SPC MD 4

MD 0004 CONCERNING FREEZING RAIN FOR PORTIONS OF CNTRL/NRN PA AND SRN NY

MESOSCALE DISCUSSION 0004
NWS STORM PREDICTION CENTER NORMAN OK
0139 PM CST FRI JAN 08 2016

AREAS AFFECTED...PORTIONS OF CNTRL/NRN PA AND SRN NY

CONCERNING...FREEZING RAIN 

VALID 081939Z - 090045Z

SUMMARY...PRECIPITATION WILL OVERSPREAD THE AREA LATER THIS
AFTERNOON INTO THE EARLY EVENING. AREAS OF FREEZING RAIN WITH RATES
OF 0.05 INCH PER 3 HOURS WILL BE POSSIBLE INTO THE EVENING HOURS.

DISCUSSION...MOSAIC RADAR IMAGERY AND SFC OBSERVATIONS INDICATE A
SHIELD OF PRECIPITATION EXTENDING FROM LOWER MI SEWD ACROSS LAKE
ERIE TO THE UPPER OHIO VALLEY...SPREADING NEWD. THIS ACTIVITY IS IN
ASSOCIATION WITH A PLUME OF LOW-LEVEL WARM ADVECTION PRECEDING
ILL-PHASED SHORTWAVE TROUGHS EXTENDING FROM THE MID-MS VALLEY TO THE
MID-ATLANTIC. DESPITE NEAR/ABOVE-FREEZING SFC TEMPERATURES IN MANY
AREAS ACROSS THE REGION...DEWPOINTS IN THE TEENS AND 20S SUGGEST
THAT WET-BULB COOLING WILL OCCUR. GIVEN WET-BULB SFC TEMPERATURES
BELOW 32F...THE POTENTIAL FOR FREEZING RAIN WILL EXIST AS LOW-LEVEL
SATURATION OCCURS BEHIND THE LEADING EDGE OF THE PRECIPITATION-
RELATED REFLECTIVITY SHIELD. THE POTENTIAL FOR FREEZING RAIN WILL
MOST LIKELY SPREAD ACROSS THE REGION IN THE 21Z-01Z TIME FRAME...AND
CONTINUE INTO THE EVENING HOURS. WHILE WARMING OF THE LOW-LEVEL
THERMAL PROFILE IS EXPECTED IN THE WARM-ADVECTION PATTERN...SUCH
WARMING WILL BE OFFSET BY INITIAL EVAPORATION-RELATED COOLING TO
KEEP SFC TEMPERATURES BELOW 32F IN MANY AREAS -- PARTICULARLY IN
SHELTERED VALLEYS -- INTO THE EVENING HOURS. PRECIPITATION WILL
GENERALLY BE LIGHT...WITH FREEZING-RAIN RATES OF 0.05 INCH PER 3
HOURS POSSIBLE.

..COHEN.. 01/08/2016

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...BGM...BUF...CTP...PBZ...CLE...

LAT...LON   41227933 41647982 42147981 42727888 42957774 42777640
            42477598 41607601 41077676 40777754 40777838 41227933 

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