Alert archive / Michigan / Severe Thunderstorm Warnings in 2003

Severe Thunderstorm Warning 120, NWS Grand Rapids, MI

August 2, 2003Mason County, Michigan

NWS Grand Rapids, MI issued this severe thunderstorm warning at Aug 2, 2003, 12:23 PM EDT for Mason County, Michigan. It was in force for 52 min. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 2, 2003, 12:23 PM EDT (16:23 UTC)
Expired: Aug 2, 2003, 1:15 PM EDT
In force: 52 min
Issued by: NWS Grand Rapids, MI
Area: Counties, with a storm outline in the text

County Mason County, MI

The radar

The Grand Rapids radar (KGRR), 138 km from the middle of the area, began a volume at 16:26 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.

The nearest sounding before it

Green Bay/Straub, WI (KGRB), launched 12:00Z, 4.4 hours before the alert went out and 146 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: 90 J/kg
Mixed-layer CIN: -98 J/kg
Mixed-layer LCL: 1009 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: 35 m²/s²
0-3 km storm-relative helicity: 59 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Grand Rapids, MI wrote its last area forecast discussion before this severe thunderstorm warning went out at Aug 2, 11:06 AM EDT, 1 hour 17 minutes earlier.

Area forecast discussion, Aug 2, 11:06 AM EDT, 1 hour 17 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1105 AM EDT SAT AUG 02 2003

...UPDATED FOR LATE MORNING CLOUDS MIXING OUT...

A STRATUS DECK HAD FORMED UNDER THE RADIATION INVERSIONS SHOWN WELL
ON THE DTX 12Z SOUNDING.  THE WATER VAPOR LOOP SHOWS ONE SHORTWAVE
MOVING THROUGH SOUTHERN LWR MI AT 14Z WHILE AN AREA OF NVA WAS
CROSSING LAKE MICHIGAN.  BEHIND THAT WAS A BETTER SHORTWAVE OVER SRN
MN.  THE RUC AND ETA AGREE THE BEST Q VECTOR CONVERGENCE WILL BE
OVER NRN LWR MI AND IN/OH THIS THIS AFTERNOON.  ALSO THEY BOTH SHOW
AN AREA OF LOW LEVEL DRY AIR (925 TO 700 MB) DRY POCKET OVER SW
LOWER MICHIGAN. THE SURFACE MAP SHOWS THE LOW OVER WI.  MSAS SHOWED
THE BEST INSTABILITY OVER IN/IL WITH SFC LI BELOW -4C.  THERE WAS A
FEW ISOLATED SHOWERS OVER MASON COUNTY BUT STRONG CELLS JUST NORTH
OF THERE AT 1100 AM.

I EXPECT THE LOW CLOUDS TO BURN OFF BETWEEN 11 AM AND 1 PM OVER MOST
OF THE CWA AND THAT WILL BE REPLACED BY A CU DECK. GIVEN THE
VERTICAL TOTALS NEAR 26C...SFC LI FORECAST TO BE NEAR -5C OVER MOST
OF THE CWA AND THE 500 COLD POOL JUST OFF TO THE WEST... PLUS THE
SHORTWAVE FROM MN ROTATING IN THIS AFTERNOON I BELIEVE SHOWERS AND
THUNDERSTORMS WILL RAPIDLY DEVELOP INLAND FROM THE LAKE SHORE THIS
EARLY THIS AFTERNOON AND PERSIST INTO THE LATE EVENING.  WIND SHEAR
IS WEAK BUT CAPES FORECAST NEAR 2000 J/KG... SO STILL LOOKS LIKE
SEVERE WOULD BE POSSIBLE ANYWHERE IN THE CWA THIS AFTERNOON.  HAIL
WOULD BE THE MOST LIKELY SEVERE WEATHER THREAT SINCE FREEZING LEVEL
NEAR 12000 FT. DUE TO HIGH CAPES...WIND CAN NOT BE RULED OUT EITHER.
ALSO SLOW MOVING STORMS COULD RESULT IN LOCAL URBAN AND SMALL STREAM
FLOODING FROM SOME OF THE HEAVIER STORMS. HOWEVER...SINCE THE
HIGHEST SFC DEWPOINTS... BEST DYNAMICS (DPVA AND QVEC CONVERGENCE)
IS SOUTH JUST SOUTH OF MI... I WOULD EXPECT THE BEST COVERAGE OF
SEVERE THUNDERSTORMS WILL BE THERE.

SO... WILL GO WITH VARIABLE CLOUDINESS AND SCT THUNDERSTORMS THIS
AFTERNOON WITH A 40 PERCENT POP. NO REAL CHANGE TO THE GOING
FORECAST.

.GRR...NONE.

WDM

Hazardous weather outlook, Aug 2, 6:57 AM EDT, 5 hours 26 minutes before

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The office that day

Everything else NWS Grand Rapids, MI issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 1, 8:09 PM EDT	Severe Thunderstorm Warning	GRR	Van Buren	51 min
Aug 1, 8:43 PM EDT	Severe Thunderstorm Warning	GRR	Allegan	62 min
Aug 1, 9:00 PM EDT	Severe Thunderstorm Warning	GRR	Barry	75 min
Aug 1, 9:31 PM EDT	Severe Thunderstorm Warning	GRR	Mecosta	59 min
Aug 1, 9:36 PM EDT	Severe Thunderstorm Warning	GRR	Kent	54 min

Nearby

Severe Thunderstorm Warnings in Michigan, 2003 Every severe thunderstorm warning in 2003

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.