716
FXUS63 KIWX 041954
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
354 PM EDT SAT JUL 4 2009
SHORT TERM.../TONIGHT THROUGH SUNDAY NIGHT/
LOW PRESSURE LOCATED OVER MISSOURI MAKING SLOW PROGRESS TO THE
EAST. BROAD AREA OF PRECIP IN ASCENT REGION NORTH OF A WEAK LLEVEL
BNDRY HAS BEEN TRACKING OUT OF ILLINOIS INTO WEST AND SOUTHERN
PORTIONS OF THE CWA THIS AFTERNOON. PRECIP IS FALLING FROM
ELEVATED LAYER AND FIGHTING DRIER AIR BELOW KEEPING AMOUNTS QUITE
LIGHT THUS FAR. WITH MAIN LLEVEL CIRCULATION REMAINING TO OUR SE
AND FORCING FROM ASCENT WANING/FOLLOWING SAGGING BNDRY A CONTINUED
EROSION OF QPF TO THE NE IS EXPECTED. FURTHER SOUTH...PERSISTENT
AREA OF LIGHT SHRA/DZ WILL CONTINUE TO DRIFT EAST AND WEAKEN WITH
LINGERING SCT LIGHT SHRA POSSIBLE THROUGH THE EVENING. WITH VERY
LIMITED INSTABILITY...EXTREMELY WARM AIR ALOFT ON 00Z
SOUNDINGS...AND NO LIGHTNING OBSERVED UPSTREAM ALL DAY...HAVE
REMOVED THUNDER MENTION FOR THE REMAINDER OF THE AFTERNOON.
12Z MODELS ARE SLOW TO CLEAR OUT THIS SYSTEM...BUT AS WITH QPF IN
THE NW TODAY...FEEL THINGS ARE BEING OVERDONE AND HAVE KEPT POPS
TONIGHT VERY SIMILAR TO PREV FCST. UPR LOW THEN SAGS TOWARDS THE
NORTHERN GREAT LAKES ON SUNDAY AS WEAK RIDGING AT THE SFC MOVES IN.
MODELS ATTEMPT TO SPIT OUT SOME LIGHT QPF NEAR THE NORTHERN COUNTIES
ON SUNDAY NIGHT AS COLDER AIR ALOFT WORKS SOUTH...BUT NOT WORTH A
MENTION IN THE GRIDS. OTHERWISE...CONTINUED NW FLOW WITH H85 TEMPS
INDICATIVE OF HIGHS NEAR 80 ON SUNDAY.
LONG TERM
CLOSED LOW EXPECTED TO BE OVER SE ONTARIO AT START OF LONG TERM PD
MON MORNING WITH A RATHER SHARP RIDGE AXIS OVER THE ROCKIES. LOW
EXPECTED TO MOVE SLOWLY ESE INTO NEW ENGLAND AND GRADUALLY WEAKEN
THROUGH MID WEEK. 12Z NAM SUGGESTED A SGFNT SHRTWV IN THE NW FLOW
WILL DIG SE ACROSS THE GRTLKS ON TUE. WITH LATEST GFS/ECMWF/GEM
INDICATING A MUCH WEAKER SYSTEM WITH LITTLE OR NO QPF IN OUR AREA,
LEFT FCST FOR TUE DRY. SIMILAR PROBLEMS CROP UP ON WED AS GFS
SUGGESTING CONVECTION WILL DEVELOP IN THE STRONGER WAA UPSTREAM OVER
THE UPR MS VALLEY AND ADVECT/PROPAGATE SE-EWD INTO OUR CWA. GFS
APPEARS TO BE SUFFERING FROM CONVECTIVE FEEDBACK WITH ITS SOLUTION
AND SPREADING ITS QPF TOO FAR EAST INTO THE DRIER AND MORE STABLE
AIR. GEM/ECMWF ARE MORE REASONABLE IN KEEPING THIS WAA INDUCED
CONVECTION WEST OF OUR CWA ACROSS THE MID-UPR MS VALLEY WED... THUS
LEFT THIS PD DRY. MEDIUM RANGE MODELS HAVE BEEN FAIRLY CONSISTENT
INDICATING A RATHER STRONG SHRTWV WILL MOVE OVER TOP OF THE PLAINS
RIDGE THU AND THROUGH THE GRTLKS FRI/SAT. WITH MOIST/UNSTABLE
AIRMASS EXPECTED TO BE IN PLACE, FORCING ASSOCIATED WITH
SHRTWV/CDFNT MAY BE SUFFICIENT TO KICK OFF SOME CONVECTION, SO ADDED
A CHC OF TSTMS TO FRI NGT.
AVIATION
RAIN SHOWERS ASSOC WITH LOW PRESSURE OVER MISSOURI ERODING AS
THEY NEAR TERMINALS. WITH MAIN FORCING FOR ASCENT LOCATED TO THE
SW AND NOT PROGGED TO MAKE MORE NW PROGRESS...EXPECT THIS GENERAL
TREND TO CONTINUE INTO THE EVENING. HAVE HANDLED KSBN WITH VCSH
WITH QUESTIONABLE PROGRESS AND LITTLE PRECIP FALLING UPSTREAM AT
KVPZ DESPITE ELEVATED 88D RETURNS. FURTHER SOUTH CLOSER TO FORCING
AT KFWA...TEMPO GROUP FOR PERIODIC LIGHT SHRA GRADUALLY WORKING IN
OVER THE NEXT FEW HOURS...AND WILL REASSESS TRENDS LATER THIS
AFTERNOON. CIGS ARE GENERALLY VFR EVEN TO THE EAST UNDER MORE
PERSISTENT RAINFALL...AND HAVE KEPT VFR CONDS THROUGH THE PD.
GRADUAL IMPROVEMENT OVERNIGHT AND INTO SUNDAY WITH LIGHT E/NE
WINDS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
MI...NONE.
OH...NONE.
LM...NONE.
SHORT TERM...LUD
LONG TERM...JT
AVIATION...LUD
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