Expires:No;;260417
FXUS63 KIND 261050
AFDIND
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
550 AM EST THU NOV 26 2009
.AVIATION...DISCUSSION FOR 26/12Z TAFS.
DRIER AIR HAD FILTERED INTO THE FORECAST AREA EARLY THIS MORNING 
WITH CEILINGS HAVING LIFTED BACK UP TO VFR LEVELS AT ALL BUT KLAF. 
STRONG UPPER LOW PRESSURE THOUGH WILL MOVE ACROSS THE LOWER GREAT 
LAKES TODAY...BRINGING DEEPER MOISTURE BACK INTO THE REGION THIS 
MORNING. LARGE SWATH OF LIGHT RAIN/SNOW IN THE VICINITY OF A SURFACE 
TROUGH DROPPING SOUTHEAST ACROSS ILLINOIS. THIS TROUGH WILL SWING 
INTO THE FORECAST AREA LATE THIS MORNING...AND SHIFT ACROSS THE 
TERMINALS THROUGH THE REMAINDER OF THE DAY. CEILINGS WILL FALL BACK 
INTO THE MVFR CATEGORY BY MID MORNING...AND STAY THERE FOR MOST IF 
NOT ALL OF THE REST OF THE FORECAST PERIOD AS LOWER LEVELS REMAIN 
SATURATED. PRECIPITATION WILL IMPACT THE TERMINALS FROM LATE MORNING 
THROUGH THE AFTERNOON. LOW LEVEL THICKNESSES REMAIN MARGINAL FOR 
LIGHT SNOW TO MIX IN WITH THE RAIN...AND WILL CONTINUE TO CARRY A 
RAIN/SNOW SHOWER MIX AT KIND...KHUF AND KLAF. IT APPEARS AT THIS 
TIME THAT PRECIPITATION WILL LARGELY FALL AS RAIN AT KBMG. BRIEF 
PERIODS OF IFR CONDITIONS ARE POSSIBLE AS WELL...ESPECIALLY AT KLAF 
WHERE PRECIPITATION RATES MAY BE HEAVIER AT TIMES. WINDS WILL VEER 
FROM SOUTHWEST TO WEST THROUGH THE DAY WITH GUSTS AT 20-25KTS.
TROUGH WILL SHIFT EAST THIS EVENING WITH PRECIPITATION ENDING AT ALL 
TERMINALS NEAR OR SHORTLY AFTER DARK. MODEL SOUNDINGS CONTINUE TO 
SHOW PLENTY OF LOW LEVEL MOISTURE WITH CYCLONIC FLOW KEEPING 
NORTHWEST WINDS AT A STEADY 10-15KT CLIP. WHILE SOME CLEARING OF THE 
STRATOCUMULUS DECK WILL BE POSSIBLE EARLY FRIDAY MORNING AT KHUF AND 
KBMG...EXPECT MVFR CEILINGS TO PERSIST FOR MUCH OF THE NIGHT. MORE 
SUBSTANTIAL CLEARING OF THE LOWER CLOUDS WILL COME AFTER SUNRISE 
FRIDAY AS A HIGH PRESSURE RIDGE BUILDS INTO CENTRAL INDIANA FROM THE 
WEST.
&&
.DISCUSSION...POTENT UPPER AIR SYSTEM CURRENTLY DROPPING SOUTHEAST 
ACROSS NORTHWEST ILLINOIS EXPECTED TO PASS THROUGH THE FORECAST AREA 
LATER TODAY. THIS SYSTEM WILL EVENTUALLY CARVE OUT A LONG WAVE 
TROUGH...HOWEVER THE OVERALL PATTERN REMAINS PROGRESSIVE WITH UPPER 
RIDGING RETURNING TO THE AREA BY THE WEEKEND. MODELS IN GOOD 
AGREEMENT WITH THE MAIN FEATURES. FORECAST FOCUS CENTERS ON POPS AND 
PRECIPITATION TYPE WITH THE UPPER AIR SYSTEM TODAY.
FOR TODAY...MODEL DATA SUGGEST MAIN FORCING WITH THE INCOMING SYSTEM 
WILL MOVE THROUGH DURING THE AFTERNOON HOURS. WILL CONTINUE WITH 
HIGH POPS OVER THE NORTHERN TWO THIRDS OF THE FORECAST AREA FOR 
MAINLY THE AFTERNOON HOURS...TAPERING TO CHANCE POPS FARTHER SOUTH 
WHERE FORCING WILL BE WEAKER. THICKNESSES STILL SUGGEST MIXED 
PRECIPITATION AND THIS SEEMS REASONABLE GIVEN UPSTREAM OBSERVATIONS. 
SURFACE TEMPERATURES EXPECTED TO REMAIN ABOVE FREEZING...SO NOT 
EXPECTING ANY ACCUMULATIONS.
IN THE LATER PERIODS...MODEL DATA SUGGEST THE MAIN FORCING/DEEP 
MOISTURE WILL BE MOVING INTO WESTERN OHIO BY 27/00Z...SO THERE MAY 
BE SOME LINGERING CHANCES FOR LIGHT MIXED PRECIPITATION IN THE FAR 
EASTERN ZONES THIS EVENING BUT THAT APPEARS TO BE ABOUT IT AS DRIER 
AIR MOVES IN PRETTY FAST TONIGHT. MAY SEE SOME CLEARING IN THE PRE 
DAWN HOURS ON FRIDAY. 
REST OF THE SHORT RANGE PERIOD LOOKS QUIET WITH MILD TEMPERATURES 
RETURNING AS SURFACE/UPPER RIDGING BUILD INTO THE AREA. NEXT CHANCE 
FOR PRECIPITATION APPEARS TO BE AT THE TAIL END OF THE WEEKEND AND 
INTO EARLY NEXT WEEK WITH THE PASSAGE OF A NORTHERN STREAM SYSTEM.
LOW LEVEL THICKNESSES SUGGEST THE GFS MOS HIGHS TODAY MAY BE A 
COUPLE OF DEGREES TOO WARM. WILL NUDGE THEM DOWN A BIT. GUIDANCE IN 
THE REST OF THE PERIODS LOOK OK.
&&
.IND WATCHES/WARNINGS/ADVISORIES...NONE. 
&&
$$
PUBLIC...JAS
AVIATION...RYAN