868  
FXUS63 KIND 302306  
AFDIND  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE INDIANAPOLIS IN  
706 PM EDT THU MAR 30 2017  
   
UPDATE
 
 
THE AVIATION SECTION HAS BEEN UPDATED BELOW.  
 

 
   
SYNOPSIS
 
 
ISSUED AT 334 PM EDT THU MAR 30 2017  
 
SEVERE WEATHER IS POSSIBLE THROUGH THIS EVENING AS A STRONG LOW  
PRESSURE SYSTEM MOVES THROUGH THE REGION. COOL...DAMP AND CLOUDY  
WEATHER IS EXPECTED ON FRIDAY AS AN UPPER LOW MOVES THROUGH CENTRAL  
INDIANA. HIGH PRESSURE WILL BUILD IN FOR THE WEEKEND WITH DRY AND  
SEASONABLE WEATHER. UNSETTLED CONDITIONS WILL RETURN FOR NEXT WEEK  
HOWEVER AS A SERIES OF STORM SYSTEMS PASS THROUGH THE OHIO VALLEY.  
 

 
   
NEAR TERM /REST OF THIS AFTERNOON AND TONIGHT/
 
 
ISSUED AT 334 PM EDT THU MAR 30 2017  
 
SCATTERED CONVECTION BEGINNING TO TAKE OFF INTENSITY-WISE ACROSS  
WEST CENTRAL INDIANA AS A WARM FRONT SLOWLY LIFTS NORTH THROUGH THE  
AREA. 19Z TEMPERATURES REMAINED IN THE 50S NORTH OF THE FRONT WHILE  
SOUTH OF THE BOUNDARY...TEMPS HAD RISEN INTO THE 70S.  
 
THE PRIMARY FOCUS FOR THE NEAR TERM IS THE POTENTIAL FOR SEVERE  
WEATHER OVER THE NEXT 6 HOURS OR SO.  
 
WARM FRONT CURRENTLY ALIGNED AT 19Z FROM NORTHERN VERMILLION COUNTY  
E/SE THROUGH THE INDY METRO INTO RUSH COUNTY. CONVECTION HAS FIRED  
ACROSS WEST CENTRAL INDIANA AND THE NORTHERN WABASH VALLEY AND  
QUICKLY BECOME SEVERE AS DIRECTIONAL SHEAR IS MAXIMIZED IN THE  
VICINITY OF THE BOUNDARY. THE FOCUS FOR SEVERE WEATHER AND THE  
THREAT FOR ROTATING STORMS SHOULD FOCUS NEAR AND NORTH OF THE  
RETREATING WARM FRONT OVER THE NEXT 2-3 HOURS. 0-1/0-3KM STORM  
RELATIVE HELICITY VALUES ARE ALSO MAXIMIZED IN AN AXIS ALONG THE  
FRONT. SHORT RANGE GUIDANCE SUGGESTIVE THAT THE FRONT AND DEEPER  
HELICITY SHOULD BE NORTHEAST OF THE ENTIRE FORECAST AREA BY 22-23Z.  
AGAIN...THE GREATEST TORNADO THREAT WILL EXIST OVER THESE NEXT 3  
HOURS OR SO...FOCUSED LARGELY NORTHEAST OF INTERSTATE 74 AS THE WARM  
FRONT CONTINUES LIFTING NORTH.  
 
THE SECONDARY IMPACT WILL BE THE SQUALL LINE DEVELOPING ACROSS  
CENTRAL AND SOUTHERN ILLINOIS ALONG THE COLD FRONT. HI-RES GUIDANCE  
PROGRESSES THIS ACTIVITY EAST INTO THE FORECAST AREA AFTER 22-23Z  
AND QUICKLY ACROSS THE FORECAST AREA THROUGH MID EVENING. DAMAGING  
WINDS WILL BE THE PRIMARY THREAT WITH THE LINEAR CONVECTION THIS  
EVENING WITH HELICITIES DIMINISHING. AS WITH ANY QLCS SCENARIO  
THOUGH...CANNOT RULE OUT QUICK SPINNERS ASSOCIATED WITH ANY KINKS IN  
THE LINE. STILL HAVE SOME CONCERNS HOW INTENSE THE LINE WILL BE WHEN  
IT ARRIVES AS ALREADY THERE ARE HINTS THAT THE DEEPER LOW LEVEL  
FORCING IS SHIFTING EAST AS A SLUG OF DRIER WELL MIXED AIR WITH  
DEWPOINTS IN THE LOWER TO MIDDLE 50S NOTED INTO OUT SOUTHWEST  
COUNTIES. MAY END UP BEING MORE OF A MESSY CONVECTIVE LINE WITH  
INDIVIDUAL STORMS PULSING IN INTENSITY.  
 
THE COLD FRONT WILL SWEEP ACROSS THE FORECAST AREA BY MIDNIGHT WITH  
THE SEVERE WEATHER THREAT OVER BY LATE EVENING. THIN AXIS OF DRY AIR  
WILL BE DRAWN THROUGH THE REGION IMMEDIATELY BEHIND THE FRONT AND  
MAY ENABLE SKIES TOP BRIEFLY CLEAR OR GO PARTLY CLOUDY AT THE LEAST.  
ARRIVAL OF THE UPPER LOW INTO THE REGION DURING THE PREDAWN HOURS  
WILL SPREAD LOWER STRATUS BACK ACROSS THE FORECAST AREA LONG WITH  
THE POTENTIAL FOR A FEW LIGHT RAIN SHOWERS.  
 
TEMPS...A GENERAL MODEL BLEND LOOKED REASONABLE FOR LOWS TONIGHT.  
SHOULD SEE MOST AREAS FALL INTO THE UPPER 40S BY DAYBREAK.  
 

 
   
SHORT TERM /FRIDAY THROUGH SUNDAY/
 
 
ISSUED AT 334 PM EDT THU MAR 30 2017  
 
FORECAST CHALLENGES FOCUS ON PRECIP CHANCES FRIDAY AS THE UPPER LOW  
SLOWLY TRAVERSES THROUGH THE REGION.  
 
STRATUS DECK ASSOCIATED WITH UPPER LOW WILL EXPAND ACROSS THE AREA  
EARLY FRIDAY WITH THE ENTIRE FORECAST AREA INFLUENCED BY THE UPPER  
LOW AS IT TRACKS EAST THROUGH THE OHIO VALLEY. THE PRESENCE OF A  
TRAILING SURFACE TROUGH SAGGING SOUTHEAST THROUGH THE FORECAST AREA  
WILL COMBINE WITH WEAK AND SHALLOW INSTABILITY TO SUPPORT PERIODIC  
SCATTERED LIGHT RAIN SHOWERS FOR MUCH OF THE DAY...GRADUALLY  
FOCUSING OVER THE EASTERN COUNTIES DURING THE AFTERNOON AND EVENING.  
 
SURFACE RIDGE WILL BUILD INTO THE REGION FROM THE WEST BEGINNING  
FRIDAY NIGHT WITH PROGRESSIVELY DRIER AIR EXPANDING SOUTH INTO  
CENTRAL INDIANA BY SATURDAY MORNING. WITH THAT BEING SAID...MODEL  
SOUNDINGS AND RH PROGS CONTINUE TO HIGHLIGHT A SHALLOW MOISTURE  
LAYER REMAINING TRAPPED BENEATH AN INVERSION ON FRIDAY NIGHT. EXPECT  
THE STRATUS TO LINGER ACROSS MUCH OF THE REGION FOR MOST IF NOT ALL  
OF THE NIGHT...WITH MORE SUBSTANTIAL CLEARING ON SATURDAY MORNING AS  
THE DRIER AIR FINALLY EATS INTO THE BOUNDARY LAYER AND WEAKENS THE  
INVERSION.  
 
THE HIGH PRESSURE RIDGE WILL SERVE AS THE PRIMARY INFLUENCE ON  
WEATHER OVER CENTRAL INDIANA THROUGH MOST OF THE REST OF THE SHORT  
TERM AS IT TRACKS EAST THROUGH THE GREAT LAKES. ONCE THE STRATUS  
BREAKS OVER THE REGION EARLY SATURDAY...EXPECT MOSTLY CLEAR SKIES  
INTO EARLY SUNDAY BEFORE CLOUDS INCREASE WITH MID AND UPPER LEVEL  
MOISTURE ARRIVING AHEAD OF THE NEXT STORM SYSTEM COMING OUT OF THE  
SOUTHERN PLAINS. PREDOMINANT EASTERLY FLOW IN THE LOWER LEVELS  
THOUGH WILL KEEP THE BOUNDARY LAYER DRY UNTIL SUNDAY EVENING AT THE  
EARLIEST.  
 
TEMPS...WITH THE COLD ADVECTION ASSOCIATED WITH THE UPPER LOW AND  
CLOUDS/RAIN EXPECTED...UNDERCUTTING MOS FOR FRIDAY AND LEANING MUCH  
CLOSER TO THE MET GUIDANCE. SOME LOCATIONS MAY NOT GET OUT OF THE  
UPPER 40S. AN OVERALL MODEL BLEND WORKED WELL FOR HIGHS SUNDAY AND  
LOWS THROUGHOUT THE PERIOD.  
 

 
   
LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/
 
 
ISSUED AT 334 PM EDT THU MAR 30 2017  
 
CENTRAL INDIANA AND THE OHIO VALLEY WILL REMAIN UNDER AN ACTIVE  
WEATHER REGIME THROUGHOUT THE EXTENDED AS THE PARADE OF STORM  
SYSTEMS CONTINUES TO TRACK ACROSS THE REGION.  
 
FIRST WAVE OF LOW PRESSURE WILL KICK OUT OF EAST TEXAS EARLY MONDAY  
AND TRACK NORTHEAST THROUGH THE OHIO AND TENNESSEE VALLEYS. CENTRAL  
INDIANA WILL RESIDE NORTH OF THE SURFACE WAVE TRACK...WITH RAIN AND  
EMBEDDED THUNDERSTORMS IMPACTING MOST OF THE AREA AND ESPECIALLY  
SOUTHERN PORTIONS OF CENTRAL INDIANA IN CLOSER PROXIMITY TO THE  
TRACK OF THE LOW.  
 
HIGH PRESSURE AND RIDGING ALOFT WILL BRING DRY WEATHER FOR TUESDAY  
AND TUESDAY NIGHT...BEFORE RAIN ASSOCIATED WITH THE NEXT SYSTEM  
ARRIVES FOR WEDNESDAY. MODELS HAVE BEEN TRENDING FURTHER NORTH WITH  
THIS LOW PRESSURE SYSTEM...SETTING THE STAGE FOR ANOTHER ROUND OF  
RAIN AND THUNDERSTORMS TO IMPACT THE OHIO VALLEY AHEAD OF THE LOW  
AND ITS ASSOCIATED COLD FRONT WEDNESDAY AFTERNOON AND NIGHT. COOLER  
AND SHOWERY WEATHER IS EXPECTED FOR THURSDAY IN THE WAKE OF THE COLD  
FRONTAL PASSAGE...WITH DRY AND CHILLY WEATHER POTENTIALLY TO FOLLOW  
FOR LATE NEXT WEEK.  
 

 
   
AVIATION /DISCUSSION FOR THE 31/00Z TAFS/
 
 
ISSUED AT 706 PM EDT THU MAR 30 2017  
 
MAINLY VFR THROUGH THE EVENING WITH OCCASIONAL PERIODS OF MVFR IN  
SHOWERS AND SCATTERED STORMS. MORE WIDESPREAD MVFR CEILINGS AND  
LATER IFR CEILINGS WILL MOVE INTO THE AREA LATE TONIGHT INTO  
TOMORROW.  
 
AREA OF SHOWERS AND STORMS AHEAD OF THE COLD FRONT WILL MOVE  
THROUGH OVER THE FIRST HOUR OR TWO OF THE TAF PERIOD. THUNDER  
THREAT WILL END THEREAFTER BUT A FEW SHOWERS WILL CONTINUE TO BE  
POSSIBLE OVERNIGHT AND INTO TOMORROW AS THE UPPER LOW MOVES  
THROUGH THE REGION. THE UPPER LOW WILL ALSO BE ACCOMPANIED BY SOME  
IFR CEILINGS.  
 
WINDS WILL BE VARIABLE AND OCCASIONALLY GUSTY EARLY IN THE PERIOD,  
BECOMING MORE WESTERLY AND NORTHWESTERLY WITH TIME POST FRONTAL  
PASSAGE.  
 

 
   
IND WATCHES/WARNINGS/ADVISORIES
 
NONE.  
 

 
 

 
 
SYNOPSIS...RYAN  
NEAR TERM...RYAN  
SHORT TERM...RYAN  
LONG TERM....RYAN  
AVIATION...NIELD  
 
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