Severe Thunderstorm Warning 7, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
408 PM EST FRI MAR 28 2003

MAIN FOCUS FOR THIS AFTERNOON WAS TIMING THE PCPN OUT OF THE CWA AS
THE LOW PRESSURE OVER NORTHERN MI AND TRAILING COLD FRONT ACROSS THE
CENTER OF THE STATE EXITS.  MUCH COLDER AIR POURS IN BEHIND THIS
SYSTEM...POSSIBLY LEADING TO SOME LAKE EFFECT SHOWERS FOR THE
WEEKEND.

AT 20Z THE COLD FRONT LIES ACROSS THE EASTERN PORTION OF THE CWA.
THE FRONT WILL QUICKLY EXIT THIS EVENING.  A BAND OF POST FRONTAL
RAIN SHOWERS EXTENDS ACROSS MUCH OF LAKE MICHIGAN.  THIS BAND WILL
CROSS THE CWA THIS EVENING AND WILL THEN BE QUICKLY REPLACED BY
DRIER AIR AND SUBSIDENCE THAT IS SLIDING ACROSS IA ATTM. BACK EDGE
OF THE PCPN SHOULD BE CROSSING LAKE MICHIGAN BY 00Z...AND BE EAST OF
THE CWA BY MIDNIGHT.  WILL INCLUDE THE MENTION OF THUNDER IN THE
SOUTHEAST...OTHERWISE THE EVENING SHOULD BE THUNDER FREE.  THE CLOUD
COVER WILL LIKELY STAY IN PLACE OVERNIGHT AS THE LOW LEVELS REMAIN
MOIST.  WITH THE FRONT THROUGH MUCH OF THE CWA TEMPS ARE DROPPING
LATE THIS AFTERNOON...WITH MID 40S ALREADY IN THE NORTHWEST CWA.
DESPITE THE CLOUD COVER HANGING ON TEMPS OVERNIGHT WILL DIVE INTO
THE 30S WITH STRONG COLD AIR ADVECTION BEHIND THE FRONT.

BY SATURDAY THE COLD ADVECTION CONTINUES.  DELTA T/S ACROSS THE LAKE
WILL BE MARGINAL AS H8 TEMPS DROP TO -10 TO -12C.  WILL ONLY INCLUDE
SNOW SHOWERS FOR THE NORTHWEST COUNTIES WHERE DELTA T/S SHOULD BE
EFFICIENT TO PRODUCE ENOUGH INSTABILITY FOR SNOW SHOWERS.  ACROSS
THE
SOUTH THE LOW LEVEL MOISTURE SLOWLY DECREASES.  SO WOULD EXPECT A
FAIR AMOUNT OF CLOUDS EARLY WITH A LITTLE SUNSHINE MIXING IN BY
AFTERNOON.  WITH THE ONGOING CCA IT WILL BE MUCH COLDER TOMORROW...
TEMPS WILL STRUGGLE TO REACH 40.

A H8 THERMAL TROF SLIDES INTO THE REGION SATURDAY NIGHT AND SUNDAY.
THE LOW LEVEL FLOW IS EXPECTED TO VEER TO THE NORTH BY SATURDAY
EVENING AND THEN NORTHEAST BY EARLY SUNDAY.  THIS WILL KEEP ANY LAKE
EFFECT OFFSHORE...SO WILL ONLY CARRY A FEW FLURRIES EARLY IN THE
NW.  CLOUD COVER WILL BE TRAPPED UNDER AN INVERSION SATURDAY
NIGHT...BUT AS THE NORTH FLOW DEVELOPS SOME CLEARING SHOULD MOVE IN
ACROSS THE NORTH LATE SATURDAY NIGHT...AND SPREAD SOUTH EARLY
SUNDAY.  THE MODELS DIFFER A BIT LATER SUNDAY AS THE UPPER TROF
MOVES OVERHEAD.  ALL PUSH SOME DPVA OUR WAY...BUT THERE IS THE
QUESTION OF THE MOISTURE AVAILABLE.  SINCE THIS TROF...AND THE COLD
POOL OF AIR...WILL BE OVERHEAD DURING THE DAYTIME SOME INSTABILITY
SNOW SHOWERS MAY DEVELOP.  WILL CARRY A LOW POP FOR THIS BY
AFTERNOON.

SURFACE HIGH PRESSURE SLIDES IN OVERNIGHT SUNDAY NIGHT.  TOUGH CLOUD
FORECAST AS INVERSION COULD KEEP THE CLOUDS IN PLACE...WHILE A DRIER
NORTHEAST FLOW TRIES TO ERODE THEM.  FOR NOW WILL KEEP IT MOSTLY
CLOUDY...BUT WILL BRING LOW TEMPS DOWN INTO THE TEENS TO ACCOUNT FOR
SOME CLEARING.

JK

EXTENDED FORECAST DISCUSSION...

AFTER THIS WEEKENDS COOL DOWN...NEXT WEEK WILL BEGIN TO FEATURE MORE
SEASONAL TEMPS. FOR MONDAY...THE MID LVL TROUGH BEGINS TO PUSH EAST
THROUGH THE GREAT LAKES REGION. A 500MB VORT APPEARS TO SLIDE SE OUT
OF ALBERTA THAT WILL REMAIN NORTH OF LWR MI THROUGH MON. THIS SYSTEM
DOES NOT APPEAR TO BE MOISTURE STARVED. 850MB TEMPS IN THE -6 TO -10
RANGE SHOULD PRODUCE A MIX OR RAIN AND SNOW THROUGH ONSET AND EARLY
AFTERNOON...TEMPS WILL CONTINUE TO RISE THROUGH THE AFTERNOON WHICH
MAY BE ENOUGH TO CHANGE THE MIX OVER TO ALL RAIN BY MID TO LATE
AFTERNOON.

TUE WILL FEATURE HIGH 850MB RH VALUES...WITH DRY AIR MOVING IN LATE
IN THE DAY. WILL KEEP MENTION OF SHOWERS THROUGH MORNING
HOURS...THEN MOISTURE EXITS THE REGION RESULTING IN PARTLY CLOUDY
SKIES THROUGH THE AFTERNOON. WITH THE BROAD RIDGE BUILDING INTO THE
NATIONS MID SECTION. THIS RIDGE MAY INFLUENCE THE JET WHICH FOR LATE
TUE IS PROGGED TO BE SPREADING ACROSS THE NORTHERN PLAINS...DOWN
INTO LWR MI. LWR MI APPEARS TO BE NEAR A JET STREAK LATE TUE...AT
THIS TIME WILL GO AHEAD AND BUMP THE SHOWERS UP TO A CHANCE OF
SHOWERS AND THUNDERSTORMS.

WED THROUGH FRI...RIDGE FROM EARLY IN THE WEEK SHIFTS EAST AND
RETURN FLOW IS PROGGED FOR LATE IN THE WEEK FOR THE TENNESSEE
VALLEY...SPREADING NORTH INTO THE GRT LKS REGION. THE JET LOOKS TO
REMAIN NORTH OF THE GRT LKS THROUGH REMAINDER OF WEEK. THINKING IS
THAT PRECIP MAY STILL OCCUR WITH A WARM FRONT WED STILL IS PROGGED
TO MOVE NORTH THROUGH THE REGION. WITH TIME OF YEAR...POSSIBILITY OF
BREAKS IN THE SKIES DURING THE DAY FOR WED THROUGH FRI...AND
POSITION OF JET WILL GO WITH MENTION OF SHOWERS AND THUNDERSTORMS
WED THROUGH FRI.

BEACHLER

.GRR...NONE.

MIZ037>040-043>046-050>052-056>059-064>067-071>074-291100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1152 AM EST FRI MAR 28 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR THE SOUTHWEST QUARTER OF LOWER
MICHIGAN.

.DAY ONE...TODAY AND TONIGHT

A COLD FRONT WILL SWEEP ACROSS THE AREA THIS AFTERNOON AND EVENING
AND BRING SOUTHWEST LOWER MICHIGAN A CHANCE OF SEVERE THUNDERSTORMS.
THE STORM PREDICTION CENTER HAS PLACED SOUTH CENTRAL AND SOUTHEAST
LOWER MICHIGAN IN A SLIGHT RISK FOR SEVERE STORMS...BUT ALL OF
SOUTHWEST LOWER MICHIGAN HAS THE POTENTIAL FOR STRONG TO SEVERE
STORMS. THE TIME OF THE GREATEST THREAT WILL BE BETWEEN NOON AND 6
PM. AGAIN...LOCATIONS ALONG AND SOUTH OF INTERSTATE 96 HAVE THE BEST
CHANCE AT SEVERE WEATHER TODAY.

STRONG AND DAMAGING WINDS WILL BE THE GREATEST THREAT FROM STORMS
TODAY...BUT HAIL TO THREE QUARTERS OF AN INCH AND HEAVY RAINFALL ARE
POSSIBLE AS WELL. WINDS IN EXCESS OF 65 MPH WILL BE A DISTINCT
POSSIBILITY WITH THE STRONGEST OF STORMS. STORM MOTION WILL BE TO
THE NORTHEAST AT 50 MPH.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON AND EVENING.

OSTUNO

MIZ040-046-051-052-058-059-065>067-072>074-290000-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
129 PM EST FRI MAR 28 2003

THE STORM PREDICTION CENTER HAS ISSUED A SEVERE THUNDERSTORM WATCH
FOR PORTIONS OF THE SOUTHWEST QUARTER OF LOWER MICHIGAN EFFECTIVE
UNTIL 700 PM EST FRIDAY EVENING. THIS WATCH INCLUDES THE FOLLOWING
COUNTIES

IN CENTRAL MICHIGAN
     CLARE...ISABELLA...MONTCALM AND GRATIOT

IN SOUTH CENTRAL MICHIGAN
     IONIA...CLINTON...INGHAM...EATON...JACKSON AND CALHOUN

IN SOUTHWEST MICHIGAN
     BARRY AND KALAMAZOO

EJO MWH