769  
FXUS63 KIWX 181021  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
621 AM EDT FRI SEP 18 2020  
   
SYNOPSIS
 
 
ISSUED AT 249 AM EDT FRI SEP 18 2020  
 
MUCH COLDER TEMPERATURES WILL BE FELT INTO THE WEEKEND WITH  
TEMPERATURES MUCH BELOW NORMAL. HIGHS TODAY WILL ONLY BE IN THE  
60S, AND LOWS TONIGHT WILL FALL INTO THE 30S, WITH POTENTIAL  
FROST. TEMPERATURES WILL START TO REBOUND ON SUNDAY, AND WARM  
THROUGH MID-WEEK. THE NEXT CHANCE FOR RAIN WILL BE THURSDAY.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 249 AM EDT FRI SEP 18 2020  
 
COLD UPPER LEVEL TROUGHING AND SURFACE HIGH PRESSURE WILL KEEP THE  
AREA COOL YET DRY TODAY, WITH HIGHS ONLY IN THE MID 60S. WINDS  
WILL BE NORTHEAST AND SLIGHTLY BREEZY, BUT WILL DIMINISH TO AROUND  
5 MPH AFTER SUNSET. THESE LIGHT WINDS AND CLEAR SKIES WILL COMBINE  
TO PRODUCE GOOD RADIATIONAL COOLING CONDITIONS, AND TEMPERATURES  
ARE EXPECTED TO FALL INTO THE 30S ACROSS THE FORECAST AREA. FROST  
WILL THEREFORE BE POSSIBLE, ESPECIALLY TO THE NORTHEAST, AND A  
FROST ADVISORY IS BEING ISSUED FOR LATE TONIGHT INTO SATURDAY  
MORNING.  
 

 
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 249 AM EDT FRI SEP 18 2020  
 
UPPER TROUGHING WILL START TO SHIFT EAST ON SATURDAY, AND HIGH  
PRESSURE RIDGING WILL BUILD IN FROM THE SOUTHWEST GOING INTO THE  
FIRST PART OF NEXT WEEK. TEMPERATURES WILL GRADUALLY WARM DURING  
THIS PERIOD, GETTING INTO THE UPPER 70S TO NEAR 80 BY WEDNESDAY,  
WITH DRY CONDITIONS PERSISTING. TROUGHING RETURNS ON THURSDAY  
WITH MODELS BRINGING A SHORTWAVE INTO THE REGION. THERE IS STILL A  
LOT OF UNCERTAINTY THOUGH WITH MODEL DIFFERENCES IN LOCATION AND  
AMOUNT OF MOISTURE. DECIDED TO KEEP THE SLIGHT CHANCE OF SHOWERS  
SUPPORTED BY THE NBM AND CANADIAN, ALTHOUGH THIS MAY END UP BEING  
ANOTHER MOSTLY DRY FRONT.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)  
ISSUED AT 614 AM EDT FRI SEP 18 2020  
 
THERE IS LITTLE CHANGE TO THE TAFS FOR THIS ISSUANCE. WINDS PICK  
UP A BIT AT SBN LATER THIS MORNING. VFR THROUGH THE TAF PERIOD  
WITH HIGH PRESSURE IN PLACE.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...FROST ADVISORY FROM 2 AM EDT /1 AM CDT/ TO 9 AM EDT /8 AM CDT/  
SATURDAY FOR INZ003>009-012>018-020-022>027-032>034.  
 
BEACH HAZARDS STATEMENT UNTIL 3 PM CDT THIS AFTERNOON FOR INZ003.  
 
MI...FROST ADVISORY FROM 2 AM TO 9 AM EDT SATURDAY FOR MIZ077>081.  
 
BEACH HAZARDS STATEMENT UNTIL 8 AM EDT THIS MORNING FOR MIZ077.  
 
OH...FROST ADVISORY FROM 2 AM TO 9 AM EDT SATURDAY FOR OHZ001-002-004-  
005-015-016-024-025.  
 
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LMZ046.  
 

 
 

 
 
SYNOPSIS...COBB  
SHORT TERM...COBB  
LONG TERM...COBB  
AVIATION...BROWN  
 
VISIT US AT WWW.WEATHER.GOV/IWX  
 
FOLLOW US ON FACEBOOK...TWITTER...AND YOUTUBE AT:  
WWW.FACEBOOK.COM/NWSNORTHERNINDIANA  
WWW.TWITTER.COM/NWSIWX  
WWW.YOUTUBE.COM/NWSNORTHERNINDIANA  
 
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