148  
FXUS63 KIWX 301749  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
149 PM EDT SAT APR 30 2016  
   
SYNOPSIS
 
 
ISSUED AT 144 PM EDT SAT APR 30 2016  
 
RAIN WILL CONTINUE OVER THE AREA INTO THE OVERNIGHT HOURS WITH  
MOST AREAS RECEIVING BETWEEN ONE HALF TO ONE INCH OF RAINFALL. LOWS  
SUNDAY MORNING WILL RANGE FROM THE MIDDLE 40S IN SOUTH CENTRAL  
MICHIGAN TO NEAR 50 INTO CENTRAL INDIANA. HIGHS ON SUNDAY WILL BE  
IN THE MID 50S TO MID 60S WITH STILL A CHANCE OF SHOWERS AND  
POSSIBLE THUNDERSTORMS.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 354 AM EDT SAT APR 30 2016  
 
DRY CONDITIONS SHOULD PERSIST FOR MOST AREAS THROUGH 12Z THIS  
MORNING AS SFC WARM FRONT AND INCREASED THETA E SURGE REMAINS FROM  
EAST OF KANSAS CITY TO NORTH OF ST LOUIS INTO NW KENTUCKY. WHILE  
NORTHWARD PROGRESS IS BEING MADE IT IS VERY SLOW AS SUGGESTED TO  
BY MAJORITY OF MODELS. SOME LIGHTER PRECIP WAS NOTED FROM SE IOWA  
INTO CENTRAL IL BUT LITTLE MORE THAN SPRINKLES NOTED. SUSPECT THIS  
AREA WILL WEAKEN SOME AS IT PROGRESSES NORTH AND ENCOUNTERS A  
SOMEWHAT DRIER NE FLOW BUT COULD BRING SOME SPRINKLES OR BARELY  
MEASURABLE PRECIP INTO FAR SW AREAS PRIOR TO 12Z. BASED ON THIS  
HAVE CONTINUED WITH A SOMEWHAT SLOWER TREND TO ARRIVAL OF RAIN AS  
ISENTROPIC LIFT BEGINS AFTER 12Z SAT AND PEAKS 18Z TO 00Z SUN WITH  
40 TO 50 KT CROSS FLOW OVER 295 TO 300K PRESSURE SURFACES YIELDING  
WHAT SHOULD TURN OUT TO BE A LARGE AREA OF STEADY RAIN. CAN'T RULE  
OUT SOME THUNDER EMBEDDED WITHIN THE AREA...BUT GREATEST CHANCE  
FOR CONVECTION WOULD OCCUR ON THE SOUTHERN FLANK OF THE AREA  
CLOSER TO THE WARM FRONT AND LIMITED INSTABILITY. HAVE LEFT SLGT  
CHC THUNDER MENTION LATE AM INTO EARLY EVE GENERALLY SOUTH OF US  
30 WITH NO SIG CHANGES FOR THE AREA ON THE NEW DAY 1 SPC OUTLOOK.  
MOST LOCATIONS SHOULD SEE ONE HALF TO THREE QUARTERS OF AN INCH OF  
RAIN WITH POTENTIAL FOR SOME LOCATIONS TO SEE AN INCH OR SO.  
 
RAINFALL COULD BEGIN TO WIND DOWN TOWARDS 00Z SUN IN SW AREAS BUT  
HAVE KEPT CAT POPS INTO EARLY EVE BEFORE TAPERING OFF TO CHC  
SHOWERS/STORMS INTO THE OVERNIGHT HOURS. NO MAJOR CHANGES IN  
TEMPERATURES AS WARM FRONT WILL GENERALLY REMAIN NEAR/SOUTH OF  
US-24 CORRIDOR BY 12Z SUN.  
 

 
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 354 AM EDT SAT APR 30 2016  
 
A LULL IN GREATER RAIN COVERAGE SHOULD CONTINUE INTO EARLY SUNDAY AS  
LEAD SHORT WAVE SHIFTS OFF TO THE NORTHEAST AND LOW LEVEL FLOW  
BECOMES MORE VEERED. RAIN SHOWER COVERAGE SHOULD INCREASE ONCE AGAIN  
BY SUNDAY AFTERNOON AS DAMPENING/SHEARING UPPER LEVEL PV ANOMALY  
APPROACHES THE SOUTHERN GREAT LAKES/OHIO VALLEY. IT STILL APPEARS AS  
THOUGH BEST CHANNELED DCVA SHOULD AFFECT ESPECIALLY SOUTHEAST HALF  
OF FORECAST AREA SUNDAY AFTERNOON. OF LOW CONFIDENCE FOR SUNDAY IS  
CONVECTIVE POTENTIAL AND EXTENT OF THUNDER. SUBTLE DIFFERENCES IN  
LOW LEVEL FEATURES WILL HAVE A LARGE IMPACT ON THERMODYNAMIC  
PROFILES SUNDAY WITH NAM/GFS EXHIBITING QUITE A LARGE DIFFERENCE IN  
AFTERNOON INSTABILITY. 00Z NAM REMAINS A FAST/STRONG OUTLIER IN  
TERMS OF SFC REFLECTION THROUGH THE AREA EARLY SUNDAY MORNING IN  
COMPARISON TO BULK OF OTHER GUIDANCE. HAVE SOME CONCERN THAT NAM MAY  
BE TOO INFLUENCED BY PRIOR 12-24 HOUR UPSTREAM CONVECTION AND  
PERHAPS A LITTLE CONTAMINATED WITH SFC/LOW LEVEL EVOLUTION EARLY  
SUNDAY. WITH PREFERENCE TO SLOWER EC/GFS...LOW LEVEL THERMAL  
RIDGING/INSTABILITY AXIS WOULD EXHIBIT GREATER NORTHWARD ADVANCEMENT  
ACROSS CENTRAL/NORTHERN PORTIONS OF THE FORECAST AREA SUNDAY  
AFTERNOON. WHILE MID LEVEL LAPSE RATES SHOULD STEEPEN SUNDAY  
AFTERNOON DUE TO DIFFERENTIAL ADVECTION...DEPTH OF MOISTURE AND  
ABILITY TO REALIZE THESE STEEPER MID LEVEL LAPSE RATES REMAINS AN  
ITEM OF LOWER CONFIDENCE. DID EXPAND ISOLD THUNDER MENTION ACROSS  
FAR NORTHERN INDIANA. CANNOT COMPLETELY RULE OUT POTENTIAL OF FEW  
STRONGER STORMS ACROSS SOUTHEAST HALF OF THE AREA SUNDAY AFTERNOON  
GIVEN POTENTIAL WEAK-MODERATE INSTABILITY AND INCREASING SHEAR  
PROFILES ASSOCIATED WITH UPPER SPEED MAX NOSING ACROSS THE OHIO  
RIVER VALLEY PLACING THE AREA IN FAVORABLE LEFT EXIT REGION...BUT  
AGAIN CONFIDENCE IS ON THE LOW SIDE DUE TO UNCERTAINTY IN REGARDS TO  
WHERE SHARPER BAROCLINIC ZONE/LOW LEVEL MOISTURE GRADIENT SETS UP.  
 
FOR SUNDAY NIGHT...POCKET OF STEEPER MID LEVEL LAPSE RATES SHOULD BE  
EXITING THE EAST WITH UPPER PV ANOMALY SLOW TO DEPART. THIS SHOULD  
ALLOW FOR SCATTERED SHOWERS TO PERSIST INTO SUNDAY EVENING BEFORE  
DIMINISHING OVERNIGHT. CLOUDS WILL DECREASE ON EARLY MONDAY WITH  
JUST SOME FAIR WEATHER CU DEVELOPING IN THE AFTERNOON. HIGHS ON  
MONDAY SHOULD REACH INTO THE UPPER 50S/LOWER 60S...BUT AIR MASS WILL  
BE CONSIDERABLY DRIER.  
 
GENERAL THEME OF THE REMAINDER OF THE LONG TERM REMAINS UNCHANGED  
WITH UPPER VORT EXPECTED TO DROP ACROSS GREAT LAKES REGION  
WEDNESDAY/THURSDAY WITH NEXT FROPA FOR WEDNESDAY. LOW LEVEL W-NW  
FLOW WILL LIMIT SIGNIFICANT MOISTURE RETURN AHEAD OF THIS FRONT BUT  
WILL KEEP CHANCE POPS IN PLACE WITH BAND OF SHOWERS LIKELY TO  
ACCOMPANY THIS FRONTAL BOUNDARY. UPON COLLABORATION WITH SURROUNDING  
WFOS DID GO A LITTLE COOLER FOR THE THURSDAY-FRIDAY PERIOD AS  
CONFIDENCE IN BROAD LOW LEVEL THERMAL TROUGHING IS BEGINNING TO  
INCREASE FOR THIS PERIOD WHICH SHOULD KEEP TEMPS BELOW SEASONABLE  
NORMS FOR END OF THE WEEK.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)  
ISSUED AT 1254 PM EDT SAT APR 30 2016  
 
YET ANOTHER SLOW UPPER LEVEL PLAINS SYSTEM TO LIFT/FILL INTO THE  
SOUTHWEST UPPER GREAT LAKES THROUGH THE PERIOD. PERSISTENCE OF  
COLD SIDE OF OCCLUDING FRONTAL SYSTEM TO WARRANT DETERIORATING  
FLIGHT CONDS ESPCLY WITH RESPECT TO CIGS THROUGH THE PERIOD WITH  
IFR/LIFR CIGS LIKELY FOR MAJORITY OF OVERNIGHT PERIOD...WITH  
GRADUALLY LIFTING CIGS INTO MIDDAY SUNDAY WITH INCREASED MIXING  
DEPTH.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
MI...NONE.  
OH...NONE.  
LM...NONE.  

 
 

 
 
SYNOPSIS...MURPHY  
SHORT TERM...FISHER  
LONG TERM...MARSILI  
AVIATION...MURPHY  
 
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