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Centrally located in Elkhart Indiana
Tuesday the 9th
000 FXUS63 KIWX 092350 AFDIWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 650 PM EST TUE MAR 9 2010 .AVIATION... INITIAL WAVE OF MOISTURE CONVERGENCE IS MOVING ACROSS TAF SITES AT THIS ISSUANCE TIME. DRY LOWER LEVELS IS INHIBITING MUCH MORE THAN SPRINKLES OR VERY LIGHT SHOWERS WITH ONLY SMALL POCKETS OF HEAVIER SHRA THAT COULD RESTRICT VIS FOR ONLY A BRIEF PERIOD. WILL NOT INCLUDE ANY RESTRICTIONS FOR THIS BAND THAT WILL EXIT TAF SITES BY 02Z. STILL EXPECT A SECOND BANDED AREA OF PRECIPITATION TO DEVELOP THIS EVENING ACROSS MO AND SOUTHERN IL AND MOVE NORTH. EASTERN EXTENT OF PRECIPITATION REMAINS IN QUESTION BUT PERSISTENT MOISTURE ADVECTION AND SATURATION THIS EVENING SHOULD PROVIDE A MORE CONDUCIVE ATMOSPHERE FOR RAIN LATE. LOWERING CIGS AND MVFR BR DEVELOPMENT EXPECTED ANYWAY SO MVFR CONDITIONS AFTER 06Z ANTICIPATED WITH OR WITHOUT RAINFALL. SOME UPSTREAM IFR CIGS COULD ALSO PUSH IN LATE TONIGHT. MODEL SOUNDINGS INDICATE LOW LEVEL MOISTURE TO HANG AROUND WED MORNING BUT DRYING ALOFT AND SUBSIDENCE COULD MIX OUT LOWER CLOUDS IN AFTERNOON. RAISED CIGS TO HIGH END BKN MVFR FOR NOW BUT VFR CONDITIONS NOT OUT OF QUESTION IN AFTERNOON. && .SHORT TERM.../TONIGHT THROUGH WEDNESDAY NIGHT/... CLOSED WAVE OVER THE CENTRAL PLAINS WILL SLOWLY DRIFT NORTHEAST WITH SFC LOW MOVING INTO CENTRAL IA AND MID LEVEL CIRCULATION WEST OVER NEBRASKA. THIS WAVE WILL WEAKEN AHEAD OF OPENING/ABSORPTION INTO FOLLOWUP WAVE WHICH IS PRESENTLY TRANSITING THE DESERT SOUTHWEST ALONG THE PERIPHERY OF 180 KNOT SOUTHERN STREAM JET. THIS SETS THE STAGE FOR A COUPLE OF BANDS OF THETA-E ADVECTION TO SWEEP ACROSS THE CWA BRINGING A CHANCE FOR SHOWERS THIS EVENING AND AGAIN LATE TONIGHT INTO WEDNESDAY. THE FIRST ASCENT REGION CURRENTLY PLAYING OUT OVER ILLINOIS LIFTING NORTHEAST ON THE FRINGE OF THE CWA. OP MODELS CONSISTENTLY WEAKEN FORCING AS IT NEARS AND ARE VERY PESSIMISTIC ON MEASURABLE PCPN. DESPITE BROAD AREA OF RETURNS ON 88D MOSAIC ONLY A THIN STRIPE ALONG WESTERN EDGE IS GENERATING SFC REPORTS OF PRECIP. THE AIRMASS OVER THE CWA IS STILL QUITE DRY THROUGH THE COLUMN AS EVIDENCED BY 12Z DTX SOUNDING AND 16Z TAMDAR FLIGHT FROM KFWA...AND AS THIS REGION MOVES IN IT SHOULD CONTINUE TO STRUGGLE. HWVR...MANY SITES ARE MEASURING AND THIS BAND IS PROGRESSING BETTER THAN MODEL QPF FCSTS WOULD SUGGEST AND WILL RETAIN CHC POPS IN THE WEST HALF CONCURRENT WITH THE ASCENT REGION PASSING. SECOND WAVE OF THETA-E ADV ARRIVES LATE TONIGHT INTO WEDNESDAY MORNING. WHEREAS PREV MODEL CYCLES DISPLAYED A MORE ROBUST WAVE SUPPORTED BY A HEALTHY LLEVEL JET THE 12Z NAM/WRF/GFS GUIDANCE DISSOLVES THIS SUPPORT AND LACKING LLEVEL CONVERGENT FORCING AND WITH UNIMPRESSIVE LAPSE RATES UNTIL LATER IN THE DAY...THIS BAND HAS LOST MUCH OF ITS ANTICIPATED PUNCH. STILL EXPECT A REGION OF SHRA TO PROGRESS THROUGH THE CWA AND KEPT CHC POPS BUT AMOUNTS SHOULD REMAIN ON THE LIGHT SIDE. WILL KEEP WEDNESDAY HIGHS SIMILAR TO TODAY ASSUMING LINGERING MOISTURE/CLOUDS WILL DAMPEN WARMUP HOWEVER IF INCREASINGLY STRONG MARCH SUN CAN MIX OUT LLEVEL MOISTURE WITH DRIER AIR RETURNING ALOFT...TEMPS COULD RISE HIGHER ESP IN THE SOUTHWEST WHICH CLEARS OUT EARLIEST. H85 TEMPS ARE SIMILAR TO TODAY HOWEVER LIMITING POTENTIAL BUST SHOULD THIS OCCUR. && .LONG TERM.../THURSDAY THROUGH TUESDAY/... UPPER LOW LIFTING OUT OF SOUTHWESTERN STATES WILL ABSORB STALLED WAVE BRINGING SHOWERS TO THE SHORT TERM AND THEN BECOME STALLED ITSELF. MODEL GUIDANCE VARIES WIDELY WITH DETAILS BUT IN GENERAL WOBBLE THIS LOW AROUND THE EASTERN PORTION OF THE COUNTRY THROUGH EARLY NEXT WEEK RESULTING IN MOSTLY CLOUDY SKIES...MODERATE TEMPS WITH HIGHS NEAR CLIMO IN THE UPPER 40S TO NEAR 50...AND CHANCES FOR SHOWERS THROUGH THE WEEKEND. TOWARDS END OF THE PD MODELS DIVERGE AS THIS LOW CONTINUES TO DRIFT NEAR THE EASTERN SEABOARD AND HIGHLY AMPLIFIED RIDGING DEVELOPS ALONG THE WEST COAST. OVERALL...FEW CHANGES TO THE GRIDS WITH CHANCES FOR SHOWERS NEARLY EVERY DAY AND MILD TEMPS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ SHORT TERM...LUD LONG TERM...LEWIS/LUD AVIATION...LASHLEY |