Alert archive / Michigan / Mesoscale Discussions in 2011

Mesoscale Discussion 474

April 19, 201118 counties in Michigan; 12 counties in Wisconsin

The Storm Prediction Center issued this mesoscale discussion at Apr 19, 2011, 5:52 PM EDT for 18 counties in Michigan; 12 counties in Wisconsin. It was in force for 4 hr.

The area

The outline as issued.

The facts

Issued: Apr 19, 2011, 5:52 PM EDT (21:52 UTC)
Expired: Apr 19, 2011, 9:45 PM EDT
In force: 4 hr
Issued by: the Storm Prediction Center

All 30 counties

Antrim County, MI, Benzie County, MI, Charlevoix County, MI, Cheboygan County, MI, Crawford County, MI, Delta County, MI, Emmet County, MI, Grand Traverse County, MI, Kalkaska County, MI, Leelanau County, MI, Manistee County, MI, Menominee County, MI, Missaukee County, MI, Montmorency County, MI, Oscoda County, MI, Otsego County, MI, Presque Isle County, MI, Wexford County, MI, Brown County, WI, Calumet County, WI, Door County, WI, Kewaunee County, WI, Manitowoc County, WI, Marinette County, WI, Menominee County, WI, Oconto County, WI, Outagamie County, WI, Shawano County, WI, Waupaca County, WI, Winnebago County, WI

The radar

The NCL Michigan radar (KAPX), 132 km from the middle of the area, began a volume at 21:53 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 12:00Z, 9.9 hours before the alert went out and 142 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 957 m above ground
0-6 km bulk shear: 72 kt
0-1 km storm-relative helicity: -67 m²/s²
0-3 km storm-relative helicity: -7 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

788 
ACUS11 KWNS 192153
SWOMCD
SPC MCD 192152
MIZ000-WIZ000-200145-

MESOSCALE DISCUSSION 0474
NWS STORM PREDICTION CENTER NORMAN OK
0452 PM CDT TUE APR 19 2011

AREAS AFFECTED...NERN WI...NRN LOWER MI...FAR SERN UPPER MI

CONCERNING...HEAVY SNOW

VALID 192152Z - 200145Z

AN ENE-TO-WSW-ORIENTED BAND OF SNOW WITH RATES UP TO 1 IN/HR WILL
MOVE E-NEWD ACROSS NERN WI...NRN LOWER MI...AND FAR SERN THROUGH THE
LATE AFTERNOON INTO THE EVENING.

ASCENT DRIVEN BY STRONG LOW/MID-LEVEL FRONTOGENESIS TO THE NORTH OF
SFC LOW PRESSURE OVER THE MID-MISSISSIPPI VALLEY REGION WILL
INTERACT WITH DEEP SUBFREEZING PROFILES THROUGHOUT THE TROPOSPHERE
TO PROMOTE A BAND OF SNOW MOVING E-NEWD ACROSS THE DISCUSSION AREA.
THE STRONG ASCENT WILL BE ENHANCED BY UPPER-LEVEL DIVERGENCE IN THE
RIGHT-ENTRANCE REGION OF A JET STREAK MOVING OVER LAKE SUPERIOR INTO
CENTRAL ONTARIO. THESE FACTORS WILL SUPPORT SNOWFALL RATES OF 1
IN/HR WITH THE HEAVIEST SNOW. RUC/NAM FORECAST SOUNDINGS DEPICT
NEARLY ISOTHERMAL PROFILES WITHIN THE 850-650-MB LAYER WITH
TEMPERATURES BETWEEN 0C AND -5C...WHICH WILL SUPPORT THE EFFICIENT
AGGREGATION OF SNOWFLAKES. NAM FORECAST SOUNDINGS INDICATE WEAK
ELEVATED INSTABILITY ABOVE THE 650-MB LEVEL DEVELOPING AROUND 00Z
/YIELDING UP TO 100 J PER KG/ ACROSS NRN LOWER MICHIGAN...
POTENTIALLY ALLOWING SOME LIGHTNING-PRODUCING CONVECTION...WHICH
WILL BE ASSOCIATED WITH THE HIGHEST SNOWFALL RATES. THE EXPERIMENTAL
HRRR INDICATES MOST OF THE HEAVY SNOW HAVING MOVED OUT OF NERN WI BY
05Z...AND OUT OF NRN LOWER MI AND FAR SERN UPPER MI AFTER 07Z.

..COHEN.. 04/19/2011

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

ATTN...WFO...APX...GRR...MQT...GRB...

LAT...LON   44548368 44268551 44118677 43928792 44038873 44368922
            44818925 45358871 45608790 45888675 46028451 45718361
            45088330 44548368

Nearby

Mesoscale Discussions in Michigan, 2011 Mesoscale Discussions in Wisconsin, 2011 Every mesoscale discussion in 2011

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.