923  
FXUS63 KIWX 241402  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
1002 AM EDT THU APR 24 2014  
   
SYNOPSIS
 
 
ISSUED AT 1000 AM EDT THU APR 24 2014  
 
WARM AND DRY CONDITIONS ARE EXPECTED TODAY AS A WARM FRONT LIFTS  
NORTH OF THE AREA. HIGHS THIS AFTERNOON WILL BE IN THE 60S WITH BREEZY  
SOUTHEAST WINDS. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE REGION  
TONIGHT BRINGING A CHANCE FOR RAIN THROUGH FRIDAY MORNING. LOWS  
TONIGHT WILL BE IN THE UPPER 40S TO LOWER 50S.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 400 AM EDT THU APR 24 2014  
 
SPRINKLES ASSOCIATED WITH WEAK BAND OF 295K ISENTROPIC ASCENT  
CONTINUE TO STRUGGLE IN THE FACE OF VERY DRY/STABLE LOW LEVEL  
ENVIRONMENT. HAVE SEEN A FEW RAIN REPORTS IN OUR WESTERN COUNTIES  
THOUGH AND WILL MENTION A CHANCE OF SPRINKLES THROUGH THE EARLY  
MORNING FOR OUR WEST/NORTHWEST ZONES. WARM FRONTAL FEATURE WILL LIFT  
NORTH BY LATER THIS MORNING AND EXPECT A DRY AND WARM DAY FOR THE  
BULK OF THE AREA. INCREASING SOUTHERLY WINDS/WAA WILL SUPPORT  
AFTERNOON HIGHS CLIMBING INTO THE MID TO UPPER 60S FOR MOST  
LOCATIONS. PAIR OF MIDLEVEL WAVES...REMAINING LARGELY  
UNPHASED...WILL THEN CROSS THE REGION OVERNIGHT. LATEST 00Z MODELS  
CONTINUED SLOWER TREND AND PRECIP NOW LOOKS TO HOLD OFF UNTIL LATE  
TONIGHT. SOUTHERN WAVE WILL BE THE MAIN FEATURE FOR OUR AREA.  
HEALTHY DOSE OF CVA FROM SHARP CYCLONIC CURVATURE IN THE MID...AND  
UPPER...LEVEL FLOW WILL SUPPORT GOOD UVM AND WEAK CYCLOGENESIS  
ACROSS THE REGION. STILL EXPECT WIDESPREAD LIGHT-MODERATE RAIN AS  
THIS FEATURE PASSES EARLY FRIDAY MORNING GIVEN THETA-E SURGE AHEAD  
OF THE LOW AND PW VALUES RETURNING TO NEARLY 1.25 INCHES. LATER  
TIMING WILL LIMIT OUR THUNDER POTENTIAL AS ALREADY MINUSCULE  
PREFRONTAL INSTABILITY WANES AFTER SUNSET. NEUTRAL STABILITY  
OVERNIGHT WILL AID THE SYNOPTIC FORCING THOUGH...FURTHER SUPPORTING  
HIGH POPS AND MODEST QPF VALUES IN THE 0.2-0.5 INCH RANGE. OVERNIGHT  
LOWS WILL REMAIN MILD IN WARM/MOIST AIR ADVECTION AHEAD OF THE  
FRONT. EXPECT MINS ONLY IN THE UPPER 40S TO LOWER 50S FOR MOST  
LOCATIONS.  
 

 
   
LONG TERM
 
(FRIDAY THROUGH WEDNESDAY)  
ISSUED AT 400 AM EDT THU APR 24 2014  
 
WITH TREND TO A SLOWER AND MORE DOMINANT SOUTHERN STREAM  
TROUGH...HAVE EXTENDED LIKELY POPS ACROSS EASTERN HALF OF THE AREA  
INTO EARLY FRIDAY MORNING WITH NAM/GFS TIME HEIGHT SECTIONS  
DEPICTING FAIRLY STEEP FRONTAL CIRCULATION IN DEFORMATION FORCING  
PORTION OF THIS SYSTEM. EXACT PLACEMENT OF STRONGEST DEFORMATION  
WILL DEPEND SOMEWHAT ON IMPACTS TO LOW/MID LEVEL WIND FIELD OF  
NORTHERN STREAM TROUGH TRACKING ACROSS THE WESTERN GREAT LAKES. SOME  
WEAK ELEVATED INSTABILITY MAY SUPPORT AN ISOLD TSTORM PARTICULARLY  
ACROSS FAR SOUTHEAST EARLY FRIDAY...BUT CONFIDENCE MUCH TOO LOW FOR  
INCLUSION AT THIS TIME. PRECIP TO EXIT EASTERN AREAS LATE MORNING OR  
TOWARD MIDDAY WITH BREEZY/DRY CONDITIONS IN THE AFTERNOON AS  
STRONGER LOW LEVEL DRY AIR ADVECTION WORKS INTO THE AREA BEHIND THE  
FRONT. SECONDARY SHORT WAVE AND POCKET OF 850-700 HPA NOW ALSO  
APPEARS TO BE A BIT MORE DELAYED AND CONTINUED TREND OF PREVIOUS  
FORECAST IN PUSHING BACK TIMING OF LOW CHANCE -RW POPS UNTIL LATE  
FRIDAY NIGHT. MIXING HEIGHTS ALSO NOT LOOKING QUITE AS IMPRESSIVE AS  
PREVIOUS RUNS FRIDAY AFTERNOON...BUT FAIRLY DEEP MIXING FRIDAY  
AFTERNOON SHOULD ALLOW FOR HIGHS FROM MID 60S TO LOWER 70S.  
 
MAIN FORECAST CHALLENGE FOR SATURDAY WILL BE HOW FAR SOUTH SFC/NEAR  
SFC FRONT PROGRESSES BEFORE STALLING. SETUP APPEARS TO FAVOR A SHARP  
NORTH TO SOUTH THERMAL GRADIENT ACROSS THE AREA WITH AREAS ADJACENT  
TO LAKE MICHIGAN LIKELY STRUGGLING TO THE 50 DEGREE MARK. NAM  
CERTAINLY APPEARS TO BE AN OUTLIER WITH A FURTHER NORTH SFC TROUGH  
POSITION SATURDAY AFTERNOON. DID ADD SOME SHARPENING TO THIS  
GRADIENT FOR MAX TEMPS SATURDAY...BUT HAVE UTILIZED BLENDED  
GFS/NAM/EC APPROACH. WHILE WEAK ISENTROPIC UPGLIDE WILL LIKELY  
COMMENCE LATER SATURDAY AFTERNOON PARTICULARLY ACROSS WESTERN  
PORTIONS OF THE AREA...ANY MOISTURE OF NOTE SHOULD BE HIGHLY  
ELEVATED WHICH SHOULD SUPPORT NOTHING MORE THAN SPRINKLES AT BEST.  
 
TRANSITION TO A MORE STABLE WAVE PATTERN TO FOLLOW FOR LATE WEEKEND  
WITH BLOCKING TYPE PATTERN DEVELOPING. AMPLIFICATION OF THE PATTERN  
WILL ALLOW FOR MID/UPPER RIDGING TO GET PINCHED FROM THE NORTHERN  
GREAT LAKES INTO THE OHIO RIVER VALLEY WHICH WILL DELAY ANY MOISTURE  
RETURN OF NOTE UNTIL LATER SUNDAY. TEMP FORECAST SOMEWHAT TRICKY FOR  
SUNDAY WITH STRENGTHENING LOW LEVEL INVERSION AND INCREASING HIGH  
CLOUDINESS POSSIBLY MAKING FOR A FEW DEGREES OF COOLING IN  
COMPARISON TO SATURDAY. DEEPENING EASTERLY FLOW IN RESPONSE TO  
PRESSURE FALLS TO THE WEST WILL MAINTAIN DRY LOW LEVEL TRAJECTORIES  
AND HAVE MAINTAINED JUST SLIGHT CHANCE -RW POPS SUNDAY  
AFTERNOON...RAMPING UP TO CHANCE SUNDAY NIGHT.  
 
EC/GFS CONTINUE TO BE IN GENERAL AGREEMENT WITH A COMPLICATED  
PHASING OF RETROGRADING SOUTHEAST CANADIAN AND CENTRAL CONUS PV  
ANOMALIES FOR EARLY NEXT WEEK. THIS PHASING PRODUCES A SLIGHTLY MORE  
NORTHWARD POSITION TO THE CONSOLIDATED MID/UPPER HEIGHT MINIMUM  
TOWARD THE END OF THIS FORECAST PERIOD. WITH DETAILS IN THIS  
SOLUTION LIKELY TO CHANGE OVER NEXT DAY OR TWO...HAVE GENERALLY  
STAYED THE COURSE WITH BROADBRUSH CHANCE RW POPS THROUGH MUCH OF THE  
MON-WED PERIOD WITH COOLER THAN NORMAL TEMPS PERSISTING.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)  
ISSUED AT 632 AM EDT THU APR 24 2014  
 
LOW LEVEL WARM FRONTAL BOUNDARY WILL CONTINUE TO LIFT NORTHWARD  
THIS MORNING WHICH WILL TAKE ANY LINGERING SPRINKLES NORTH OF  
KSBN BY 14Z. VFR CONDITIONS TO PERSIST THROUGH THIS EVENING WITH  
DRY LOW LEVELS PERSISTING. AN OVERALL SLOWING TREND HAS BEEN NOTED  
IN GUIDANCE REGARDING NEXT SYSTEM FOR TONIGHT AND HAVE INTRODUCED  
RAIN AT KSBN BY 06Z...AND AT KFWA BY 09Z. AN ISOLATED THUNDERSTORM  
IS POSSIBLE BUT POINT PROBABILITIES ARE TOO LOW FOR INCLUSION AT  
THIS TIME. DETERIORATING TREND TO MVFR IS EXPECTED TOWARD THE END  
OF THIS PERIOD IN ASSOCIATION WITH PRECIP. SOUTHEAST WINDS TO  
INCREASE IN SPEEDS TODAY AS RIDGE DEPARTS TO THE EAST...WITH SOME  
GUSTS TO 20 TO 25 KNOTS POSSIBLE LATE MORNING INTO THIS AFTERNOON.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
MI...NONE.  
OH...NONE.  
LM...SMALL CRAFT ADVISORY UNTIL 11 PM EDT THIS EVENING FOR LMZ043-046.  
 

 
 

 
 
SYNOPSIS...CEO  
SHORT TERM...AGD  
LONG TERM...MARSILI  
AVIATION...MARSILI  
 
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