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NYC/PHL 12/21-12/22 Threat

hazwoper

By hazwoper,
in New York City Metro

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ravensrule

ravensrule

Posted
Posted

yea i know i have seen it sometimes where it has been almost 30-1 ratios. Around here that very rarely happens except for that one clipper in nyc area 2004. It's still fun to look at, it ends the night on a positive note lol

True after this weekends whiff and me wasting 60 hours on this threat i would love to get some decent snow for Christmas.

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earthlight

earthlight

Posted
Posted

Just finished a new forecast on the blog. Included the discussion regarding the threat of interest below. I'm out for tonight dudes.

Long Term

Aforementioned storm system is forecast to track north and east towards the North Atlantic, and then slowly retrograde west as it is captured by the Polar Vortex which phases in late in the Short Term period. The next feature of interest ejects east from the Pacific by early week, and then slides east within the fast upper level flow over the CONUS. Depending on the degree of confluence over the region; i.e how fast the upper level low moves away to the north and east, potential does exist for some flurries or light snow as a northern stream shortwave comes through the Northern Plains and then towards the Mid-Atlantic states. Forecast models have backed off on the potential for light QPF with this event..so we removed pops for now..but they could easily come back in (as slight chance) if later packages see a trend towards some light QPF.

Beyond this, the same general pattern continues with strong blocking in place and an active Pacific flow. Long range models (specifically now GFS and ECMWF) indicate another strong Pacific shortwave ejecting east by Day 5..and interacting with the northern stream by Day 6. The pattern then becomes very complicated as far as the interaction between these two features. Two important features to note on most modeling are the positioning of the blocking to our northeast (stopping the system from cutting northwest) and the presence of a large ridge building on the West coast of the USA (helping in amplification on the East coast).

Medium range (+144-+160) superensemble forecasts are very impressive and trigger some analogs which produced moderate to significant snowfall events in our area. With the ECMWF, GFS and GEFS means strongly supportive of a mean surface low track from the TN Valley off the east coast...we included 30 percent pops on Christmas Day. Too far out to target any specifics as the pattern could very well change significantly from what is modeled.

For temperatures...continued below normal highs and overnight lows.

JH

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atownwxwatcher

atownwxwatcher

Posted
Posted

HPC is getting on board

PRELIMINARY EXTENDED FORECAST DISCUSSIONNWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD400 AM EST SUN DEC 19 2010 VALID 12Z THU DEC 23 2010 - 12Z SUN DEC 26 2010 ...INCREASING CHANCES FOR A MAJOR WINTER STORM FROM THE MIDWEST TOTHE EAST COAST TOWARD CHRISTMAS...USED THE 00Z ECMWF FOR THE PRELIMINARY FRONTS AND PRESSURES FORDAYS 3 THROUGH 7. THE 00Z ECMWF WAS IN PHENOMENALLY GOODAGREEMENT WITH THE GFS WITH THE TRACK AND RELATIVE INTENSITY OFTHE MAJOR WAVE TRACKING ACROSS THE MIDWEST DAY 5 TO OFF THE MIDATLANTIC COAST DAY 7. FURTHERMORE...THE 00Z/19 GEFS MEAN IS VERYCLOSE TO THE 12Z/18 ECENS MEAN WITH THE SAME SYSTEM...ADDITIONALLYPARTICULARLY ROBUST SUPPORT. USED THE ECMWF SINCE ITS DETAILSTEND TO VERIFY BETTER IN THE MEDIUM RANGE...WHICH MAY HELP TO SORTOUT THE NOISY SHORTWAVE ENERGY RESURGING INTO THE WEST THISPERIOD.CISCO

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Sn0waddict

Sn0waddict

Posted
Posted

HPC is getting on board

PRELIMINARY EXTENDED FORECAST DISCUSSIONNWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD400 AM EST SUN DEC 19 2010 VALID 12Z THU DEC 23 2010 - 12Z SUN DEC 26 2010 ...INCREASING CHANCES FOR A MAJOR WINTER STORM FROM THE MIDWEST TOTHE EAST COAST TOWARD CHRISTMAS...USED THE 00Z ECMWF FOR THE PRELIMINARY FRONTS AND PRESSURES FORDAYS 3 THROUGH 7. THE 00Z ECMWF WAS IN PHENOMENALLY GOODAGREEMENT WITH THE GFS WITH THE TRACK AND RELATIVE INTENSITY OFTHE MAJOR WAVE TRACKING ACROSS THE MIDWEST DAY 5 TO OFF THE MIDATLANTIC COAST DAY 7. FURTHERMORE...THE 00Z/19 GEFS MEAN IS VERYCLOSE TO THE 12Z/18 ECENS MEAN WITH THE SAME SYSTEM...ADDITIONALLYPARTICULARLY ROBUST SUPPORT. USED THE ECMWF SINCE ITS DETAILSTEND TO VERIFY BETTER IN THE MEDIUM RANGE...WHICH MAY HELP TO SORTOUT THE NOISY SHORTWAVE ENERGY RESURGING INTO THE WEST THISPERIOD.CISCO

Wowzers no kidding.

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Voyager

Voyager

Posted
Posted

mt holly has 40 i believe, correct me if im wrong but i believe thats what i saw.

Even ultra conservative State College has 40%.

Friday Night: A chance of snow. Mostly cloudy, with a low around 20. Chance of precipitation is 30%.

Christmas Day: A chance of snow. Cloudy, with a high near 27. Chance of precipitation is 40%.

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Edge Weather

Edge Weather

Posted
Posted

PRELIMINARY EXTENDED FORECAST DISCUSSION

NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

900 AM EST SUN DEC 19 2010

VALID 12Z THU DEC 23 2010 - 12Z SUN DEC 26 2010

THE FORECAST SPREAD/SOLUTION ENVELOPE REMAINS SMALLER THAN NORMAL

AS MODELS AND ENSEMBLES AGREE QUITE WELL WITH DEVELOPMENT AND

EVOLUTION OF AN AMPLIFIED AND STEADILY PROGRESSIVE MID-LATITUDE

FLOW PATTERN FROM THE ERN PACIFIC ACROSS THE LOWER 48 OVER THE

COMING HOLIDAY WEEK. THIS STORMY PATTERN WILL BE HIGHLIGHTED BY

THE INLAND SURGE OF DYNAMIC/COOLING/DESTABILILZING SHORT RANGE ERN

PACIFIC TROUGH ENERGY ALOFT OUT FROM THE INTERMOUNTAIN

WEST/ROCKIES THU OVER/THROUGH A MID-UPPER LEVEL MEAN RIDGE

POSITION BEFORE DIGGING/AMPLIFYING SEWD ACROSS THE CENTRAL US AND

INTO AN ERN SEABOARD BY CHRISTMAS. THIS SETS THE STAGE FOR

POTENTIAL FOR A SIGNIFICANT SWATH OF WINTER PCPN ACROSS THE NATION

AND LEADING TO WELL ORGANIZED HOLIDAY WEEKEND EAST COAST WINTER

STORM CYCLOGENESIS. UPSTREAM FLOW ACROSS THE CENTRAL THEN ERN

PACIFIC BY THEN BECOMES MORE OF A MESS HOWEVER WITH INCREASING

SOLUTION SPREAD...SO FORECAST CONFIDENCE DECREASES RAPIDLY WITH

TIME THERE AND INLAND INTO THE WRN US EVEN THOUGH THE BULK OF

GUIDANCE DOES ALLOW ANOTHER POTENT MID-UPPER LEVEL TROUGH TO REACH

THE WEST COAST CHRISTMAS WEEKEND WITH A RENEWED THREAT FOR MORE

HEAVY PCPN/UNSETTLED WEATHER SLAMMING INLAND.

OVERALL...WHILE GUIDANCE DOES OFFER SOME DIFFERENCES AN OVERALL

SOLUTION CLOSE TO THAT SIMILARILY PROVIDED BY RECENT GFS/ECMWF AND

GFS/ECMWF ENSEMBLE MEANS SEEMS REASONABLE AND RUN TO RUN

CONSISTENT. THE MANUALLY ADJUSTED UPDATED HPC PRELIM GUIDANCE

PACKAGE MAINTAINED CLOSE CONTINUITY WITH ONLY SOME MINOR TWEAKS

FROM OUR EARLIER ISSUANCE. HEAVY SENSIBLE WEATHER FOCUS IS OFTEN

MORE FICKLE AS PER IMPORTANT SMALLER SCALE DIFFERENCES AND

INTERACTIONS THAT STILL FALL WITHIN NOISE LEVELS AT MEDIUM RANGE

TIME SCALES...BUT THE FLOW REGIME CERTAINTY SUPPORTS A BUSY/STORMY

HOLIDAY PERIOD.

CISCO/SCHICHTEL

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Ridingtime

Ridingtime

Posted
Posted

FWIW Henry listed some negatives and positives regarding the 12/25 storm - IMHO the positives outweigh the negatives .....

http://www.accuweath...s-day-storm.asp

Not sure what he means at "models not in agreement with this storm" when the GFS and the Euro have been showing "phenomenally good agreement" according to the HPC.

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