000 FXUS63 KIND 051723 AFDIND AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 120 PM EDT SUN JUL 5 2009 .AVIATION...FOR 18Z TAFS TAFS FROM KIND AND SOUTHWARD WILL START OUT MVFR. PARTIAL CLEARING WILL CONTINUE TO PROGRESS SOUTH ACROSS CENTRAL INDIANA THIS AFTERNOON AND ALL TAFS WILL BE VFR BY LATE AFTERNOON. MOST TAFS SHOULD BE CLR-FEW030 BY 01Z AS WEAK HIGH PRESSURE OVER THE NORTHERN PLAINS BUILD TOWARDS CENTRAL INDIANA. THERE IS LOTS OF DISAGREEMENT BETWEEN VARIOUS MODELS AND FORECAST SCHEMES ON AMOUNT OF FOG TONIGHT. DEWPOINTS ARE PRESENTLY IN THE LOWER 60S WHICH IS NEAR THE CROSS OVER TEMPERATURE FOR FOG. MODELS DROP DEWPOINTS IN THE MID 50S LATE TONIGHT WHICH WOULD KILL ANY FOG. HOWEVER THERE WERE NUMEROUS AREAS OF IFR FOG THIS MORNING IN CLEAR AREAS NORTH OF THE FRONT. BEING THE SAME AIRMASS I CAN'T BELIEVE MODELS NO INDICATION OF ANY FOG...AS MODELS MAY BE OVER DOING THIS DRYING A BIT TOO MUCH. WILL MENTION MVFR FOG LATE TONIGHT FOR NOW. IT SHOULD BECOME QUICKLY VFR AFTER SUNRISE MONDAY AND WITH A FEW CU BY LATE MORNING. && .DISCUSSION... FORECAST FOCUS WILL BE ON THE DEPARTURE OF RAIN AND CLOUDS TODAY. THE EARLY MORNING SURFACE MAP SHOWS LOW PRESSURE JUST SOUTH OF KSTL ON THE MISSISSIPPI RIVER. A WARM FRONT WAS EXTENDING EAST ACROSS FAR SOUTHERN INDIANA AND A COLD FRONT TRAILS THROUGH THE SOUTHERN PLAINS. HIGH PRESSURE WAS OVER THE NORTHERN PLAINS AND INTO THE LAKES REGION. ALOFT AT H5 THE PATTERN SHOWED GENERALLY A LONGWAVE RIDGE OVER THE WESTERN 2/3RDS OF THE COUNTRY WITH TROUGHING OVER THE NORTHEASTERN CONUS. THE MODELS INITIALIZED WELL AND WERE REMARKABLY SIMILAR ON TEMPS AND POPS THE FIRST THREE DAYS OF THE PERIOD. USED A BLEND OF MOS GUIDANCE FOR THIS PACKAGE. FOR TODAY THE QUESTIONS WILL BE ON THE DEPARTURE OF PRECIP AND CLOUDS. THE SURFACE LOW WILL DRIFT ACROSS TENNESSEE BY EARLY THIS AFTERNOON. THE ISENTROPIC LIFT WILL COME TO AN END. HOWEVER IT WILL BE SLOWER FOR CLOUDS AND DRIZZLE TO END. THE TIME HEIGHTS SHOW SATURATED LOW LEVELS AND WEAK UPWARD MOTION IN CENTRAL AND SOUTHERN PARTS OF THE AREA UNTIL MID MORNING. SO WILL MENTION A CHANCE OF SHOWERS IN THE FAR SOUTH THIS MORNING AND SOME DRIZZLE IN CENTRAL AREAS THROUGH MID MORNING. THE UPWARD MOTION SEEMS TO BE CAUSED BY A SLOW MOVING MID LEVEL TROUGH THAT WILL NOT REALLY CLEAR THROUGH THE AREA UNTIL 18Z. WITH THE TROUGHING REMAINING TO OUR NORTH MUCH OF THE DAY AND TRAPPED LOW LEVEL MOISTURE...WILL BE PESSIMISTIC ON CLEARING SKIES AND NOT DO SO VERY QUICKLY. BY EVENING THERE WILL BE DRIER AIR ARRIVING AS THE TROUGH FINALLY PASSES BUT UNTIL THEN WILL KEEP CLOUDINESS MENTIONED IN THE FORECAST. FOR HIGHS TODAY IT WILL BE WARMER THAN YESTERDAY BY A FEW DEGREES. BUT WITH CLOUDS AND A MOIST ATMOSPHERE THE TEMPS SHOULD HOLD IN THE MID 70S EXCEPT IN THE UPPER 70S IN THE NORTHWEST WHERE MORE CLEARING HAPPENS. OVERNIGHT MORE CLEARING SHOULD TAKE PLACE WITH SUBSIDENCE IN THE WAKE OF THE PASSING MID LEVEL TROUGH. HEIGHTS WILL ACTUALLY FALL SLIGHTLY OVERNIGHT AS THE H5 LOW NORTH OF THE LAKES WOBBLES SOUTH. TEMPS WILL DROP INTO THE UPPER 50S IN RURAL SPOTS BUT REMAIN IN THE LOWER 60S IN URBAN LOCATIONS. MONDAY AND TUESDAY LOOK TO BE VERY SIMILAR DAYS AS THE H5 TROUGHING CARVES OUT OVER THE NORTHEAST AND SLOWS THE PATTERN DOWN. THE H8 TEMPS WILL BE AROUND +15C BOTH DAYS WHICH WILL EXPERIENCE A GOOD MIX INTO THE MID 80S. BY MID AND LATTER PARTS OF THE WEEK THE FORECAST BECOMES A BIT LESS CERTAIN. THE GENERAL QUESTION WILL HINGE AROUND THE MOVEMENT OF ENERGY FROM A DEEPENING TROUGH OVER THE PACIFIC NORTHWEST. H5 RIDGING WILL BE IN PLACE OVER THE CENTRAL PLAINS STATES BY WEDNESDAY. ENERGY FROM THE PACIFIC TROUGH WILL THEN ENCOUNTER THIS RIDGE AND THE QUESTION FOR INDIANA WEATHER WILL BE IF THIS ENERGY CAN REMAIN STRONG ENOUGH AND NOT BE DAMPENED BY THE RIDGE. THE GFS MODEL IS SHOWING QPF BY THURSDAY AND THE NAM IS HINTING AT PRECIP BY EARLY WEDNESDAY. THE ECMWF REMAINS DRY THROUGH THE TIME PERIOD. GIVEN UNCERTAINTY WILL OPT TO KEEP THE FORECAST DRY FOR NOW. TEMPS WILL WARM STEADILY BY LATE WEEK AS HOTTER WEATHER ARRIVES WITH THE EASTWARD PROGRESSION OF THE STRONG PLAINS RIDGE. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ AVIATION...JH PUBLIC...JOHNSON