FXUS63 KIND 221940
AFDIND

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE INDIANAPOLIS IN
235 PM EST TUE DEC 22 2009

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT...
MODEL DATA SUGGEST LONG WAVE FEATURES WILL REMAIN PROGRESSIVE OVER 
THE NEXT SEVERAL DAYS...WITH DEVELOPING TROUGH CURRENTLY OVER THE 
WEST COAST MOVING INTO THE PLAINS BY FRIDAY MORNING. UPPER LEVEL 
RIDGE CURRENTLY OVER THE MIDWEST IS EXPECTED TO DRIFT EASTWARD TO 
NEAR THE EAST COAST. OPERATIONAL AND ENSEMBLE DATA SUGGEST SURFACE 
SYSTEM TO TRACK FROM ARKANSAS INTO WESTERN ILLINOIS OR IOWA BY 
FRIDAY MORNING. MODELS IN GOOD AGREEMENT ON THE MAJOR FEATURES. 
FORECAST FOCUS CENTERS ON POPS AND PRECIPITATION TYPE THROUGHOUT THE 
SHORT RANGE PERIOD.

MODEL DATA SUGGEST AN AREA OF ENHANCED MID LEVEL LIFT CURRENTLY IN 
THE ARKANSAS/SOUTHERN MISSOURI AREA WILL BE MOVING UP THROUGH 
ILLINOIS LATE TONIGHT AND ON WEDNESDAY...BRUSHING THE WESTERN PARTS 
OF THE FORECAST AREA. REGIONAL RADARS ARE INDICATING SOME SPOTTY 
ECHOES IN THAT AREA WITH A GRADUAL INCREASE IN THE COVERAGE OVER THE 
PAST COUPLE OF HOURS. AS A RESULT...WILL BE PULLING CHANCE POPS FOR 
FOR LIGHT PRECIPITATION LATE TONIGHT A LITTLE FARTHER EAST...UP TO 
ABOUT THE WESTERN HALF OF THE AREA. CRITICAL THICKNESSES SUGGEST 
MAINLY LIQUID...ALTHOUGH THE FAR NORTHERN ZONES MAY GET SOME LIGHT 
SNOW OR SLEET. THE MAJORITY OF THE MODEL DATA SUGGEST THE FREEZING 
LINE TONIGHT WILL SET UP NEAR A VERMILLION-MONROE COUNTY LINE...SO 
FREEZING RAIN POSSIBLE NORTHEAST OF THAT LINE. 

WILL CONTINUE WITH LIKELY POPS BY WEDNESDAY AFTERNOON IN THE WESTERN 
ZONES...AND CHANCE POPS ELSEWHERE AS AREA OF LIFT CONTINUES TO MOVE 
NORTH ACROSS ILLINOIS. AGAIN...FREEZING RAIN APPEARS POSSIBLE OVER 
THE NORTHEAST TWO THIRDS OF THE AREA WEDNESDAY MORNING...BUT THE 
FREEZING LINE SHOULD SHIFT NORTHEAST DURING THE DAY. 

APPEARS THE BEST CHANCES FOR ORGANIZED PRECIPITATION WILL BE 
WEDNESDAY NIGHT THROUGH THURSDAY NIGHT AS SEVERAL WAVES OF ORGANIZED 
LIFT MOVE INTO THE AREA. WILL CONTINUE WITH LIKELY POPS IN THE WEST 
WEDNESDAY NIGHT AND CHANCE POPS EAST FOR WEDNESDAY NIGHT...AND HIGH 
POPS ALL AREAS BY THURSDAY. AGAIN...PINNING DOWN THE FREEZING LINE 
AT THIS TIME IS DIFFICULT...BUT THE VARIOUS MODEL DATA SUGGEST 
FREEZING RAIN POSSIBLE WEDNESDAY NIGHT INTO THURSDAY MORNING OVER 
ABOUT NORTHEAST ONE HALF OF THE FORECAST AREA. BY THURSDAY AFTERNOON 
AND NIGHT...TEMPERATURES SHOULD WARM ENOUGH TO END THE FREEZING RAIN 
THREAT. ADVISORIES FOR WINTER PRECIPITATION MAY EVENTUALLY BE NEEDED 
OVER SOME OF THE NORTHWEST ZONES BY WEDNESDAY NIGHT INTO THURSDAY AS 
IT APPEARS THESE AREAS MAY GET CLOSE TO ADVISORY CRITERIA.

BASED ON LOW LEVEL THICKNESSES...DON/T HAVE A MAJOR PROBLEM WITH THE 
GFS MOS GUIDANCE...HOWEVER THE NUMBERS MAY BE ABOUT 5 DEGREES TOO 
WARM BY THURSDAY. WILL NUDGE THE NUMBERS DOWN A BIT BY THAT PERIOD.

&&

.LONG TERM...FRIDAY THROUGH TUESDAY...
OCCLUDED FRONT SHOULD BE SOMEWHERE WITHIN THE FORECAST AREA AT 12Z 
FRIDAY MORNING...PROGRESSING EAST OF THE REGION BY MIDDAY FRIDAY AND 
TAKING BULK OF THE HEAVIER RAINFALL WITH IT. MODEL CONSENSUS NOW 
SHOWING A WELL DEVELOPED DRY SLUG OF AIR WRAPPING AROUND THE STACKED 
LOW PRESSURE OVER THE UPPER MIDWEST. HAVE LOWERED TO 30 POPS DURING 
THE AFTERNOON...HOWEVER THERE IS A GROWING LIKELIHOOD AT AN EXTENDED 
PERIOD OF DRY WEATHER OVER CENTRAL INDIANA DURING THE DAY FRIDAY.  
COLDER AIRMASS WILL GRADUALLY ADVECT INTO THE REGION BEHIND THE 
FRONT ON FRIDAY WITH ATMOSPHERE BECOMING SUFFICIENTLY COOLED FOR 
PRECIPITATION TO FALL AS SNOW BY FRIDAY EVENING. WINDS WILL REMAIN 
GUSTY ALL DAY...PERHAPS IN EXCESS OF 30MPH.

SCATTERED SNOW SHOWERS ARE EXPECTED ALL WEEKEND NOW AS THE UPPER LOW 
AND ATTENDANT SURFACE REFLECTION TRUDGE SLOWLY EAST-NORTHEAST ACROSS 
THE GREAT LAKES. STRONG SURFACE HIGH PRESSURE AND A DEEP RIDGE ALOFT 
OVER THE CANADIAN MARITIMES CERTAINLY APPEAR TO BE KEEPING THE SYSTEM 
FROM MOVING WITH ANY SORT OF RAPIDITY. SEVERAL UPPER LEVEL 
DISTURBANCES WILL RIPPLE AROUND THE PARENT UPPER LOW AND THROUGH THE 
REGION OVER THE WEEKEND. THESE DISTURBANCES WILL COMBINE WITH 
PERSISTENT COLD ADVECTION AND SHALLOW WEAK INSTABILITY TO ENABLE 
SCATTERED SNOW SHOWERS THROUGH SUNDAY NIGHT AND POSSIBLY INTO MONDAY 
AS UPPER LOW DEPARTS TO THE NORTHEAST. WITH HIGH TEMPERATURES 
LARGELY REMAINING IN THE 20S AND LOWS IN THE TEENS THROUGH THE 
WEEKEND...LIQUID TO SNOW RATIOS WILL BE ENHANCED OVER THE STANDARD 
10:1 AND IT SEEMS PLAUSIBLE THAT LIGHT ACCUMULATIONS ARE LIKELY OVER 
AN EXTENDED TIME PERIOD FROM FRIDAY NIGHT THROUGH SUNDAY. WITH A 
CONTINUED TIGHT PRESSURE GRADIENT...BREEZY CONDITIONS CAN BE 
EXPECTED ALL WEEKEND. HIGH PRESSURE WILL OVERSPREAD THE OHIO VALLEY 
MONDAY AND TUESDAY PROVIDING POSSIBLY THE FIRST SIGNIFICANT TASTE OF 
SUNSHINE IN QUITE A WHILE. TEMPERATURES WILL REMAIN CHILLY THROUGH 
THE END OF THE EXTENDED. 

UNSETTLED WEATHER LIKELY TO RETURN BY THE MIDDLE OF NEXT WEEK AS 
BOTH ECMWF/OP GFS SUGGESTING LOW PRESSURE DEVELOPS IN THE NORTHERN 
GULF AND MOVES ACROSS THE EASTERN U S. TOO FAR OUT TO DETERMINE 
IMPACTS IF ANY TO CENTRAL INDIANA...BUT THIS WILL BE SOMETHING TO 
KEEP AN EYE ON OVER THE WEEKEND AND INTO EARLY NEXT WEEK.

&&

.AVIATION...DISCUSSION FOR 22/18Z TAFS.
LIGHT SNOW FROM EARLIER THIS MORNING HAD SHIFTED EAST OF ALL OF THE 
TERMINALS AS OF MIDDAY. MUCH OF THE FORECAST AREA REMAINED 
UNDERNEATH A LOW MVFR/IFR STRATUS DECK WITH VISIBILITIES HOLDING 
BETWEEN 3-5SM. SOME BREAKS IN THE CLOUDS HAD DEVELOPED ACROSS 
SOUTHERN INDIANA IN RESPONSE TO SOME DRIER AIR ALOFT. WITH LOW LEVEL 
FLOW PREDOMINANTLY OUT OF THE SOUTHEAST FOR THE REMAINDER OF THE 
DAY...ANTICIPATE THESE BREAKS TO A MID LEVEL DECK WILL REACH KBMG 
AND POSSIBLY KHUF AND KIND DURING THE LATE AFTERNOON AND EARLY 
EVENING. KLAF REMAINS TOO FAR ENTRENCHED IN THE STRATUS DECK AND 
SHOULD REMAIN BELOW 3000FT THROUGH THE AFTERNOON.

ISENTROPIC LIFT WILL DEVELOP THIS EVENING AND OVERSPREAD CENTRAL 
INDIANA FROM THE WEST. MODEL SOUNDINGS INDICATING THAT THE LOW LEVEL 
MOISTURE WILL REESTABLISH WITH MVFR AND POSSIBLY IFR STRATUS 
REDEVELOPING BY LATE EVENING. AT KLAF WHERE ISENTROPIC LIFT WILL BE 
STRONGEST...HAVE A GROWING CONCERN AT A PERIOD OF FREEZING DRIZZLE 
OR FREEZING RAIN OVERNIGHT. HAVE LOWERED TO IFR CONDITIONS HERE 
AFTER 03Z WITH JUST A VCSH MENTION AT THIS TIME. WILL CONTINUE TO 
MONITOR CLOSELY THROUGH THE REST OF THE AFTERNOON. FURTHER SOUTH AT 
KHUF...APPEARS TEMPERATURES WILL REMAIN WARM ENOUGH FOR ANY LIGHT 
PRECIPITATION TO FALL MAINLY AS RAIN. WILL EMPLOY VCSH HERE AS WELL. 
UNCERTAIN IF PRECIPITATION WILL MAKE IT AS FAR EAST AS KBMG AND KIND 
AT THIS TIME. PRECIPITATION SHOULD DIMINISH WEDNESDAY MORNING WITH 
MVFR CONDITIONS PERSISTING INTO THE AFTERNOON. EASTERLY WINDS WILL 
PICK UP THROUGH THE NIGHT...WITH SUSTAINEDS NEAR 15KTS BY WEDNESDAY 
MORNING.

&&

.IND WATCHES/WARNINGS/ADVISORIES...NONE. 

&&

$$

SHORT TERM...JAS
LONG TERM...RYAN
AVIATION...RYAN