355  
FXUS63 KIWX 201658  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
1158 AM EST MON JAN 20 2025  
   
KEY MESSAGES  
 
- THE COLD WEATHER ADVISORY REMAINS IN EFFECT UNTIL 10 AM EST WEDNESDAY  
AREA-WIDE. WIND CHILLS AS LOW AS 25 BELOW ZERO WILL BE  
POSSIBLE.  
 
- ADDITIONAL LAKE EFFECT SNOW ACCUMULATIONS OF UP TO 4 INCHES  
ARE EXPECTED IN SOUTHWEST LOWER MICHIGAN. THE WINTER WEATHER  
ADVISORY FOR BERRIEN AND CASS COUNTIES REMAINS IN EFFECT UNTIL  
7 AM EST MONDAY. THE MORNING AND EVENING COMMUTES MAY BE  
HAZARDOUS.  
 
- MAINLY DRY WITH TEMPERATURES RETURNING TO NEAR NORMAL BY THE END  
OF THE WEEK.  
 
 
   
DISCUSSION  
 
ISSUED AT 244 AM EST MON JAN 20 2025  
 
CLEARING SKIES OVERNIGHT HAVE SET THE STAGE FOR A BITTERLY COLD  
MORNING TO START THE NEW WORK WEEK. EXPECT LOWS THIS MORNING TO BE  
RIGHT AROUND 0 DEGREES, WITH WIND CHILLS 15 TO 20 BELOW ZERO. HIGHS  
ONLY REACH BETWEEN 5 TO 10 DEGREES LATER THIS AFTERNOON AS A LARGE  
AREA OF HIGH PRESSURE DOMINATES OVER THE CENTRAL CONUS. THIS AREA OF  
HIGH PRESSURE IS BRINGING IN COLD AIR ALL THE WAY FROM SIBERIA,  
ALTHOUGH THE AIRMASS SHOULD MODERATE AS IT MAKES ITS WAY TOWARDS OUR  
FORECAST AREA. THANKS TO SNOWMELT EARLIER IN THE WEEK, AIR  
TEMPERATURES AND WIND CHILLS WILL LIKELY BE A BIT 'WARMER' THAN WHAT  
MODELS HAD PREVIOUSLY FORECASTED SEVERAL DAYS AGO AS THE LACK OF  
SNOW ON THE GROUND ALLOWS FOR MORE HEAT TO BE TRANSFERED BETWEEN THE  
GROUND AND THE AIR. NEVERTHELESS, 850 MB TEMPERATURES WILL BE  
BETWEEN 20 TO 25 BELOW ZERO, WITH A BRIEF PERIOD AS LOW AS 30 BELOW  
ZERO ON TUESDAY. AT THE SURFACE, THIS TRANSLATES TO AIR TEMPERATURES  
ONLY AS HIGH AS THE SINGLE DIGITS DURING THE DAY AND BELOW ZERO AT  
NIGHT. AN AREA-WIDE COLD WEATHER ADVISORY REMAINS IN EFFECT THROUGH  
10 AM EST WEDNESDAY FOR WIND CHILLS AS LOW AS 25 BELOW ZERO AT  
TIMES. CLEARING SKIES OVERNIGHT WILL AGAIN ALLOW FOR LOWS IN THE  
SINGLE DIGITS BELOW ZERO TONIGHT AND MONDAY NIGHT (EXCEPT FOR CLOSER  
TO LAKE MICHIGAN WHERE LAKE EFFECT SNOW AND CLOUDS ACT AS A BLANKET  
TO KEEP COLDER WIND CHILLS AT BAY). AS THE AREA OF HIGH PRESSURE  
EXPANDS AND MOVES EAST, IT WILL CENTERED OVER OUR FORECAST AREA BY  
EARLY WEDNESDAY MORNING. REGARDLESS OF WHAT THE WIND CHILLS END UP  
BEING (AS THERE'S NOT MUCH DIFFERENCE BETWEEN -15 AND -25), THIS  
DANGEROUS COLD WILL BE BRUTAL. SEVERAL DAYS OF PROLONGED BITTER COLD  
WILL TAKE A TOLL ON ANYONE OUTDOORS, WITH FROSTBITE POSSIBLE IN AS  
LITTLE AS 30 MINUTES! LIMIT EXPOSURE OUTDOORS AND DRESS IN SEVERAL  
LAYERS TO STAY WARM.  
 
CURRENT RADAR IMAGERY SHOWS LAKE EFFECT SNOW SHOWERS ACROSS  
SOUTHWEST LOWER MICHIGAN AND NORTH OF THE TOLL ROAD IN ST JOSEPH AND  
ELKHART COUNTIES. LOW LEVEL WINDS ARE CONVERGING, WITH A FEW  
DOMINANT BANDS OF HEAVIER LAKE EFFECT SNOW, ESPECIALLY ACROSS  
SOUTHERN BERRIEN COUNTY. DECENT LAPSE RATES AND MOISTURE, AS WELL AS  
INVERSION HEIGHTS AROUND 6-7 KFT SHOULD ALLOW FOR LAKE EFFECT SNOW  
TO PERSIST TODAY, ALTHOUGH SUBTLE SHIFTS IN THE BANDS MAY ALLOW FOR  
ACCUMULATIONS TO VARY WIDELY OVER SOUTHWEST LOWER MICHIGAN. THE  
WINTER WEATHER ADVISORY REMAINS IN EFFECT FOR BERRIEN AND CASS  
COUNTIES IN MICHIGAN WHERE UP TO 4 INCHES OF ADDITIONAL SNOW  
ACCUMULATION IS EXPECTED THROUGH TUESDAY MORNING. IN SOUTHWEST LOWER  
MICHIGAN, REDUCED VISIBILITIES ARE EXPECTED AND TRAVEL WILL BE  
HAZARDOUS TODAY, ESPECIALLY ALONG THE I-94 CORRIDOR. GUSTY WEST  
WINDS OF 20 TO 25 MPH WILL ALSO LEAD TO SOME BLOWING SNOW. HI RES  
MODEL GUIDANCE DEPICTS THAT AS THE WINDS SHIFT TO BECOME MORE WEST-  
SOUTHWEST AND A RIDGE BUILDS TO THE SOUTHEAST OF OUR FORECAST AREA,  
THE LAKE EFFECT SNOW BANDS WILL FINALLY SHIFT OUT OF OUR AREA BY  
TUESDAY. THE ONLY CHANGE MADE TO THE WINTER WEATHER ADVISORY WAS TO  
EXTEND IT UNTIL 7 AM EST TUESDAY TO ACCOUNT FOR A LONGER DURATION OF  
LAKE EFFECT SNOW. THE ADVISORY MAY NEED TO BE EXTENDED FURTHER  
INTO TUESDAY IN THE NEXT FORECAST UPDATE.  
 
TEMPERATURES WILL BEGIN TO WARM UP BACK TOWARDS SEASONABLE LEVELS  
(BUT STILL BELOW FREEZING) BY MID TO LATE NEXT WEEK. AS THE ARCTIC  
AIR AND HIGH PRESSURE SYSTEM EXIT TO THE EAST, IT COULD BE WINDY AT  
TIMES ON WEDNESDAY AND THURSDAY WITH A STRONG PRESSURE GRADIENT  
ACROSS OUR FORECAST AREA. HAVE KEPT SLIGHT CHANCE POPS IN FOR  
THURSDAY WITH MODELS SUGGESTING A CLIPPER-TYPE SYSTEM COULD SWEEP  
THROUGH THE AREA. THE LATEST LONG RANGE GUIDANCE FAVORS NEAR NORMAL  
TEMPERATURES AND A MOSTLY DRY PATTERN FOR THE END OF NEXT WEEK AND  
INTO NEXT WEEKEND. IT IS POSSIBLE HIGHS GET TO ABOVE FREEZING ON  
SUNDAY AND NEXT MONDAY.  
 
 
   
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/  
 
ISSUED AT 1149 AM EST MON JAN 20 2025  
 
WINDS HAVE BACKED ENOUGH OVER NORTHWEST INDIANA TO ALLOW LAKE  
CLOUDS AND SNOW SHOWERS TO MOVE NORTH OF THE SBN TERMINAL. TO  
THE SOUTH, A LARGE HIGH PRESSURE AREA HAD SETTLED OVER KY. THE  
FLOW NORTH OF THIS SYSTEM WAS KEEPING BRISK WINDS OVER NORTHERN  
INDIANA. WINDS SOUTHWEST TO WEST SHOULD PREVAIL THROUGH THE END  
OF THE TAF PERIOD. THE AIRMASS APPEARS TOO DRY TO SUPPORT ANY  
CLOUDS, SO HAVE KEPT VFR CONDITIONS WITH CLEAR SKIES AND  
UNRESTRICTED VISIBILITIES.  
 
 
   
IWX WATCHES/WARNINGS/ADVISORIES  
 
IN...COLD WEATHER ADVISORY UNTIL 10 AM EST /9 AM CST/ WEDNESDAY FOR  
INZ005>009-012>015-017-018-020-022>027-032>034-103-104-  
116-203-204-216.  
OH...COLD WEATHER ADVISORY UNTIL 10 AM EST WEDNESDAY FOR OHZ001-002-  
004-005-015-016-024-025.  
MI...COLD WEATHER ADVISORY UNTIL 10 AM EST WEDNESDAY FOR MIZ078>081-  
177-277.  
WINTER WEATHER ADVISORY UNTIL 7 AM EST TUESDAY FOR MIZ078-177-  
277.  
MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST TUESDAY FOR LMZ043-046.  
HEAVY FREEZING SPRAY WARNING UNTIL 5 PM EST TUESDAY FOR LMZ043-  
046.  
 
 
 
 
 
DISCUSSION...JOHNSON  
AVIATION...SKIPPER  
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