Mesoscale Discussion 1

Issued

Jan 2, 2012, 12:37 AM EST (05:37 UTC)

Expired

Jan 2, 2012, 4:30 AM EST

In force

4 hr

Issued by

the Storm Prediction Center

Counties Cattaraugus County, NY, Chautauqua County, NY, Cuyahoga County, OH, Geauga County, OH, Crawford County, PA, Erie County, PA, Warren County, PA

The Cleveland radar (KCLE), 138 km from the middle of the area, began a volume at 05:38 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.

302 
ACUS11 KWNS 020537
SWOMCD
SPC MCD 020537 
PAZ000-NYZ000-OHZ000-020930-

MESOSCALE DISCUSSION 0001
NWS STORM PREDICTION CENTER NORMAN OK
1137 PM CST SUN JAN 01 2012

AREAS AFFECTED...PORTIONS NERN OH NEAR LE...EXTREME NWRN
PA...EXTREME WRN NY.

CONCERNING...HEAVY SNOW 

VALID 020537Z - 020930Z

OCNL SNOWFALL RATES NEAR 2 INCHES/HOUR ARE POSSIBLE AS LAKE-EFFECT
BAND ORGANIZES OVER FAR WRN NY AND EXTREME NWRN PA THROUGH ABOUT
07Z...THEN SHIFTS SWD AT OBLIQUE ANGLE ALONG SRN SHORE.  PRIND RATES
NEAR 2 INCHES/HOUR SHOULD BECOME MORE BRIEF/ISOLATED AFTER ABOUT
09Z. GUSTS ABOVE 35 KT AND LOCALIZED BLIZZARD CONDITIONS ALSO MAY
OCCUR ALONG IMMEDIATE SHORELINE.

SFC MESOANALYSES AND REFLECTIVITY ANIMATIONS INDICATE AXIS OF
CONVERGENCE ZONE WITH PRECIP...GETTING BETTER DEFINED AT 05Z FROM
NWRN LE...NEAR POINT PELEE CANADA...TO WRN-MOST NY.  MODIFIED
SOUNDINGS SUGGEST CONTINUED COOLING ALOFT WILL OFFSET POST-FRONTAL
CAA ENOUGH TO NOT ONLY MAINTAIN...BUT PERHAPS INCREASE...BUOYANCY
FOR PARCELS IN THIS BAND.  MODIFIED RUC SOUNDINGS INDICATE UP TO
ABOUT 100 J/KG MLCAPE IS POSSIBLE...ENCOMPASSING ENTIRE DENDRITIC
GROWTH LAYER AND EXTENDING PARTLY INTO HIGHER-ELEVATION THERMAL
LAYERS SUITABLE FOR LTG GENERATION.  AS SUCH...ISOLATED THUNDER-SNOW
MAY OCCUR.  FCST SOUNDINGS ALSO SUGGEST PASSAGE OF AIR MASS ACROSS
SRN LM HAS SUPPLIED MOISTURE THROUGH SUFFICIENTLY DEEP LAYER TO
REDUCE POTENTIAL FOR DRYING THROUGH VERTICAL MIXING.  LOW-LEVEL RH
MAY BE INCREASED SOMEWHAT AS ENTIRE LOWER TROPOSPHERE COOLS...WITH
CONTINUED VERTICAL FLUXES FROM LAKE.  OVER-WATER FETCH LENGTH OF
LOW-LEVEL TRAJECTORIES HAS INCREASED...AND SHORT-TERM PROGS
REASONABLY INDICATE FAVORABLE QUASI-ZONAL FLOW DISTANCES ALONG MUCH
OF LE THROUGH ABOUT 09Z. THEREAFTER...LOW- AND MIDDLE-LEVEL FLOW
SHOULD VEER IN RESPONSE TO EWD PASSAGE OF MID-UPPER TROUGH AND
RELATED EWD SHIFT OF ACCOMPANYING ISALLOBARIC/ISALLOHYPSIC FIELDS. 
THIS PROCESS...IN TURN...SHOULD SHIFT SNOW BAND SWWD ALONG SRN SHORE
OF LE...WITH CONCURRENT SLOW WEAKENING IN SNOW RATES AS FETCH
DISTANCE DECREASES.

..EDWARDS.. 01/02/2012

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

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

LAT...LON   42427909 42437872 42217862 41887905 41647949 41488004
            41458089 41358155 41488207 41508200 41498181 41558162
            41728136 41978050 42277976 42357952 42427909

Mesoscale Discussions in Pennsylvania, 2012Mesoscale Discussions in New York, 2012Mesoscale Discussions in Ohio, 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.