The threat of damaging winds and large hail is increasing (read MD 1227 for detailed background information), and the SPC has issued a severe thunderstorm watch for southern MI. The watch is effective until midnight.
A watch means that conditions are right for severe thunderstorms to form in and close to the watch area (and we have seen some storms form in SW MI very quickly this afternoon).
The watch is in response to storms which developed quickly in SW Michigan around 5pm today, and shortly thereafter became severe. They are moving west, relatively slowly right now, and are expected to persist or continue developing. They are already severe, with significant lightning, heavy rainfall, and tops at 55,000 feet.
Primary threats from storms in this area are:
- damaging winds (70mph gusts possible)
- some large hail up to 1.5 inches in diameter is possible
- few tornadoes are possible
SEL6
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 366
NWS STORM PREDICTION CENTER NORMAN OK
640 PM EDT TUE JUN 25 2013
THE NWS STORM PREDICTION CENTER HAS ISSUED A
* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHERN LOWER MICHIGAN
LAKE ERIE
* EFFECTIVE THIS TUESDAY NIGHT FROM 640 PM UNTIL MIDNIGHT EDT.
* PRIMARY THREATS INCLUDE...
SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE
A FEW LARGE HAIL EVENTS TO 1.5 INCHES IN DIAMETER POSSIBLE
A FEW TORNADOES POSSIBLE
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES EAST AND WEST OF A LINE FROM 15 MILES NORTH OF ANN
ARBOR MICHIGAN TO 40 MILES SOUTH SOUTHWEST OF JACKSON MICHIGAN.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU6).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 361...WW 362...WW
363...WW 364...WW 365...
DISCUSSION...TSTMS NOW FORMING IN SW LWR MI...ALONG INTERSECTION OF
LAKE BREEZE BOUNDARY AND W-E OUTFLOW BOUNDARY FROM EARLIER
STORMS...EXPECTED TO PERSIST AND POSSIBLY STRENGTHEN AS LOW-LVL
CONVERGENCE/HEATING CONTINUE ACROSS REGION. AREA VWP DATA WITH
MODERATE...UNIDIRECTIONAL DEEP WLY WINDS SUGGEST POTENTIAL FOR A FEW
SUSTAINED STORMS/BOWING SEGMENTS CAPABLE OF DMGG WIND...MARGINALLY
SVR HAIL...AND PERHAPS A TORNADO THROUGH MID TO LATE EVE AS THE
ACTIVITY MOVES/PROPAGATES MAINLY EWD.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM
MOTION VECTOR 27035.
...CORFIDI