Mesoscale Discussion 2236

Issued

Dec 26, 2012, 2:14 PM EST (19:14 UTC)

Expired

Dec 26, 2012, 7:45 PM EST

In force

6 hr

Issued by

the Storm Prediction Center

The Binghamton radar (KBGM), 79 km from the middle of the area, began a volume at 19:13 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

174 
ACUS11 KWNS 261914
SWOMCD
SPC MCD 261914 
NYZ000-NJZ000-PAZ000-270045-

MESOSCALE DISCUSSION 2236
NWS STORM PREDICTION CENTER NORMAN OK
0114 PM CST WED DEC 26 2012

AREAS AFFECTED...SRN/CNTRL NY...FAR NRN PA

CONCERNING...HEAVY SNOW 

VALID 261914Z - 270045Z

SUMMARY...HEAVY SNOW WITH RATES OF 1-2 IN/HR WILL ADVANCE NWD/NEWD
INTO AND ACROSS THE TWIN TIERS REGION OF NRN PA AND SRN NY DURING
THE NEXT FEW HOURS BEFORE APPROACHING PARTS OF SERN NY AND UPSTATE
NY LATER THIS AFTERNOON. LOCALIZED SNOW RATES TO 3 IN/HR MAY ALSO
OCCUR. HEAVY SNOW WILL CONTINUE INTO THIS EVENING.

DISCUSSION...ISENTROPIC ASCENT WITHIN THE WARM CONVEYOR BELT OF A
LARGE EXTRATROPICAL CYCLONE OVER THE ERN CONUS WILL SUPPORT AN
INCREASE IN THE THREAT FOR HEAVY SNOW FOR THE REMAINDER OF THIS
AFTERNOON. THE HEAVY SNOW WILL CONTINUE INTO THIS EVENING...AS THE
CYCLONE TRACKS NEWD.

RECENT SFC OBSERVATIONS INDICATE HEAVY SNOW IN IPT AND BFD IN
ASSOCIATION WITH A W/E-ORIENTED BAND OF ENHANCED REFLECTIVITY PER
RADAR MOSAIC DATA. THIS BAND MARKS THE LEADING EDGE OF HEAVY SNOW
THAT WILL PERSIST INTO THIS EVENING. THE LEADING EDGE WILL ADVANCE
NWD ACROSS THE TWIN TIERS REGION OF NRN PA/SRN NY...REACHING A
WELLSVILLE-ELM-BGM LINE AROUND/SHORTLY BEFORE 20Z...AND REACHING
LOCATIONS FARTHER NORTH TOWARD THE FINGER LAKES REGION INCLUDING ITH
AND SYR MAINLY AFTER 21Z. SNOWFALL RATES WILL ALSO INCREASE FROM THE
POCONOS INTO SERN NY THROUGH 00Z...WITH SNOW SPREADING ACROSS THE
CAPITAL DISTRICT AROUND ALB AFTER 00Z.

THE STRONGLY ASCENDING BRANCH OF A DEEP FRONTOGENETIC CIRCULATION
CROSSING THE AREA WILL AUGMENT ISENTROPIC ASCENT INTERSECTING
SATURATED DENDRITIC GROWTH ZONES BETWEEN 550 MB AND 490 MB. THIS
WILL SUPPORT PERSISTENT SNOWFALL RATES OF 1-2 IN/HR INTO THIS
EVENING. FURTHERMORE...MODESTLY STEEPENING MID-LEVEL LAPSE
RATES...ACCOMPANYING ADIABATIC COOLING PROCESSES ASSOCIATED WITH
DCVA PRECEDING THE MID-LEVEL CYCLONE CENTER...WILL SUPPORT NARROW
ELEVATED CAPE LAYERS TO LOCALLY ENHANCE SNOWFALL RATES. ISOLATED
INSTANCES OF 3-IN/HR SNOWFALL RATES...AND A LIGHTNING STRIKE OR
TWO...CANNOT BE RULED OUT WITH CONVECTIVELY ENHANCED PRECIPITATION.

AFTER 00Z ACROSS PARTS OF SERN NY AND FAR NERN PA...WARM ADVECTION
BETWEEN 850 AND 700 MB MAY SUPPORT SUFFICIENT MELTING OF FALLING
HYDROMETEORS ATOP SUBFREEZING SFC TEMPERATURES TO SUPPORT SLEET AND
FREEZING RAIN. A PHASE CHANGE TO RAIN COULD OCCUR WHERE SFC
TEMPERATURES RISE ABOVE FREEZING.

..COHEN.. 12/26/2012

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

ATTN...WFO...OKX...ALY...PHI...BGM...BUF...CTP...

LAT...LON   42367354 41347358 41057403 41637551 41767799 42027880
            42307939 42487939 42737885 42987884 43097889 43257889
            43367855 43377681 43687553 43317403 42367354

Mesoscale Discussions in New York, 2012Mesoscale Discussions in Pennsylvania, 2012Every mesoscale discussion in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.