290  
FXUS63 KIND 280432  
AFDIND  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE INDIANAPOLIS IN  
1132 PM EST SAT FEB 27 2021  
   
UPDATE
 
 
THE AVIATION SECTIONS HAVE BEEN UPDATED BELOW.  
 

 
   
SYNOPSIS
 
 
ISSUED AT 241 PM EST SAT FEB 27 2021  
 
A LOW PRESSURE SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA LATE  
TONIGHT INTO SUNDAY. ANOTHER WEAKER LOW PRESSURE SYSTEM MAY AFFECT  
PARTS OF THE AREA TOWARDS THE MIDDLE OF NEXT WEEK. HIGH PRESSURE IS  
EXPECTED ACROSS THE AREA BY THE LATTER PORTIONS OF NEXT WEEK.  
 

 
   
NEAR TERM /TONIGHT AND SUNDAY/
 
 
ISSUED AT 1000 PM EST SAT FEB 27 2021  
 
QUIET EVENING SO FAR ACROSS THE REGION BUT WIDESPREAD RAIN IS  
ORGANIZING JUST TO THE SOUTH OF THE FORECAST AREA AS A WARM FRONT  
LIFTS NORTH AND A LOW LEVEL JET APPROACHES FROM THE SOUTHWEST. THE  
FRONT WILL SHIFT NORTH INTO THE AREA OVERNIGHT WITH RAIN SPREADING  
NORTH AND ENCOMPASSING MOST OF THE FORECAST AREA BY 08-09Z. THE LOW  
LEVEL JET WILL MOVE INTO THE REGION AFTER 06Z WITH STRONGER LIFT  
FOCUSED NEAR THE EVENTUAL LOCATION OF THE BOUNDARY WHICH SHOULD GET  
INTO THE SOUTHERN PART OF THE FORECAST AREA BY DAYBREAK SUNDAY.  
 
THE HEAVIEST RAINFALL WITH THIS SYSTEM WILL REMAIN NEAR AND SOUTH OF  
THE OHIO RIVER AS CONVECTION OVERNIGHT AND SUNDAY MORNING INCREASES  
RAINFALL RATES. THIS CONVECTION MAY ACTUALLY ROB THE MOISTURE  
ADVECTION NORTH INTO CENTRAL INDIANA SLIGHTLY BUT THE PRESENCE OF A  
MID LEVEL DEFORMATION AXIS AND BROAD OVERRUNNING ALONG THE BOUNDARY  
SHOULD MORE THAN COMPENSATE WITH A RESPECTABLE SOAKING BY MIDDAY  
SUNDAY NEAR AND SOUTH OF THE I-70 CORRIDOR.IN ADDITION...WHILE  
CONVECTION WILL BE FOCUSED SOUTH OF THE AREA...THERE REMAINS A LOW  
THREAT FOR ISOLATED THUNDERSTORMS LATE TONIGHT. STILL ANTICIPATE 1  
TO 1.5 INCHES FOR THE SOUTHERN HALF OF THE FORECAST AREA WITH  
LIGHTER AMOUNTS FURTHER NORTH.  
 
INCREASED POPS SLIGHTLY OVERNIGHT OTHERWISE FORECAST IS IN GOOD  
SHAPE. PERTINENT PORTIONS OF THE AFTERNOON DISCUSSION FOLLOWS.  
 
A SHORT WAVE TROUGH CURRENTLY OVER THE NORTHERN ROCKIES IS PROGGED  
BY SHORT TERM MODEL DATA TO MOVE EAST INTO THE GREAT LAKES BY SUNDAY  
AFTERNOON. MODELS SUGGEST A STRONG 850MB JET AROUND 50 KTS WILL NOSE  
INTO THE OHIO VALLEY BY LATE TONIGHT INTO SUNDAY MORNING, ASSOCIATED  
WITH THE UPPER TROUGH. THERE APPEARS TO BE QUITE A BIT OF CONVERGENT  
FLOW NEAR THE 850MB LEVEL OVER THE SOUTHERN HALF OF THE FORECAST  
AREA LATE TONIGHT INTO SUNDAY MORNING, ON THE NORTH SIDE OF THE LOW  
LEVEL JET NOSE. AS A RESULT, EXPECTING CONSIDERABLE LIFT TO DEVELOP  
LATE TONIGHT INTO SUNDAY MORNING OVER THE SOUTHERN HALF OF THE  
FORECAST AREA.  
 
BASED ON ABOVE, WILL BRING IN HIGH POPS FOR LATE TONIGHT INTO SUNDAY  
MORNING, ESPECIALLY OVER THE SOUTHERN HALF OF THE FORECAST AREA. AS  
THE LOW LEVEL JET SHIFTS OFF TO THE EAST LATER SUNDAY MORNING, WILL  
GRADUALLY PARE BACK THE POPS FROM THE WEST. ALTHOUGH IT APPEARS FROM  
THE MODEL DATA THAT MOST OF THE ORGANIZED LIFT WILL HAVE SHIFTED OFF  
TO THE EAST BY SUNDAY AFTERNOON, MAY KEEP A POP GOING THROUGH SUNDAY  
AFTERNOON OVER PARTS OF THE AREA, WITH THE PASSAGE OF THE TRAILING  
OCCLUSION/COLD FRONT.  
 
DUE TO THE PRESENCE OF THE STRONG LIFT, AND PROGGED PRECIPITABLE  
WATERS RISING TO 1.00-1.50 INCHES, HEAVY RAINFALL AMOUNTS ARE  
POSSIBLE OVER THE SOUTHERN HALF OF THE AREA. FLASH FLOOD GUIDANCE  
SUGGESTS THE GROUND CAN PROBABLY TAKE AROUND 2 INCHES OF RAIN BEFORE  
PROBLEMS ARISE, SO NOT PLANNING ON ANY KIND OF HEADLINES AT THIS  
TIME.  
 
EMBEDDED LIGHTNING STRIKES MAY ALSO OCCUR OVER THE SOUTH DUE TO SOME  
WEAK ELEVATED INSTABILITY AND THE STRONG LIFT.  
 
DUE TO THE STRONG WARM ADVECTION EXPECTED LATER TONIGHT, LOWS  
TONIGHT WILL PROBABLY OCCUR EARLY IN THE NIGHT, WITH TEMPERATURES  
SLOWLY RISING LATE. GFS MOS TEMPERATURE GUIDANCE GENERALLY ACCEPTED  
IN THIS PERIOD, BASED OFF OF LOW LEVEL THICKNESS PROGS.  
 

 
   
SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/
 
 
ISSUED AT 241 PM EST SAT FEB 27 2021  
 
MODEL DATA SUGGEST THE GREAT LAKES TROUGH WILL CONTINUE MOVING EAST  
OF THE LOCAL AREA BY MONDAY, WITH UPPER RIDGING DEVELOPING BY MONDAY  
NIGHT AND TUESDAY. AT THE SURFACE, HIGH PRESSURE IS EXPECTED TO MOVE  
THROUGH THE AREA INTO TUESDAY. THIS SHOULD RESULT IN DRY WEATHER  
THROUGHOUT MOST OF THIS PERIOD. A CUTOFF LOW IS EXPECTED TO APPROACH  
THE MIDWEST FROM THE SOUTHWEST BY LATE DAY TUESDAY. AT THIS TIME, IT  
APPEARS THE BULK OF THE PRECIPITATION THREAT LOOKS TO HOLD OFF UNTIL  
AFTER THIS PERIOD.  
 
PROGGED LOW LEVEL THICKNESSES SUGGEST THE GFS MOS TEMPERATURE  
GUIDANCE LOWS SUNDAY NIGHT LOOK A LITTLE WARM. WILL NUDGE DOWN THE  
GUIDANCE LOWS A CATEGORY IN THAT PERIOD. THE REST OF THE PERIODS  
LOOK OK FOR NOW.  
 

 
   
LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/
 
 
ISSUED AT 241 PM EST SAT FEB 27 2021  
 
THE LONG TERM WILL START OFF WITH AN UPPER WAVE THAT WILL MOVE  
QUICKLY EAST ACROSS THE OHIO AND TENNESSEE VALLEY AREA. THERE IS  
GENERAL AGREEMENT THAT ANY BRIEF WIDESPREAD RAIN WILL BE SOUTH OF  
THE AREA, AND THE GFS 12Z AND GFS TRENDS, ESPECIALLY, WOULD KEEP IT  
ALL SOUTH OF CENTRAL INDIANA. THAT SAID, CAN NOT COMPLETELY RULE OUT  
A FEW SHOWERS TUESDAY NIGHT, ESPECIALLY OVER SOUTH CENTRAL SECTIONS.  
THUS, WILL KEEP THE BLEND SMALL CHANCE TO CHANCE POPS THEN.  
SOUNDINGS AND LOW LEVEL CRITICAL THICKNESSES SUPPORT A RAIN AND SNOW  
MIX ASSUMING THERE ARE SHOWERS AROUND.  
 
THE REST OF NEXT WEEK THROUGH SATURDAY, LOOKS DRY OR AT LEAST MOSTLY  
DRY DUE TO SUBSIDENCE UNDER THE INFLUENCE OF SURFACE HIGH PRESSURE  
AND A DRY COLUMN. WITH LIMITED CLOUD COVER, LOOK FOR ABOVE NORMAL  
TEMPERATURES WITH HIGHS MOSTLY IN THE LOWER AND MIDDLE 50S.  
 

 
   
AVIATION /DISCUSSION FOR 280600Z TAF ISSUANCE/
 
 
ISSUED AT 1132 PM EST SAT FEB 27 2021  
 
IMPACTS: SUB-IFR CONDITIONS IN RAIN WILL EXPAND INTO THE TERMINALS  
OVERNIGHT AND CONTINUE THROUGH SUNDAY MORNING. CEILINGS WILL SLOWLY  
RECOVER TO MVFR LEVELS BY SUNDAY AFTERNOON AND EVENING. WIND GUSTS  
AT 20 TO 25KTS WILL DEVELOP SUNDAY AFTERNOON AS WELL.  
 
DISCUSSION: WIDESPREAD RAIN IS STEADILY EXPANDING NORTH INTO THE  
REGION LATE THIS EVENING AS A WARM FRONT LIFTS NORTH OUT OF TENNESSEE  
AND LOWER OHIO VALLEYS. WIDESPREAD RAIN AND IFR/LIFR CEILINGS WILL  
ARRIVE FROM THE SOUTH OVER THE NEXT FEW HOURS. RAIN WILL CONTINUE  
INTO SUNDAY MORNING BEFORE SHIFTING EAST FROM THE TERMINALS BY  
MIDDAY.  
 
EASTERLY WINDS THIS EVENING WILL VEER TO S/SE OVERNIGHT WITH THE  
WARM FRONT MOVING INTO THE AREA. AS A COLD FRONT SWEEPS ACROSS THE  
AREA SUNDAY AFTERNOON...WINDS WILL SHIFT TO WESTERLY AND BECOME  
GUSTY. DESPITE DRIER AIR ALOFT ADVECTING INTO CENTRAL INDIANA SUNDAY  
EVENING...A STRONG LOW LEVEL INVERSION WILL LINGER WITH MORE  
SUBSTANTIAL CLEARING OCCURRING DURING THE PREDAWN HOURS MONDAY.  
 

 
   
IND WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
SYNOPSIS...JAS  
NEAR TERM...JAS/RYAN  
SHORT TERM...JAS  
LONG TERM....KOCH  
AVIATION...RYAN  
 
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