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February Winter Storm Prospects


WeatherX

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HPC

http://www.hpc.ncep.noaa.gov/discussions/hpcdiscussions.php?disc=pmdhmd

PREFERENCE: GFS

THE NAM DIRECTS THIS WAVE SLIGHTLY EAST OF THE ECMWF...WITH A

RETURN INFLUX OF MOISTURE AT LEAST 12 HOURS FASTER FROM THE GULF

OF MEXICO. BY 00Z/04 SATURDAY...THE NAM HAS SPREAD THE BEST LOW

LEVEL FORCING NORTH OF THE OHIO RIVER IN ILLINOIS AND INDIANA. BY

THE MIDDLE OF DAY 3...THE NAM SHEARS SIGNIFICANT MID LEVEL

MOISTURE EASTWARD ALL THE WAY TO THE MID ATLANTIC COAST...WITH

LESS SUPPRESSION INDICATED FROM THE NORTHERN STREAM THAN THE

ECMWF. THE GFS SOLUTION IS ROUGHLY TWO-THIRDS OF THE WAY TOWARD

THE NAM PROGRESSION/PLACEMENT FROM THE ECMWF...A POSITION WHICH IS

HARMONIOUS WITH MULTI-DAY MEANS. THE GEM GLOBAL AND UKMET ARE

BETWEEN THE ECMWF AND GFS SOLUTIONS.

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HPC is going with the GFS while Upton is going with the Euro.

where do you see that ? HPC supports the euro

EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

229 PM EST WED FEB 01 2012

VALID 12Z SAT FEB 04 2012 - 12Z WED FEB 08 2012

THE HIGHEST CONFIDENCE FEATURE ON TODAYS MEDIUM RANGE WEATHER

CHARTS IS A NEGATIVE HEIGHT ANOMALY CENTERED ROUGHLY NEAR

40N/155W. WHILE THE MEDIUM RANGE STARTS OUT WITH PREDOMINANTLY

ABOVE NORMAL HEIGHTS OVER MUCH OF NOAM...THE MEAN POSITION OF THE

NEGATIVE PACIFIC HEIGHT ANOMALY...COMBINED WITH A SHARPENING RIDGE

OVER WRN CANADA/ERN ALASKA...EVENTUALLY FAVORS THE DEVELOPMENT OF

A SIGNIFICANT DOWNSTREAM TROF ALONG THE ATLANTIC COAST. MOST

GUIDANCE SUGGESTS THAT RAPID STRENGTHENING/SHARPENING OF THE RIDGE

OVER WRN CANADA/ERN ALASKA ...COMBINED WITH FAIRLY STRONG POSITIVE

HGT ANOMALIES OVER THE ERN/NRN ATLC BY MID-LATE PERIOD SHOULD

PROMOTE SIGNIFICANT ERN NOAM TROFFING.

NO CHANGES WERE MADE TO THE FINAL GRAPHICS. THE NEW 12Z ECMWF

CONFIRMED OUR EARLIER DECISION

TO SUBSTITUTE THE 00Z/01 ECMWF ENSEMBLE MEAN IN OUR UPDATED PRELIM

BLEND FORM THE CORRESPONDING 12Z/12 ECMWF MEAN. THIS KEPT US

AWAY FROM THE GFS/GEFS ENSEMBLE MEAN FAMILY OF SOLUTIONS. THE

ECMWF SPAGHETTI PLOTS WERE REASONABLY CLUSTERED ON THEIR PHASING

OF KEY SHORTWAVE FEATURES AFFECTING THE LOWER 48 THIS PERIOD.

THE NEW 12Z GFS RUN WAS CONSISTENT WITH ITS 00Z RUN...KEEPING IT

AT ODDS WITH THE THE PREFERRED SLOWER 00Z/01 ECMWF/ECENS

MEAN/UKMET GUIDANCE WE USED IN THE UPDATED PRELIM. THE

INTERMEDIATE 06Z GFS RUN HAD TRENDED TOWARDS THE PREFERRED ECMWF

SOLUTION FOR DAYS 4-5. THE NEW 12Z GFS RUN USED NRN STREAM ENERGY

FROM CANADA TO SHEAR OUT THE CLOSED LOW FORMING IN THE CENTRAL

PLAINS STATES LATE SAT. THIS NRN STREAM ENERGY THEN TAKES OVER AND

WHISKS THE SYS RAPIDLY EWD ACROSS THE MID ATLANTIC REGION ON SUN.

THE 12Z/01 UKMET HANDLED THE CENTRAL PLAINS CLOSED LOW FAIRLY

SIMILARLY TO OUR PREFERRED 00Z/01 ECMWF/ECENS MEAN/UKMET

SOLUTIONS. THE CANADIAN GOT OVER 12 HOURS FASTER THAN THE UKMET BY

SUN DAY 4 IN MOVING THE CLOSED LOW OUT BUT STILL KEEPS IT INTACT.

THE REX BLOCK CONFIGURATION IN PLACE AT THE START OF THE MEDIUM

RANGE PERIOD FAVORS THE SLOWER ECMWF CLUSTER THAT ULTIMATELY

BRINGS THE CNTRL PLAINS FEATURE TOWARD THE UPR MS VLY OR GRTLKS

MON. THE 12Z/01 ECMWF TRUMPED THE OTHER 12Z DETERMINISTIC GUIDANCE

CONTINUITY-WISE AND GAVE VERY GOOD SUPPORT TO OUR IDEAS IN THE

PRELIM PROGS.

DAYS 6-7 TUE-WED... GUIDANCE DETAILS DIFFER SOMEWHAT BUT THERE IS

GOOD AGREEMENT FROM THE ENSEMBLE MEANS/ECMWF/CMC TOWARD LOWER ERN

CONUS HGTS THAN FCST BY THE GFS DAY 6 AS PER TELECONNECTIONS ON

THE TROF/RIDGE PATTERN UPSTREAM. FARTHER WWD...GIVEN THE TIME

RANGE...THERE WAS FAIRLY GOOD AGREEMENT IN REGARD TO ERN PAC

ENERGY FCST TO REACH THE WEST COAST AROUND TUE. THE NEW 12Z ECMWF

WAS ON TRACK HERE. THE NRN PART OF THIS ENERGY SHOULD WEAKEN AS IT

HEADS INTO THE WRN NOAM MEAN RIDGE WHILE SRN ENERGY SHOULD SETTLE

INTO A DEVELOPING MEAN TROF NEAR BAJA CALIF. CA COULD SEE SOME

PRECIP FROM THIS SYS TUE OR WED. THE ONLY OTHER IMPORTANT PCPN

EVENT SHOULD OCCUR OVER THE WEEKEND IN ASSOCIATION WITH THE SYS

SCOOTING E FROM THE MID MS VLY INTO THE MID ATLANTIC. AN ARCTIC

FRONT MAY USHER IN COLDER AIR INTO THE NE BY THE END OF THE

PERIOD.

FLOOD

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Model Diagnostic Discussion-written by Cisco is where Snow88 gets his info from.

Extended Forecast Discussion written by Flood at HPC is where WeatherX is getting his from.

Seems as if they don't talk to each other down at HPC?? :axe:

http://www.hpc.ncep....l/discuss.shtml

He selectively skipped reading the final HPC disco, because the model diagnostics sounded better.

:weenie:

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john

i think you're onto something when you said yesterday that the heightened period for next week may be very short lived. Here's PHL AFD...They have been using the NAEFS and it's worked out pretty well for them. Also the way they do their afd's is amazing. Take a look at this. it's a little depressing though:

THE WARMEST METEOROLOGICAL WINTER ON RECORD IN PHILADELPHIA WAS IN 1931-32 WITH AN AVERAGE TEMPERATURE OF 43.3 DEGREES. THIS WAS DURING AN ENSO NEUTRAL WINTER. WHILE THE WEATHER PATTERN WILL GET COLDER NEXT WEEK, WE ARE LOOKING AT THIS RELATIVELY SPEAKING AFTER A WEEK IN WHICH WE HAVE HAD DOUBLE DIGIT ABOVE DEPARTURES FROM NORMAL. ONE OF THE BIGGEST REASONS THIS WINTER HAS BEEN SO UNSEASONABLY WARM HAS BEEN THAT THE NORTH ATLANTIC OSCILLATION HAS SPENT NEARLY THE ENTIRE SEASON SO FAR IN A POSITIVE MODE. WHEN THIS TELECONNECTION INDEX IS POSITIVE, COLD AIR MASSES IN CANADA ARE NOT BLOCKED FROM EXITING TO THE EAST. THUS EVEN WHEN THE CONTINENTAL NORTH AMERICAN WEATHER PATTERN HAS BEEN COLDER, THESE SHOTS OF COLDER THAN NORMAL AIR HAVE BEEN ABLE TO MAKE A HASTY EXIT OFF THE EAST COAST. THE LATEST NORTH ATLANTIC OSCILLATION OUTLOOK OFF THE GFS MODEL HAS IT NEAR NEUTRAL THROUGH ABOUT THE 6TH OF THIS MONTH AND THEN TURNING POSITIVE AGAIN THROUGH THE MIDDLE OF THE MONTH. THE OFFICIAL CPC OUTLOOK FOR THE MONTH OF FEBRUARY FAVORS WARMER THAN NORMAL WEATHER TO CONTINUE ACROSS OUR REGION. THIS BEGS THE QUESTION TOMORROW IF PUNXSUTAWNEY PHIL SEES HIS SHADOW, DOES THAT MEAN WE HAVE SIX MORE WEEKS OF THIS KIND OF WINTER?

THE TEN WARMEST WINTERS ON RECORD IN PHILADELPHIA, OUR CURRENT RANK AND THE PACIFIC ENSO STATE.

1931-32...43.3 DEGREES...ENSO NEUTRAL

1889-90...42.2 DEGREES...WEAK LA NINA

2001-02...41.3 DEGREES...ENSO NEUTRAL

2011-12...40.6 DEGREES THRU JAN 31 WITH A BORDERLINE WEAK TO MDT LA

NINA

1997-98...40.4 DEGREES...ONE VERY STRONG EL NINO

1932-33...39.9 DEGREES...ENSO NEUTRAL

1879-80...39.7 DEGREES...WEAK LA NINA

1990-91...39.1 DEGREES...ENSO NEUTRAL

1912-13...39.0 DEGREES...ENSO NEUTRAL

1936-37...39.0 DEGREES...ENSO NEUTRAL

1948-49...38.8 DEGREES...ENSO NEUTRAL

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The 18z GFS super ensemble is still indicative of a favorable pattern through days 8 to 14. I don't think there is any reason to veer from the original idea of February 10-15 offering the potential for a moderate winter storm and below normal temperature departures.

Maybe near normal? Below normal temps would be a stretch along with any snow chances. That map is pretty ugly actually as Canada is flooded with warmth.

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Maybe near normal? Below normal temps would be a stretch along with any snow chances. That map is pretty ugly actually as Canada is flooded with warmth.

Are you this dense?

2009-2010 winter, all of Canada was above normal, yet that due to the great Greenland block, it didn't stop us from getting a boatload of snow for the season along with 4 KU events.

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Maybe near normal? Below normal temps would be a stretch along with any snow chances. That map is pretty ugly actually as Canada is flooded with warmth.

Those are 500mb height anomalies, not surface temperatures. So the anomalies are showing positive departures in favorable areas for us. The are positive departures centered both over Greenland and British Columbia in relation to a west coast/western Canada ridge and some ridging near the NAO region.

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http://www.cpc.ncep....index_ensm.html

The NAO is definitely the number one reason why this winter has been so abnormally warm. It went slightly negative once since Dec 1, and you have to go back to October to see just more sustained slightly negative conditions.

I didn't totally agree with PHL on that one, the problem has more been the GOA low, the NAO can be -5 but if the GOA low is there its still gonna be above normal. We had a very +NAO in 93-94 and a large portion of 02-03 the NAO was positive...at the end of the day if you have the BC or GOA ridge you can do fine with a +NAO.

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I didn't totally agree with PHL on that one, the problem has more been the GOA low, the NAO can be -5 but if the GOA low is there its still gonna be above normal. We had a very +NAO in 93-94 and a large portion of 02-03 the NAO was positive...at the end of the day if you have the BC or GOA ridge you can do fine with a +NAO.

very interesting points...i am praying that the next ten days delivers

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I didn't totally agree with PHL on that one, the problem has more been the GOA low, the NAO can be -5 but if the GOA low is there its still gonna be above normal. We had a very +NAO in 93-94 and a large portion of 02-03 the NAO was positive...at the end of the day if you have the BC or GOA ridge you can do fine with a +NAO.

Well... you could always go over to the Philly subforum and argue the point with Rainshadow (he's the author).

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The GFS has had a cutoff for days. Not sure what people are talking about.

The idea of the cutoff was modeled beautifully by the GFS 2 days before the euro caught on and the GFS never waivered. The euro had the cutoff idea in the fantasy range but lost it for several runs in the medium range and didn't catch on until inside of 96 hours.

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Those are 500mb height anomalies, not surface temperatures. So the anomalies are showing positive departures in favorable areas for us. The are positive departures centered both over Greenland and British Columbia in relation to a west coast/western Canada ridge and some ridging near the NAO region.

Yes, I translated those anomalies to what the surface tempearture departures would be given the pattern.

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