FXUS63 KAPX 212342
AFDAPN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
742 PM EDT MON JUL 21 2003

QUICK UPDATE TO EVENING PRECIP COVERAGE IN GRIDS/ZONES. HEAT OF THE 
DAY IS BEING USED UP...AND LOWERED POPS TO AT MOST SCT FOR THE 
EVENING AS PRECIP WANES. WILL TAKE A HARDER LOOK ON PRECIP COVERAGE 
OVERNIGHT LATER ON. JZ

ORIGINAL AFTERNOON DISCUSSION FOLLOWS...

.SHORT TERM...
.SYNOPSIS...SFC LOW IS SITTING OVER THE MI/IN/OH BORDER WITH A 500 
MB SHORTWAVE TROUGH MOVING THROUGH JUST BEHIND IT IN N LOWER. WITH 
500 MB TROUGH IS RATHER BROAD OVER THE REGION. THE FIRST CONCERN 
WILL BE PRECIPITATION ASSOCIATED WITH THIS FEATURE AS IT ATTEMPTS TO 
MOVE OUT OF THE GREAT LAKES BY THURSDAY. CLOUD COVER WITH THIS 
FEATURE WILL ALSO CAUSE SOME TEMPERATURE PROBLEMS.

MODELS ARE IN GOOD AGREEMENT WITH THE MAIN FEATURES. THE CONVECTIVE 
PARAMETERIZATIONS IN THE MODELS LOOK TO BE CAUSING THE GREAT 
DIFFERENCES IN THE QPF FIELDS. ALSO AT 78 AND 84 HOURS THE ETA TRIES 
TO BLAST THE NEXT FRONT INTO W UPPER A BIT FAST COMPARED TO THE 
ENSEMBLE MEANS AND THE GFS.

TONIGHT...NICE LITTLE BURST OF PRECIP ACROSS NORTH CENTRAL LOWER 
MICHIGAN EARLY THIS AFTERNOON AS STORMS DEVELOPING BETWEEN ACB-GLR 
GOT HUNG UP ON ALONG ITS' OUTFLOW BOUNDARY (SOUTHWEST OUTFLOW 
RUNNING INTO EAST/NORTHEAST SYNOPTIC FLOW)...RESULTING IN NEARLY 
STATIONARY CONVECTION OVER EASTERN ANTRIM/SOUTHERN OTSEGO COUNTIES.  
STORM DUMPED A GOOD DEAL OF PEA SIZED HAIL HERE AT APX ALONG WITH 
2.37 INCHES OF RAIN IN 50 MINUTES...THUS PROMPTING THE FFW FOR 
ANTRIM/OTSEGO COUNTIES.  SHORT WAVE TROUGH CUTTING ACROSS NORTHEAST 
LOWER MICHIGAN ATTM...WITH SHOWERS/THUNDERSTORMS OVER MUCH OF 
NORTHEAST LOWER MICHIGAN.  PRECIPITATION MORE SCATTERED ACROSS 
EASTERN UPPER THOUGH CONVECTION DEVELOPING OVER ONTARIO HAS BEEN 
DRIFTING SOUTH INTO THE SOO.  BULK OF THE PRECIP WILL BE AHEAD OF 
THE SHORT WAVE TRACK...THOUGH SCATTERED PRECIP WILL ROTATE AROUND 
THE BACKSIDE OF THE WAVE THROUGH THE EVENING HOURS.  SOME MOISTURE 
LINGERS OVERNIGHT ACROSS THE AREA ALONG WITH MODESTLY STEEP MID 
LEVEL LAPSE RATES (MAINLY THE EASTERN HALF) THOUGH FORCING WILL BE 
LACKING WITH WEAK DOWNWARD FORCING/ISENTROPIC DESCENT.  WILL JUST 
LINGER IN A CHANCE OF SHOWERS LATE OVER NORTHEAST LOWER.  

JPB

TUESDAY...THE CHANCE OF SHOWERS IN NE LOWER CONTINUES FOR THE 
MORNING HOURS AS THE LAST OF THE SHORTWAVE MOVES THROUGH THE REGION. 
WITH THE 500 MB LOW OVER E UPPER AND N LOWER WILL LEAVE IN THE 
CHANCE FOR SHOWERS IN THE AFTERNOON AND ISOLATED THUNDER AS THE 
1000-500 MB LAPSE RATE IS AROUND 7C/KM AND 850 MB RH REMAINS AROUND 
80%. WE WILL CONTINUE WITH A SELF DESTRUCT SUNSHINE AS THE COLD POOL 
ALOFT AND ANY WARMING FROM THE SUN WILL QUICKLY FILL IN ANY BREAKS 
IN THE CLOUD COVER. CONTINUED WITH THE MAV/FWC HIGH TEMPERATURES WITH 
THE CLOUD COVER EXPECTED. THOUGH THE FWC NUMBERS WERE SLIGHTLY 
HIGHER THIS RUN THAN LAST. 

TUESDAY NIGHT...WITH THE DIURNAL HEATING SUBSIDING, SHOWERS SHOULD 
QUICKLY DISAPPEAR AND THE LOW LEVEL MOISTURE MAY END UP TRAPPED. 
WITH THE SFC HIGH BUILDING IN WINDS COULD DROP LOW ENOUGH TO ALLOW 
FOG FOR THE NIGHT, THOUGH IT MAY BE RATHER LIGHT NOT LIMITING 
VISIBILITY MUCH. 

WEDNESDAY/WEDNESDAY NIGHT...THE 500 MB TROUGH BECOMES MORE OF AN OPEN 
WAVE, BUT WITH THE 500 MB FLOW STILL NOT PICKING UP THE TROUGH IT 
BARELY MOVES TO THE EAST. ON FIRST INCLINATION, I WANTED TO YANK THE 
CHANCE POPS OUT OF THE AREA, BUT THE 1000-850 LAPSE RATE IS AROUND 
8+C/KM SO THE CHANCE FOR DIURNAL HEATING TO KICK OFF ANY SHOWERS 
REMAINS FOR AT LEAST ANOTHER DAY. IT'S NOT UNTIL OVERNIGHT THAT THE 
850 RIDGE BEGINS TO BUILD INTO THE REGION AND BY THAT TIME THE 
DIURNAL HEATING WOULD HAVE SUBSIDED. 500 AND 700 MB RIDGES BUILD IN 
AS WELL WITH THE SFC HIGH OVER LAKE MICHIGAN. THE 700-500MB RH IS 
BELOW 30% AND THE 850 RH DROPS BELOW 50%. SO EXPECTING THE SKY TO 
SCATTER OUT A BIT OVERNIGHT.

THURSDAY...HIGH PRESSURE CONTROLS THE REGION FOR THE DAY AND 
TEMPERATURES WILL BEGIN TO WARM AS THE RETURN FLOW BEGINS IN THE 
AFTERNOON. LATE IN THE AFTERNOON, HIGH CLOUDS WILL BE MOVING INTO NW 
LOWER AND E UPPER AHEAD OF THE NEXT SYSTEM. ETA TRIES TO BLAST THE 
SYSTEM IN SO THAT THE FRONT COULD MOVE THROUGH OVERNIGHT, BUT THE 
ENSEMBLE MEANS LOOK MORE LIKE THE GFS AT 84 HOURS SO WILL KEEP THE 
PRECIPITATION FOR THE NIGHT AS WELL. 

.LONG TERM...ENSEMBLE MEANS ARE IN GOOD AGREEMENT TODAY WITH THE 
OPERATIONAL GFS A BIT OF AN OUTLIER IN THE DAYS 5 THROUGH 7 TIME 
FRAMES. THOUGH COMPARED TO THE ECMWF THE SFC LOOKS SOMEWHAT SIMILAR. 
BUT THE CONSENSUS WITH THE MODELS WOULD BEAR OUT THE ECMWF 
OPERATIONAL/GFS ENSEMBLE MEAN SOLUTION. SO THE FORECAST WILL LOOK 
LIKE THIS. FRIDAY, FRONT APPROACHES LATE IN THE DAY SO WILL CONTINUE 
WITH A DRY FORECAST FOR THE TIME BEING, TIMING WOULD SUGGEST THAT 
THE FRONT DOESN'T COME THROUGH UNTIL SATURDAY MORNING. WILL PROBABLY 
TWEAK THE CLOUD COVER UP THOUGH ON FRIDAY. SATURDAY, WILL CONTINUE 
WITH THE CHANCE OF THUNDERSTORMS. THE SOUTHERN PART OF THE FORECAST 
AREA WILL HAVE A SMALLER CHANCE THAN THE NORTH, BUT WILL KEEP IT IN 
N LOWER FOR NOW. SUNDAY WILL HAVE THE CHANCE OF THUNDERSTORMS AS THE 
LOW PASSES NORTH OF LAKE SUPERIOR AND THE COLD FRONT BEGINS TO MOVE 
THROUGH. MONDAY, WILL PUT IN A CHANCE OF RAIN SHOWERS AS THE FRONT 
LOOKS TO BE JUST THROUGH THE FORECAST AREA BY 12Z. 

.APX...NONE.

$$

LUTZ