Alert archive / Minnesota / Severe Thunderstorm Watches in 2008

Severe Thunderstorm Watch 908

September 26, 200820 counties in Minnesota

The Storm Prediction Center issued this severe thunderstorm watch at Sep 26, 2008, 12:39 PM CDT for 20 counties in Minnesota. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued
Sep 26, 2008, 12:39 PM CDT (17:39 UTC)
Expired
Sep 26, 2008, 10:00 PM CDT
In force
9 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt

Counties Aitkin County, MN, Becker County, MN, Beltrami County, MN, Carlton County, MN, Cass County, MN, Clearwater County, MN, Cook County, MN, Crow Wing County, MN, Douglas County, MN, Grant County, MN, Hubbard County, MN, Itasca County, MN, Koochiching County, MN, Lake County, MN, Mahnomen County, MN, Morrison County, MN, Otter Tail County, MN, Saint Louis County, MN, Todd County, MN, Wadena County, MN

The radar

The Duluth radar (KDLH), 140 km from the middle of the area, began a volume at 18:00 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.

What SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
20%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
50%
One or more hailstones of 2 inches or more
40%
Six or more combined severe hail and wind reports
80%

Warnings issued inside it

10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Sep 26, 5:07 PM CDTSevere Thunderstorm WarningDLHItasca, Saint Louis53 min
Sep 26, 5:19 PM CDTSevere Thunderstorm WarningDLHCass, Itasca41 min
Sep 26, 5:27 PM CDTSevere Thunderstorm WarningFGFHubbard, Wadena63 min
Sep 26, 5:40 PM CDTSevere Thunderstorm WarningDLHCass, Crow Wing65 min
Sep 26, 5:58 PM CDTSevere Thunderstorm WarningDLHSaint Louis47 min
Sep 26, 6:00 PM CDTSevere Thunderstorm WarningDLHCass, Itasca45 min
Sep 26, 6:38 PM CDTSevere Thunderstorm WarningDLHCook, Lake39 min
Sep 26, 6:43 PM CDTSevere Thunderstorm WarningDLHAitkin, Cass, Crow Wing, Itasca, Saint Louis62 min
Sep 26, 7:02 PM CDTFlash Flood WarningDLHAitkin, Cass, Crow Wing, Itasca, Saint Louis108 min
Sep 26, 7:32 PM CDTSevere Thunderstorm WarningDLHSaint Louis43 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

International Fa, MN (KINL), launched 12:00Z, 5.7 hours before the alert went out and 141 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, International Fa, MN at 12:00Z on 2008-09-26Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 594 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, International Fa, MN at 12:00Z on 2008-09-26The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 49 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
594 J/kg
Mixed-layer CIN
-295 J/kg
Mixed-layer LCL
967 m above ground
0-6 km bulk shear
40 kt
0-1 km storm-relative helicity
49 m²/s²
0-3 km storm-relative helicity
178 m²/s²
Significant tornado parameter
0.0
Supercell composite
4.2

Open this sounding in Storm Lab

The text

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

728 
WWUS20 KWNS 261741
SEL8  
SPC WW 261741
MNZ000-LSZ000-270300-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 908
NWS STORM PREDICTION CENTER NORMAN OK
1240 PM CDT FRI SEP 26 2008

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF 

       NORTHERN MINNESOTA
       LAKE SUPERIOR

EFFECTIVE THIS FRIDAY AFTERNOON AND EVENING FROM 1240 PM UNTIL
1000 PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 85
STATUTE MILES EAST AND WEST OF A LINE FROM 50 MILES WEST
NORTHWEST OF ELY MINNESOTA TO 25 MILES SOUTHWEST OF BRAINERD
MINNESOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE
ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...TSTMS ARE EXPECTED TO INCREASE IN BOTH COVERAGE AND
INTENSITY THIS AFTERNOON ALONG COLD FRONT AND IN ADVANCE OF SHORT
WAVE TROUGH TRANSLATING EWD INTO THE REGION.  DAYTIME
HEATING...MODEST BOUNDARY LAYER MOISTURE AND STEEP MIDLEVEL LAPSE
RATES WILL ALL CONTRIBUTE TO A DECREASING CAP AND THE DEVELOPMENT OF
MODERATE INSTABILITY WITH MLCAPE APPROACHING 2000 J/KG.  AS
SUCH...ONGOING ELEVATED STORMS ARE EXPECTED TO BECOME PROGRESSIVELY
SURFACE-BASED WITHIN AN ENVIRONMENT OF STRENGTHENING VERTICAL SHEAR
WHICH WILL ATTEND SHORT WAVE TROUGH.  THUS...POTENTIAL WILL EXIST
FOR A FEW SUPERCELL STRUCTURES CAPABLE OF LARGE HAIL AND DAMAGING
WIND GUSTS.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 24030.


...MEAD/HALES

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Sep 26, 4:39 AM CDTMesoscale DiscussionSPCBecker, Cass, Hubbard, Itasca, Koochiching, Saint Louis and 1 more96 min
Sep 26, 10:15 AM CDTMesoscale DiscussionSPCBecker, Beltrami, Cass, Clay, Clearwater, Crow Wing and 9 more90 min
Sep 26, 5:14 PM CDTMesoscale DiscussionSPCAitkin, Benton, Carlton, Cass, Crow Wing, Douglas and 19 more91 min
Sep 26, 6:44 PM CDTMesoscale DiscussionSPCAitkin, Carlton, Cass, Crow Wing, Hubbard, Itasca and 5 more61 min

Nearby

Severe Thunderstorm Watches in Minnesota, 2008Every severe thunderstorm watch in 2008

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.