Alert archive / Michigan / Mesoscale Discussions in 2012

Mesoscale Discussion 855

May 20, 20125 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at May 20, 2012, 8:07 PM EDT for 5 counties in Michigan. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued
May 20, 2012, 8:07 PM EDT (00:07 UTC)
Expired
May 20, 2012, 9:00 PM EDT
In force
53 min
Issued by
the Storm Prediction Center
Chance of a watch
5%

Counties Lake County, MI, Muskegon County, MI, Newaygo County, MI, Oceana County, MI, Ottawa County, MI

The radar

The Grand Rapids radar (KGRR), 91 km from the middle of the area, began a volume at 00:07 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.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 00:00Z, 0.1 hours before the alert went out and 189 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Green Bay/Straub, WI at 00:00Z on 2012-05-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 524 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Green Bay/Straub, WI at 00:00Z on 2012-05-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -76 square meters per square second.193958Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
524 J/kg
Mixed-layer CIN
-40 J/kg
Mixed-layer LCL
1809 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
-76 m²/s²
0-3 km storm-relative helicity
24 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

229 
ACUS11 KWNS 210007
SWOMCD
SPC MCD 210007 
MIZ000-210100-

MESOSCALE DISCUSSION 0855
NWS STORM PREDICTION CENTER NORMAN OK
0707 PM CDT SUN MAY 20 2012

AREAS AFFECTED...W-CNTRL LOWER MI

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 210007Z - 210100Z

PROBABILITY OF WATCH ISSUANCE...5 PERCENT

SUMMARY...AN ISOLATED DMGG WIND THREAT MAY EXIST WITHIN THE NEXT 1-2
HRS AS TSTMS CURRENTLY OVER LAKE MICHIGAN MOVE INLAND. A WW IS NOT
CURRENTLY ANTICIPATED.

DISCUSSION...A CLUSTER OF TSTMS CURRENTLY OVER LAKE MICHIGAN IS
APPROACHING WRN PORTIONS OF LOWER MI ALONG A PRE-FRONTAL CONFLUENCE
ZONE. 00Z SFC OBS SHOW LARGE T-TD SPREADS EXIST ALONG THE ERN LAKE
MICHIGAN SHORE AND POINTS EASTWARD...AS TEMPERATURES ARE IN THE
MIDDLE 80S AS OF 00Z. GIVEN STEEP LOW-LEVEL LAPSE RATES AND THE
LIKELY PRESENCE OF A WELL-MIXED BOUNDARY LAYER...ENHANCED DOWNDRAFT
POTENTIAL VIA EVAPORATIVE COOLING COULD RESULT IN A FEW ISOLD DMGG
WIND GUSTS ACROSS THIS AREA AS CONVECTION MOVES INLAND. THE THREAT
SHOULD DECREASE BEYOND 1-2 HRS WITH THE LOSS OF DIURNAL HEATING AND
BOUNDARY LAYER STABILIZATION.

..ROGERS/MEAD.. 05/21/2012

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

ATTN...WFO...APX...GRR...

LAT...LON   43958571 43588570 43208575 42888597 42798617 43098626
            43438643 43658654 43868640 44168630 44348602 44268569
            43958571

Nearby

Mesoscale Discussions in Michigan, 2012Every mesoscale discussion in 2012

Sources

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.