474
FXUS63 KIWX 101723
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
1223 PM EST FRI JAN 10 2025
KEY MESSAGES
- SNOW ARRIVES FROM WEST TO EAST STARTING MID MORNING. 2 TO 4
INCHES IS EXPECTED. THE EVENING COMMUTE WILL BE IMPACTED.
- LAKE EFFECT SNOW TONIGHT THROUGH SATURDAY MORNING.
- VERY COLD EARLY NEXT WEEK WITH BELOW-ZERO WIND CHILLS AND
ADDITIONAL CHANCES FOR SNOW.
DISCUSSION
ISSUED AT 320 AM EST FRI JAN 10 2025
THE WINTER WEATHER FORECAST FOR TODAY REMAINS ON TRACK WITH
WIDESPREAD 2 TO 4 INCHES OF SNOW EXPECTED. THE WINTER WEATHER
ADVISORY WAS A BYPRODUCT OF NEIGHBORING OFFICES HOISTING ADVISORIES.
THE MORNING COMMUTE WILL NOT BE IMPACTED. HOWEVER, ANTICIPATE A SLOW
EVENING COMMUTE. SNOW BEGINS MID MORNING TOWARD MICHIANA AND ENDS
AFTER THE EVENING RUSH. TOWARD NORTHWEST OHIO, SNOW BEGINS ON EITHER
SIDE OF NOON, TAPERING OFF NEAR MIDNIGHT.
A POSITIVE-TILTED TROUGH IS EXITING THE DAKOTAS THIS MORNING WHILE A
SECOND, DEEPER, TROUGH IS EJECTING NORTHEAST OUT OF TEXAS. UPPER-
LEVEL CONVERGENCE IS SPILLING OVER THE MID-MISSISSIPPI VALLEY
ALLOWING RADAR RETURNS TO BLOSSOM THERE. THE 500-MB JET IS
FORECAST TO AMPLIFY OVER THE TENNESSEE RIVER VALLEY THIS
AFTERNOON AND WILL BE THE PRIMARY DRIVER OF OUR SNOW TODAY. DEW
POINTS CURRENTLY IN THE SINGLE-DIGITS NEED TO BE OVERCOME. AMID
THIS BUCKED JET STREAM, MOISTURE ADVECTION IS POSITIVE AS NOTED
BY DEW POINTS IN THE MID-TO- UPPER TEENS FROM CHICAGO SOUTHWARD.
TIME HEIGHT CROSS SECTIONS INDICATE FAVORABLE FRONTOGENESIS BY
LATE MORNING WHICH WILL WORK TO OVERCOME WHAT SHALLOW WEDGE OF
DRY AIR REMAINS.
JUST AS THIS SNOW TAPERS OFF, THE LAGGING DAKOTAS TROUGH RACES
THROUGH AFTER SUNSET AND PROVIDES ANOTHER PERIOD OF LIGHT SNOW.
BECAUSE OF ITS SWIFT FORWARD PACE, THIS TROUGH WILL BRING
LITTLE ADDITIONAL ACCUMULATION BUT BREEZY CONDITIONS WILL
DEVELOP TONIGHT AS WILL LAKE EFFECT. WIND GUSTS WILL BE FROM THE
WEST AT ABOUT 20 MPH.
BEYOND THIS BUSY 24 HOUR PERIOD, AN ACTIVE UPPER-AIR PATTERN BRING
MULTIPLE DISTURBANCES THROUGH THE REGION. CLIPPER SYSTEMS, LAKE
EFFECT SNOW AND ARCTIC AIR ARE ALL EXPECTED IN THE DAYS AHEAD. FIRST,
FREEZING DRIZZLE WAS ADDED TO THE FORECAST SUNDAY AS THE NEXT LOW
PRESSURE SYSTEM MOVES OVER THE GREAT LAKES. WHILE THE THERMAL
PROFILE OVERALL IS SUPPORTIVE OF SNOW, DEEP SATURATION IS SLOW TO
OCCUR. AS A RESULT, THE LOW-LEVEL SATURATES BELOW THE DGZ FAVORING
FREEZING DRIZZLE. THROUGH THE DAY, A TRANSITION TO SNOW IS EXPECTED.
THIS WILL NEED TO BE MONITORED CLOSELY.
THEN, AN ARCTIC FRONT RACES IN MONDAY NIGHT AND TUESDAY MORNING
BRINGING ANOTHER CHANCE FOR LIGHT SNOW FOLLOWED BY BITTER COLD.
WIND CHILLS TUESDAY AND WEDNESDAY MORNING WILL BE BELOW ZERO.
AVIATION /18Z TAFS THROUGH 18Z SATURDAY/
ISSUED AT 1217 PM EST FRI JAN 10 2025
HAVE TRIED TO CAPTURE TRENDS IN THE NEW TAFS, BUT THE BATTLE
BETWEEN THE SNOW AND DRY LOW LEVELS IS RESULTING IN CHALLENGING
FLIGHT CONDITIONS OVER THE NEXT 12 HOURS OR SO. LIGHT SNOW HAS
BEEN FALLING FOR A FEW HOURS AT KSBN WITH MAIN IMPACTS BEING
LOWER VSBY (AT TIMES IFR) MAINLY DUE TO FINER FLAKE SIZE. CIGS
HAVE BEEN SLOW TO LOWER, BUT SHOULD CATCH UP OVER THE NEXT
COUPLE OF HOURS WITH OVERALL IFR CONDITIONS PERSISTING INTO THE
EVENING. AFTER 4Z, THE BACK EDGE OF THE SNOW SHOULD SHIFT EAST
WITH A MVFR CIG LEFT IN PLACE FOR THE REST OF THE PERIOD.
AT KFWA, DRY AIR IS WINNING, RESULTING IN A SIG DELAY IN THE
ONSET OF FLIGHT IMPACTS. THE SNOW SHOULD QUICKLY FILL IN OVER
THE NEXT SEVERAL HOURS, LIKELY IMPACTING VSBY MORE THAN CIGS TO
START AS WAS THE CASE AT KSBN. THE SNOW WILL LINGER INTO THE
EVENING BEFORE QUICKLY ENDING BEFORE 6Z.
IWX WATCHES/WARNINGS/ADVISORIES
IN...WINTER WEATHER ADVISORY UNTIL 1 AM EST /MIDNIGHT CST/ SATURDAY
FOR INZ005>009-012>015-017-018-020-022>027-032>034-103-
104-116-203-204-216.
OH...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR OHZ001-002-
004-005-015-016-024-025.
MI...WINTER WEATHER ADVISORY UNTIL 1 AM EST SATURDAY FOR MIZ078>081-
177-277.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...FISHER
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