'Possible" northeast Sandy/nor'easter
Posted by
Fred on 10/24/2012, 9:54 am
Here is local(Long Island,NYC) disscussion
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
ONCE AGAIN...THE FOCUS ON THE LONG TERM IS THE EVOLUTION OF A
HIGHLY AMPLIFIED FLOW INTERACTING WITH TROPICAL CYCLONE SANDY.
SIMILAR TO 24 HOURS AGO...GLOBAL MODELS ARE IN POOR AGREEMENT WITH
THIS SYSTEM...WITH THE 00Z ECMWF THE MOST AGGRESSIVE AND THE WORST
CASE SCENARIO FOR THE FORECAST AREA. THIS SOLUTION IS THE CLOSEST TO
THE EAST COAST AND EVENTUALLY TAKES IT INTO THE NORTHERN MID
ATLANTIC REGION MON INTO TUE. THIS SCENARIO WOULD BRING HEAVY
RAINS...STRONG WINDS...AND COASTAL FLOODING INTO THE AREA. THE
ECMWF HAS MAINTAINED THE BEST CONTINUITY...WHILE THE GFS AND GGEM
HAVE VARIED SIGNIFICANTLY WITH THE TRACK. THE LATTER TWO MODELS TAKE
THE STORM SYSTEM WELL EAST OF THE FORECAST AREA...BUT THERE WOULD BE
POTENTIAL MARINE IMPACTS AND POSSIBLE RAINFALL WITH AN INVERTED TROUGH
EXTENDING NW FROM THE OFFSHORE LOW. NEARLY HALF OF THE GEFS MEMBERS
THOUGH SUPPORT THE RETROGRESSION OF THE LOW ACROSS THE NORTHERN MID
ATLANTIC AND NEW ENGLAND STATES. RIGHT NOW...WILL CONTINUE TO USE
A CONSERVATIVE MIDDLE OF THE ROAD APPROACH AND HAVE MADE ONLY
SMALL CHANGES TO THE GRIDS SINCE THE 12Z TUE CYCLE.
THE FORECAST SEEMS TO HINGE ON THE MAGNITUDE OF THE RIDGE PASSING TO
THE NORTH OF THE LOW FRI-SAT...AND THEN THE APPROACHING UPPER TROUGH
OVER THE GREAT LAKES AND OHIO VALLEY STATES SUN INTO MON. THE
BIGGEST DIFFERENCE APPEARS TO BE AN INCOMING JET MAX/SHORT WAVE OVER
THE TN/OH VALLEY ON SUN...WHICH IS STRONGEST IN THE ECMWF. THIS
FEATURE ALLOWS THE UPPER TROUGH TO BECOME NEGATIVELY TILTED STEERING
THE LOW IN A MORE NORTHERLY DIRECTION. THE OTHER GLOBAL MODELS ARE
WEAKER...AND THUS ALLOWS THE LOW TO TAKE A RIGHT HAND TURN OUT TO
SEA. THE DIFFERENCE IN THE SPACING BETWEEN THE COASTAL LOW AND THIS
SHORT WAVE IS SMALL IN THE GRAND SCHEME...BUT WILL MAKE ALL THE
DIFFERENCE IN WHETHER THE FORECAST AREA IS IMPACTED OR NOT. THIS
REMAINS A LOW CONFIDENCE....BUT POTENTIALLY HIGH IMPACT FORECAST.
PRIOR TO THAT TIME...A HIGH AMPLITUDE RIDGE ALONG THE EAST COAST ON
FRI WILL BUILD OFFSHORE ON SAT...WITH SURFACE HIGH PRESSURE ALONG
THE NEW ENGLAND COAST ALSO BUILDING OFFSHORE. FRI AND SAT WILL BE
DRY WITH ABOVE NORMAL TEMPS WITH THE ANOMALOUS UPPER RIDGE OVER THE
REGION. 500 MB HEIGHTS APPROACH 580 DM ON FRI...GRADUALLY FALLING ON
SAT IN RESPONSE TO THE APPROACHING UPPER TROUGH.
CLOUDS INCREASE SAT INTO SAT NIGHT WITH A CHANCE OF SHOWERS FROM SUN
INTO TUE IN ASSOC WITH THE POSSIBLE STORM. IN ADDITION...EVEN WITH A
SCENARIO OF THE LOW BEING WELL OFFSHORE...THERE IS THE POTENTIAL FOR
RAINFALL WITH AN INVERTED TROUGH EXTENDING NW FROM THE OFFSHORE LOW.
THE INVERTED TROUGH IS IN RESPONSE TO THE HEIGHT FALLS ASSOCIATED WITH
THE UPPER TROUGH. OFTEN...THIS FEATURE IS REFERRED TO AS A NORLUN TROUGH
AND DEPENDING UPON WHERE IT SETS UP...CAN ALSO PRODUCE HEAVY RAIN.
A FULL MOON IS ON MON. A STRENGTHENING EASTERLY FLOW WOULD AT THE
LEAST RESULT IN A MINOR COASTAL FLOOD EVENT SUN INTO TUE.
ONCE AGAIN...THERE IS A LOT OF UNCERTAINTY WITH THIS FORECAST WITH
THE GUIDANCE SUPPORTING MANY DIFFERENT LOW TRACK SCENARIOS. WITH THE
INCOMING ENERGY MOVING IN OFF THE PAC TODAY...UPPER AIR DATA SHOULD
HELP MODELS COME INTO BETTER AGREEMENT THE NEXT 24H.
REFER TO THE NATIONAL HURRICANE CENTER ADVISORIES AND FORECASTS FOR
FURTHER DETAILS ON SANDY. |
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'Possible" northeast Sandy/nor'easter - Fred, 10/24/2012, 9:54 am Post A Reply
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