Mesoscale Discussion 6

Issued

Jan 2, 2012, 6:24 PM EST (23:24 UTC)

Expired

Jan 2, 2012, 9:30 PM EST

In force

3 hr

Issued by

the Storm Prediction Center

Counties DeKalb County, IN, Elkhart County, IN, LaGrange County, IN, Noble County, IN, Saint Joseph County, IN, Whitley County, IN, Allegan County, MI, Cass County, MI, Saint Joseph County, MI, Van Buren County, MI

The Northern Indiana radar (KIWX), 58 km from the middle of the area, began a volume at 23:26 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.

071 
ACUS11 KWNS 022325
SWOMCD
SPC MCD 022324
INZ000-MIZ000-030230-

MESOSCALE DISCUSSION 0006
NWS STORM PREDICTION CENTER NORMAN OK
0524 PM CST MON JAN 02 2012

AREAS AFFECTED...PORTIONS OF SWRN LOWER MI...NRN IND

CONCERNING...HEAVY SNOW

VALID 022324Z - 030230Z

A NW-SE-ORIENTED LAKE EFFECT SNOW BAND OFF SRN LAKE MI WILL LIKELY
PIVOT CLOCKWISE -- I.E. BECOME REORIENTED MORE MERIDIONALLY --
DURING THE NEXT FEW HOURS WHILE ALSO CONTAINING SNOW RATES OF 2
IN/HR. AFTER 05Z...SNOW RATES WILL LIKELY TAPER OFF.

A CONSOLIDATED...10-MILE-WIDE SNOW BAND CURRENTLY STRETCHES FROM 25
NNE BENTON HARBOR MI TO THE MI/IND STATE LINE ABOUT 30 S KALAMAZOO
TO 25 NNE FORT WAYNE IND. WSR-88D DATA INDICATE REFLECTIVITY VALUES
OF 35-40 DBZ WITHIN THE CORE OF THIS BAND BETWEEN 1.4 AND 2.2 KFT
AGL...WHERE 2-IN/HR SNOW RATES ARE POSSIBLE. DURING THE NEXT FEW
HOURS...RUC FORECAST WIND PROFILES INDICATE MEAN CONVECTIVE-LAYER
/SFC-700-MB/ FLOW VEERING /ATTAINING MORE OF A NLY COMPONENT/ IN
ASSOCIATION WITH THE EWD PROGRESSION OF THE E-CONUS DEEP-LAYER
TROUGH. IN RESPONSE...THE BAND WILL LIKELY PIVOT CLOCKWISE AND
POTENTIALLY APPROACH THE SOUTH BEND AND FORT WAYNE AREAS. AS THE
BAND BECOMES REORIENTED...LOW-LEVEL FLOW TRAJECTORIES WILL
EXPERIENCE AN INCREASING FETCH LENGTH OVER LAKE SRN MI...WHERE WATER
TEMPERATURES IN THE LOWER 40S WILL REINFORCE HEAT/MOISTURE FLUXES
INTO THE NEAR-SURFACE LAYER. THIS WILL MAINTAIN THE RELATIVELY DEEP
CONVECTIVE LAYER CHARACTERIZED BY 50-100 J/KG OF MLCAPE. AND...WITH
THE CAPE-BEARING LAYER ENCOMPASSING THE DENDRITIC GROWTH ZONE...SNOW
RATES OF 2-IN/HR WILL LIKELY CONTINUE TO BE SUPPORTED THROUGH AROUND
05Z. THEREAFTER...DIMINISHING SNOW RATES ARE ANTICIPATED AS ABUNDANT
MID-LEVEL DRY AIR ON THE BACKSIDE OF THE TROUGH /PER WATER VAPOR
LOOP/ IS VERTICALLY TRANSPORTED VIA LARGE-SCALE SUBSIDENCE INTO THE
CONVECTIVE LAYER...THEREBY FORCING IT TO BECOME INCREASINGLY SHALLOW
AND DRY.

..COHEN.. 01/02/2012

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

ATTN...WFO...IWX...GRR...

LAT...LON   42618612 42038542 41448494 41158488 41078535 41388608
            41848653 42168647 42418640 42618612

Mesoscale Discussions in Indiana, 2012Mesoscale Discussions in Michigan, 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.