995  
FXUS63 KIWX 131724  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
1224 PM EST MON JAN 13 2025  
   
KEY MESSAGES
 
 
- BREEZY AND COLD TODAY. WESTERLY WIND GUSTS OF 20 TO 25 MPH  
AND HIGH TEMPERATURES ONLY NEAR 20.  
 
- VERY COLD TONIGHT THROUGH THURSDAY MORNING WITH BELOW ZERO  
WIND CHILLS OUTSIDE OF LAKE EFFECT CLOUDS.  
 
- PERIODS OF LAKE EFFECT SNOW FOR SOUTHWEST MICHIGAN THROUGH  
THURSDAY.  
 

 
   
DISCUSSION
 
 
ISSUED AT 249 AM EST MON JAN 13 2025  
 
BLUSTERY CONDITIONS IN THE VICINITY OF THE A COLD FRONT THAT PASSED  
THROUGH EARLY THIS MORNING ARE EASING. BUT, THE PRESSURE  
GRADIENT NEVER FULLY RELAXES SUCH THAT WESTERLY WIND GUSTS OF  
20 TO 25 MPH ARE EXPECTED. SKIES ARE GRADUALLY CLEARING OUTSIDE  
OF THE WESTERLY LAKE EFFECT BELT ALLOWING TEMPERATURES TO FALL  
INTO THE TEENS. LAKE EFFECT IS ONGOING JUST NORTH OF BERRIEN  
COUNTY WHERE THE LAKE FETCH IS A LITTLE BETTER. DRY AIR AND  
STIFF WEST WIND TODAY WILL LIMIT LAKE EFFECT ACCUMULATION TO  
LESS THAN 1 INCH. SNOW SHOWERS COULD SPILL AS FAR SOUTH AS THE  
IN TOLL ROAD.  
 
UPSTREAM, THE UPPER-LOW SCHEDULE TO PROVIDE A REINFORCING BLAST  
OF ARCTIC AIR IS DIGGING INTO MINNESOTA. THIS ARRIVES BY  
DAYBREAK TUESDAY BRINGING A QUICK DOSE OF SYNOPTIC SNOW TO  
CENTRAL INDIANA AND REINVIGORATES LAKE EFFECT. HIGH RESOLUTION  
GUIDANCE FAVORS NO-SNOW WITH THE INCOMING CLIPPER WHILE GLOBAL  
MODELS CONTINUE TO ADVERTISE SNOW ACROSS CENTRAL INDIANA.  
PATTERN RECOGNITION SUGGESTS IT'S WORTHWHILE TO RETAIN A SNOW  
MENTION TUESDAY. BUT, BASED ON THE LATEST TRAJECTORY THROUGH THE  
CENTRAL PART OF INDIANA, I HAVE REDUCED POPS LOCALLY. LAKE  
EFFECT WILL REJUVENATE AS THIS UPPER-LOW AND ARCTIC FRONT MOVE  
THROUGH. THIS ACTIVITY IS THEN UNDERCUT BY HIGH PRESSURE  
WEDNESDAY MORNING.  
 
AS MENTIONED IN THIS SPACE, WIND CHILLS BOTTOM OUT TUESDAY  
MORNING THROUGH THURSDAY MORNING WITH WIND CHILLS OF 0 TO 10  
BELOW OUTSIDE OF LAKE EFFECT CLOUDS.  
 
WE'LL THAW OUT FRIDAY AND SATURDAY WITH HIGHS IN THE MID-TO-UPPER  
30S THANKS TO A BUILDING SOUTHEAST RIDGE. A MIX OF RAIN AND SNOW  
OCCURS DURING THIS TIME, CERTAINLY MAKING FOR SLOPPY CONDITIONS  
WHERE SNOWPACK REMAINS. BITTER COLD AGAIN STARTING SUNDAY INTO  
NEXT WEEK. GUIDANCE HAS SOME ABSOLUTELY FRIGID 850MB TEMPERATURES;  
8 TO 10C COLDER THAN THIS FIRST ARCTIC BLAST. ENSEMBLE  
FORECASTS INDICATE THERE IS A 50-70% PROBABILITY OF SINGLE-  
DIGIT TEMPERATURES AT TIMES MONDAY THROUGH WEDNESDAY OF NEXT  
WEEK.  
 

 
   
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
 
 
ISSUED AT 1216 PM EST MON JAN 13 2025  
 
GENERAL MVFR FLIGHT RULE THIS PERIOD. LAKE STRATOCU PLUME  
PERSISTS OFF LAKE MICHIGAN INVOF KSBN AND JUST ENOUGH MOISTURE  
DEPTH WITHIN SHALLOW POST ARCTIC BOUNDARY TO SUPPORT LIGHT SNOW  
WHICH SHOULD PERSIST FOR ANOTHER HOUR OR TWO BEFORE MORE  
VIGOROUS DRY ENTRAINMENT OCCURS. OTHERWISE VEERING TO WRLY LOW  
LEVEL FLOW THROUGH THIS AFTN EXPECTED TO ALLOW LAKE CLOUD PLUME  
TO EDGE SOUTH FOR A TIME INTO THE KFWA VCNTY LATE DAY.  
 
UPSTREAM DISTURBANCE OVER NRN MN WILL SWING ACROSS THE TERMINALS  
TUE MORNING WITH A PERIOD OF LIGHT SNOW AND IFR CONDITIONS FOR A  
TIME. SOME UNCERTAINTY/SPREAD IN ARRIVAL TIME AND GIVEN LATE  
PERIOD TIMING WILL AWAIT LATER GUIDANCE BEFORE INCLUSION.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...NONE.  
OH...NONE.  
MI...NONE.  
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EST WEDNESDAY FOR LMZ043-046.  
 

 
 

 
 
DISCUSSION...BROWN  
AVIATION...T  
 
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