Mega Nor'easter slams NE States: Web Cams from area posted

[cycloneye]

GFS on it's 12z run shows a big one. Let's see what the other models have about this.My cousin will travel to Boston that weekend and he has never seen snow,so I guess his wish will come thru.

[cycloneye]

The 12z ECMWF is similar as GFS on track,but less strong on the 26. But,by the 27th,it is very powerful as GFS.

[cycloneye]

Latest HPC discussion:

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
151 PM EST SUN DEC 19 2010

VALID 12Z WED DEC 22 2010 - 12Z SUN DEC 26 2010

...STORMY HOLIDAY WEATHER...

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
OVER THE ERN SEABOARD BY CHRISTMAS. THIS SETS THE STAGE FOR
POTENTIAL FOR A SIGNIFICANT SWATH OF WINTER PCPN ACROSS THE NATION
AND LEADS 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 FINAL HPC GUIDANCE PACKAGE
MAINTAINS CLOSE CONTINUITY AFTER CONSIDERATION OF GENERALLY
SUPPORTIVE LATEST 12 UTC GUDIANCE 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

[Stephanie]

This is probably storm that was initially thought to hit Christmas Eve/Christmas Day. I've noticed that the development had slowed down in the earlier models today.

I don't know if your cousin will make it into Boston if the storm develops. It depends upon when he's traveling versus when the storm comes. I hope that he does get to see some snow for Christmas.

[cycloneye]

Here is the long range discussion from Boston NWS. They are not sold entierly yet on it.

http://forecast.weather.gov/product.php ... hlight=off

CHRISTMAS AND SUNDAY...
THERE IS THE POTENTIAL FOR A SIGNIFICANT WINTER STORM SOMETIME
CHRISTMAS INTO SUNDAY...BUT A LOT HAS TO HAPPEN BETWEEN NOW AND THEN
FOR THIS TO OCCUR. THE 12Z GFS/ECMWF CURRENTLY SHOW LOW PRESSURE
TRACKING ACROSS THE SOUTHERN U.S. INTERACTING WITH A STRONG PIECE OF
NORTHERN STREAM ENERGY. THE MODELS BOTH SHOW THESE TWO FEATURES
COMING TOGETHER OVER THE MID ATLANTIC ALLOWING FOR A STRONG COASTAL
STORM TO DEVELOP. TAKEN VERBATIM...BOTH THE ECMWF/GFS WOULD
INDICATE A STRONG NOREASTER WITH THE POTENTIAL FOR HEAVY SNOW AND
STRONG WINDS.

HOWEVER...ITS IMPORTANT TO REMEMBER THAT THIS POTENTIAL EVENT IS 6
TO 7 DAYS A WAY. ITS ALMOST A GUARANTEE THAT THE MODELS WILL
UNDERGO NUMEROUS CHANGES ON THE EVOLUTION OF THIS POTENTIAL STORM
FOR SEVERAL DAYS. A CHANGE IN TIMING COULD MEAN A LACK OF PHASING
OR ALLOWING THE LOW PRESSURE TO ESCAPE TO OUR SOUTH...MISSING THE
REGION. IN FACT...SEVERAL GFS ENSEMBLES SHOW THE STORM PASSING FAR
ENOUGH SOUTH TO GIVE US JUST A GLANCING BLOW OR A MISS. SO A BIG
STORM IS CERTAINLY NOT A LOCK DESPITE 12Z ECMWF/GFS.

ALL WE CAN SAY IS THERE IS THE POTENTIAL FOR A SIGNIFICANT
STORM...BUT CONFIDENCE IS LOW IN THIS TIME RANGE.

[cycloneye]

This is probably storm that was initially thought to hit Christmas Eve/Christmas Day. I've noticed that the development had slowed down in the earlier models today.

I don't know if your cousin will make it into Boston if the storm develops. It depends upon when he's traveling versus when the storm comes. I hope that he does get to see some snow for Christmas.

Yes,the timing will be very important to see if he arrives in Boston on time before the storm hits.Let's see what happens in the comming days as the models will be finetuning their scenarios as the moment for it to start to develop off the Carolinas draws closer.

[cycloneye]

00z ECMWF has a classic track of a good dose of snow for the NE.GFS is a little more east with the track.

[cycloneye]

Here is the latest HPC discussion that has still some uncertainties about the track.

EXTENDED FORECAST DISCUSSION...NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
215 PM EST MON DEC 20 2010

VALID 12Z THU DEC 23 2010 - 12Z MON DEC 27 2010

SOUTH AND EAST...
THE 12Z ECMWF IS SLOW/MORE CLOSED THAN THE OTHER DETERMINISTIC
GUIDANCE WITH ENERGY MOVING THROUGH THE SOUTHWEST AND SOUTHERN
PLAINS...WITH LESS THAN ONE-QUARTER OF THE OVERALL 00Z GLOBAL
ENSEMBLE GUIDANCE SUPPORTING ITS SOLUTION...IMPLYING IT IS TOO
SLOW. HOWEVER...ALL OF THE 12Z GUIDANCE TRENDED SLOWER WITH THIS
SYSTEMS PROGRESSION...SO SOME SLOWING WAS MADE TO THE MORNING
PRESSURES. TELECONNECTIONS FARTHER NORTH IMPLY STRONGER ENERGY
SHOULD BE MOVING THROUGH THE NORTHERN TIER OF THE COUNTRY RATHER
THAN THE SOUTHERN TIER...WHICH SHOULD ABSORB THE SOUTHWESTERN
ENERGY AS IT MOVES INTO THE PLAINS/MIDWEST. EITHER WAY...A
SURFACE LOW IS EXPECTED TO MOVE THROUGH THE SOUTHERN PLAINS
INTO/NEAR THE DEEP SOUTH BEFORE MOVING OFFSHORE MUCH OF THE
EASTERN SEABOARD. THE BIGGER QUESTION IS HOW CLOSE TO THE NEW
ENGLAND COAST THIS CYCLONE WILL TRACK. THE 00Z ECMWF IS THE MOST
NORTHWESTERLY OF THE GUIDANCE AT THE SURFACE...AND IF THIS SURFACE
LOW WERE MOVING UP THE EAST SIDE OF AN AMPLIFIED TROUGH RATHER
THAN A PROGRESSIVE CLOSED CYCLONE...A MORE COASTAL TRACK FOR NEW
ENGLAND WOULD MAKE SENSE. SINCE THIS DOES NOT APPEAR TO BE THE
CASE...AND THE 12Z ECMWF BACKED OFF THIS IDEA SOMEWHAT...THE 00Z
ECMWF CYCLONE TRACK ALONG THE EAST COAST IS PROBABLY TOO FAR
NORTHWEST/TOO CLOSE TO THE COAST. OTHER GUIDANCE...INCLUDING THE
ENSEMBLE MEAN SOLUTIONS...MOVE THIS SYSTEM CLOSER TO THE GULF
STREAM...A NATURAL BAROCLINIC ZONE/AREA OF TEMPERATURE GRADIENT
OFFSHORE THE EAST COAST...WHICH APPEARS MORE LIKELY CONSIDERING
THE FLOW PATTERN ALOFT. THE 12Z CANADIAN MOVES IT DUE EAST AS IT
EMERGES INTO THE ATLANTIC...TAKING NEW ENGLAND OUT OF THE PICTURE.
DETAIL ISSUES WITH MID-LEVEL CYCLONE PLACEMENT ACROSS EASTERN
CANADA HAVE LED TO INCREASED SPREAD OF THE LOW TRACK AS IT LEAVES
THE EAST COAST. PER PREFERENCES ACROSS THE PLAINS AND WEST LATE
IN THE PERIOD...STARTED WITH THE 00Z CANADIAN HERE...ALTHOUGH THE
00Z ECMWF ENSEMBLE MEAN/00Z GEFS MEAN/12Z GFS ARE REASONABLE
ALTERNATIVES. EITHER WAY...WINTER WEATHER SHOULD SPREAD FROM THE
CENTRAL PLAINS EASTWARD ACROSS THE TENNESSEE VALLEY THROUGH THE
MID-ATLANTIC STATES...AS WELL AS SNOW SHOWERS UNDER THE BASE OF
THE UPPER LEVEL LOW ACROSS THE GREAT LAKES AND NORTHEAST. THE
IMPACT OF THIS SYSTEM ACROSS THE MID-ATLANTIC AND NORTHEAST
REMAINS SOMEWHAT OF A QUESTION MARK...AS THE 12Z GUIDANCE HAS
GENERALLY DRIED OUT OF THE MID-ATLANTIC STATES YET INCREASED
AMOUNTS IN PORTIONS OF SOUTHEAST NEW ENGLAND. FOR THE TIME BEING
THE MORE NORTHWESTERN 00Z ECMWF TRACK AND THE SLOW PACE OF THE 12Z
ECMWF SOLUTION APPEAR TO BE LOWER PROBABILITY ALTERNATIVE
SCENARIOS.

ROTH

[HURRICANELONNY]

Man nobody is barking. Must be the holidays. Could be a big Noreaster. I miss them growing up in pa. Never knew if I'd wake up to a blanket of new snow or a flurrie. Then I had to go to school. Bummer.

[psyclone]

the northeast has another shot after a swing and a miss with the last one.

[angelwing]

I am hearing all kinds of things about this possible snow storm, latest I heard on kyw was "possible snow Christmas day into Sunday", but they didn't say how much. I also heard about a possible 2-4 inches where I live in Lansdale for Christmas and also that AC will have snow...at this point I don't know who to believe.

[cycloneye]

It looks like things are comming together and the consensus is more solid for a mega storm for the Mid-Atlantic and NE.

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
308 AM EST TUE DEC 21 2010

VALID 12Z SAT DEC 25 2010 - 12Z TUE DEC 28 2010


...CHRISTMAS WEEKEND NOREASTER STILL ON TRACK...
...MOIST PACIFIC JET SHIFTS AIM TO THE NORTHWEST COAST...


THE PRELIMINARY FRONTS AND PRESSURES FOR DAYS 3 THROUGH 7 ARE
BASED ON THE 00Z/21 DETERMINISTIC ECMWF. THE GEM GLOBAL IS CLOSE
TO THE ECMWF WITH THE HANDLING OF THE WAVE CROSSING THE DEEP SOUTH
AND TURNING UP THE ATLANTIC SEABOARD...SAVE A TIMING LEAD OF ABOUT
6 HOURS THROUGH DAY 5...AND A PULL TO THE LEFT INLAND THEREAFTER.
THE TREND IN ALL THE GUIDANCE OVER THE PAST COUPLE DAYS HAS BEEN
SLOWER WITH THIS SYSTEM...DUE TO THE DISTURBANCE TAKING THE SCENIC
ROUTE...SO TO SPEAK...ALONG THE GULF COAST BEFORE HEADING TO THE
MID ATLANTIC WATERS. THE MORE SOUTHERLY TRACK OWES TO MUCH LESS
INTERACTION WITH SHORTWAVE ENERGY CROSSING THE DAKOTAS AND UPPER
MIDWEST...WHICH IS USUALLY THE CASE WHEN STRONG BLOCKS LIKE THE
ONE THIS MONTH REFLEX THEIR SUPPRESSIVE MIGHT. THE GFS TAKES UP
THE NORTHERN/FAST SIDE OF THE 00Z/21 GUIDANCE ENVELOPE...WITH THE
UKMET DEFINING THE SOUTHERN EDGE. THE ECMWF IS PREFERRED OVER THE
EAST DUE TO ITS SLOWER SOLUTION AND MORE CLIMATOLOGICAL LOW TRACK
ALONG THE WESTERN EDGE OF THE WARM WATERS ASSOCIATED WITH THE GULF
STREAM. THE ECMWF IS ALSO PREFERRED OVER THE WEST...PRIMARILY
BECAUSE ITS SEA LEVEL PRESSURES TEND TO VERIFY BEST AT THE MEDIUM
RANGE. THE REINTENSIFICATION OF THE EASTERN TROUGH/VORTEX SHOULD
SHUNT THE UPSTREAM FLOW COMING OFF THE PACIFIC NORTHWARD TO THE
OREGON AND WASHINGTON COASTS THIS PERIOD AS PER THE ECMWF.

THE ECMWF TRACK OF THE EAST COAST CYCLONE WOULD HAVE HIGH IMPACT
OVER THE HOLIDAY WEEKEND ALONG AND EAST OF THE INTERSTATE 95
CORRIDOR FROM WASHINGTON TO BOSTON. OF PARTICULAR CONCERN IS THE
SLOW CRAWL OF THE MATURE STORM TOWARD THE ATLANTIC BENCHMARK SOUTH
OF LONG ISLAND THE DAY OR TWO AFTER CHRISTMAS. THIS PHASE OF THE
STORM WOULD COME ABOUT ONLY IF THE MID LEVEL TROUGH IS ABLE TO
CLOSE OFF...WHICH IS ENTIRELY POSSIBLE IN THE STRONG BLOCKING
REGIME. WILL MANUALLY MOVE THE CENTER ALONG SLIGHTLY FASTER LATE
DAY 6 INTO DAY 7 THAN THE RAW ECMWF RUN WOULD INDICATE...BASED ON
THE WEIGHT OF THE ENSEMBLES AND OTHER DETERMINISTIC MODELS.


CISCO

[cycloneye]

12z Canadian has a monster nor'easter.

http://moe.met.fsu.edu/cgi-bin/cmctc2.c ... =Animation

[srainhoutx]

Luis, your brother but get ready. If the Euro is correct the qpf output suggest 2 feet of snow in Boston. All the of the I-95 corridor is at or near the 1 foot range as well.

[cycloneye]

Luis, your brother but get ready. If the Euro is correct the qpf output suggest 2 feet of snow in Boston. All the of the I-95 corridor is at or near the 1 foot range as well.

Yikes Steve,that is a powerhouse blizzard type that the Euro has at 12z.I think my cousin will be stuck in Boston for a while as he has to travel to Rhode Island.

[cycloneye]

Here is the text by HPC this afternoon about the east coast storm.

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
302 PM EST TUE DEC 21 2010

VALID 12Z FRI DEC 24 2010 - 12Z TUE DEC 28 2010


...POTENTIAL EAST COAST WINTER STORM AFTER CHRISTMAS...

THE MAIN ISSUE INVOLVES THE INTERACTION OR PHASING
OF MULTIPLE STREAMS OVER THE EASTERN CONUS...WHICH MAY RESULT IN A
SIGNIFICANT EAST COAST WINTER STORM BEGINNING DAY 4. OWING TO
UNCERTAINTY IN INITIAL CONDITIONS...DIFFERENCES IN MODEL
CONFIGURATIONS INCLUDING RESOLUTION...AND DIFFERENCES IN DATA
ASSIMILATION TECHNIQUES...DETERMINISTIC GUIDANCE IN THIS REGION IS
UNUSUALLY SENSITIVE...WITH LARGE DIFFERENCES BETWEEN INDIVIDUAL
MODELS...POOR RUN-TO-RUN CONTINUITY...AND LARGE ENSEMBLE SPREADS.
THUS...THE APPROACH FOR THE EASTERN CONUS SYSTEM IS TOWARD THE
MODEL CONSENSUS AND FORECAST CONTINUITY. THE ONLY ADJUSTMENT MADE
WITH THE FINAL PRESSURES/FRONTS PROGS IN THE EAST WAS TO NUDGE THE
FINAL POSITIONS AND INTENSITY OF THE DEVELOPING CYCLONE TOWARD A
CONSENSUS OF THE LAST 2 RUNS OF THE ECMWF/12Z CANADIAN/00Z ECMWF
ENSEMBLE MEAN...WITH THE FINAL POSITIONS CLOSEST TO THE 00Z ECMWF.
AFTER DISCOUNTING THE 12Z UKMET DUE TO ITS OUTLIER DEPICTIONS IN
MULTIPLE AREAS...THE 12Z ECMWF LIES NEAR THE SLOW OR SOUTHWESTERN
EDGE OF THE ENTIRE GUIDANCE ENVELOPE...AND GIVEN THE MULTIPLE
UNCERTAINTIES HIGHLIGHTED ABOVE...WOULD RATHER SEE ADDITIONAL
GUIDANCE COME INTO BETTER AGREEMENT WITH THE 12Z ECMWF BEFORE
USING ENTIRELY...WHICH IN TERMS OF PROBABILITIES...LIES WITHIN THE
LOWEST 10 PERCENT OF ALL SOLUTIONS...POSSIBLY A LITTLE LESS. IF
THE NEW ECMWF VERIFIES...THE FORECAST TRACK OF THE DEVELOPING LOW
WILL NOT CHANGE APPRECIABLY. HOWEVER...ITS SPEED WILL BE MUCH
SLOWER...RESULTING IN GREATER MOISTURE TRANSPORT FROM THE ATLANTIC
AND THE POTENTIAL FOR HIGHER QPF THAN CURRENTLY FORECAST.

JAMES

[HURRICANELONNY]

Here is the text by HPC this afternoon about the east coast storm.

EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
302 PM EST TUE DEC 21 2010

VALID 12Z FRI DEC 24 2010 - 12Z TUE DEC 28 2010


...POTENTIAL EAST COAST WINTER STORM AFTER CHRISTMAS...

THE MAIN ISSUE INVOLVES THE INTERACTION OR PHASING
OF MULTIPLE STREAMS OVER THE EASTERN CONUS...WHICH MAY RESULT IN A
SIGNIFICANT EAST COAST WINTER STORM BEGINNING DAY 4. OWING TO
UNCERTAINTY IN INITIAL CONDITIONS...DIFFERENCES IN MODEL
CONFIGURATIONS INCLUDING RESOLUTION...AND DIFFERENCES IN DATA
ASSIMILATION TECHNIQUES...DETERMINISTIC GUIDANCE IN THIS REGION IS
UNUSUALLY SENSITIVE...WITH LARGE DIFFERENCES BETWEEN INDIVIDUAL
MODELS...POOR RUN-TO-RUN CONTINUITY...AND LARGE ENSEMBLE SPREADS.
THUS...THE APPROACH FOR THE EASTERN CONUS SYSTEM IS TOWARD THE
MODEL CONSENSUS AND FORECAST CONTINUITY. THE ONLY ADJUSTMENT MADE
WITH THE FINAL PRESSURES/FRONTS PROGS IN THE EAST WAS TO NUDGE THE
FINAL POSITIONS AND INTENSITY OF THE DEVELOPING CYCLONE TOWARD A
CONSENSUS OF THE LAST 2 RUNS OF THE ECMWF/12Z CANADIAN/00Z ECMWF
ENSEMBLE MEAN...WITH THE FINAL POSITIONS CLOSEST TO THE 00Z ECMWF.
AFTER DISCOUNTING THE 12Z UKMET DUE TO ITS OUTLIER DEPICTIONS IN
MULTIPLE AREAS...THE 12Z ECMWF LIES NEAR THE SLOW OR SOUTHWESTERN
EDGE OF THE ENTIRE GUIDANCE ENVELOPE...AND GIVEN THE MULTIPLE
UNCERTAINTIES HIGHLIGHTED ABOVE...WOULD RATHER SEE ADDITIONAL
GUIDANCE COME INTO BETTER AGREEMENT WITH THE 12Z ECMWF BEFORE
USING ENTIRELY...WHICH IN TERMS OF PROBABILITIES...LIES WITHIN THE
LOWEST 10 PERCENT OF ALL SOLUTIONS...POSSIBLY A LITTLE LESS. IF
THE NEW ECMWF VERIFIES...THE FORECAST TRACK OF THE DEVELOPING LOW
WILL NOT CHANGE APPRECIABLY. HOWEVER...ITS SPEED WILL BE MUCH
SLOWER...RESULTING IN GREATER MOISTURE TRANSPORT FROM THE ATLANTIC
AND THE POTENTIAL FOR HIGHER QPF THAN CURRENTLY FORECAST.

JAMES

[cycloneye]

GFS is the outlier as many of the discussions by the regional NWS are saying.This one is from Mount Holly,NJ.

http://forecast.weather.gov/product.php ... hlight=off

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...

ALL EYES REMAIN FOCUSED ON AN EVENT FOR THE SECOND HALF OF THE
HOLIDAY WEEKEND.

SOME OF THE MODEL GUIDANCE HAS COME INTO BETTER AGREEMENT, BUT
THERE REMAINS ENOUGH OF A SPREAD AND AT DAY 5, THIS STILL REMAINS
A LOWER THAN AVERAGE CONFIDENCE FCST.

ONE TREND THAT HAS DEVELOPED IS THAT VIRTUALLY ALL OF THE
GUIDANCE, WITH THE EXCEPTION OF THE GFS HAS TRENDED SLOWER WITH
THE UPCOMING STORM. AS A RESULT, CHRISTMAS DAY NOW LOOKS DRY,
DEPENDING ON THE ULTIMATE TIMING, SATURDAY NIGHT COULD END UP
MOSTLY DRY AS WELL.

VIRTUALLY ALL OF THE MDLS WANT TO BRING AT LEAST SOME PRECIP TO
THE AREA DURG THE SUNDAY INTO MONDAY TIME FRAME. THE MAIN
QUESTIONS REMAIN THE TIMING ULTIMATE PATH OF THE STORM WHICH WILL
AFFECT PRECIP AMTS (AND PSBLY PRECIP TYPE AS WELL).

THE 12Z GFS HAS A MUCH WEAKER SFC LOW, VIRTUALLY NO WELL DEFINED
VORT AND AS A RESULT IS MUCH MORE PROGRESSIVE WITH THE H5 PATN AND
KEEPS A MUCH WKR SFC LOW WELL TO OUR S AND E. THE 12Z GFS SOLN IS
AS CLOSE TO A NON-EVENT AS THE MDLS ARE SHOWING ATTM. HOWEVER, THE
GFS IS THE OUTLIER AND IS BEING DISCOUNTED ATTM.

THE 12Z UKMET HAS STUCK TO ITS GUNS ONCE AGAIN WITH A MORE ELY
SOLN, EVEN THOUGH IT HAS TRENDED WWD WITH ITS LATEST CYCLE. ITS
POSN AT 27/12Z IS WELL OFF THE NC CST. THE UKMET TENDS TO BE ONE
OF THE MORE RELIABLE MDLS, SO WHILE IT IS AN OUTLIER WITH THE
LATEST MDL CYCLE, IT REMAINS TO BE SEEN IF IT WILL CONTINUE TO BE
SO.

THE LATEST CMC HAS TRENDED A BIT SLOWER AND FURTHER E AT 12Z,
AFTER A MARKED WWD SHIFT LAST NIGHT. ON THE OTHER HAND, THE 12Z
ECMWF HAS TRENDED SLOWER BUT FURTHER W. BOTH THE CMC AND ECMWF
SOLNS WOULD BE A MORE SIGNIFICANT EVENT FOR THE REGION, WITH THE
ECMWF POSN ULTIMATELY BRINGING PRECIP TYPE INTO QUESTION
ESPECIALLY FOR SRN AND ERN SECTIONS.

THE LATEST NAEFS STILL INDICATES MORE OF A GLANCING BLOW FOR THE
REGION, WITH THE INDIVIDUAL MEMBERS PRESENTING ALL DIFFERENT
SCENARIOS.

SO, WHAT DOES THIS ALL MEAN? WELL, UNCERTAINTY PREVAILS, AS IT
SHOULD AT DAY 5, BUT INDICATIONS ARE THAT AT LEAST SOMETHING WILL
OCCUR IN THE SUNDAY/MONDAY TIME FRAME. AGAIN, THE UKMET WOULD AND
GFS WOULD INDICATE THE MOST MINIMAL EVENTS WITH THE CMC AND ECMWF
BEING MORE SIGNIFICANT. THE ULTIMATE TIMING, TRACK AND INTENSITY
OF THE LOW DETERMINE WHAT OCCURS AND THOSE DETAILS WILL HOPEFULLY
BE REFINED BY THE MDLS IN THE COMING DAYS. MDL POSNS VARY EXCEPT
FOR THE CMC AND ECMWF, WHERE THERE ARE TIMING DIFFS.

DEPENDING ON THE TIMING OF THE SYSTEM IT COULD BE OVER EARLY
MONDAY OR LINGER A BIT LONGER AS WELL, WITH IMPROVING CONDS. DRY
AND WINDY WX WILL BE IN STORE FOR TUESDAY WITH HIGH PRESSURE TO
THE W. IT WILL BE COLD THRU THE PD, WITH TEMPS AVERAGING 5-10
DEGREES BELOW NRML

[Stephanie]

Well, I am seeing my family on December 26, so I do hope that IF the storm develops, which it certainly does look like it will, it'll occur later in the evening. I would hate to see anyone's actual Christmas Day's festivities be impacted.

Winter of 2009-2010 redux???

[cycloneye]

A very good discussion by HPC about this potential big nor'easter.

http://www.hpc.ncep.noaa.gov/preepd/preepd.html

PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
312 AM EST WED DEC 22 2010

VALID 12Z SUN DEC 26 2010 - 12Z WED DEC 29 2010


...EUROPEAN CENTRE GUIDANCE STAYS THE COURSE ON POWERFUL EAST
COAST STORM DECEMBER 26-27...

WILL STICK WITH THE CONSISTENT ECMWF FOR THE PRELIMINARY FRONTS
AND PRESSURES FOR DAYS 3-7. FOR THREE CONSECUTIVE MODEL
CYCLES...THE DETERMINISTIC ECMWF HAS INDICATED A
MASSIVE...DEEP...SLOW-MOVING CYCLONE HUGGING THE CAROLINA AND MID
ATLANTIC COASTS THE TWO DAYS FOLLOWING CHRISTMAS. THE ECMWF AND
UKMET WERE THE FIRST OF THE GLOBAL NUMERICAL MODELS TO SWITCH FROM
TRACKING THIS WAVE ALONG 40N THROUGH THE MIDWEST...TO A SUPPRESSED
PATH ACROSS THE DEEP SOUTH. SINCE THIS BREAK-AWAY...THE UKMET
SPLIT OFF EVEN FARTHER SOUTH...WITH THE ECMWF LOCKING ONTO AN
EVOLUTION THAT TAKES THE DEVELOPING LOW TO THE FLORIDA PANHANDLE
AND THEN SHARPLY UP THE EASTERN SEABOARD. THE GEM GLOBAL FOLLOWED
THE EUROPEAN CENTRE TRACK ON ITS 00Z/21 RUN...BUT HAS SWUNG THE
SYSTEM OUT WIDER OVER THE ATLANTIC THE LAST TWO RUNS. THE GFS HAS
SHIFTED TO THE SOUTHERN ROUTE ACROSS THE GULF STATES ON ITS
CURRENT RUN...BUT LIKE THE GEM GLOBAL...DIRECTS THE CYCLONE WELL
SOUTH AND EAST OF CAPE HATTERAS. THE ECENS MEMBERS HAVE AVERAGED
CLOSE TO THE DETERMINISTIC ECMWF...WITH MANY MEMBERS FOLLOWING IT
EXACTLY...AND OTHERS TRACKING A BIT FARTHER OFFSHORE. THE
EUROPEAN CENTRE GUIDANCE HAS THE ADVANTAGE IN DEVELOPMENTAL
SYSTEMS WITH ITS HIGH RESOLUTION...AND IS FURTHER AIDED BY ITS
4D-VAR ANALYSIS IN GENERAL. ITS ENSEMBLE MEMBERS ARE MORE HIGHLY
RESOLVED THAN THE GEFS MEMBERS...AND WITH DYNAMIC...DEVELOPMENTAL
SYSTEMS...THE EUROPEAN GUIDANCE SHOULD HAVE THE EDGE.
INDEED...THE GEFS MEAN HAS BEEN CONSISTENTLY FLATTER WITH THE PATH
OF THE BIG STORM...WHICH IS CERTAINLY IN LINE WITH THE LOWER
RESOLUTION. EVEN SO...FOUR 00Z/22 GEFS MEMBERS STILL TRACKED
COMPARABLY TO THE ECMWF...SHOWING A DEEP NOREASTER AND A HIGH
IMPACT STORM FOR THE MAJOR METROPOLITAN AREAS ASTRIDE INTERSTATE
95 FROM WASHINGTON TO BOSTON. TO WIT...THESE GEFS MEMBERS ARE
GOING AGAINST THEIR LOWER RESOLUTION/LESS DEVELOPMENTAL NATURE.
THE ECMWF HAS MUCH CLIMATOLOGY ON ITS SIDE AS WELL...WITH ITS
TRACK WEST OF THE GULF STREAM...AND THE BOMBING PHASE NEAR AND
NORTH OF CAPE HATTERAS.

THE MOST UNUSUAL...AND THREATENING...ASPECT OF THE ECMWF FORECAST
IS THE RELATIVELY LOW LATITUDE AT WHICH THE STORM MATURES AND
STALLS/LOOPS. MORE TYPICALLY...SYSTEMS WILL CLOSE OFF AND HOVER
OVER THE WATERS SOUTH OF NOVA SCOTIA...AS WITH THE MOST RECENT
CYCLONE STILL AFFECTING DOWNEAST MAINE. THE ECMWF SHOWS THE
UPCOMING CIRCULATION COMING TO A HALT JUST EAST OF THE DELMARVA
PENINSULA...WHICH PUTS THE VERY POPULATED AREAS OF THE EASTERN MID
ATLANTIC...LONG ISLAND...AND SOUTHERN NEW ENGLAND IN A PROLONGED
PERIOD OF HIGH WINDS AND HEAVY PRECIPITATION...MOSTLY SNOW. THE
EXTRAORDINARY NEGATIVE NAO THIS MONTH COULD CERTAINLY SUPPORT SUCH
AN ANOMALY. EVEN BEFORE THE RAPID DEEPENING PHASE OF THE
SYSTEM...AREAS OF THE DEEP SOUTH FROM THE INTERIOR GULF COAST
STATES TO GEORGIA AND THE MOUNTAINS AND PIEDMONT OF THE CAROLINAS
MAY SEE A VERY RARE WHITE CHRISTMAS...AGAIN...CONSISTENT WITH THE
REMARKABLE DISRUPTION AT HIGH LATITUDES.

WHILE THE EASTERN VORTEX RELOADS AND EXPANDS...THE FLOW STREAMING
OFF THE PACIFIC WILL BE LARGELY SHUNTED FARTHER NORTH THAN RECENT
DAYS...WITH THE POLAR JET TAKING AIM AT THE WASHINGTON COAST.
SOME FLOW WILL SPLIT INTO THE FAR SOUTHWEST...BUT WITH NOT NEARLY
THE ROBUSTNESS OF THE PAST WEEK.


CISCO