Marine Hail in Lake Huron, September 30, 2002

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
500 AM EDT MON SEP 30 2002

ON THE CURRENT SURFACE MAP...997 MB LOW PRESSURE WAS OVER SOUTHERN
MANITOBA WITH A 1005 MB LOW OVER SOUTHWEST NEBRASKA. WARM FRONT HAS
PUSHED NORTHWARD INTO EXTREME SOUTHERN ONTARIO. REGIONAL RADARS SHOW
CONVECTIVE COMPLEX WHICH FIRED ON 50 KNOT LOW LEVEL JET CONTINUES
OVER EASTERN WISCONSIN NORTHEAST INTO THE CENTRAL UPPER PENINSULA.
FORECAST CHALLENGES ONCE AGAIN INCLUDE TEMPERATURES AND POPS TODAY
INTO TUESDAY NIGHT.

TODAY...LOW LEVEL JET PUSHES NORTHEASTWARD INTO THE WESTERN HALF OF
THE UPPER PENINSULA THIS MORNING. AS A RESULT...EXPECT ORGANIZED
CONVECTION TO MOVE INTO EASTERN UPPER MICHIGAN (NUMEROUS -SHRA/TSRA)
WITH SCATTERED ACTIVITY OVER EXTREME N LOWER. CAN NOT RULE OUT
ISOLATED ACTIVITY OVER THE REMAINDER OF N LOWER THIS MORNING (IN THE
WARM SECTOR WITH DEWPOINTS IN THE LOWER 60S FOR THE MOST PART). A
CAP FORMS THIS AFTERNOON SO DO NOT EXPECT ANY ACTIVITY OVER N LOWER
BUT ANOTHER SHORT WAVE WILL BRING SCATTERED POPS TO E UPPER THIS
AFTERNOON. THE NEXT DILEMMA IS CLOUD COVER AND HIGH TEMPERATURES.
LAST EVENINGS SOUNDINGS INDICATED PLUS 20 AIR AT 850 MB AT DVN AND
PLUS 17 AT GRB. WITH A SOUTHWEST STEERING FLOW AT 850...THIS AIR
WILL ADVECT INTO FORECAST AREA TODAY. MODEL SOUNDINGS INDICATE THAT
ITS FAIRLY MOIST FROM 700 MB UP BUT LOTS OF DRY AIR BELOW THAT. SO
WILL NOT GO BALLISTIC WITH HIGH TEMPERATURES DUE TO LOWERING SUN
ANGLE AND LOTS OF MID/HIGH CLOUDS EXPECTED. IT STILL LOOKS
UNSEASONABLY WARM BUT NOT QUITE TO RECORD LEVELS. FORECAST HIGHS
WILL BE GENERALLY RANGE FROM 78 TO 83 N LOWER AND ONLY THE LOWER 70S
E UPPER WITH ABUNDANT CLOUD COVER. THE ONLY RECORD THAT DAY SHIFT
SHOULD HAVE TO KEEP AN EYE ON APPEARS TO BE THE 85 DEGREES AT HTL.

TONIGHT...THE COMBINATION OF A THETA-E RIDGE MOVING OVER THE AREA
AND A SHORT WAVE WILL LEAD TO LOW CHANCE POPS OVERNIGHT OVER MUCH OF
NORTHERN LOWER. ANOTHER LOW LEVEL JET FORMS OVER NORTHERN WISCONSIN
AND MOVES ACROSS E UPPER AND EXTREME NORTHERN LOWER MICHIGAN
OVERNIGHT SO WILL GO WITH SCATTERED POPS IN THESE AREAS. WILL ISSUE
HAZARDOUS WEATHER OUTLOOK FOR SLIGHT POSSIBILITY OF DAMAGING WINDS
(50 KNOTS AT AROUND 900 MB) AND HAIL (FREEZING LEVEL ABOUT 12,500
FEET AND WET BULB ZERO HEIGHTS AROUND 11,000 FEET). LOW TEMPERATURES
SHOULD REMAIN ON THE MILD SIDE WITH LOWS ONLY IN THE LOWER 60S.
SOUTH TO SOUTH WINDS OF 10 TO 15 MPH SHOULD INHIBIT FOG FORMATION.

TUESDAY...COLD FRONT BEGINS TO WORK ITS WAY SOUTHEASTWARD ACROSS THE
FORECAST AREA. HOWEVER...MODEL SOUNDING INDICATE LIMITED MOISTURE
(900-700 MB RH 50-60 PERCENT AT 18Z WHICH DECREASES TO 30-40 PERCENT
BETWEEN 18Z-00Z). MEANWHILE...UPPER LEVEL DYNAMICS REMAIN WELL NORTH OF
THE FORECAST AREA. 850 MB TEMPERATURES REMAIN PRETTY HIGH INTO THE
AFTERNOON AND RANGE FROM PLUS 17-18 (ETA/NGM) TO 13-14 (AVN). AS A
RESULT HAVE BUMPED UP HIGH TEMPERATURES TO LOWER 70S E UPPER TO
AROUND 80 SOUTHERN COUNTIES OF N LOWER.

TUESDAY NIGHT...MOISTURE INCREASES THROUGH THE NIGHT (900-700 MB RH
INCREASES TO 60-70 PERCENT BY 06Z AND 80-90 PERCENT BY 12Z) AND A
SHORT WAVE MOVES ACROSS N LOWER. MODELS ARE HINTING THAT A WEAK
SURFACE WAVE MOVES ALONG THE FRONT. STILL UNCERTAIN HOW THINGS ARE
GOING TO COME TOGETHER SO WILL GO WITH CHANCE POPS FOR NOW.

NO OTHER CHANGES TO THE FORECAST.

COORDINATED WITH GRR...MQT...DTX.

.APX...NONE.

SULLIVAN