458
FXUS63 KIWX 191736
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
136 PM EDT SUN APR 19 2026
KEY MESSAGES
- FREEZE CONDITIONS EXPECTED TONIGHT.
- BREEZY WITH SCATTERED RAIN SHOWERS THIS AFTERNOON.
- AFTER A COOL START TO THE WEEK, TEMPERATURES TREND WARMER
STARTING TUESDAY.
DISCUSSION
ISSUED AT 134 AM EDT SUN APR 19 2026
SKIES ARE GRADUALLY CLEARING ALONG THE I-69 CORRIDOR EARLY THIS
MORNING AS YESTERDAY'S COLD FRONT CONTINUES TO TRACK SLOWLY EAST.
TEMPERATURES HAVE REMAINED SOMEWHAT ELEVATED (LOW-40S) THANKS TO
STEADY NORTHWEST WIND DUE TO A DECENT PRESSURE GRADIENT FROM THE
DEPARTING LOW. THESE WINDS DIMINISH THROUGH THE MORNING AND
THERE MAY STILL BE ENOUGH TIME FOR AT LEAST PATCHY FROST TO
DEVELOP. DEW POINTS IN THE LOW-20S THIS HOUR SUGGEST A QUICK
DROP OF TEMPERATURES ARE FAVORED ONCE WINDS ABATE.
NEW FOR THIS FORECAST PACKAGE IS THE INCLUSION OF SCATTERED SHOWERS
THIS AFTERNOON. A COMPACT, MID-LEVEL WAVE IS EXITING THE DAKOTAS
THIS MORNING. STRONG UPPER-LEVEL SUPPORT, MODEST MOISTURE PROFILES
AND NON-ZERO INSTABILITY POINT TO DIURNALLY-DRIVEN RAIN SHOWERS
AS THIS WAVE MOVES THROUGH. WITH THE FREEZING LEVEL NEAR 3,000
FT AND - 10C AROUND 6,000 FT, CANNOT RULE OUT GRAUPEL FROM THE
STRONGEST (TALLEST) SHOWERS THIS AFTERNOON. THIS ACTIVITY WILL
DIMINISH WITH SUNSET. OTHERWISE TODAY, BREEZY AND COOL WITH
NORTHWEST WIND GUSTS NEAR 30MPH AND HIGH TEMPERATURES STRUGGLING
TO REACH 50 DEGREES ALONG AND NORTH OF US 30.
THE EARLY MONDAY MORNING FREEZE WATCH HAS BEEN UPGRADED TO FREEZE
WARNING. HIGH PRESSURE BECOMES CENTERED OVER NORTHERN ILLINOIS WITH
850-MB TEMPERATURES OF -10C NOTED, GOOD FOR WIDESPREAD LOWS NEAR
30; CLOSER TO 25 NEAR HILLSDALE, MI. WITH HIGH PRESSURE OVERHEAD,
THIS MAKES HIGH TEMPERATURES MONDAY THE COOLEST OF THE WEEK AS
HIGHS HARDLY REACH 50 DEGREES AREA WIDE.
A TROUGH ARRIVING ONSHORE TO THE WEST COAST SHUNTS HIGH PRESSURE
EAST BY TUESDAY. THE RESULT IS A RAPID WARM UP FOR THE MIDWEEK
PERIOD AS AN UPPER-LEVEL RIDGE DEVELOPS OVER THE CENTRAL US AND
EVENTUALLY SPREADS OVER THE MIDWEST. RAIN CHANCES THIS WEEK ARE
LIMITED TO A 20- 30% CHANCE TUESDAY NIGHT COURTESY OF SHORTWAVE
ALOFT, AND A 60% CHANCE ON FRIDAY THANKS TO A COLD FRONT.
AVIATION /18Z TAFS THROUGH 18Z MONDAY/
ISSUED AT 130 PM EDT SUN APR 19 2026
A STRONG UPPER VORT LOBE WILL DROP ACROSS THE REGION THIS
AFTERNOON. GOOD LOW LEVEL MIXING AND DRY AIRMASS HAS LED TO SFC
DEW POINTS BOTTOMING OUT THIS AFTERNOON. THIS SHOULD LIMIT
STRENGTH OF SURFACE BASED INSTABILITY. GIVEN STRENGTH OF VORT
LOBE AND STRONG MID LEVEL COLD POOL WOULD STILL EXPECT
ISOLATED-SCATTERED SHOWERS TO PROGRESS THROUGH NORTHEAST INDIANA
BUT WILL BE SHORT-LIVED IF THEY OCCUR AND IN A BRIEF TEMPORAL
WINDOW FROM 19Z TO 23Z. WINDS WILL RELAX THIS EVENING WITH LOSS
OF BOUNDARY LAYER MIXING, EVENTUALLY BECOMING LIGHT AND
VARIABLE AS A BROAD LOW LEVEL ANTICYCLONE DROPS ACROSS THE GREAT
LAKES AND OHIO VALLEY.
IWX WATCHES/WARNINGS/ADVISORIES
IN...FREEZE WARNING FROM MIDNIGHT EDT /11 PM CDT/ TONIGHT TO 11 AM
EDT /10 AM CDT/ MONDAY FOR INZ005>009-012>015-017-018-020-
022>027-032>034-103-104-116-203-204-216.
OH...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 11 AM EDT MONDAY FOR
OHZ001-002-004-005-015-016-024-025.
MI...FREEZE WARNING FROM MIDNIGHT TONIGHT TO 11 AM EDT MONDAY FOR
MIZ078>081-177-277.
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR LMZ043-
046.
DISCUSSION...BROWN
AVIATION...MARSILI
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