Mesoscale Discussion 101

Issued

Feb 13, 2014, 1:23 PM EST (18:23 UTC)

Expired

Feb 13, 2014, 6:30 PM EST

In force

5 hr

Issued by

the Storm Prediction Center

The Albany radar (KENX), 115 km from the middle of the area, began a volume at 18:24 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.

321 
ACUS11 KWNS 131823
SWOMCD
SPC MCD 131823 
MEZ000-MAZ000-NHZ000-CTZ000-VTZ000-NYZ000-132330-

MESOSCALE DISCUSSION 0101
NWS STORM PREDICTION CENTER NORMAN OK
1223 PM CST THU FEB 13 2014

AREAS AFFECTED...PORTIONS OF ERN NY...SRN VT...CNTRL/SRN
NH...CNTRL/WRN MA...CT...COASTAL SRN MAINE

CONCERNING...HEAVY SNOW 

VALID 131823Z - 132330Z

SUMMARY...HEAVY SNOW WITH RATES OF 1-3 INCHES/HOUR -- LOCALLY 
HIGHER -- WILL CONTINUE TO SHIFT NEWD ACROSS PARTS OF ERN NY AND NEW
ENGLAND INTO THE LATE AFTERNOON.

DISCUSSION...SFC OBSERVATIONS AND MOSAIC RADAR IMAGERY SUGGEST A
SOLID SHIELD OF HEAVY SNOW ARCING ENE FROM NERN PA INTO SRN NEW
ENGLAND. THIS ACTIVITY IS BEING SUPPORTED BY VERY STRONG DEEP ASCENT
AIDED BY INTENSE WARM ADVECTION SUPPLIED BY A STRONG LLJ -- E.G.
65-KT ELY/S AT 1.5-KM AGL SAMPLED BY OKX VWP. SFC PRESSURE FALLS OF
6-8 MB PER 2 HOURS HAVE BEEN NOTED OFF THE LONG ISLAND AND CT COAST
IN ASSOCIATION WITH THE WARM ADVECTION. THE NEWD TRANSLATION OF
RELATED DEEP FRONTOGENETIC CIRCULATIONS BENEATH STRONG UPPER
DIVERGENCE OFFERED BY A COUPLED JET STRUCTURE WILL SUPPORT THE NEWD
TRANSLATION OF HEAVY SNOW. THROUGH THE LATE AFTERNOON HOURS...THE
HEAVIEST SNOW -- WITH RATES OF 2-3 INCHES PER HOUR AND LOCALLY
HIGHER -- WILL LIKELY SHIFT NEWD ACROSS PARTS OF CNTRL/WRN MA...SERN
VT...SRN NH...AND COASTAL SRN MAINE WHERE THE ELEVATED INFLUX OF
OCEAN-MODIFIED TRAJECTORIES WILL CONTRIBUTE TO HIGHER PW ALONG WITH
MEAGER ELEVATED BUOYANCY. AN ISOLATED LIGHTNING STRIKE OR TWO MAY
ACCOMPANY THE HIGHEST SNOWFALL RATES.

ON A TEMPORARY BASIS...WEAKENING MID-LEVEL ASCENT AND THE INFLUX OF
A MID-LEVEL DRY SLOT PER WATER VAPOR LOOPS ARE CONTRIBUTING TO A
DECREASE IN SNOW RATES IN THE WAKE OF THE HEAVIEST SNOW -- I.E.
ACROSS PORTIONS OF SERN NY AND NRN NJ. A SIMILAR DECREASE IN
SNOWFALL RATES WILL EXTEND NEWD INTO SRN NEW ENGLAND INTO THE LATE
AFTERNOON. HOWEVER...WITH SUFFICIENT LOW-LEVEL ASCENT LINGERING IN
THESE AREAS FOR MORE SHALLOW PRECIPITATION GENERATION...LIGHT
FREEZING RAIN/DRIZZLE AND PERHAPS LIGHT SNOW GRAINS WILL REMAIN A
CONCERN IN THE WAKE OF THE HEAVIER SNOW. FREEZING RAIN RATES OF
0.01-0.03 INCH/HOUR WILL BE POSSIBLE. PRECIPITATION MAY CHANGE TO
LIQUID RAIN WHERE SFC TEMPERATURES REMAIN ABOVE 32F...SIMILAR TO
CURRENT CONDITIONS AROUND PARTS OF THE NYC METRO AND LONG ISLAND. A
RENEWED POTENTIAL FOR HEAVIER WINTER PRECIPITATION WILL EXIST DURING
THE EVENING AS A MID-LEVEL VORT MAX CURRENTLY OVER THE NC/VA
PIEDMONT AFFECTS THE AREA.

..COHEN.. 02/13/2014

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

ATTN...WFO...GYX...BOX...BTV...OKX...ALY...BGM...

LAT...LON   41867471 43177400 43917245 44157117 43557026 42997071
            42097166 41307303 41007390 41867471

Mesoscale Discussions in New York, 2014Mesoscale Discussions in New Hampshire, 2014Mesoscale Discussions in Massachusetts, 2014Every mesoscale discussion in 2014

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.