870  
FXUS63 KIWX 190737  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
337 AM EDT TUE MAR 19 2019  
   
SYNOPSIS
 
 
ISSUED AT 337 AM EDT TUE MAR 19 2019  
 
ANOTHER QUIET DAY WITH HIGHS IN THE UPPER 40S UNDER PARTLY CLOUDY  
SKIES. LIGHT RAIN IS EXPECTED ON WEDNESDAY BUT DRY CONDITIONS RETURN  
FOR THE REST OF THE WEEK WITH TEMPERATURES SLOWLY CLIMBING THROUGH  
THE WEEKEND.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 337 AM EDT TUE MAR 19 2019  
 
ANOTHER QUIET WEATHER DAY ON TAP AS CONFLUENT W/NW FLOW ALOFT  
MAINTAINS GENERAL SUBSIDENCE AND SURFACE HIGH PRESSURE OVER A LARGE  
SECTION OF THE EASTERN CONUS. THERE WILL STILL BE A FAIR AMOUNT  
OF CLOUDS AS LOW LEVEL FLOW BACKS LATER IN THE DAY AND WARM/MOIST  
AIR ADVECTION INCREASES STRATOCU POTENTIAL. SATELLITE IMAGERY ALSO  
SHOWS A PLETHORA OF UPPER LEVEL CLOUDS FROM PV ANOMALY WELL  
UPSTREAM AND THESE HIGHER-BASED CLOUDS WILL PASS THROUGH OUR AREA  
TODAY. SOME SUN EXPECTED AT TIMES BUT ANTICIPATE PARTLY CLOUDY  
SKIES FOR MUCH OF THE DAY. DESPITE THE CLOUD COVER...SLOW BUT  
STEADY WAA (850MB TEMPS CLIMBING NEAR -5C) SHOULD PUSH HIGHS INTO  
THE UPPER 40S BY LATE IN THE DAY. FORECAST SOUNDINGS ALSO CONSISTENT  
IN SHOWING MIXING DEPTHS OF 5-6 KFT THIS AFTERNOON...AIDING DIURNAL  
TEMP RISE. NEXT SYSTEM APPROACHES LATE TONIGHT AND CARRIED SOME LOW  
CHANCE POPS IN THE FAR WEST BUT BULK OF THE EVENT WILL BE AFTER 12Z  
WED. INCREASING CLOUDS AND SOUTHERLY WINDS WILL LEAD TO A MILDER  
NIGHT WITH LOWS AT OR JUST ABOVE THE FREEZING MARK.  
 

 
   
LONG TERM
 
(WEDNESDAY THROUGH MONDAY)  
ISSUED AT 337 AM EDT TUE MAR 19 2019  
 
A FAIRLY COMPLICATED PATTERN EVOLUTION FOR WED...THOUGH RESULTANT  
SENSIBLE WEATHER IS NOT VERY IMPACTFUL. ROBUST SHORTWAVE CURRENTLY  
DIVING THROUGH THE NORTHERN PLAINS WILL EVENTUALLY ROUND THE BASE OF  
THE LONGWAVE TROUGH AND PHASE WITH SECONDARY JET STREAK/VORT MAX  
DIVING DUE SOUTH OUT OF NUNAVUT AND INTO THE GREAT LAKES. NET RESULT  
IS A FAIRLY HEALTHY LOCAL INCREASE OF 285-290K ISENTROPIC ASCENT  
WED. GRADIENT TIGHTENING AHEAD OF CONVERGENT BOUNDARY YIELDS 50 KT  
LLJ ORIENTED PERPENDICULAR TO (SOMEWHAT) TIGHTLY PACKED ISOBARS.  
THIS ALSO PUSHES MIXING RATIOS NEAR 4 G/KG IN THAT LAYER. SOUNDINGS  
SUGGEST NOT QUITE ENOUGH LOW LEVEL MOISTURE ADVECTION TO GENERATE  
ANY ELEVATED CAPE/THUNDER BUT STABILITY IS CERTAINLY REDUCED. THIS  
WILL SUPPORT A WIDESPREAD LIGHT RAIN EVENT WED. OUTSIDE CHANCE OF A  
FEW SNOWFLAKES AT THE VERY ONSET BUT HARDLY EVEN WORTH MENTIONING AS  
WAA AND DIURNAL CLIMB QUICKLY PUSH SURFACE WET BULB TEMPS WELL ABOVE  
FREEZING. BULK OF OUR PRECIP WILL BE DRIVEN BY ISENTROPIC ASCENT/  
THETA-E ADVECTION BUT CHANCE FOR SCT SHOWERS WILL CONTINUE INTO WED  
NIGHT WITH PASSAGE OF STRONG MIDLEVEL VORT MAX AND ASSOCIATED COLD  
FRONT. ONCE AGAIN A VERY LOW CHANCE OF A FEW WET SNOWFLAKES WITH WED  
NIGHT SHOWERS BUT CERTAINLY NO ACCUMULATION OR IMPACTS.  
 
THU-SAT PERIOD STILL LOOKING QUIET. FLOW BECOMES ALMOST DUE  
NORTHERLY DURING THE PERIOD AND WILL MAINTAIN COOL CONDITIONS. SOME  
POTENTIAL FOR PRECIP THU NIGHT WITH ANOTHER WAVE DIVING SOUTH  
THROUGH THE GREAT LAKES BUT CURRENT TRACK (AS SUGGESTED BY 00Z  
DETERMINISTIC SUITE) WOULD KEEP BEST CVA TO OUR NE. WILL CONTINUE  
WITH DRY FORECAST BUT KEEP AN EYE OUT FOR POSSIBLE TRACK SHIFTS.  
SOUTHWEST FLOW RETURNS SUN WITH A BRIEF WARMUP AND RAIN CHANCES INTO  
MONDAY. HOWEVER...LATEST GUIDANCE NOW SUGGESTS A QUICK EXIT OF  
REMNANT UPPER LOW TO OUR SOUTH WITH STRONG HIGH PRESSURE BUILDING  
OVER THE GREAT LAKES. THIS WOULD YIELD A RETURN TO DRY (AND COOL)  
CONDITIONS BY TUE/WED OF NEXT WEEK.  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)  
ISSUED AT 133 AM EDT TUE MAR 19 2019  
 
A QUIET AVIATION WEATHER PERIOD WILL BE IN STORE FOR THE NEXT 24  
HOURS. AN EXITING WEAK SHORT WAVE ACROSS NORTHWEST OHIO SHOULD  
KEEP MOST OF VFR LOW CLOUDS EAST OF TERMINALS OVERNIGHT, WITH  
MAINLY JUST CIRRUS OVERSPREADING TERMINALS THROUGH DAYBREAK. VERY  
LOW END PROBABILITY MAY EXIST FOR PATCHY SHALLOW FOG THIS MORNING,  
BUT WILL CONTINUE TO OMIT FROM FORECAST DUE TO LOW CONFIDENCE.  
SCT-BKN DIURNAL VFR CU IS EXPECTED TO DEVELOP AGAIN THIS  
AFTERNOON. STRONGER SHORT WAVE IS EXPECTED TO BRING SOME LIGHT  
RAIN SHOWERS BACK TO NORTHERN INDIANA WELL AFTER THIS FORECAST  
VALID PERIOD BY WEDNESDAY MORNING. WINDS TO REMAIN LIGHT THROUGH  
THIS PERIOD, WITH SOUTHWEST WINDS OF AROUND 10 KNOTS THIS  
AFTERNOON DURING PEAK MIXING.  
 

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

 
 

 
 
SYNOPSIS...AGD  
SHORT TERM...AGD  
LONG TERM...AGD  
AVIATION...MARSILI  
 
VISIT US AT WWW.WEATHER.GOV/IWX  
 
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WWW.TWITTER.COM/NWSIWX  
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA  
 
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