SPC MESOSCALE DISCUSSION 2403 FOR N CNTRL AND NERN PA/CNTRL NY AND
THE CATSKILLS OF NY
CONCERNING...FREEZING RAIN...

VALID 170203Z - 171100Z

FREEZING RAIN CURRENTLY DEVELOPING ACROSS NORTH CENTRAL
PENNSYLVANIA SHOULD SPREAD EAST INTO CENTRAL NEW YORK/NORTHEAST
PENNSYLVANIA...AND THE CATSKILLS OF NEW YORK BY 0900Z. 
ACCUMULATIONS WILL BE LIGHT FOR THE FIRST COUPLE OF HOURS...WITH
RATES INCREASING TO ABOUT .05 INCH PER 3 HOURS AFTER 0500Z...
ESPECIALLY IN THE DEEPER/COLDER VALLEYS.

WARM ADVECTION/ISENTROPIC LIFT WILL GRADUALLY INCREASE ACROSS THE
INTERIOR NORTHEAST OVERNIGHT.  18Z ETA 300K ISENTROPIC LEVEL
INDICATES CONDENSATION PRESSURE DEFICITS OF LESS THAN 10 MB ACROSS
MUCH OF NORTHERN PA/WRN NY THROUGH 1200Z...WITH STRONGEST PRESSURE
ADVECTION SPREADING INTO AREA AROUND 0600Z.  ALTHOUGH SURFACE
TEMPERATURES ARE MARGINAL CURRENTLY WITH READINGS AROUND
FREEZING...WET BULB TEMPERATURES ARE MAINLY IN THE UPPER 20S F. 
AFTER A COUPLE OF HOURS OF LIGHT RAIN...WET BULB COOLING SHOULD
RESULT IN AREAS OF GLAZE...PARTICULARLY IN THE DEEPER VALLEYS IN
CENTRAL NEW YORK AND THE CATSKILLS WHERE WET BULB TEMPERATURES ARE
IN THE MID 20S.  

SINCE THE SUBFREEZING LAYER IS EXTREMELY SHALLOW OVER NORTH CENTRAL
PENNSYLVANIA...THE GLAZE SHOULD BE VERY LOCALIZED AND THE
PRECIPITATION MAY CHANGE BACK TO RAIN AFTER 0600Z AS WARM ADVECTION
JUST OFF THE SURFACE CONTINUES TO INCREASE.  

..CRAVEN.. 12/17/01