FXUS61 KPHI 241603
AFDPHI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
1100 AM EST TUE FEB 24 2004

TALE OF TWO FORECAST AREAS.  THE NORTHWEST PORTION OF THE FORECAST 
AREA IS GETTING PRETTY MUCH WHAT WAS ADVERTISED. ALREADY AN INCH OF 
SNOW ON GRASSY AREAS AROUND RDG.  THE SOUTHEAST PORTION OF THE 
FORECAST AREA HAS BEEN HIGH AND DRY...WONDERING WHERE THE 
PRECIPITATION IS.  06Z MESOETA AND EARLY MORNING RUC RUNS GET SOME 
CREDIT...AS THEY SHOWED PRECIPITATION ADVANCE COMING TO A HALT 
DURING THE MID TO LATE MORNING.  THEY ALSO SHOWED PRECIPITATION 
RESUMING ITS SOUTHEAST ADVANCE IN THE AFTERNOON...AND HAVE GONE THAT 
WAY WITH THE FORECAST.  STILL GOOD AMOUNT OF ECHOES ON RADAR AT CTP 
AND LWX...SWINGING THIS WAY.  

RAISED HIGH TEMPS FOR THIS AFTERNOON IN PRECIP FREE AREA...BUT 
EXPECT TEMPS TO COOL DOWN RATHER QUICKLY ONCE PRECIPITATION MOVES 
INTO THESE AREAS.  LEFT ANTICIPATED PRECIPITATION TYPE PRETTY MUCH 
INTACT AS WET BULB TEMPS AND ANTICIPATED ATMOSPHERIC SOUNDINGS 
SUPPORT CURRENT FORECAST. 

NEW SPS HAS BEEN ISSUED...ZFP...AFM...PFM ARE OUT.  NOW WE JUST NEED 
SOME PRECIPITATION WHERE WE DO NOT YET HAVE IT.

.PHI WATCHES/WARNINGS/ADVISORIES...
PA...NONE.
NJ...NONE.
DE...NONE.
MD...NONE.
MARINE/OCEAN...NONE.
MARINE/DEL BAY...NONE.
&&

$$

SZATKOWSKI


------------PREVIOUS AFD BELOW------------------------------

.DISCUSSION...WEAK LOW PRES WILL MOVE BY TO THE S BEFORE GETTING 
ABSORBED BY A STRONGER LOW E OF THE CAROLINAS. THIS STRONGER LOW 
WILL HEAD OUT TO SEA AND NOT AFFECT THE FCST AREA.

EVEN SO...THE FIRST AREA OF LOW PRES MOVES BY WITH SOME WEAK 
FRONTGENESIS OCCURRING ARND 850 MB. THIS COMBINED WITH WEAK 
ISENTROPIC LIFT AND WARM ADVCNT SHOULD BE ENOUGH TO KEEP THE PCPN 
GENERATING AS IT HEADS E FROM WRN PA AND OHIO. 

PER PCPN TYPE TODAY...SFC TEMPS SHOULD BE IN THE LOW 30S NORTH AND 
MID 30S AS FAR S AS ILG AND PHL. SINCE THE SOUNDING IS BELOW 
FREEZING EXCEPT IN THE LOWEST LVLS...MAINLY SNOW IS EXPECTED. 
HOWEVER...WHEN THE PCPN IS VERY LIGHT...IT SHOULD MELT ALLOWING FOR 
A MIXTURE OF RAIN AND WET SNOW. THE GFS FCST MORE PCPN THAN THE ETA 
AND GENLY LOOKS HIGH CONSIDERING THE DRY BLYR THAT MUST BE SATURATED 
BEFORE SNOW CAN REACH THE GROUND. RADAR SHOWS ECHOES ALFT SUPPORTING 
FCST SOUNDINGS AND THE IDEA OF VIRGA UNTIL AFTER SUNRISE. 

SINCE THE SNOW WILL BE FALLING DURING THE DAYTIME WITH TEMPS AT OR A 
BIT ABOVE 32...ACCUMULATION WILL BE MORE DIFFICULT...EXCEPT ON 
GRASSY AREAS. 

FARTHER TO THE SOUTH...THE ABOVE 32 DEGR LAYER IS DEEP ENOUGH TO 
MELT MOST OF THE PCPN THAT FALLS. HOWEVER...AS SLIGHTLY COLDER AIR 
BUILDS DOWN FROM THE N THIS AFTN...A MIX WITH SNOW SHOULD OCCUR 
SOUTH TOO BUT WITHOUT ACCUMULATION.

ONE MORE POINT...TEMPS WILL DROP WELL BELOW FREEZING TNGT. ANY 
MOISTURE REMAINING ON THE ROADS COULD FREEZE BEFORE DRIER AIR MOVES 
IN AND SLIPPERY CONDITIONS COULD DEVELOP.

HIGH PRES N OF THE GREAT LAKES WILL BUILD IN TNGT AND INTO THE WKND.

FOR THE MARINE...SCA MAY BE NEEDED WED AS THE SFC PRES GRADIENT 
TIGHTENS A BIT ALLOWING FOR SOME INCR IN WINDS.

&&