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The expiration time in the watch graphic is amended if the watch is
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Watch Status Reports.
SEL9
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 639
NWS STORM PREDICTION CENTER NORMAN OK
820 PM EDT WED AUG 22 2007
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
SOUTHWEST AND CENTRAL LOWER MICHIGAN
LAKE MICHIGAN
EFFECTIVE THIS WEDNESDAY NIGHT AND THURSDAY MORNING FROM 820 PM
UNTIL 100 AM EDT.
HAIL TO 1.5 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 35
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 15 MILES SOUTH OF
MUSKEGON MICHIGAN TO 15 MILES EAST OF FLINT MICHIGAN. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU9).
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 637...WW 638...
DISCUSSION...A SMALL MCS OVER LAKE MI WILL MOVE INLAND OVER SW LOWER
MI AND CONTINUE EWD ALONG AN INSTABILITY GRADIENT INTO CENTRAL LOWER
MI THROUGH THE EARLY OVERNIGHT HOURS. RESIDUAL STEEP LAPSE RATES IN
THE LOW LEVELS...ALONG WITH STRONG INSTABILITY AND 35-40 KT MOTION
OF THE COLD POOL...SHOULD SUPPORT A THREAT FOR DAMAGING WINDS GUSTS
FOR THE NEXT FEW HOURS.
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 500. MEAN STORM
MOTION VECTOR 27035.
...THOMPSON
Note:
The Aviation Watch (SAW) product is an approximation to the watch area.
The actual watch is depicted by the shaded areas.
SAW9
WW 639 SEVERE TSTM MI LM 230020Z - 230500Z
AXIS..35 STATUTE MILES NORTH AND SOUTH OF LINE..
15S MKG/MUSKEGON MI/ - 15E FNT/FLINT MI/
..AVIATION COORDS.. 30NM N/S /15SSW MKG - 13E FNT/
HAIL SURFACE AND ALOFT..1.5 INCHES. WIND GUSTS..60 KNOTS.
MAX TOPS TO 500. MEAN STORM MOTION VECTOR 27035.
LAT...LON 43458623 43478344 42458344 42458623
THIS IS AN APPROXIMATION TO THE WATCH AREA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE WOUS64 KWNS
FOR WOU9.
Watch 639 Status Report Messages:
STATUS REPORT #4 ON WW 639
VALID 230435Z - 230540Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 20 NNE ARB
TO 25 ENE FNT TO 30 E MBS.
..BROYLES..08/23/07
ATTN...WFO...GRR...DTX...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC087-099-125-147-151-157-230540-
MI
. MICHIGAN COUNTIES INCLUDED ARE
LAPEER MACOMB OAKLAND
ST. CLAIR SANILAC TUSCOLA
$$
LCZ422-460-LHZ442-443-463-464-230540-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
ST. CLAIR RIVER
LAKE ST. CLAIR (U.S. PORTION)
HARBOR BEACH TO PORT SANILAC MI
PORT SANILAC TO PORT HURON MI
LAKE HURON HARBOR BEACH TO PORT SANILAC 5 NM OFF SHORE TO
US/CANADIAN BORDER
LAKE HURON... PORT SANILAC TO PORT HURON 5 NM OFF SHORE TO
US/CANADIAN BORDER
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #3 ON WW 639
VALID 230335Z - 230440Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 10 NE JXN TO
25 NNE LAN TO 10 WSW MBS.
..BROYLES..08/23/07
ATTN...WFO...GRR...DTX...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC049-087-093-099-125-145-147-151-155-157-230440-
MI
. MICHIGAN COUNTIES INCLUDED ARE
GENESEE LAPEER LIVINGSTON
MACOMB OAKLAND SAGINAW
ST. CLAIR SANILAC SHIAWASSEE
TUSCOLA
$$
LCZ422-460-LHZ442-443-463-464-230440-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
ST. CLAIR RIVER
LAKE ST. CLAIR (U.S. PORTION)
HARBOR BEACH TO PORT SANILAC MI
PORT SANILAC TO PORT HURON MI
LAKE HURON HARBOR BEACH TO PORT SANILAC 5 NM OFF SHORE TO
US/CANADIAN BORDER
LAKE HURON... PORT SANILAC TO PORT HURON 5 NM OFF SHORE TO
US/CANADIAN BORDER
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #2 ON WW 639
VALID 230230Z - 230340Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 N BEH TO
15 SE GRR TO 30 NE GRR TO 30 SE RQB.
..BROYLES..08/23/07
ATTN...WFO...GRR...DTX...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC005-015-037-045-049-057-065-067-087-093-099-125-145-147-151-
155-157-230340-
MI
. MICHIGAN COUNTIES INCLUDED ARE
ALLEGAN BARRY CLINTON
EATON GENESEE GRATIOT
INGHAM IONIA LAPEER
LIVINGSTON MACOMB OAKLAND
SAGINAW ST. CLAIR SANILAC
SHIAWASSEE TUSCOLA
$$
LCZ422-460-LHZ442-443-463-464-LMZ845-230340-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
ST. CLAIR RIVER
LAKE ST. CLAIR (U.S. PORTION)
SOUTH HAVEN TO HOLLAND MI
HARBOR BEACH TO PORT SANILAC MI
PORT SANILAC TO PORT HURON MI
LAKE HURON HARBOR BEACH TO PORT SANILAC 5 NM OFF SHORE TO
US/CANADIAN BORDER
LAKE HURON... PORT SANILAC TO PORT HURON 5 NM OFF SHORE TO
US/CANADIAN BORDER
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
STATUS REPORT #1 ON WW 639
VALID 230130Z - 230240Z
SEVERE WEATHER THREAT CONTINUES RIGHT OF A LINE FROM 35 S MKG TO
15 WSW GRR TO 25 NE MKG.
..BROYLES..08/23/07
ATTN...WFO...GRR...DTX...
&&
STATUS REPORT FOR WS 639
SEVERE WEATHER THREAT CONTINUES FOR THE FOLLOWING AREAS
MIC005-015-037-045-049-057-065-067-081-087-093-117-123-125-145-
155-157-230240-
MI
. MICHIGAN COUNTIES INCLUDED ARE
ALLEGAN BARRY CLINTON
EATON GENESEE GRATIOT
INGHAM IONIA KENT
LAPEER LIVINGSTON MONTCALM
NEWAYGO OAKLAND SAGINAW
SHIAWASSEE TUSCOLA
$$
LMZ845-230240-
CW
. ADJACENT COASTAL WATERS INCLUDED ARE
SOUTH HAVEN TO HOLLAND MI
$$
THE WATCH STATUS MESSAGE IS FOR GUIDANCE PURPOSES ONLY. PLEASE
REFER TO WATCH COUNTY NOTIFICATION STATEMENTS FOR OFFICIAL
INFORMATION ON COUNTIES...INDEPENDENT CITIES AND MARINE ZONES
CLEARED FROM SEVERE THUNDERSTORM AND TORNADO WATCHES.
$$
Note:
Click for Complete Product Text.
Tornadoes
Probability of 2 or more tornadoes
|
Low (<5%)
|
Probability of 1 or more strong (F2-F5) tornadoes
|
Low (<2%)
|
Wind
Probability of 10 or more severe wind events
|
Mod (40%)
|
Probability of 1 or more wind events > 65 knots
|
Low (20%)
|
Hail
Probability of 10 or more severe hail events
|
Low (10%)
|
Probability
of 1 or
more hailstones > 2 inches
|
Low (<5%)
|
Combined Severe Hail/Wind
Probability of 6 or more combined severe hail/wind events
|
Mod (50%)
|
For each watch, probabilities for particular events inside the watch
(listed above in each table) are determined by the issuing forecaster.
The "Low" category contains probability values ranging from less than 2%
to 20% (F2-F5 tornadoes), less than 5% to 20% (all other probabilities),
"Moderate" from 30% to 60%, and "High" from 70% to greater than 95%.
High values are bolded and lighter in color to provide awareness of
an increased threat for a particular event.
weather.gov 
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