAT WILL LIKELY BE SNOW IN THE MOUNTAINS.
THE STRENGTH OF THE FRONT AND THE WLY FLOW JUST BEHIND IT SHOULD
EASILY GIVE US SNOW ADVISORY CRITERIA IN THE CASCADES...AND HEAVY
SNOW WARNING AMOUNTS -- 12+ INCHES IN 12 HOURS OR 18+ INCHES IN 24
HOURS -- ARE POSSIBLE.
THE UPPER TROUGH WILL DIG OVER WRN WA SAT NIGHT AND SUN MORNING...
WHILE THE GFS SHOWS A WEAK SURFACE LOW MOVING FROM THE S SIDE OF
VANCOUVER ISLAND INTO NW OREGON. THE EUROPEAN AND UK MODELS SHOW THE
TROUGH DIGGING MUCH MORE STRONGLY THAN THE GFS DOES...WHICH WOULD
PROBABLY BE A DRIER SCENARIO FOR WRN WA...AND THE CANADIAN SEEMS TO
BE BETWEEN THEM. THERE IS EVERY REASON TO BELIEVE THAT THE AIR MASS
WILL BE COLD ENOUGH TO SUPPORT LOW ELEVATION SNOW SAT NIGHT AND SUN
MORNING -- IT STILL LOOKS LIKE THE 1000-850 MB THICKNESS WILL BE
BELOW 1300 M WITH THE 850 MB TEMPS AROUND -7 C. THE LIMITING FACTOR
WILL PROBABLY BE PCPN. WHILE THE COLDEST AIR WILL BE IN THE N
INTERIOR...IT MAY BE ENTIRELY DRY THERE...AND I DON`T EXPECT A PUGET
SOUND CONVERGENCE ZONE. MOST OF THE PCPN WILL PROBABLY FALL ALONG
THE COAST AND IN THE S PART OF WRN WA. SO AT THIS TIME A WIDESPREAD
SIGNIFICANT SNOW EVENT IS UNLIKELY...BUT WE COULD SEE LOCAL AMOUNTS
OF 1 TO 3 INCHES.
I WILL ISSUE A SPECIAL WEATHER STATEMENT WITH THE MORNING PACKAGE TO
TALK ABOUT SNOW OVER THE HOLIDAY WEEKEND.
SUN NIGHT AND MON LOOK MOSTLY DRY AS AN UPPER RIDGE FOLLOWS THE
TROUGH. THE COLD AIR SHOULD STAY IN PLACE OVER WRN WA AS A SURFACE
HIGHS MOVES SE THROUGH BC AND INTO WRN MONTANA. ANOTHER FRONTAL
SYSTEM WILL PROBABLY SPREAD PCPN OVER THE COLD AIR AROUND TUE. THE
LONGER RANGE MODELS HAVE BEEN INCONSISTENT WITH REGARD TO HOW THIS
WILL PLAY OUT...BUT I THINK OUR CURRENT EXTENDED FORECAST COVERS IT
FINE FOR NOW.
MCDONNAL
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