Moisture Transport from GOM Picking Up
Posted by JAC on 12/25/2010, 6:28 pm



PROBABILISTIC HEAVY SNOW AND ICING DISCUSSION
NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD
520 PM EST SAT DEC 25 2010

VALID 00Z SUN DEC 26 2010 - 00Z WED DEC 29 2010

DAYS 1-3...

...SOUTHEAST/MID ATLANTIC/NORTHEAST...
MODELS ARE CONVERGING ON A CYCLONE TRACK FOR A LOW FORECAST TO
DEVELOP OFF THE SOUTHEAST COAST TONIGHT AND RAPIDLY INTENSITY
SUNDAY/SUNDAY EVENING OFF THE MID ATLANTIC/LONG ISLAND/NEW ENGLAND
COAST. EVERY OPERATIONAL MODEL SOLUTION RESULTS IN A HEAVY SNOW
FORECAST ACROSS THE MID ATLANTIC AND NORTHEAST...WITH
PROBABILITIES INCREASING FOR AN AXIS OF 1-2 FEET OF SNOW TO OCCUR.
THE METRO AREAS FROM NEW YORK TO BOSTON AND PORTLAND MAINE HAVE
THE HIGHEST PROBABILITY OF HEAVY SNOW/HEAVIEST FORECAST
ACCUMULATIONS...AND THE HIGHEST RESULTANT IMPACT. WASHINGTON DC
AND PHILADELPHIA INTO INTERIOR NY/VT/NH ARE IN A TIGHT QPF
GRADIENT WHERE SLIGHT ADJUSTMENTS IN THE CYCLONE TRACK AND
RESULTANT PLACEMENT OF THE MID LEVEL FRONTOGENESIS AXIS WILL HAVE
A SIGNIFICANT IMPACT ON THE ACCUMULATIONS.

A WELL DEFINED AXIS OF 850-500 MB FRONTOGENESIS AND DEFORMATION
AXIS SUPPORTS THE SNOW RAPIDLY INCREASING WITHIN A BAND WITHIN AN
AREA OF STRONG 700 MB THETA-E ADVECTION AND CONVERGENCE IN ADVANCE
OF THE LOW OVER THE MID ATLANTIC STATES SUNDAY INTO NEW
YORK/SOUTHERN NEW ENGLAND SUNDAY AFTERNOON...CONTINUING UP INTO
MAINE SUNDAY NIGHT.
THE PERIOD OF MOST RAPID DEEPENING SUNDAY AFTERNOON AND EVENING
FAVORS THE DEVELOPMENT OF A BAND OF INTENSE 1-2 INCH PER HOUR
SNOWFALL RATES IN NY/LONG ISLAND INTO SOUTHERN NEW ENGLAND...WITH
PEAK FRONTOGENESIS SHOWN IN THE 18Z NAM/GFS ACROSS LONG ISLAND TO
SOUTHEAST NEW ENGLAND DURING THIS PERIOD. THE MODEL CONSENSUS
SHOWS A CHANGE OVER FROM SNOW TO RAIN OVER CAPE COD MA AND THE
ISLANDS...KEEPING POTENTIALS NOW AMOUNTS LOWER THERE. THIS IS
ALSO THE CASE FOR EASTERN NC...WITH THE 850 MB LOW TRACK ONSHORE
OVERNIGHT TO 12Z SUN SUGGESTING THE CHANGEOVER TO SNOW OCCURS ONCE
THE LOW PASSES IN FAR EASTERN NC/COASTAL SOUNDS...WITH SUSTAINED
SNOW FURTHER NORTH IN CENTRAL NC AND SOUTHEAST VA ABOUT A DEGREE
TO THE LEFT OF THE 850 MB LOW TRACK.

THE MANUAL GRAPHICS USED A BLEND OF THE 12Z NAM/00-12Z ECMWF/12Z
ECMWF ENSEMBLE MEAN/12Z CANADIAN REGIONAL GEM/12Z UKMET QPFS AND
THERMAL PROFILES FOR THE SNOWFALL TOTALS
ACROSS THE EASTERN US. THE 12Z GFS HAD THE HIGHEST TOTAL
PRECIPITATION DUE TO BOTH MORE RAPID DEEPENING THAN OTHER
SOLUTIONS AND A SLIGHTLY SLOWER/FURTHER WEST LOW TRACK.
THE 12Z GEFS MEAN AND 18Z GFS ARE MUCH LOWER THAN THE OPERATIONAL
12Z GFS QPF ACROSS NJ...AND IN BETTER AGREEMENT WITH THE DOMINANT
MODEL/09-15Z SREF MEAN CLUSTER.




45
In this thread:
Blizzard warning/watch to be issue at 4pm for tomorrow-mon.30-5omph winds,tides 3-6' above normal - Fred, 12/25/2010, 12:58 pm
< Return to the front page of the: message board | monthly archive this page is in
Post A Reply
This thread has been archived and can no longer receive replies.