HAMweather.com Area Forecast Discussion for County Warning Area PHI

Thu, 16 Feb 2012 07:28:41 GMT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1246 AM EST THU FEB 16 2012

.SYNOPSIS...
HIGH PRESSURE ALONG THE EAST COAST WILL MOVE OFFSHORE TODAY AHEAD
OF AND APPROACHING LOW PRESSURE SYSTEM AND ITS ASSOCIATED OCCLUDED 
FRONT THAT WILL CROSS THE AREA TONIGHT. HIGH PRESSURE WILL BRIEFLY
BUILD IN FRIDAY NIGHT INTO SATURDAY. A STORM DEVELOPING ACROSS
CENTRAL PORTION OF THE COUNTRY WILL MOVE OFF THE CAROLINA COAST IS
EXPECTED TO REMAIN JUST TO OUR SOUTH ON SUNDAY. HIGH PRESSURE IS
THEN EXPECTED ONCE AGAIN LATE MONDAY INTO EARLY TUESDAY.

.NEAR TERM /UNTIL 7 AM THIS MORNING/...
GRIDS ADJUSTED AGAIN DOWNWARD SLIGHTLY AT 1230 AM FOR THE RADIATIONAL
COOLING IN PROGRESS. BLV RADIATIONAL COOLING SHOULD PROGRESS TIL
BETWEEN 07-11Z WHEN A SOLID DECK OF 10000 FT OVC ARRIVES. LIGHT
WIND.

POST MORTEM YDY: GLOBAL MODELS DID NOT AT ALL HANDLE THE SUBTLE
LIGHT PA/NJ QPF THAT OCCURRED YDY IN THE 12Z-20Z TIME FRAME...NOT
ONLY ON THE 00Z/15 RUN BUT ALSO FOR DAY 2 ON THE 00Z/14 CYCLE. IN
THIS CASE...THE NAM AND ASSTD SPC WRF PERFORMED ADMIRABLY.

.SHORT TERM /7 AM THIS MORNING THROUGH 6 AM FRIDAY/...
A MID LEVEL SHORT WAVE THAT WAS LOCATED OVER THE SOUTHERN PLAINS 
THIS AFTERNOON WILL PROGRESS TO THE EAST. THE FEATURE IS EXPECTED TO 
PASS OVER OUR REGION LATE ON THURSDAY RESULTING IN ANOTHER LIGHT 
PRECIPITATION EVENT.

LIGHT PRECIPITATION WILL BEGIN TO SPREAD INTO OUR REGION FROM THE
WEST DURING THE MID TO LATE MORNING HOURS. THE PRECIPITATION WILL
BE MAINLY IN THE FORM OF RAIN. TSEC FROM THE 00Z NAM SUGGESTS PCPN
SHOULD BEGIN AS A PERIOD OF SNOW IN THE ELEVATED TERRAIN OF THE POCS
WITH A FAIRLY STRONG UVM SIGNAL JUST ABOVE THE MAX DENDRITIC GROWTH
ZONE. LITTLE OR SNOW ACCUMULATION ANTICIPATED ATTM. SHOULD THE
COLUMN END UP JUST A TOUCH COLDER THAN MODELED...THERE COULD BE AN
INCH OF WET SNOW.

THE UKMET IS ALSO COLD ENOUGH TO SUGGEST SNOW AND ITS 2M TEMPS
ARE COLDER THAN PREV CYCLES FOR THIS AFTN. 
'
WITH SO MUCH RADIATIONAL COLD NOW IN PLACE COMBINED WITH A SEALING OFF
OF SUNSHINE...THINK WE'LL BE LOWERING TEMPS BY 3-5F TODAY IN OUR
CWA...ESP PA AND THE N2/3RD'S OF NJ.

WITH A DEVELOPING SOUTHERLY FLOW, TEMPERATURES ARE FORECAST TO RISE 
INTO THE 40S..EXCEPT POSSIBLY LOWER 50S DE/MD THURSDAY AFTERNOON
BUT IN THE POCONOS SHOULD ONLY TOP OUT IN THE 35-40F RANGE.

THE RAIN IS FORECAST TO LINGER INTO THURSDAY EVENING AS THE MID 
LEVEL SHORT WAVE PASSES OFF THE COAST. A SURFACE BOUNDARY FROM THE 
WEST IS EXPECTED TO FOLLOW, PASSING THROUGH OUR REGION AFTER 
MIDNIGHT. ONCE THE FRONT PASSES, THE PRECIPITATION SHOULD COME TO AN 
END. TEMPS WARM ALOFT AS THE LIFT PASSES BY AND THE AIRMASS DRIES
OUT ABOVE 3000 FT AND SO...IF IT DOESN'T SNOW BY 7PM IN THE POCONOS...
BELIEVE IT UNLIKELY TO MIX W SNOW AFTER 7P.

.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
THE BEGINNING OF THE EXTENDED IS EXPECTED TO BE DRY FOR FRIDAY 
THROUGH SATURDAY AS HIGH PRESSURE WILL BE BUILDING IN FROM THE WEST 
AND THE STORM SYSTEM EXITS OUR AREA AND CONTINUES TO MOVE NORTHEAST 
INTO CANADA. FRIDAY MAY BE A BIT GUSTY AS THE PRESSURE GRADIENT 
BETWEEN THE APPROACHING HIGH AND THE DEPARTING LOW REMAINS A BIT 
TIGHT. HOWEVER, BY SATURDAY IT SLACKENS AND WINDS ARE EXPECTED TO 
DIMINISH. 

THEN THE FOCUS TURNS TO THE POTENTIAL FOR A COASTAL STORM FOR 
SUNDAY. THE GFS IS NOW BRINGING THE COASTAL STORM RIGHT ALONG OUR 
COAST, WHICH WOULD SIGNIFICANTLY INCREASE PRECIPITATION POTENTIAL. 
HOWEVER, THE ECMWF AND CANADIAN GEM KEEP THE SYSTEM SUPPRESSED TO 
OUR SOUTH, BUT DO TRY TO BRING SOME LIGHT PRECIPITATION ON THE OUTER 
EDGE OF THE SYSTEM INTO OUR AREA. WE HAVE NOT DECIDED TO JUMP FULL 
ON BOARD WITH THE GFS AT THIS POINT BEING IT IS STILL THE OUTLIER OF 
THE LONG TERM MODELS, SO FOR NOW WE ONLY HAVE A CHANCE OF PRECIP 
STARTING SATURDAY NIGHT AND CONTINUING INTO SUNDAY. IF FUTURE MODEL 
RUNS, ESPECIALLY ON OTHER MODELS, KEEPS SHOWING A GREATER POTENTIAL 
FOR PRECIPITATION, WE MAY NEED TO INCREASE POPS EVEN MORE. DEPENDING 
ON WHEN THE PRECIP STARTS AND HOW FAR NORTH IT MOVES, WE COULD HAVE 
A MIXTURE OF PRECIPITATION TYPE ACROSS THE AREA, ESPECIALLY FOR 
AREAS IN OUR NORTHERN ZONES.

HIGH PRESSURE IS THEN EXPECTED TO BUILD ACROSS THE EAST COAST FOR 
MONDAY INTO TUESDAY. THIS SHOULD PROVIDE A PRECIPITATION FREE 
BEGINNING OF THE WEEK. HOWEVER, THE GFS/ECMWF ARE INDICATING THE 
POTENTIAL FOR A STORM SYSTEM TO AFFECT THE AREA DURING THE MIDDLE OF 
NEXT WEEK. THE TIMING AND PLACEMENT OF THE SYSTEM AND ITS 
PRECIPITATION WILL COME INTO BETTER FOCUS OVER THE NEXT SEVERAL DAYS.

TEMPERATURES IN THE EXTENDED ARE EXPECTED TO BEGIN ABOVE NORMAL 
FRIDAY AND SATURDAY, THEN RETURN CLOSE TO NORMAL OR JUST BELOW 
NORMAL FOR SUNDAY THROUGH TUESDAY.

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG,
KILG, KMIV, KACY AND SURROUNDING AREAS.

THROUGH 12Z...OTHER THAN SOME PATCHY MVFR VSBY IN RADIATIONAL
COOLING FLIRTING WITH KMIV/KACY... LOOKING AT A VFR MORNING WITH
CIGS AOA 10000 FT ARRIVING FM W TO E BETWEEN 07Z-11Z. CIGS LOWERING
TO 6000 FT NEAR 12Z IN E PA/DE. LIGHT WIND.

AFTER 12Z THU...VFR CIGS TO START THEN LOWERING TO MVFR CONDS IN
SHOWERY RAINS DURING THE AFTN...POSSIBLY IFR BY NIGHTFALL VCNTY
KABE AND PROBABLY IFR CONDS IN SNOW/RAIN IN THE POCONOS WITH RDGS
OBSCD BY 21Z. THE EXCEPTION MAY BE KACY/KMIV WHERE VFR CIGS COULD
PREVAIL ALL DAY WITH JUST SCT LIGHT SHOWERS IN THE AFTN.

TONIGHT...IFR CONDS /ESPECIALLY CIGS/ EXPECTED FOR AT LEAST A PORTION
OF THE NIGHT WITH SHOWERY PCPN ENDING NEAR MIDNIGHT. WIND SHIFTING
FROM LIGHT SOUTH TO NORTHWEST. CONDS MAY IMPROVE MVFR OR VFR CIGS
TOWARD 12Z FRI BUT AM CAUTIOUS.  

OUTLOOK... 
VFR CONDITIONS ARE EXPECTED FOR MUCH OF THE EXTENDED PART OF THE
FORECAST WITH THE EXCEPTION OF SATURDAY NIGHT INTO SUNDAY.
DEPENDING ON THE TRACK OF A POTENTIAL COASTAL STORM, SATURDAY INTO
SUNDAY MAY HAVE LOW CIGS/VSBYS AND PRECIPITATION. IF THE STORM
PASSES FAR ENOUGH TO OUR SOUTH, CONDITIONS MAY NOT BE AS POOR. AS
THE NEXT COUPLE OF DAYS PROGRESSES, WE SHOULD GET A BETTER HANDLE
OF THE FORECAST.

WINDS ARE EXPECTED TO BE A BIT GUSTY AT TIMES IN THE EXTENDED 
PERIOD, ESPECIALLY DURING THE AFTERNOONS ON FRIDAY, MONDAY, AND 
TUESDAY. DEPENDING ON HOW CLOSE THE COASTAL STORM GETS TO OUR AREA 
SUNDAY, WINDS MAY INCREASE EVEN MORE ON SUNDAY.

.MARINE...
NO HEADLINES ANTICIPATED THROUGH TONIGHT AS LIGHT N WINDS BECOME
SSE 5-15 KTS THU THEN SHIFT NW LATE THIS COMING THU NIGHT.

FWIW... THERE WAS A 4 HR PERIOD OF SCA CONDS VCNTY 44009 DURING
MIDDAY WED ...NICELY MODELED BY THE 00Z/15 NAM.

OUTLOOK... A COUPLE OF PERIODS OF ADVISORY LEVEL WINDS ARE
POSSIBLE DURING THE EXTENDED PORTION OF THE FORECAST. THE FIRST IS
FRIDAY WHEN WINDS COULD BE A BIT GUSTY BETWEEN THE DEPARTING LOW
AND AN APPROACHING HIGH. THE NEXT POTENTIAL COULD START AS EARLY
AS SATURDAY NIGHT AND MAY LAST INTO MONDAY, DEPENDING ON THE TRACK
OF A COASTAL LOW THAT IS FORECAST TO MOVE OFF THE CAROLINA COAST
LATE IN THE WEEKEND. THE GFS MODEL IS QUICKER WITH THE HIGHER
WINDS, WHILE THE OTHER MODELS ARE LATER WITH THE WINDS. FOR NOW WE
HAVE DECIDED TO GO WITH THE LATTER.

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE...NONE.