FXUS63 KAPX 311013
AFDAPN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GAYLORD MI
613 AM EDT THU JUL 31 2003

EARLY MORNING MCS IN THE SW ZONES HAS MOSTLY RUN ITS COURSE. A FEW 
CELLS REMAIN OVER CENTRAL LAKE MI AND UPSTREAM...MOVING NE. WILL 
REDUCE MORNING POPS TVC/CAD/MBL AREA TO SCATTERED. NO OTHER CHANGES. 

ORIGINAL EARLY MORNING DISCUSSION FOLLOWS...

POORLY ORGANIZED LOW PRESSURE WAS CENTERED NEAR THE MN/CANADA 
BORDER. PARENT 500MB LOW WAS MUCH BETTER DEFINED ON WV IMAGERY... 
STACKED ON TOP OF THE SURFACE LOW. CONSIDERABLE CONVECTION WAS 
OCCURRING NEAR AND EAST OF THE LOW...AND HAD FINALLY MANAGED TO 
CROSS THE LAKE INTO NW LOWER MI. FORECAST CONTINUES TO HINGE ON 
CONVECTIVE COVERAGE/INTENSITY AS STACKED LOW EVER SO SLOWLY DRIFTS 
TOWARD WESTERN LAKE SUPERIOR.

MODELS AGREE ON MOVING UPPER LOW TO MN ARROWHEAD/FAR WESTERN 
SUPERIOR TODAY...THEN LEAVING IT THERE INTO THE START OF THE 
WEEKEND. SURFACE LOW PRESSURE WILL REMAIN BROAD AND DIFFUSE AS IT 
DRIFTS INTO THE WESTERN LAKES. 

THIS MORNING...CONVECTIVE BAND JUST TO OUR WEST HAS MOVED OUT AHEAD 
OF THE SURFACE COLD FRONT. MCS HAS TURNED SE TO MAXIMIZE LOW LEVEL 
INFLOW...BUT SHOWERS ON THE LEFT FLANK ARE WORKING INTO NW LOWER MI. 
LOW-LEVEL INFLOW WILL DIMINISH DURING THE MORNING...AND WITH THE 
CONVECTION MOVING AWAY FROM THE UPPER LOW/BEST DYNAMIC SUPPORT 
EXPECT A GRADUAL WEAKENING TREND THRU THE AM. RADAR TRENDS SUPPORT 
HIGH POPS ALONG PARTS OF LAKE MI SHORELINE IN NW LOWER...LESS POPS 
TO THE NORTH AND EAST...AND A DRY MORNING IN THE SE ZONES.

THIS AFTERNOON/EVENING...WILL SEE ENOUGH FILTERED SUNSHINE TO BOOST 
TEMPS INTO THE 75-85 DEGREE RANGE. WITH SURFACE DEW POINTS CLIMBING 
INTO THE LOWER 60S AND SLIGHT COOL ADVECTION ALOFT...1000-1500J/KG 
OF CAPE IS EXPECTED. BETWEEN OUTFLOW BOUNDARIES...LAKE BREEZES 
(950MB WINDS PROGGED AT 5-10KT TODAY...WEAKEST ON HURON SIDE)...AND 
A WEAK SURFACE TROF IN CENTRAL LOWER MI...WE AUGHT TO HAVE ENOUGH 
BOUNDARIES AROUND TO ALLOW CONVECTION TO REDEVELOP. BEST DYNAMIC 
FOCUS WILL REMAIN ACROSS WI AS A SHORTWAVE ROTATES AROUND THE UPPER 
LOW. WILL GO WITH SCT AFTERNOON SHRA/TSRA ALL ZONES. WIND FIELDS ARE 
PRETTY PATHETIC...LESS THAN 30KT FROM 400MB ON DOWN...BUT THERE IS 
DECENT DIRECTIONAL SHEAR IN THE 0-3KM LAYER...ESPECIALLY IN THE EAST 
AND NORTH. WOULD NOT RULE OUT ISOLATED SVR LATE THIS AFTERNOON INTO 
THIS EVENING IN LOCALES WITH MAXIMUM INSTABILITY (SAY 82/62)...WHICH 
WOULD PUSH CAPES NEAR 2K J/KG. WET MICROBURSTS (SOME DRY ALOFT WITH 
700MB DEW POINT DEPRESSIONS AROUND 10C) AND MARGINAL HAIL (FREEZING 
LEVELS 11.5-12K FT...WET BULB ZERO 10-10.5K FT) ARE BOTH WITHIN 
THE REALM OF POSSIBILITY.

OVERNIGHT...ANOTHER MCS WILL BE DEVELOPING ACROSS WI/WESTERN UPPER 
MI THIS EVENING ALONG THE STALLED COLD FRONT. MUCH LIKE THIS 
MORNING...IT WILL MAKE AN ATTEMPT TO CROSS THE LAKE INTO EASTERN 
UPPER/NW LOWER AFTER MIDNIGHT. QUASI-WARM FRONT PROGGED TO LIFT 
NORTH ACROSS NORTHERN LOWER...REACHING THE STRAITS TOWARD DAWN. WITH 
A BIT OF SYNPOTIC SUPPORT (DPVA) ENTERING THE PICTURE...AND IN 
GENERAL A LITTLE MORE MOISTURE AND INFLOW PRESENT (20-25KT 850MB LOW 
LEVEL JET DEVELOPS)...THIS ONE SHOULD HAVE SOME SUCCESS CROSSING THE 
LAKE. WILL GO LIKELY POPS OVERNIGHT FROM MBL TO THE LEELANAU AND IN 
WESTERN CHIP/MACK COUNTIES...WITH POPS DIMINISHING TO THE EAST...AND 
DRY AGAIN IN THE FAR EAST.

FRIDAY...SEE THURSDAY. VERY LITTLE CHANGES...WITH ANOTHER DYING 
MORNING MCS IN THE WEST/NORTH...LEAVING BEHIND BOUNDARIES TO ALLOW 
AFTERNOON CONVECTION TO FIRE. CLOUD COVER WILL PROBABLY BE A BIT 
MORE PREVALENT...THANKS TO PERSISTENT WEAK DPVA FORCING CROSSING 
FROM THE WEST. THIS WILL LIKELY KEEP MAX TEMPS A LITTLE SHORT OF 
TODAYS...BUT SLIGHTLY HIGHER SURFACE DEW POINTS (PUSHING MID 60S) 
SHOULD COMPENSATE...AND AGAIN PRODUCE CAPES IN THE 1K TO 2K. SVR 
POTENTIAL IS AGAIN MARGINAL...A MORE MOIST AIRMASS/LESS DRY AIR 
ALOFT WILL MAKE WET MICROBURSTS MORE DIFFICULT...AND FREEZING 
LEVELS/WET BULB ZEROS RISE TO LEVELS THAT ARE BORDERLINE HOSTILE FOR 
HAIL (12-12.5K FT AND 11K FT RESPECTIVELY). WIND FIELDS REMAIN VERY 
WEAK...BUT ON THE OTHER HAND THERE IS SOME SYNOPTIC SUPPORT THAT MAY 
ALLOW FOR MORE STORM ORGANIZATION.

FRIDAY NIGHT...MODELS CONTINUE TO ARGUE FOR A DOUBLE-BARRELED 
SURFACE LOW...ONE BACK UNDER THE 500MB LOW NEAR THE MN ARROWHEAD... 
AND A SECOND WAVE NEAR CENTRAL LAKE MI. I DO NOT SEE A LOT OF 
DYNAMIC SUPPORT FOR THIS 2ND LOW...BUT MODEL AGREEMENT AND 
CONSISTENCY ON ITS EXISTANCE IS GETTING HARD TO ARGUE WITH. MOIST 
SOUTHERLY FLOW INCREASES INTO THE FORECAST AREA...AND GFS/ETA BOTH 
LOOK RATHER DAMP. WILL INCREASE POPS TO SCT/50 ACROSS THE FORECAST 
AREA FOR NOW.

NO CHANGES TO LATER PERIODS. WE/LL BE DEALING WITH UNSETTLED WEATHER 
FOR AWHILE YET.

.APX...NONE.

$$

ZOLTOWSKI