000 
FXUS63 KIWX 161907
AFDFWA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
207 PM EST WED AUG 16 2000

FORECAST PROBLEM IS PCPN CHANCES LATE TNGT AND THURSDAY AND SVR WX
POTENTIAL. MAX TEMPS THU ALSO A FCST PROBLEM.

18Z SFC MAP SHOWED HIGH PRES OVR GREAT LAKES WITH QSTNRY FNT FM WV/KY
NW TO IA/NE. WRN PORTION OF FNT BEGINNING TO MOVE BACK NE
AS WMFNT AS HIGH PRES MOVES EAST AND LOW LEVEL FLOW
INCREASES. ELEVATED CONVECTION WAS OCCURRING OVR ND AND MN IN AREA OF
STRONG CONVERGENCE AND THETA E ADVECTION.

MODELS SIMILAR IN BRINGING FNT BACK ACRS FA THU AS SFC LOW MOVES TO
WRN INDIANA BY 00Z/FRI. LOW LEVEL JET FCST TO STRENGTHEN TONIGHT
WITH ETA STRONGEST WITH H8 50KT JET. PROFILER NETWORK ALREADY
SHOWING 20 TO 30 KT AT H85 ACRS NE. MODELS AGREE WITH NOSE OF JET
INTO NRN IA/SRN MN...SHIFTING TO NRN IL/SRN WI BY 12Z/THU. THETA E
ADVECTION IMPRESSIVE OVERNIGHT AND MOISTURE QUICKLY RETURNS TO NW FA
BY SUNRISE. MID LEVEL OMEGA ALSO INCREASES ACRS NW FA TOWARD SUNRISE
AND THICKNESS SCHEMES SUPPORT SE ADVECTION OF MCS OVERNIGHT.
CONVECTION AT 18Z APPEARS TO BE AHEAD OF 12Z MODELS 6HR FCST
POSITION. THUS LOW CHC POP IN NW WL BE MAINTAINED FOR AFTER
MIDNIGHT.

12Z ETA IMPRESSIVE WITH WIND SPEED AND DIRECTIONAL SHEAR THU AHEAD
OF SFC LOW. NGM/AVN WEAKER BUT STRONG SHEAR STILL EVIDENT. H8 TEMPS
WARM TO 20C SRN FA THU WITH WAA WHILE DWPTS RISE TO MID TEENS.
SFC DWPTS ALSO RESPOND WITH 70S POOLING BACK INTO FA BY AFTN.
THIS RESULTS IN MUCAPES OF 3000J/KG AND LI/S TO -6 OVR SRN FA.
H7 TEMPS ACRS FA REMAIN BLO 10C BUT NOT BY MUCH. CAP EVIDENT IN
MODELS JUST TO SW OF FA. DAY2 OUTLOOK OF SLIGHT RISK JUSTIFIED AND
HAVE DECIDED TO INCLUDE SVR MENTION IN ZONES. LIMITING FACTORS WILL
BE AMOUNT OF DEBRIS CLOUDS FM OVERNIGHT MCS AND RETURN OF LOW LEVEL
MOISTURE. FEEL DEBRIS CLOUDS WL THIN ENOUGH TO ALLOW
DESTABILIZATION...ESPECIALLY IN THE SOUTH. LOOPING SFC PLOT AND SAT
INDICATES LOW LEVEL MOISTURE ALREADY ADVECTING EAST AND INTO WRN IL
SO EXPECT THIS TREND TO CONT ACRS FA THRU THU AFTN.

TEMPS WL HAVE A WIDE SPREAD ACRS FA ON THU AS MORE BREAKS IN SRN FA
ALLOWS TEMPS TO REBOUND INTO THE 80S. NORTHERN FA WL BE INFLUENCED
MORE BY CLOUDS/PCPN IN THE MORNING SO TEMPS SHLD BE COOLER.
HOWEVER...ANY BREAKS THIS AREA WL ALLOW FOR A QUICK WARM UP AND
SOME DESTABILIZATION IN THE AFTERNOON. GENERALLY FOLLOWED WARMER MOS
IN THE SOUTH AND A COOLER BLEND IN THE NORTH.

FNT MOVES SOUTH OF AREA THU NIGHT WITH LINGERING SHOWERS AND FEW
THUNDERSTORMS...ESPECIALLY SOUTH. DRIER CONDITIONS FOR FRIDAY WITH
COOLER TEMPS AND BKN CU. REMAINDER OF WEEKEND SHAPING UP TO BE
PLEASANT AS SECONDARY FNT DROPS SOUTH DRY BUT KEEPS COOL AIR IN
PLACE WITH LOWS IN THE 50S AND HIGHS IN THE 70S. MODELS AGREE ON
KEEPING MOISTURE WEST AND SOUTH OF FA.

.IWX...NONE

LASHLEY