350
FXUS63 KIWX 191324
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
924 AM EDT SUN APR 19 2026
KEY MESSAGES
- FROST AND FREEZE CONDITIONS THIS MORNING AND AGAIN MONDAY
MORNING.
- BREEZY WITH SCATTERED RAIN SHOWERS THIS AFTERNOON. A FEW RAIN
SHOWERS MAY BRING SOME GUSTS OF 30 TO 40 MPH.
- AFTER A COOL START TO THE WEEK, TEMPERATURES TREND WARMER
STARTING TUESDAY.
UPDATE
ISSUED AT 918 AM EDT SUN APR 19 2026
THE FROST ADVISORY HAS BEEN EXPIRED THIS MORNING AS SOUTHWEST
WINDS IN ADVANCE OF NEXT SFC TROUGH IS PROVIDING VERY BRIEF,
WEAK WARM ADVECTION. AN IMPRESSIVE WATER VAPOR PRESENTATION TO
THE NEXT UPSTREAM VORT MAX IS NOTED THIS MORNING ACROSS SE
MN/WESTERN WI, WHICH WILL DROP SOUTHEAST ACROSS THE SOUTHERN
GREAT LAKES DURING PEAK HEATING THIS AFTERNOON. DESPITE DRY
SFC/LOW LEVELS AND TEMPS ONLY MAXING UP IN THE UPPER 40S TO
AROUND 50, TIMING OF THIS VORT MAX DURING PEAK HEATING AND A
STRONG COLD POOL ALOFT WILL DRIVE DIURNALLY DRIVEN RAIN SHOWERS.
STRENGTH OF THIS COLD POOL COULD SUPPORT 100-200 J/KG OF
SURFACE BASED CAPE FOR A BRIEF TIME THIS AFTERNOON. DEPENDING ON
EXTENT OF LOW LEVEL DEW POINT DEPRESSIONS, SOME GRAUPEL IS
POSSIBLE IN ASSOCIATION WITH THE STRONGER RAIN SHOWERS OR EVEN A
FEW GUSTS INTO THE 30 TO 40 MPH RANGE DUE TO EVAPORATIVE
COOLING PROCESSES. KEPT THUNDER OUT OF THE FORECAST BUT AN
ISOLATED THUNDERSTORM WOULD NOT BE OUT OF THE QUESTION,
PARTICULARLY FAR NORTH/NORTHEAST WHERE MID LEVEL COLD POOL
STRENGTH IS THE GREATEST.
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 /12Z TAFS THROUGH 12Z MONDAY/
ISSUED AT 618 AM EDT SUN APR 19 2026
COMPLETED SOME FINE-TUNING OF THE TAFS WITH THIS ISSUANCE,
PRIMARILY AT KSBN. A COMPACT WAVE CONTINUES TO TRACK OUT OF THE
NORTHERN PLAINS, NOW SPREADING THROUGH MINNESOTA. UPSTREAM
OBSERVATIONS SHOW POCKETS OF MVFR CONDITIONS WITH SNOW (WE'LL
SEE RAIN). TIME OF ARRIVAL TO KSBN AND KFWA APPEARS ON TRACK.
BREEZY TODAY WITH WIND BECOMING NORTHWESTERLY. LIGHT WIND
OVERNIGHT AS HIGH PRESSURE ARRIVES.
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.
UPDATE...MARSILI
DISCUSSION...BROWN
AVIATION...BROWN
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