Severe Thunderstorm Warning 143, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
300 PM EDT FRI JUL 16 2004

.SHORT TERM...
SHOWERS AND THUNDERSTORMS DEVELOPED AS EXPECTED.  WE HAD SOME
REPORTS OF PEA SIZE HAIL.  THE SHORT WAVE RESPONSIBLE FOR THE STORMS
FORMATION WAS OVER CENTRAL WISCONSIN...AND DROPPING SOUTHEAST.  MSAS
SHOWS THEN ENTIRE REGION WITH LIFTED INDEX VALUES LOWER THAN -4 AND
THE MOST UNSTABLE AIR IS IN SOUTHERN LAKE MICHIGAN WHERE THE LIFTED
INDEX IS -8 DEG C.  NO CAP EXISTS IN LAPS SOUNDINGS.  SO...HERE IN
SOUTHWEST LOWER MICHIGAN...WE WILL SEE ONGOING SHOWERS AND
THUNDERSTORMS THROUGH THE EVENING.  WILL KEEP LIKELY PROBABILITIES
GOING FOR A COUPLE OF HOURS.  WITH THE WET BULB ZERO AROUND 10K
FEET...HAIL IS THE PRIMARY THREAT.  HOWEVER A BRIEF WET MICROBURST
CANNOT BE RULED OUT AS THETA E DECREASES > 20 DEG K THROUGH 600 MB.
I DID NOTICE SOME 40KT OUTBOUNDS ON RADAR WITH ONE OF THE CELLS TO
OUR EAST.

FOR SATURDAY...THE MOISTURE IS SLOWER TO DEPART...AND WE ARE PROGGED
TO BECOME UNSTABLE...MAINLY SOUTH.  WILL EXTEND THE PRECIPITATION
THROUGH THE DAY.

NOW THE ETA STILL HOLDS ONTO A DRY SUNDAY...WHILE THE GFS SHOWS MORE
SHOWERS AND THUNDERSTORMS DEVELOPING.  AS WE HAVE IT DRY... WILL
KEEP IT THAT WAY AS OUR UPPER LEVEL HEIGHTS WILL BE RISING.

WITH A RIDGE OF HIGH PRESSURE MOVING IN FOR MONDAY...A DRY DAY WITH
NEAR SEASONABLE TEMPERATURES IS EXPECTED.

.LONG TERM...
JUST A COUPLE OF SUBTLE CHANGES PLANNED TO THE GOING EXTENDED
FORECAST. THE UPPER RIDGE OVER THE FOUR CORNERS IS PROGGED TO
FLATTEN A BIT AS A POTENT SHORT WAVE MOVES ACROSS THE NORTHERN
ROCKIES LATE IN THE PERIOD. THE FLATTENED RIDGE WILL PRODUCE A BIT
MORE ZONAL FLOW AND NOT AS DEEP OF A TROUGH OVER THE LAKES BY THE
END OF THE WEEK WHICH WILL RESULT IN TEMPS NOT QUITE AS COLD AS
PROGGED YESTERDAY. ON THE SFC A WEAK FRONT IS STILL EXPECTED TO DROP
SOUTH LATE MONDAY NIGHT AND TUESDAY MORNING AND FOR THIS WE WILL
RETAIN THE MENTION OF TSRA. LEFT EXIT REGION OF UPPER JET ALSO
PUSHES INTO THE CWA AT THAT TIME. TUESDAY WILL STILL PROBABLY BE DRY
ALTHOUGH THERE IS SOME QUESTION AS TO THE TIMING OF THE FRONT. RIGHT
NOW IT APPEARS THE FRONT WILL MOVE THROUGH THE SOUTHEAST PORTION OF
THE CWA DURING THE MORNING. WILL ADD CHC POPS TO THE SOUTHEAST
PORTION. THE FRONT WILL STALL JUST SOUTH OF THE MICHIGAN BORDER BY
LATE TUESDAY BEFORE RETURNING NORTH TUESDAY NIGHT. HAVE ADDED POPS
LATE TUESDAY NIGHT AND WILL RETAIN THROUGH THURSDAY NIGHT. A LOW IN
WESTERN ONTARIO WILL DRAG THE NEXT COLD FRONT THROUGH THE REGION
THURSDAY AFTERNOON. NOT BUYING THE GFS DEPICTION OF A LOW DEVELOPING
IN EASTERN WISCONSIN SINCE IT APPEARS OUT OF NOWHERE...LIKELY
CONVECTIVE FEEDBACK. CANADIAN MODEL HANDLES THIS FEATURE BETTER. AS

&&

.GRR WATCHES/WARNINGS/ADVISORIES...NONE.

&&

MJS 93

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
1025 AM EDT FRI JUL 16 2004

MIZ037>040-043>046-050>052-056>059-064>067-071>074-171000-
ALLEGAN-BARRY-CALHOUN-CLARE-CLINTON-EATON-GRATIOT-INGHAM-IONIA-
ISABELLA-JACKSON-KALAMAZOO-KENT-LAKE-MASON-MECOSTA-MONTCALM-MUSKEGON-
NEWAYGO-OCEANA-OSCEOLA-OTTAWA-VAN BUREN-
1025 AM EDT FRI JUL 16 2004

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

.DAY ONE...TODAY AND TONIGHT

A SLIGHT RISK FOR SEVERE THUNDERSTORMS EXISTS ALONG AND SOUTH OF A
LINE FROM MUSKEGON TO BATTLE CREEK THIS AFTERNOON AND EVENING.  THE
PRIMARY THREAT IS FOR PENNY SIZE HAIL IN THE STRONGEST STORMS.
CLOUD TO GROUND LIGHTNING AND LOCALLY HEAVY RAINFALL WILL ACCOMPANY
ANY OF THE THUNDERSTORMS.  UP TO AN INCH OF RAIN COULD FALL IN
SLOWER MOVING STORMS.  THE AVERAGE STORM MOTION WILL BE SOUTHEAST AT
15 MPH.  THE MOST LIKELY TIMEFRAME FOR THE STRONGEST STORMS WILL BE
FROM 200 PM TO 900 PM.

A COLD FRONT OVER WISCONSIN WILL MOVE INTO LOWER MICHIGAN THIS
EVENING.  SCATTERED THUNDERSTORMS WILL FORM OUT AHEAD OF THIS FRONT
ACROSS SOUTHWEST LOWER MICHIGAN THIS AFTERNOON AND CONTINUE THROUGH
THE EVENING.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED THIS AFTERNOON AND EVENING.

DUKE MJS