132  
FXUS63 KIWX 250556  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
156 AM EDT MON MAY 25 2015  
   
SYNOPSIS
 
 
ISSUED AT 755 PM EDT SUN MAY 24 2015  
 
PRIMARILY PARTLY CLOUDY SKIES AND WARM CONDITIONS ARE EXPECTED  
OVERNIGHT. CONDITIONS WILL BE MAINLY DRY...HOWEVER A SMALL CHANCE  
FOR A SHOWER EXISTS ACROSS NORTHWEST INDIANA AND EXTREME  
SOUTHWEST LOWER MICHIGAN TOWARD DAYBREAK. A FEW MORE SHOWERS AND  
STORMS ARE POSSIBLE MONDAY AND AGAIN LATER THIS WEEK ACROSS THE  
AREA...WITH CONTINUED WARM CONDITIONS THROUGH THE WEEK.  
 

 
   
SHORT TERM
 
(THIS EVENING THROUGH MONDAY)  
ISSUED AT 350 PM EDT SUN MAY 24 2015  
 
MAIN CHALLENGE FOR SHORT TERM PERIOD IS PRECIP POTENTIAL TONIGHT  
AND MONDAY.  
 
AMPLIFIED EASTERN CONUS RIDGING WILL CONTINUE THROUGH MEMORIAL  
DAY. SHARP S/W WILL EJECT NORTHEASTWARD OUT OF BROAD WESTERN  
CONUS TROF LATE TONIGHT TOWARDS THE WESTERN GREAT LAKES ON  
MONDAY. STRENGTHENING LOW LEVEL JET WILL ADVECT INTO THE REGION  
TONIGHT...AND THROUGH THE REGION MONDAY MORNING. THIS WILL BE A  
FOCUS FOR PRECIPITATION POTENTIAL LATE TONIGHT INTO MONDAY  
AFTERNOON.  
 
THIS AFTERNOON INTO EVENING...EXPECT MOST AREAS TO REMAIN  
DRY...HOWEVER KEPT A SLIGHT CHANCE POPS ACROSS FAR NW...AS HI RES  
GUIDANCE SUGGESTS ISOLATED SHOWER/T-STORM DEVELOPMENT TOWARD 00Z  
TONIGHT. MAINLY DRY CONDITIONS ANTICIPATED THROUGH MUCH OF THE  
OVERNIGHT W/ RIDGING HOLDING ACROSS THE REGION. NO MAJOR CHANGES  
TO LOW TEMPS OVERNIGHT.  
 
KEPT POPS IN THE CHANCE RANGE TOMORROW AS SIGNS POINT AGAINST  
MORE WIDESPREAD PRECIPITATION POTENTIAL. MID/UPPER FORCING WILL  
REMAIN WEST/NW OF THE REGION LATE TONIGHT THROUGH TOMORROW.  
ALTHOUGH 925-700MB MOISTURE SLOWLY INCREASES OVER THE NEXT 12-18  
HOURS...MASSIVE DRY SLOT AT 700MB AND ABOVE WILL ROTATE THROUGH  
THE REGION WITH S/W PASSAGE. SLIGHT EML ADVECTION W/ WARM  
NOSE/CAPPING CENTERED BETWEEN 700-600MB PER MODEL SOUNDINGS  
SHOULD KEEP SHOWERS/CONVECTION MORE ISOLATED TO SCATTERED RATHER  
THAN WIDESPREAD. ONCE THIS MIXES OUT LATER IN THE AFTERNOON...LOW  
LVL JET AND UPPER FORCING WILL HAVE EXITED THE REGION...AND MIXED  
BOUNDARY LAYER WILL BE RATHER DRY. FOR WX TYPE...KEPT THUNDER OUT  
OF THE FCST UNTIL AFTER 15Z...WITH JUST A SLIGHT CHANCE OF  
THUNDER FROM 15Z THROUGH 18Z. POPS RAMP DOWN SIGNIFICANTLY FROM  
WEST TO EAST AFTER 18Z WITH DRY SLOT ROTATING THROUGH. KEPT  
TEMPERATURES SIMILAR TO PREVIOUS FCST.  
 

 
   
LONG TERM
 
(MONDAY NIGHT THROUGH SUNDAY)  
ISSUED AT 350 PM EDT SUN MAY 24 2015  
 
PIECEMEAL EJECTION OF LARGE WESTERN CONUS TROUGH WILL BRING  
PERIODIC CHANCES OF RAIN THROUGH WEDNESDAY GIVEN MOIST AND  
MODESTLY UNSTABLE ENVIRONMENT IN PLACE. BEST CHANCES OF RAIN WILL  
LIKELY BE LATE IN THE DAY ON TUESDAY WHEN MOST OF THE LATEST  
GUIDANCE SUGGEST A MORE FORMIDABLE SHORTWAVE VORT WAX WILL LIFT  
THROUGH THE GREAT LAKES. LLJ AND ASSOCIATED MOISTURE TRANSPORT  
INCREASE AHEAD OF THIS WAVE AND DECENT MIDLEVEL CVA/HEIGHT FALLS  
SHOULD PROVIDE ADEQUATE FOCUS FOR SCT-NUM SHOWERS AND  
THUNDERSTORMS...ESPECIALLY IN OUR NORTHWEST. FAVORABLE DIURNAL  
TIMING WILL ALSO ALLOW THIS WAVE TO CAPITALIZE ON SOME MARGINAL  
INSTABILITY. GIVEN THESE FACTORS AND RELATIVELY GOOD AGREEMENT IN  
12Z MODEL SUITE...WENT AHEAD AND BUMPED AFTERNOON POPS INTO  
LIKELY CATEGORY. SEVERE WEATHER RISK APPEARS LOW. 0-6 KM BULK  
SHEAR VALUES WILL BE IN THE 25-30 KT RANGE BUT PALTRY MIDLEVEL  
LAPSE RATES OF 6 C/KM OR LESS ONLY GENERATE AROUND 500 J/KG OF  
0-1KM MLCAPE DESPITE SURFACE DEWPOINTS IN THE MID TO UPPER 60S. A  
FEW STRONG STORMS MAY BE POSSIBLE IF WE CAN GET A LITTLE BETTER  
SURFACE HEATING AND/OR MOISTURE POOLING BUT CHANCES OF WIDESPREAD  
SEVERE WEATHER APPEAR LOW AT THIS POINT.  
 
CHANCES FOR CONVECTION WILL THEN CONTINUE INTO WEDNESDAY BEFORE  
SHORTWAVE RIDGING LEADS TO A MORE SUSTAINED PUSH OF SUBSIDENCE  
AND NEGATIVE THETA-E ADVECTION. DECENT PUSH OF LOW LEVEL  
CONVERGENCE ALONG FRONTAL BOUNDARY BUT MOST OF THE BETTER  
MOISTURE WILL BE STRIPPED AWAY BY THIS POINT. HELD WITH JUST HIGH  
CHANCE POPS FOR NOW. MARGINAL SHEAR/INSTABILITY SUGGEST ANOTHER  
LOW...BUT NOT ZERO...CHANCE FOR SEVERE WEATHER. AFTER A BRIEF  
BREAK ON THURSDAY...CHANCES FOR RAIN RETURN FOR FRIDAY AND THE  
WEEKEND AS A TROUGH PASSING THROUGH ONTARIO SENDS A WEAK FRONT  
INTO THE REGION. POTENTIAL EXISTS FOR THIS FRONT TO STALL  
SOMEWHERE OVER THE OHIO VALLEY BUT DETAILS HIGHLY VARIABLE AT  
THIS POINT AND WILL HOLD WITH JUST BLANKET CHANCE POPS. ABOVE  
AVERAGE TEMPS WILL EVENTUALLY SETTLE LOWER ONCE THIS BOUNDARY  
PASSES BUT EXACT TIMING OF THIS TRANSITION IS UNCERTAIN AND STAYED  
CLOSE TO INITIALIZED CONSENSUS BLEND.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)  
ISSUED AT 154 AM EDT MON MAY 25 2015  
 
PRIMARILY VFR CONDS THIS PD. LLWS CONCERN REMAINS INTACT IN  
DEFERENCE TO LLJ IN PLACE THIS MORNING. OTRWS KEPT VCSH  
MENTION/TIMING INVOF KSBN LTR THIS MORNING UNDER THE ASSUMPTION  
UPSTREAM ACTIVITY ACRS ERN IL HOLDS TOGETHER. OTRWS POOR LL MSTR RTN  
UNDERNEATH ENCROCHING DRYSLOT THIS AFTN OBVIATES ANY FURTHER  
SENSIBLE WX MENTION FOR THE VALID TAF PD.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
MI...BEACH HAZARDS STATEMENT FROM 8 AM EDT THIS MORNING THROUGH THIS  
EVENING FOR MIZ077.  
 
OH...NONE.  
LM...GALE WARNING FROM 10 AM THIS MORNING TO 4 PM EDT THIS AFTERNOON  
FOR LMZ043-046.  
 

 
 

 
 
SYNOPSIS...MURPHY  
SHORT TERM...NG  
LONG TERM...AGD  
AVIATION...T  
 
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