10/25 NWS NYC disco
Posted by
Fred on 10/25/2012, 9:06 am
.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
ONSHORE FLOW DEVELOPS FRIDAY NIGHT AND SATURDAY AHEAD OF BOTH AN
APPROACHING COLD FRONT AND THE IMPACTS OF TROPICAL CYCLONE SANDY.
DRY CONDS EXPECTED FRIDAY...BUT SOME RAIN IS POSSIBLE ON
SAT...MAINLY IN WESTERN ZONES AS TROPICAL MOISTURE BEGINS STREAMING UP
THE FRONTAL BOUNDARY. LOW CHC POPS IS SUFFICIENT FOR THIS POTENTIAL
IMPACTS FROM TROPICAL CYCLONE SANDY COULD BEGIN IMPACTING THE
REGION STARTING SATURDAY NIGHT WITH BANDS OF RAIN BEGINNING TO
SPREAD NORTH INTO THE REGION. A TIGHTENING PRES GRADIENT WILL ALSO
PRODUCE INCREASING/GUSTY EASTERLY WINDS OVER THE AREA...AS WELL
AS COASTAL FLOODING ON SUNDAY.
LOW PREDICTABILITY REMAINS IN THE 00Z/25 MODEL SUITE...WITH LARGE
VARIABILITY REMAINING WITH THE EVENTUAL TRACK OF SANDY. DUE TO THE
CONTINUED HIGH UNCERTAINTY FROM THESE MODEL INCONSISTENCIES HAVE NOT
MADE MANY CHANGES TO THE GRIDS BEYOND SUNDAY.
THE MAJORITY OF MODEL SOLNS CONTINUE TO DEPICT THE GENERAL SOLN OF
TAKING SANDY ON A NNE TRACK FROM THE CARIBBEAN TO BETWEEN 300-400
MILES SE OF CAPE HATTERAS ON SUNDAY. BEYOND THIS POINT IS WHERE
LARGE DIFFERENCES COME INTO PLAY AS A RESULT OF ITS INTERACTION WITH
AN APPROACHING UPPER TROUGH FROM THE W AND STRONG BLOCKING
DOWNSTREAM. THE GFS/GFS ENS MEAN AND CMC TRACK THE SYSTEM EASTWARD
INTO THE WESTERN ATLANTIC WATERS THROUGH SUN NIGHT/MON THEN RECURVE
IT BACK TO THE NW. THE 18Z/24 AND 00Z/25 RUNS HAVE TRENDED FURTHER
OFFSHORE THAN THE 12Z/24 RUN AND SUBSEQUENTLY TAKES THE CYCLONE
SLIGHTLY LONGER TO REACH THE COAST ONCE IT RECURVES BACK TOWARDS
NOAM. THIS IS ALSO RESULTING IN A SLIGHTLY NORTHWARD TRACK...WITH A
NORLUN TROUGH DEVELOPING ON THE WEST SIDE OF THE STORM AND THE
CYCLONE HITTING NOVA SCOTIA ON MON. AT THE OTHER END OF THE
SPECTRUM...THE 00Z/25 ECMWF HAS REMAINED CONSISTENT WITH ITS 12Z/24
RUN TRACKING THE CYCLONE INTO DELAWARE/SOUTHERN NJ MON NIGHT
ALTHOUGH IT HAS TRENDED SLIGHTLY FASTER. THE GFDL AND NOGAPS ALSO
SUPPORT THIS SOLN. THE REST OF THE GUIDANCE INCLUDING CMC...GFS ENS
MEAN AND MOST INDIVIDUAL GFS ENSEMBLE MEMBERS ARE IN BETWEEN THESE
TWO SOLNS TRACKING IT SOMEWHERE BETWEEN THE TWO PREVIOUSLY MENTIONED
LOCATIONS. A FEW GFS ENS MEMBERS STILL ARE TAKING THE STORM OUT TO
SEA...ALTHOUGH THE LIKELIHOOD OF THIS CONTINUES TO DECREASE AND
CONFIDENCE OF A POTENTIALLY HIGH IMPACT EVENT LATE THIS
WEEKEND/EARLY NEXT WEEK IS INCREASING.
AS SANDY TRACKS NORTH...BROAD H5 TROUGH WILL DIG INTO THE EASTERN
SEABOARD. WHETHER THIS TROUGH PUSHES SANDY OUT TO SEA INITIALLY
BEFORE SWINGING IT BACK TOWARDS THE NORTHEAST OR PICKS IT UP AND
BRINGS IT ALONG THE COAST REMAINS TO BE SEEN. THE GFS IS TRYING TO
BRING SANDY OUT TO SEA...WHILE THE ECMWF IS PICKING IT UP AND
BRINGING IT ALONG THE COAST.
ONCE AGAIN...THERE IS MUCH UNCERTAINTY WITH THIS FORECAST WITH THE
GUIDANCE SUPPORTING MANY DIFFERENT LOW TRACK SCENARIOS. UPPER AIR
DATA SHOULD HELP MODELS COME INTO BETTER AGREEMENT THE NEXT 24H.
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