Severe Thunderstorm Warning 57, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
748 PM EDT THU JUL 22 2010

LATEST UPDATE...AVIATION...

.SYNOPSIS...(400 PM EDT THU JUL 22 2010)
A FRONTAL BOUNDARY WILL LINGER ACROSS THE AREA THROUGH SATURDAY
LEADING TO THUNDERSTORMS WITH HEAVY RAIN AT TIMES.  SOME OF THE
STORMS COULD BE SEVERE.  A DRIER AIRMASS ARRIVES SUNDAY INTO MONDAY.

&&

.SHORT TERM...(738 PM EDT THU JUL 22 2010)
(TONIGHT THROUGH SATURDAY NIGHT)
UPGRADED THE REST OF THE CWA TO THE FLASH FLOOD WATCH.  SE COUNTIES
HAVE ALREADY SEEN HEAVY AND MORE IS ON THE WAY.

INITIAL ROUND OF STRONG TO SEVERE THUNDERSTORMS WILL TRACK THROUGH
SOUTHERN LOWER MI THROUGH 6 PM. FAVORABLE DEEP LAYER SHEAR EXISTS
AND INSTABILITY HAS INCREASED.  NEXT A LOW LEVEL JET DEVELOPS IN
WISCONSIN AND MOVES INTO LOWER MI TONIGHT.  THIS FEATURE WILL RAISE
THE RISK FOR SEVERE STORMS. ALOFT UPPER LEVEL DIVERGENCE WILL VENT
THE STORMS AND DEEP LAYER SHEAR IS MARGINALLY SUPPORTIVE OF
ORGANIZED CONVECTION. INSTABILITY REMAINS FAVORABLE FOR STRONGER
CONVECTION AND THIS WILL ALLOW FOR SOME OF THE STORMS TO BE SEVERE.
HOW ORGANIZED THE SEVERE WEATHER BECOMES DEPENDS ON THE EVOLUTION OF
THE CONVECTION AND HOW IT MODIFIES THE ENVIRONMENT.

PERHAPS A BREAK IN THE STRONGER CONVECTION ON FRIDAY AS THE FORCING
BECOMES WEAKER...BUT SATURDAY HAS A MUCH STRONGER UPPER SYSTEM
MOVING THROUGH.    DEEP LAYER SHEAR BECOMES STRONGER AND INSTABILITY
COULD BECOME SUPPORTIVE OF WIDESPREAD SEVERE WEATHER.

&&

.LONG TERM...(400 PM EDT THU JUL 22 2010)
(SUNDAY THROUGH THURSDAY)

HIGH PRESSURE WILL BUILD IN AND PRODUCE FAIR AND LESS HUMID WX
SUNDAY AND MONDAY. TEMPS WILL UNDERGO A MODERATING TREND AND IT WILL
ALSO TURN MORE HUMID FOR THE MIDDLE OF NEXT WEEK AS FLOW BECOMES
SOUTHERLY ON THE BACK SIDE OF THE HIGH PRESSURE RIDGE. THIS IN
CONJUNCTION WITH A LOW PRESSURE SYSTEM MOVING IN FROM THE WNW WILL
BRING A CHC OF THUNDERSTORMS WEDNESDAY THROUGH THURSDAY.

&&

.AVIATION...(748 PM EDT THU JUL 22 2010)
BASED ON  RADAR TRENDS HAVE FEATURE MORE THUNDER IN THE TAFS WITH
THE A 23Z UPDATED.  WILL CONTINUE THIS THUNDER IN THE FORECAST FOR
THE EVENING.  THE MAIN CELL WAS TRACKING SOUTHEAST TOWARD
KAZO...HOWEVER A STRONG LOW LEVEL JET ARRIVES OVERNIGHT THAT WILL
HELP TO PULL THE THUNDER FURTHER NORTH AND EAST INTO KGRR.  WILL
HOLD OFF ON KLAN FOR THE THUNDER...BUT THIS COULD CHANGE.  IFR
WEATHER IS EXPECTED WITH THUNDERSTORMS GIVEN THE TROPICAL
ENVIRONMENT.

CURRENTLY LESS IN THE WAY OF IFR AND THUNDER IS EXPECTED ON FRIDAY.

&&

.MARINE...(400 PM EDT THU JUL 22 2010)
BASED ON THE INCREASING WINDS AND WAVES TONIGHT...MAINTAINED THE
SMALL
CRAFT ADVISORY...THAT WILL LAST INTO FRI AFTERNOON.  WINDS AND WAVES
LIKELY TO BE HAZARDOUS FOR SMALL CRAFT PLUS CURRENTS STRONGER DUE TO
THESE CONDITIONS.  SO RIP CURRENT RISK LIKELY TO BE HIGH.

&&

.HYDROLOGY...(400 PM EDT THU JUL 22 2010)
DECIDED TO GO WITH A FLASH FLOOD WATCH THROUGH TONIGHT FOR MUCH OF
MY WRN COUNTIES.  HIGH PRECIPITABLE WATER AIRMASS WAS MOVING INTO
THE REGION.  LOW LEVEL JET IN WISCONSIN WILL STRENGTHEN AND MOVE
INTO WRN LOWER MI TONIGHT.  THIS WILL LEAD TO STRONGER MOISTURE
TRANSPORT AND CONVERGENCE OVER THE WATCH AREA TONIGHT.  THE CELLS
COULD REPEAT OVER THE SAME AREA FOR A COUPLE OF HOURS...LEADING TO
EXCESSIVE RAINFALL. EFFICIENT RAINFALL EXPECTED GIVEN THE DEEP WARM
LAYER.

&&

.GRR WATCHES/WARNINGS/ADVISORIES...
MI....FLASH FLOOD WATCH THROUGH TONIGHT ENTIRE CWA.
LM....SMALL CRAFT ADVISORY LATER TONIGHT INTO FRIDAY.

&&

SYNOPSIS:     MJS
SHORT TERM:   MJS JK
LONG TERM:    LAURENS
AVIATION:     MJS
MARINE:       MJS
HYDROLOGY:    MJS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
450 PM EDT THU JUL 22 2010

MIZ037>040-043>046-050>052-056>059-064>067-071>074-230915-
MASON-LAKE-OSCEOLA-CLARE-OCEANA-NEWAYGO-MECOSTA-ISABELLA-MUSKEGON-
MONTCALM-GRATIOT-OTTAWA-KENT-IONIA-CLINTON-ALLEGAN-BARRY-EATON-
INGHAM-VAN BUREN-KALAMAZOO-CALHOUN-JACKSON-
450 PM EDT THU JUL 22 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...THIS EVENING AND TONIGHT

AN AREA OF THUNDERSTORMS IS EXPECTED TO MOVE INTO SOUTHWEST LOWER
MICHIGAN LATE THIS AFTERNOON. THERE IS A SLIGHT RISK A FEW STORMS
COULD GET CLOSE TO SEVERE LIMITS DURING THE AFTERNOON AND EARLY
EVENING AS THE WARM FRONT PUSHES INTO THE AREA. THIS WOULD MOSTLY BE
IN THE FORM OF DAMAGING WIND GUSTS. ISOLATED TORNADOES POSSIBLE.
THE GREATEST CONCENTRATION OF RAIN AND THUNDERSTORMS WOULD ACTUALLY
BE NEAR AND NORTH OF ROUTE 10 BETWEEN 6 PM AND ABOUT MIDNIGHT.
LOCALLY HEAVY RAINFALL IS POSSIBLE IN THAT AREA. AREAS OF FLASH
FLOODING OF SMALL STREAMS AND POOR DRAINAGE AREAS WILL BE A HAZARD.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SCATTERED THUNDERSTORMS ARE EXPECTED FRIDAY BUT THE FRONT IS
EXPECTED TO BE STALLED OVER NORTHERN LOWER MICHIGAN DURING FRIDAY.
THE CLOSER ONE GETS TO THE FRONT FRIDAY... THE HIGHER THE CHANCES
OF SEEING A THUNDERSTORM. IT WOULD NOT BE OUT OF THE QUESTION AN
ISOLATED DAMAGING WIND GUST WOULD OCCUR FROM THE STRONGEST STORMS
FRIDAY AFTERNOON. THIS WOULD NOT BE A WIDESPREAD EVENT. MOST
LOCATIONS MAY NOT EVEN SEE RAIN FRIDAY DURING THE DAY.

HOWEVER WITH THE WARM FRONT NORTH OF ROUTE 10 FRIDAY HOT AND HUMID
AIR WILL MOVE INTO THE AREA. AFTERNOON TEMPERATURES SHOULD BE NEAR
90 DEGREES AND WITH DEW POINTS IN THE MID 70S THE HEAT INDEX
VALUES COULD REACH INTO THE DANGER CATEGORY... OVER 100 DEGREE FOR
SEVERAL HOURS. THIS WOULD INCREASE THE RISK OF HEAT STROKE FOR
ANYONE HAVING TO WORK OUTSIDE FRIDAY AFTERNOON.

THE PASSAGE OF THE COLD FRONT SATURDAY EVENING WILL TOUCH OFF
STRONG TO SEVERE STORMS DURING THE MID TO LATE AFTERNOON. DAMAGING
WINDS... VERY HEAVY RAINFALL WITH LOCAL FLOODING OF POOR DRAINAGE
AREAS BEING POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE THROUGH SATURDAY.

LMZ844>849-230915-
ST JOSEPH TO SOUTH HAVEN MI-SOUTH HAVEN TO HOLLAND MI-
HOLLAND TO GRAND HAVEN MI-GRAND HAVEN TO WHITEHALL MI-
WHITEHALL TO PENTWATER MI-PENTWATER TO MANISTEE MI-
450 PM EDT THU JUL 22 2010

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF SOUTHWEST LOWER
MICHIGAN.

.DAY ONE...THIS EVENING AND TONIGHT

WINDS WILL BECOME STRONG OUT OF THE SOUTHEAST LATER THIS AFTERNOON
AND CONTINUE THROUGH TONIGHT. THIS MAY LEAD TO WAVE HEIGHTS BEING
HAZARDOUS TO SMALL WATER CRAFT AND INCREASE THE THREAT OF RIP
CURRENTS.

THUNDERSTORMS WITH HEAVY RAINFALL AND GUSTY WINDS WILL MOVE
THROUGH THE NEAR SHORE WATERS LATE THIS AFTERNOON INTO EARLY
TONIGHT.

.DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY

SOUTHWEST WINDS WILL SLOWLY DECREASE FRIDAY AFTERNOON HOWEVER UNTIL
THEN WINDS AND WAVES MAY BE STRONG ENOUGH TO BE A HAZARD TO SMALL
WATER CRAFT. AN INCREASED RISK FOR RIP CURRENTS WILL EXIST ON
FRIDAY. SCATTERED THUNDERSTORMS ARE EXPECTED TOO.

THE PASSAGE OF A STRONG COLD FRONT SATURDAY EVENING IS EXPECTED TO
TOUCH OFF STRONG TO SEVERE STORMS WITH GUSTY WINDS AND INCREASED
WAVE HEIGHTS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS POSSIBLE THROUGH SATURDAY.

WDM MJS

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
945 PM EDT THU JUL 22 2010

MIZ039-040-046-230245-
CLARE-ISABELLA-OSCEOLA-
945 PM EDT THU JUL 22 2010

...SIGNIFICANT WEATHER ADVISORY...

AT 939 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM 26 MILES WEST OF HARRISON...MOVING EAST AT 35
MPH.

WINDS GREATER THAN 40 MPH...BRIEF HEAVY DOWNPOURS...ARE POSSIBLE WITH
THIS STORM.

* THE THUNDERSTORM WILL BE NEAR...
  BROWNS CORNER AND DOVER BY 1025 PM EDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

GUSTY WINDS MAY CAUSE SMALL OBJECTS SUCH AS TRASH BINS TO BLOW
AROUND. SEEK SHELTER IN A STURDY STRUCTURE UNTIL THIS STORM HAS
PASSED. A TORNADO WATCH REMAINS IN EFFECT UNTIL 300 AM EDT FRIDAY
MORNING FOR SOUTHWESTERN MICHIGAN.

&&

LAT...LON 4403 8461 4378 8460 4388 8539 4406 8537
TIME...MOT...LOC 0145Z 276DEG 31KT 4396 8524

JK

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1026 PM EDT THU JUL 22 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1020 PM     TSTM WND DMG     GANGES                  42.58N 86.21W
07/22/2010                   ALLEGAN            MI   EMERGENCY MNGR

            POWER LINES DOWN.

&&

RSUTTLE

PRELIMINARY LOCAL STORM REPORT...CORRECTED
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1028 PM EDT THU JUL 22 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0957 PM     TSTM WND DMG     GANGES                  42.58N 86.21W
07/22/2010                   ALLEGAN            MI   EMERGENCY MNGR

            POWER LINES DOWN.

&&

RSUTTLE

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1054 PM EDT THU JUL 22 2010

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1050 PM     FUNNEL CLOUD     6 NNE PAW PAW           42.30N 85.86W
07/22/2010                   VAN BUREN          MI   TRAINED SPOTTER

&&

JK