Alert archive / Michigan / Mesoscale Discussions in 2019

Mesoscale Discussion 1921

September 3, 201921 counties in Michigan

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2019, 4:20 PM EDT for 21 counties in Michigan. It was in force for 85 min.

The area

The outline as issued.

The facts

Issued
Sep 3, 2019, 4:20 PM EDT (20:20 UTC)
Expired
Sep 3, 2019, 5:45 PM EDT
In force
85 min
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 21 counties

Antrim County, MI, Cheboygan County, MI, Clare County, MI, Crawford County, MI, Gladwin County, MI, Grand Traverse County, MI, Isabella County, MI, Kalkaska County, MI, Lake County, MI, Manistee County, MI, Mecosta County, MI, Midland County, MI, Missaukee County, MI, Montmorency County, MI, Newaygo County, MI, Ogemaw County, MI, Osceola County, MI, Oscoda County, MI, Otsego County, MI, Roscommon County, MI, Wexford County, MI

The radar

The NCL Michigan radar (KAPX), 52 km from the middle of the area, began a volume at 20:24 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.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 8.3 hours before the alert went out and 239 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 12:00Z on 2019-09-03Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 61 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 12:00Z on 2019-09-03The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 443 square meters per square second.19395878Sfc1 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
61 J/kg
Mixed-layer CIN
-169 J/kg
Mixed-layer LCL
870 m above ground
0-6 km bulk shear
62 kt
0-1 km storm-relative helicity
443 m²/s²
0-3 km storm-relative helicity
346 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.3

Open this sounding in Storm Lab

The text

As transmitted.

449 
ACUS11 KWNS 032020
SWOMCD
SPC MCD 032020 
MIZ000-032145-

Mesoscale Discussion 1921
NWS Storm Prediction Center Norman OK
0320 PM CDT Tue Sep 03 2019

Areas affected...Northern Lower MI

Concerning...Severe potential...Watch unlikely 

Valid 032020Z - 032145Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated strong wind gust or two possible across
northern portions of Lower MI during the next few hours.

DISCUSSION...Recent visible satellite imagery shows a large area of
cloudiness over all of northern Lower MI. This area of cloudiness
has limited diurnal heating, keeping temperatures in the low 70s.
This limited heating has resulted in a largely stable air mass
despite advection of relatively steep mid-level lapse rates and
dewpoints in the mid 60s. Strong forcing for ascent attendant to the
approaching shortwave trough will likely result in sporadic deep
convection capable of lightning and possibly a strong wind gust or
two. Isolated nature of these storms (and the resulting severe
threat) will likely preclude the need for a watch.

..Mosier/Guyer.. 09/03/2019

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   44968594 45348545 45748454 45168340 44268357 43578438
            43418497 43508636 44308635 44968594

Nearby

Mesoscale Discussions in Michigan, 2019Every mesoscale discussion in 2019

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.