358  
FXUS63 KIWX 191437  
AFDIWX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE NORTHERN INDIANA  
937 AM EST SAT JAN 19 2019  
   
SYNOPSIS
 
 
ISSUED AT 404 AM EST SAT JAN 19 2019  
 
HAZARDOUS WINTER WEATHER IS EXPECTED TODAY, WITH WIDESPREAD SNOW  
BECOMING MODERATE TO HEAVY AT TIMES. WIND GUSTS UP TO 30 TO 35 MPH  
ARE EXPECTED, LEADING TO BLOWING AND DRIFTING SNOW. HIGHS WILL BE IN  
THE 20S. LOWS TONIGHT WILL DROP INTO THE SINGLE DIGITS, WITH WIND  
CHILLS AS COLD AS 10 BELOW ZERO. EXPECT MOSTLY CLOUDY SKIES WITH  
HIGHS IN THE TEENS SUNDAY, WITH A CHANCE FOR LAKE EFFECT IN FAR  
NORTHWESTERN INDIANA.  
 

 
   
UPDATE
 
 
ISSUED AT 927 AM EST SAT JAN 19 2019  
 
SOME MINOR CHANGES WILL BE MADE TO WSW THIS MORNING. SOME FREEZING  
RAIN HAS BEEN REPORTED ACROSS EXTREME NORTHEAST INDIANA/NORTHWEST  
OHIO THIS MORNING WITH INITIAL SATURATION ISSUES AT TEMPERATURES  
COLD ENOUGH TO SUPPORT SNOW PRODUCTION. BETTER MOISTURE WILL  
OVERSPREAD THESE AREAS OVER NEXT FEW HOURS THAT WOULD SUPPORT MORE  
SNOW PRECIP TYPES, ALTHOUGH SOME CONCERN THAT WARM LAYER ADVECTING  
NORTHEASTWARD COULD SUPPORT ADDITIONAL SLEET/FREEZING RAIN  
ACROSS THESE LOCATIONS. WILL ADD SOME ICE ACCUMULATION TO FAR  
SOUTHEAST/EAST ZONES WITH THE WSW UPDATE. HAVE ALSO NUDGED  
QPF/SNOW AMOUNTS UP SLIGHTLY ACROSS EASTERN HALF OF THE AREA THIS  
AFTERNOON WITH SUPPORT FROM LATEST NEAR TERM HRRR/NAM GUIDANCE.  
INTERACTIONS OF NORTHERN/SOUTHERN STREAM WAVE SHOULD PROMOTE  
INCREASED LOW/MID LEVEL FGEN FORCING THIS AFTERNOON PARTICULARLY  
SOUTHEAST HALF OF THE FORECAST AREA. REGIONAL RADAR MOSAIC APPEARS  
TO ALREADY INDICATE THE BEGINNINGS OF THIS RESPONSE FROM EAST  
CENTRAL ILLINOIS INTO WEST CENTRAL INDIANA. IT STILL APPEARS AS  
THOUGH A PERIOD OF STRONG WIND GUSTS TO 35 MPH (PERHAPS GREATER)  
IS POSSIBLE ACROSS THE SOUTHEAST LATER THIS AFTERNOON INTO TONIGHT  
WHICH WILL CREATE CONSIDERABLE TRAVEL DIFFICULTIES. ONLY OTHER  
CHANGE WILL BE SLIGHT ALTERATIONS IN ENDING TIMES OF WINTER STORM  
WARNING TO LATER EXPIRATIONS, PARTICULARLY ACROSS THE FAR  
SOUTHEAST ZONE WHERE STRONGER WINDS AND BLOWING AND DRIFTING SNOW  
WILL BE A CONCERN POSSIBLY INTO THE OVERNIGHT HOURS. UPDATED WSW  
WILL BE SENT BY 15Z.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 404 AM EST SAT JAN 19 2019  
 
NO CHANGES TO WINTER STORM HEADLINES THIS MORNING. IT APPEARS  
HEADLINES ARE ON TRACK, AGAIN WITH THE FOCUS ON THE WIND AND SNOW  
COMBINATION VERSUS SOLELY SNOW AMOUNTS. THE FIRST PORTION OF THE  
FORECAST HAS WORKED OUT (KNOCK ON WOOD), WITH THE SNOW ASSOCIATED  
WITH THE MID-UPPER LEVEL FGEN SITUATED NORTH OF I 80-90. SO FAR  
WE'VE RECEIVED REPORTS BETWEEN 1-2 INCHES ASSOCIATED WITH THIS.  
WINDS HAVE ALSO PICKED UP TO AROUND 10-15KTS ACROSS THE CWA.  
 
OTHERWISE, SNOW ASSOCIATED WITH OUR SOUTHERN STREAM SYSTEM IS  
CONTINUING NORTHWARD, AND WILL OVERSPREAD THE AREA THROUGH THE  
MORNING AND AFTERNOON HOURS. MODELS CONTINUE TO SHOW THE  
STRENGTHENING DEFORMATION FORCING THIS AFTERNOON, AND THINK THIS IS  
REASONABLE BASED ON WHAT WE'RE SEEING THIS MORNING. WIND GUSTS WILL  
STRENGTHEN INTO THE 25 TO 35 MPH RANGE, SO ONCE WE GET ADDITIONAL  
SNOW ACCUMULATIONS WE'LL SEE THE BLOWING AND DRIFTING BECOME MORE OF  
AN ISSUE FOR TRAVEL.  
 
MUCH COLDER AIR FILTERS IN BEHIND OUR WINTER STORM, WHICH EXITS THE  
FAR SOUTHEASTERN CWA BY LATE THIS EVENING. EXPECT MAYBE AN INCH OF  
ADDITIONAL ACCUMULATION IN THE SOUTHEAST, WITH PARTLY TO MOSTLY  
CLOUDY SKIES ELSEWHERE. MODELS SUGGEST 850MB TEMPS DROPPING TO  
AROUND -15C, AND WITH SOME BRIEF CLEARING IN THE WAKE OF THE LOW,  
EXPECT LOW TEMPS INTO THE SINGLE DIGITS BY EARLY SUNDAY MORNING.  
WIND CHILLS WILL RANGE FROM 0 TO 10 BELOW.  
 

 
   
LONG TERM
 
(SUNDAY THROUGH FRIDAY)  
ISSUED AT 404 AM EST SAT JAN 19 2019  
 
ON SUNDAY HIGH PRESSURE EXPANDS OVER MUCH OF THE GREAT LAKES REGION,  
BUILDING TO AROUND 1039 HPA. WITH NORTHEAST FLOW ACROSS LAKE  
MICHIGAN AND LINGERING MOISTURE EXPECT OUR TRADITIONAL LAKE EFFECT  
BAND TO DEVELOP ALONG THE LONG AXIS OF THE LAKE, IMPACTING THE  
CHICAGO AND FAR NW INDIANA LOCATIONS DURING THE EARLY PART OF THE  
DAY. THE UPPER LEVEL LOW OVER SOUTHERN ONTARIO AND QUEBEC WILL DROP  
ONE LAST VORT LOBE OVER THE REGION BY LATE SUNDAY AFTERNOON AND  
EVENING, WHICH WILL BRING THE LAKE EFFECT POTENTIAL INTO OUR AREA.  
GUIDANCE APPEARS TO BE TRYING TO DEVELOP A MESOLOW AT THE SOUTHERN  
END OF THE LAKE, WHICH WOULDN'T BE TOTALLY UNREASONABLE GIVEN THE  
WIND DIRECTION/WEAK SYNOPTIC SUPPORT. MOISTURE IS LIMITED HOWEVER,  
SO DON'T EXPECT TOO MUCH IN THE WAY OF ACCUMULATIONS. HAVE LOWER  
CONFIDENCE WITH RESPECT TO HOW FAR EASTWARD THE BAND/MESOLOW WILL  
DRIFT AT THIS POINT TOO, SO JUST KEPT LOW CHANCE POPS IN FROM SUNDAY  
AFTERNOON INTO THE EVENING HOURS. WITH 850HPA TEMPS AROUND -20C AND  
MOSTLY CLOUDY SKIES, DON'T EXPECT HIGHS TO REACH BEYOND THE TEENS,  
WITH WIND CHILLS IN THE SINGLE DIGITS ABOVE ZERO DURING THE  
AFTERNOON.  
 
THE REAL HORROR WILL TAKE PLACE AS SKIES CLEAR OUT SUNDAY NIGHT INTO  
MONDAY MORNING AWAY FROM LAKE MICHIGAN: WITH A FRESH SNOWPACK AND  
LIGHT WINDS BENEATH HIGH PRESSURE, EXPECT THAT IT WILL GET  
EXTRAORDINARILY COLD. LOW TEMPERATURES BY MONDAY MORNING WILL DROP  
INTO THE SINGLE DIGITS BELOW ZERO, WITH SOME PLACES IN NW OHIO  
AROUND -8F. WINDS WILL BE LIGHT, BUT COULD BE ENOUGH TO BRING WIND  
CHILLS INTO THE -10 TO -15F RANGE. EVEN WITH PARTLY CLOUDY SKIES  
DURING THE DAY ON MONDAY, HIGHS WILL PROBABLY ONLY RANGE FROM 10-16F  
BY THE AFTERNOON (WIND CHILLS AROUND OR JUST BELOW ZERO). MONDAY  
NIGHT LOWS WILL FALL INTO THE SINGLE DIGITS AND LOW TEENS, WITH WIND  
CHILLS FROM 0 TO 10 BELOW (COLDEST EAST OF I 69). CONDITIONS WILL  
REMAIN DRY THROUGH EARLY TUESDAY MORNING.  
 
OUR NEXT PRECIPITATION CHANCES ARRIVE TUESDAY AFTERNOON INTO  
WEDNESDAY EVENING AS A LOW PRESSURE SYSTEM LIFTS FROM THE CENTRAL  
PLAINS INTO THE GREAT LAKES REGION. MODELS APPEAR TO BE CLOSE IN  
TERMS OF THE TIMING OF PRECIPITATION, THOUGH THEY VARY GREATLY IN  
THE INTENSITY OF THE SYSTEM (GFS HAS 1003HPA, ECMWF HAS 1010 HPA.  
NATURALLY THIS BRINGS SOME DISAGREEMENT AS FAR AS THE OVERALL QPF  
AMOUNTS/LOCATIONS GO. THE GOOD NEWS IS THAT 850HPA TEMPS CLIMB TO  
AROUND 2-3C SO WE START TO SEE HIGHS IN THE MID-UPPER 30S TUESDAY  
AFTERNOON. THIS WILL GIVE US A RAIN/SNOW MIX DURING THE AFTERNOON  
AND EVENING HOURS TUESDAY BEFORE SHIFTING BACK TO SNOW OVERNIGHT.  
THERE MAY BE A LITTLE LAKE EFFECT DURING THE AFTERNOON WEDNESDAY  
BEFORE SUBSIDENCE AND A LACK OF MOISTURE PUT AN END TO IT.  
OTHERWISE, EXPECT DWINDLING SNOW CHANCES IN THE SOUTHEAST ASSOCIATED  
WITH THE EXITING SYSTEM. HIGHS WILL BE IN THE UPPER 20S AND 30S.  
 
WEDNESDAY NIGHT INTO THURSDAY EVENING WILL MOST LIKELY BE DRY, WITH  
OUR CWA UNDER A MINI-RIDGE OF HIGH PRESSURE BETWEEN A STRONGER LOW  
LIFTING ALONG THE EASTERN SEABOARD AND A WEAKER LOW DRIFTING ACROSS  
UPPER MICHIGAN. THERE IS A CHANCE WE COULD SEE SOME PRECIPITATION  
ACROSS OUR SOUTHEAST BUT CONFIDENCE IN THIS OCCURRING IS LOW. HIGHS  
WILL BE IN THE UPPER 20S UNDER MOSTLY CLOUDY SKIES.  
 
THURSDAY NIGHT INTO FRIDAY THE EAST COAST LOW LIFTS INTO QUEBEC,  
PHASING WITH THE WEAKER LOW OVER UPPER MICHIGAN ALONG THE WAY. THIS  
MAKES FOR AN INTERESTING FORECAST, WITH SYNOPTIC SNOW POTENTIAL  
INITIALLY THURSDAY NIGHT INTO FRIDAY MORNING, THEN TRANSITIONING TO  
MORE OF A LAKE EFFECT SNOW FOR FRIDAY AFTERNOON. THE UPPER LEVEL LOW  
SITUATED OVER JAMES BAY WILL BRING ANOTHER TROUGH (OR SURFACE LOW,  
DEPENDING ON YOUR FAVORITE MODEL) THROUGH FRIDAY NIGHT INTO  
SATURDAY, WITH POTENTIAL FOR 850HPA TEMPS TO DROP TO -20 TO EVEN  
-25C BY SATURDAY NIGHT...POTENTIALLY WORSENING SUNDAY INTO MONDAY.  
LONG STORY SHORT, IT LOOKS LIKE WE'LL SEE ANOTHER SHOT OF VERY COLD  
AIR TOWARDS THE END OF THE LONG TERM PERIOD.  
 

 
   
AVIATION
 
(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING)  
ISSUED AT 600 AM EST SAT JAN 19 2019  
 
STRONG LOW LEVEL WARM ADVECTION/MOISTURE PUSH UNDERWAY THIS HOUR  
CORRESPONDING TO MAXIMIZING ISENTROPIC LIFT AHEAD OF BIFURCATED  
UPPER TROUGH AXIS PROGRESSING OUT OF IL. WEDGE OF LOW LEVEL DRY AIR  
GIVING WAY TO RAPID SATURATION AND ACCUMULATING SNOW WITH  
ENHANCEMENT NOTED IN REF DATA SHOWING SNOW RETURNS > 30 DBZ. THUS  
EXPECT RAPID DETERIORATION THROUGH DAYBREAK IN BOTH VSBY AND CIG  
HEIGHTS AS MOD-HVY SNOW BLOSSOMS FOR A TIME. PREDOMINATE IFR WITH  
POCKETS OF LIFR THROUGH NOON INVOF KSBN AND THROUGH ABOUT 21Z INVOF  
KFWA. OTHERWISE WINDS WILL GRADUALLY ESCALATE THROUGH THE DAY,  
PEAKING LATE THIS AFTN AND EVENING WITH N-NERLY GUSTS AOA 30KTS AT  
KFWA WHERE ISALLOBARIC PUSH IS LARGEST.  
 
SOME UPTICKING IMPROVEMENT IN FLIGHT CONDITIONS EXPECTED OVERNIGHT  
WITH MVFR AND DIMINISHING WINDS.  
 

 
   
IWX WATCHES/WARNINGS/ADVISORIES
 
 
IN...WINTER STORM WARNING UNTIL 4 AM EST SUNDAY FOR INZ026-027-  
032>034.  
 
WINTER STORM WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR  
INZ008-009-012>018-020-022>025.  
 
WINTER STORM WARNING UNTIL 4 PM EST /3 PM CST/ THIS AFTERNOON  
FOR INZ003>007.  
 
MI...WINTER STORM WARNING UNTIL 4 PM EST THIS AFTERNOON FOR  
MIZ077>081.  
 
OH...WINTER STORM WARNING UNTIL 4 AM EST SUNDAY FOR OHZ016-024-025.  
 
WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR OHZ001-002-  
004-005-015.  
 
LM...SMALL CRAFT ADVISORY UNTIL 4 PM EST SUNDAY FOR LMZ043-046.  
 

 
 

 
 
UPDATE...MARSILI  
SYNOPSIS...MCD  
SHORT TERM...MCD  
LONG TERM...MCD  
AVIATION...T  
 
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