FXUS63 KAPX 030949
AFDAPN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
548 AM EDT TUE JUN 03 2003
ON THE CURRENT SURFACE MAP...1017 MB HIGH PRESSURE CONTINUES TO LIE
ACROSS THE GREAT LAKES REGION WITH 1005 MB LOW PRESSURE OVER
SOUTHERN ILLINOIS. IR SATELLITE LOOP INDICATES THAT A GOOD DEAL OF
MIDDLE AND HIGH CLOUDS ACROSS MUCH OF THE LOWER PENINSULA. WATER
VAPOR LOOP SHOWS A CUTOFF LOW SPINNING ITS WHEELS OVER SOUTHWEST
WISCONSIN. REGIONAL RADARS AND SURFACE OBSERVATIONS INDICATE RAIN
SHOWERS REMAIN TO THE SOUTH OF MICHIGAN AT THE MOMENT. MAIN FORECAST
CONCERNS REVOLVE AROUND CLOUD COVER TODAY THEN POPS WEDNESDAY INTO
THURSDAY. WILL GENERALLY FOLLOW MORE AGGRESSIVE ETA IN HANDLING OF
UPPER LOW AS ITS INITIALIZATION IS BEST (PLUS EVOLUTION IS CLOSE TO
THAT OF ECWMF AND UKMET).
TODAY...MODELS IN AGREEMENT THAT UPPER LEVEL LOW CONTINUES TO SPIN
OVER SOUTHWEST WISCONSIN WHILE WEAKENING SLIGHTLY.
MEANWHILE...SURFACE HIGH PRESSURE HOLDS ON ACROSS THE FORECAST AREA
RESULTING IN DRY CONDITIONS ACROSS THE FORECAST AREA. MID/HIGH
CLOUDS EXPECTED TO DIMINISH THIS AFTERNOON AS MEAN RH DECREASES
THROUGH THE DAY. 900/700 MB ACROSS THE FAR SOUTH STARTS OUT BETWEEN
55 AND 65 PERCENT AT 12Z WHICH FALLS TO BETWEEN 30 AND 40 PERCENT BY
00Z. ELSEWHERE...30 TO 40 PERCENT FALLS TO 20 TO 30 PERCENT. AS A
RESULT PARTLY CLOUDY SHOULD WORK IN MOST AREAS. 850 MB TEMPERATURES
ARE BETWEEN PLUS 7 AND PLUS 8 WHICH IS BARELY (LESS THAN A DEGREE)
COOLER THAN YESTERDAY SO SIMILAR HIGHS EXPECTED (UPPER 60S TO LOWER
70S).
TONIGHT...UPPER LEVEL LOW BECOMES A LITTLE MORE ORGANIZED AS A
VORTICITY CENTER EVIDENT ACROSS NORTHWEST SOUTH DAKOTA APPROACHES IT
FROM THE WEST. BUT MODELS INSIST THAT THE UPPER LOW REMAINS NEARLY
STATIONARY ACROSS SOUTHWEST WISCONSIN. 900/700 MB RH IS BETWEEN 20
AND 30 PERCENT ACROSS MOST AREAS EXPECT THE SOUTHEAST CORNER OF THE
FORECAST AREA WHERE MOISTURE BEGINS TO BACK ITS WAY INTO THAT AREA
LATE (WITH 900/700 MB RH INCREASING TO BETWEEN 70 AND 80 PERCENT BY
12Z). SO MOSTLY CLEAR/PARTLY CLOUDY ALL AREAS EXCEPT SOUTHEAST ZONES
WHERE CLOUDS WILL BE ON THE INCREASE LATE.
WEDNESDAY AND WEDNESDAY NIGHT...UPPER LOW STRENGTHENS A BIT MORE
WITH HELP FROM PREVIOUSLY MENTIONED VORT MAX AND TAKES A TRACK
ACROSS CENTRAL MICHIGAN WHICH WILL INCREASE POPS ACROSS ALL OF
NORTHERN LOWER MICHIGAN. 900/700 MB RH SKY ROCKETS THROUGHOUT THE
DAY TO BETWEEN 90 AND 95 PERCENT ACROSS THE CENTRAL AND SOUTH AND 75
AND 85 PERCENT NORTH BY 00Z. MEANWHILE ACROSS E UPPER 900/700 MB RH
ENDS UP BETWEEN 65 AND 75 PERCENT BY 00Z AS DOWNSLOPING EASTERLY
FLOW EATS AWAY AT THE MOISTURE SOMEWHAT. MODEL SOUNDINGS INDICATE
LOWER LEVELS BELOW 800 MB VERY DRY TO START THE DAY BUT MOISTEN UP
FROM SOUTH TO NORTH ACROSS NORTHERN LOWER THROUGHOUT THE DAY.
THEREFORE WILL ADD SCATTERED POPS TO SOUTHERN ZONES IN THE AFTERNOON
WITH SCATTERED POPS FOR ALL OF NORTHERN LOWER WEDNESDAY NIGHT
(HIGHEST POPS 50 SOUTH TAPERED DOWN TO 30 POPS NORTHWEST). THUNDER
CHANCES APPEAR REMOTE WITH DECENT INSTABILITY REMAINING TO THE EAST.
WILL LOWER HIGHS ON WEDNESDAY DUE TO THE ABUNDANT CLOUD COVER AND
COLD POCKET OF AIR ASSOCIATED WITH THE UPPER LOW.
THURSDAY...MODELS INDICATE THAT THE UPPER LOW WILL BE EAST OF THE AREA
AT 12Z SO WILL PULL POPS ACROSS THE EAST AS HIGH PRESSURE BUILDS IN
AT THE SURFACE AND ALOFT. WESTERLY FLOW AND 850 MB TEMPERATURES
BETWEEN PLUS 9 AND PLUS 11 SHOULD RESULT IN HIGHS IN THE LOWER TO
MIDDLE 70S.
NO CHANGES TO THE REMAINDER OF THE FORECAST.
THANKS FOR THE CHATS FROM MQT...DTX AND GRR.
.APX...NONE.
$$
SULLIVAN