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000 FXUS63 KIND 221033 AFDIND AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 530 AM EST SUN NOV 22 2009 .AVIATION...DISCUSSION FOR 221200Z TAF ISSUANCE. PATCHY IFR/LIFR CONDITIONS DUE TO FOG...AFFECTING MAINLY KBMG SO FAR...EXPECTED TO MIX OUT RATHER RAPIDLY AFTER SUNRISE...AROUND 221400Z...AS MOISTURE LAYER IS VERY SHALLOW. OTHERWISE...NO SIGNIFICANT CLOUD COVER BELOW 050...SURFACE WINDS BELOW 15 KTS THROUGH 230000Z. && .DISCUSSION... SURFACE HIGH PRESSURE RIDGE REMAINS DOMINANT FEATURE EARLY THIS MORNING...WITH CLEAR SKIES ACROSS CENTRAL INDIANA. THE PRESENCE OF LINGERING AND SHALLOW LOW LEVEL MOISTURE COMBINED WITH LIGHT EASTERLY FLOW CONTRIBUTING TO A GENERAL HAZE OVER THE REGION WITH LOCALIZED AREAS OF FOG. TEMPERATURES RANGED FROM THE MID 30S TO LOWER 40S OVER MUCH OF THE FORECAST AREA AS OF 08Z. FORECAST CHALLENGES THIS MORNING FOCUS ON TEMPERATURES/CLOUDS THROUGH MONDAY...POSSIBILITY FOR A FEW RAIN SHOWERS MONDAY AND FURTHER OUT...EVOLUTION AND ARRIVAL OF THE COLDER UNSETTLED PATTERN. CIRRUS SHIELD SLOWLY PROGRESSING NORTH THROUGH THE LOWER MISSISSIPPI VALLEY THIS MORNING AS LOW PRESSURE MOVES ALONG THE NORTHERN GULF COAST. GULF MOISTURE BEING PULLED NORTH ON BACK SIDE OF HIGH PRESSURE RIDGE WITH FAIRLY UNIFORM MID LEVEL CLOUD DECK ENCOMPASSING MUCH OF THE MID MISSISSIPPI VALLEY. DO NOT ANTICIPATE THESE CLOUDS MOVING EAST INTO THE AREA TODAY AS HIGH PRESSURE RIDGE AND LOW LEVEL EASTERLY FLOW SHOULD MAINTAIN BROAD SUBSIDENCE AND DRIER AIRMASS OVER FORECAST AREA. AFOREMENTIONED CIRRUS SHIELD TO SOUTH THOUGH WILL LIFT NORTH INT REGION THROUGH THE DAY. THE ARRIVAL OF THESE CLOUDS SHOULD DO LITTLE TO KEEP CENTRAL INDIANA FROM SEEING ABUNDANT SUNSHINE FOR MUCH OF THE DAY...AND PROVIDE FOR ANOTHER STELLAR SUNDAY FOR NOVEMBER. UPPER LOW ASSOCIATED WITH GULF COAST SYSTEM WILL BE PULLED INTO THE TENNESSEE VALLEY THIS EVENING IN RESPONSE TO AMPLIFYING UPPER LEVEL TROUGH OVER THE HIGH PLAINS. 00Z OP GFS...ECMWF AND GEM SOLNS ALL PULLING DEEPER MOISTURE FURTHER NORTH AND WEST INTO THE OHIO VALLEY BY MONDAY MORNING THAN PREVIOUS RUNS INDICATED. WHILE DEEPER FORCING WILL REMAIN DISPLACED OVER THE CENTRAL APPALACHIANS...ISENTROPIC LIFT DEVELOPS INTO THE SOUTHEAST FORECAST AREA MONDAY MORNING...MOST NOTABLY AT THE 285-295K LEVELS. E/SE FLOW THROUGH THE BOUNDARY LAYER SHOULD RETARD LOW LEVEL MOISTURE ADVECTION TO SOME DEGREE...BUT PRESENCE OF STRONGER ISENTROPIC LIFT AND MID LEVEL MOISTURE CAN NO LONGER BE IGNORED. HAVE INTRODUCED LOW CHANCES FOR RAIN ACROSS EASTERN HALF OF THE FORECAST AREA FOR MONDAY. CONSIDERING A RELATIVELY DRY BOUNDARY LAYER...EXPECT RAINFALL AMOUNTS WILL BE LIGHT AT BEST. PRESENCE OF MID LEVEL MOISTURE SHOULD ENHANCE CLOUDS ACROSS FORECAST AREA FOR MUCH IF NOT ALL OF THE DAY...WITH CEILINGS LOWERING BY MONDAY NIGHT AS MODEL SOUNDINGS SUGGEST POTENTIAL FOR STRATOCUMULUS DEVELOPMENT. REMNANT GULF COAST UPPER LEVEL WAVE WILL LIFT OFF TO THE NORTHEAST MONDAY NIGHT WITH ANY LIGHT RAIN/SPRINKLES ENDING. SKIES WILL REMAIN GENERALLY CLOUDY THOUGH MONDAY NIGHT AS DEEP MOISTURE HOLDS THROUGH THE BOUNDARY LAYER AND UNDERNEATH A DEVELOPING INVERSION. FOCUS WILL THEN SHIFT WEST AS AFOREMENTIONED SHARP UPPER TROUGH AND ASSOCIATED LOW PRESSURE APPROACH TUESDAY. VARIOUS MODELS HAVE COME INTO REASONABLE AGREEMENT WITH RESPECT TO TRACK OF LOW PRESSURE FROM NEAR KANSAS CITY TUESDAY MORNING INTO THE LOWER GREAT LAKES BY EARLY WEDNESDAY. A TRAILING COLD FRONT WILL TRAVERSE THE REGION TUESDAY NIGHT...AND SIGNAL THE ARRIVAL OF A MUCH COLDER AIRMASS FOR CENTRAL INDIANA. WILL INTRODUCE CHANCE POPS TUESDAY AFTERNOON ACROSS WESTERN FORECAST AREA AS DEEPER ISENTROPIC LIFT DEVELOPS AHEAD OF THE FRONT. BEST CHANCES FOR WIDESPREAD RAINFALL WILL COME TUESDAY NIGHT AS LOW LEVEL CONVERGENCE AXIS COMBINES WITH DEEP MOISTURE AND AREA OF MID/UPPER LEVEL DIFFLUENCE AS POLAR AND SUBTROPICAL UPPER JETS PHASE. HAVE RAISED TO 40-50 POPS FOR MUCH OF THE FORECAST AREA TUESDAY NIGHT WITH FRONT SHIFTING EAST OF THE REGION BY EARLY WEDNESDAY. MODEL SOUNDINGS SUPPORT POTENTIAL FOR GUSTIER WINDS ALONG AND IMMEDIATELY BEHIND FRONTAL BOUNDARY AS 45KT 850MB LOW LEVEL JET PASS THROUGH REGION. LOW LEVEL COLD ADVECTION BEHIND THE FRONT SHOULD MAINTAIN STRONGER WINDS INTO WEDNESDAY MORNING. MADE SOME MINOR ADJUSTMENTS TO WEDNESDAY AND THURSDAY AS INITIAL UPPER LOW MOVES EAST AND IS FOLLOWED BY DEEPER UPPER LEVEL SYSTEM FOR THANKSGIVING DAY. THE UPPER LEVEL FEATURES WILL KEEP REGION IN COLD CYCLONIC FLOW ALOFT AND PROVIDE FIRST GOOD CHANCE AT SNOWFLAKES FOR MUCH OF THE FORECAST AREA THIS FALL AS LOW LEVEL THICKNESSES FALL TO NEAR OR JUST BELOW THE CRITICAL THRESHOLDS NEEDED. TWEAKED POPS A BIT HIGHER FOR BOTH WEDNESDAY AND THURSDAY AS PLENTY OF MOISTURE REMAINS. THANKSGIVING DAY APPEARS LIKELY TO BE THE COLDEST DAY YET THIS MONTH FOR THE REGION. TEMPS...UNDER A SIMILAR AIRMASS TO SATURDAY AND SEEING HOW TEMPERATURES GENERALLY OUTPERFORMED MOS GUIDANCE...HAVE CHOSEN TO TREND AT OR A COUPLE DEGREES ABOVE GUIDANCE FOR HIGHS TODAY. POTENTIAL FOR LOWER 60S ACROSS THE SOUTHERN FORECAST AREA...AND POSSIBLY AT KLAF WHICH HAS MAINTAINED ITS WARM BIAS FOR MUCH OF THE FALL UNDER SIMILAR CONDITIONS (LIGHT WINDS/PLENTY OF SUNSHINE). TOOK SPLIT OF COOLER MAVMOS AND WARMER METMOS FOR MONDAY WHICH ENDED UP A FEW DEGREES COOLER THAN PREVIOUS FORECAST AS CLOUDS INCREASE. UNDERCUT GUIDANCE AT RURAL LOCALES TONIGHT...NEAR MAVMOS FOR LOWS ELSEWHERE TONIGHT AND OVER ENTIRE FORECAST AREA MONDAY NIGHT. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ PUBLIC...RYAN AVIATION...JAS
