Severe Thunderstorm Warning 69, NWS Grand Rapids, MI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GRAND RAPIDS MI
200 PM EDT THU JUL 13 2000

THE MAIN WX MAKER DURING THE NEXT 48 HRS CENTERS AROUND A DEVELOPING
LOW IN ONTARIO AND THE TROFS AND FRONTS ASSOCIATED WITH IT AS IT
MOVES THRU THE CWA.

THE LATEST SFC ANALYSIS SHOWS A TROF EXTENDING FROM NEAR MNM TO ORD.
DWPTS TO THE WEST ARE AROUND 70 WHILE OVR SW LWR DWPTS ARE IN THE
MID 50S. A COLD FRONT EXTENDED FROM A LOW OVER CENTRAL ONTARIO TO A
LOW IN SW MN. AS THE TROF OVER ERN WI MOVES EAST THIS EVENING THE
ATM SHOULD BEGIN TO DESTABILIZE. KAPX/KMQT 88D/S SHOW DEVELOPING
STORMS ALONG THE TROF ACROSS ERN UPR AND THE DOOR PENINSULA. SHORT
RANGE MODELS ARE SIMILAR THRU 48 HRS AND SHOW CAPE IN EXCESS OF 1000
J/KG THRU 12Z. LI/S REMAIN LOWEST IN THE NORTH TONIGHT CLOSEST TO
THE BEST DYNAMICS BUT STILL BELOW ZERO ACROSS ALL OF THE CWA. WOULD
EXPECT A FEW STORMS TO CONTINUE FIRING NEAR THE TROF THIS EVENING
ESPECIALLY IN THE NRN CWA IN THE INCREASINGLY UNSTABLE AIR BUT THE
MORE COHERENT CONCENTRATION OF STORMS SHOULD REMAIN CLOSER TO THE
COLD FRONT IN WRN WI WHERE QG FORCING IS MAXED AND THETA-E RIDGE IS
IN PLACE. THOSE DYNAMICS MOVE INTO SW LWR AROUND MIDNIGHT AND SLOWLY
CROSS THE CWA BY 12Z. THOSE DYNAMICS COUPLED WITH A STEEPENING LAPSE
RATE COULD MAKE SOME OF THE STORMS RATHER STRONG. GOING AGAINST THE
SEVERE WX THREAT WILL BE THE RELATIVE LACK OF MOISTURE. FCST
SOUNDINGS SHOW QUITE A BIT OF DRY AIR BLO 850 MB IN PLACE THROUGHOUT
THE NEXT 24 HRS. WILL GO LIKELY POPS IN THE NORTH AND CHC IN THE
SOUTH TONIGHT. BY 12Z FRIDAY THE FRONT WILL BE IN THE ERN CWA. WILL
MAINTAIN CHC POPS IN THE MORNING THERE BUT DRY IN THE WEST. AFTER
THE FRONT MOVES EAST THEN THE UPR LOW MOVES IN. MODELS SHOW A SHORT
WAVE ROTATING AROUND THE UPR LOW ON FRIDAY. CU MACRO ISN/T TOO
STRONG WITH THE CU AND FCST SOUNDINGS SHOW MOST OF THE MOISTURE IN
THE LWR LVLS. WILL GO WITH BECOMING PARTLY SUNNY ON FRIDAY. WITH THE
UPR LOW STILL IN COMMAND FRIDAY NIGHT AND DECENT CURVATURE IN PLACE
WILL GO WITH CONSIDERABLE CLOUDINESS FRI NIGHT. UPR RIDGE AXIS MOVES
CLOSER ON SATURDAY AND UPR LOW MOVES EAST SO WE SHOULD SEE A BIT
MORE SUN THEN...ESPECIALLY IN THE AFTERNOON.

WF

EXTENDED FORECAST DISCUSSION...
HIGH PRESSURE BUILDS IN BEHIND THE WAVE THAT WILL AFFECT THE LAKES
REGION TON/FRI...SO SATURDAY NIGHT (THE FIRST PERIOD OF THE
EXTENDED) SHOULD BE TRANQUIL. SURFACE RIDGING WILL LINGER ACROSS THE
AREA INTO MONDAY MORNING...AT WHICH TIME RETURN FLOW SETS UP. A
BOUNDARY WILL APPROACH THE AREA MONDAY NIGHT AND LINGER IN THE
SOUTHERN GREAT LAKES ON TUESDAY. AT THIS POINT...WILL INTRODUCE THE
MENTION OF PRECIPITATION ON TUESDAY AND HOLD OFF FOR MONDAY
NIGHT...AS THE BETTER DYNAMICS MOVE IN DURING THE DAY TUESDAY.
USED A BLEND OF THE MRF AND THE CANADIAN FOR THE EXTENDED FORECAST.

DUKESHERER

.GRR...NONE.