FXUS63 KIWX 180534
AFDFWA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1234 AM EST FRI JUL 18 2003

AVIATION DISCUSSION FOR 06Z TAFS...
RUC40 HAS DECENT HANDLE ON CURRENT MCS ALONG IL/IN BORDER AND WEAK 
VORT OVER SW WI SO WILL LEAN TOWARD THAT MODEL SOLUTION. RUC40 SHOWS 
WI VORT SLIDING SE AND HELPING TO SPARK TSRA ALONG FRONT TOWARDS 
DAWN...WHICH ACTUALLY IS ALSO SHOWN ON MESOETA AND GFS. SO...WILL 
INCLUDE VCTS FOR A FEW HOURS EARLY THIS MORNING. ENTIRE TAF FORECSAT 
PACKAGE WILL STILL BE VFR.

12

PUBLIC FORECAST DISCUSSION FOR 330 PM EST ISSUANCE...
VISIBLE SATELLITE IMAGES SHOWING COLD FRONT NICELY FROM ONTARIO... 
TO CENTRAL MICHIGAN...CENTRAL WISCONSIN AND INTO THE DAKOTAS. 
MOISTURE IS LIMITED THIS AFTERNOON OVER OUR COUNTY WARNING FORECAST 
AREA...CWFA...BUT MOISTURE IS POOLING ALONG AND JUST AHEAD OF FRONT 
AS SURFACE DEWPOINTS RISING INTO MID AND UPPER 60S. DEVELOPMENT OF 
CUMULUS AND ALTOCUMULUS CONFIRMS THE INCREASING MOISTURE. ETA HAS 
GOOD HANDLE ON THIS NARROW AREA AND MOVES DEEPER MOISTURE AND 
INSTABILITY ACROSS OUR CWFA THIS EVENING AND OVERNIGHT. LATEST LOCAL 
ANALYSIS AND PREDICTION SYSTEM...LAPS...SHOWS CAPES INCREASING 
ACROSS THE NORTH AND LIFTED INDEX DECREASING AS DEWPOINTS RISE. 
FORECAST CHALLENGE FOR TONIGHT IS HOW MUCH CONVECTION WILL FIRE 
ALONG FRONT AND WILL IT BECOME A SOLID LINE THIS EVENING. BEST 
INSTABILITY REMAINS TO OUR WEST WITH BETTER LOW LEVEL MOISTURE AND 
SFC PRESSURE FORECAST INDICATES HIGH OVER NORTHERN LAKES WILL TRY 
AND PUNCH SOUTH THROUGH WEAKER PORTION OF FRONT. WAS CONSIDERING 
LIKELY POPS BUT GIVEN THE LACK OF DEVELOPMENT SO FAR...HAVE DECIDED 
TO GO WITH HIGH CHANCE AND SCATTERED WORDING AS I DO BELIEVE 
CONVECTION WILL CONTINUE TO DEVELOP AND MOVE SOUTH WITH FRONT. IF 
RADAR TRENDS SHOW MORE DEVELOPMENT...WILL INCREASE POPS BEFORE 
ISSUANCE. 

FRONT TO GRADUALLY MOVE SOUTH OVERNIGHT AND EXIT CWFA FRI MORNING. 
AM LITTLE CONCERNED FOR RESIDUAL MOISTURE AND INSTABILITY BETWEEN 
SURFACE FRONT AND 850MB FRONT ON FRIDAY MORNING. ETA AND GFS SHOWING 
SOME LEFTOVER CAPE AND LOW LI/S DURING THE MORNING. ALSO...12Z GFS 
INDICATING SOME OMEGA MOVING OUT OF HIGH PLAINS ALONG FRONT 
INDICATING POTENTIAL FOR A COMPLEX OVERNIGHT. WITH HIGH INSTABILITY 
TO OUR WEST AND AN ERODING CAP...CANNOT ARGUE WITH THIS OCCURING. 
THIS COULD ALSO POTENTIALLY LEAVE SOME SHOWERS OR THUNDERSTORMS 
AROUND THE AREA EARLY. HAVE OPTED TO CONTINUE POPS INTO FRIDAY 
MORNING SOUTH...LINING UP WITH IND AND ILN. WIL KEEP REMAINDER OF 
FRIDAY DRY. 

NEXT CHANCE OF RAIN WILL BE SUNDAY. MODELS ARE SPEEDING UP TIMING A 
BIT WITH NEXT SHORT WAVE AND SURFACE FRONT. AGAIN...MOISTURE LOOKS 
LIMITED AHEAD OF WAVE AND POOLING DEWPOINTS WILL NEED TO OCCUR TO 
GET PRECIPITATION. WHILE MODELS BRINGING SOME LIFT AND MOISTURE IN 
FOR SUNDAY AFTERNOON...WILL OPT TO LEAVE OUT UNTIL SUNDAY EVENING 
WHEN DEEPER MOISTURE IS PROGGED INTO AREA.

GOING TEMPERATURES IN GRIDS LOOKS GOOD AND AGREE WITH LATEST MODEL 
GUIDANCE SO NO BIG CHANGES PLANNED THERE. 

SUNDAY NIGHT THROUGH THURSDAY
12Z RUN OF GFS STILL SHOWING AN UPPER TROF BECOMING ESTABLISHED 
EARLY NEXT WEEK ACROSS THE GREAT LAKES REGION. CANADIAN GEM 
ENSEMBLES ALSO SHOWING GOOD CONSISTENCY LATE MONDAY WITH A TROF OVER 
THE AREA.  MEX MOS/HPC GUIDANCE LOOK GOOD WITH A CHANCE FOR PCPN 
MONDAY...WITH COOLER CONDITIONS MON-THURS. COOL FROPA SOMETIME LATE 
SUNDAY NIGHT OR DURING THE DAY MONDAY. 

.IWX...
IN...NONE.
MI...NONE.
OH...NONE.
$$

LASHLEY/SKIPPER