269
FXUS63 KIWX 192207
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
607 PM EDT SUN APR 19 2026
KEY MESSAGES
- FREEZE CONDITIONS EXPECTED TONIGHT WITH LOWS FROM MID 20S TO
AROUND 30.
- LOW CHANCES OF RAIN RETURN FOR TUESDAY NIGHT BUT ONLY LIGHT
PRECIPITATION AMOUNTS ARE EXPECTED WHICH WILL NOT HAVE A
SIGNIFICANT IMPACT ON FLOODING CONCERNS.
- AFTER A COOL START TO THE WEEK, TEMPERATURES TREND WARMER
STARTING TUESDAY.
DISCUSSION
ISSUED AT 244 PM EDT SUN APR 19 2026
WATER VAPOR IMAGERY THIS AFTERNOON DEPICTS A STRONG UPPER LEVEL VORT
MAX DROPPING SOUTHEAST ACROSS THE WESTERN GREAT LAKES. LOW LEVELS
HAVE MIXED OUT NICELY IN ADVANCE OF THIS FEATURE WITH DEW POINTS
BOTTOMING OUT TO AROUND 20 DEGREES IN SPOTS. THESE LOW LEVEL DEW
POINT TRENDS SHOULD MAKE INSTABILITY A BIT MORE OF A STRUGGLE WITH
MAX SFC BASED CAPES EXPECTED AROUND 100 J/KG FOR A FEW HOURS THIS
AFTERNOON. DESPITE LIMITED INSTABILITY, WOULD EXPECT A FEW HIGHER
BASED SHOWERS TO DEVELOP GIVEN STRENGTH OF MID/UPPER LEVEL FORCING
AND A STRONG MID LEVEL COLD POOL (-18 TO 20 DEG C AT 700 MB). SOME
ENHANCEMENT TO FRONTAL CONVERGENCE WITH FLOW OFF LAKE MICHIGAN COULD
HELP INITIATE THESE SHOWERS, AND THESE LOW RAIN CHANCES SHOULD BE
PROGRESSIVE FROM WEST TO EAST FOLLOWING THE STRONGER VORTICITY
ADVECTION WITH THE UPPER TROUGH. GIVEN LARGE DEW POINT DEPRESSIONS,
ANY RAINFALL AMOUNTS WILL BE LIGHT.
SOME LOW CLOUDS MAY LINGER INTO THIS EVENING DOWNWIND OF LAKE
MICHIGAN WITH SOME WEAK LAKE RESPONSE POSSIBLE, BUT OTHERWISE
CLEARING SKIES ARE EXPECTED AS A BROAD LOW LEVEL ANTICYCLONE
EVENTUALLY SHIFTS ACROSS THE REGION OVERNIGHT. THE ORIENTATION
OF THE LOW LEVEL THERMAL TROUGH FROM SOUTHEAST CANADA INTO THE
EASTERN GREAT LAKES AND PORTIONS OF THE OHIO VALLEY STILL
SUGGESTS COLDEST MINS IN MID 20S ACROSS SOUTH CENTRAL LOWER
MICHIGAN INTO FAR NORTHWEST OHIO. CONFIDENCE IS STILL ON THE
HIGH SIDE THAT ALL AREAS SHOULD BE BELOW FREEZING FOR MINS
TONIGHT, SO NO CHANGES PLANNED TO THE FREEZE WARNING AT THIS
TIME.
MONDAY WILL BE A QUIET TRANSITION AS SOUTHERN GREAT LAKES/OHIO
VALLEY BECOME POSITIONED IN UPPER LEVEL INFLECTION ZONE BETWEEN
EASTERN CONUS TROUGH/WESTERN CONUS RIDGE. BROAD SYNOPTIC SCALE
SUBSIDENCE IN THIS PATTERN WILL PROVIDE MOSTLY CLEAR SKIES WITH
BELOW NORMAL TEMPERATURES CONTINUING. SOME PATCHY FROST IS POSSIBLE
AGAIN MONDAY NIGHT ACROSS THE FAR EAST, BUT GIVEN DEPARTURE OF LOW
LEVEL RIDGE AXIS, LOW LEVEL GRADIENT SHOULD BE STRONG ENOUGH DURING
THE OVERNIGHT HOURS INTO TUESDAY MORNING TO LIMIT THIS POTENTIAL.
TUESDAY WILL FEATURE A BETTER MIXING DAY AS LOW LEVEL SOUTHWEST FLOW
INCREASES DOWNSTREAM OF A WEAK, LOW AMPLITUDE NORTHWEST FLOW
SHORT WAVE TROUGH AND THE LOW LEVEL RIDGE AXIS SHIFTS OFF THE
MID ATLANTIC COAST. BREEZY/WINDY CONDITIONS ARE EXPECTED ON
TUESDAY AND DEEP MIXING COMBINED WITH STRONGER WAA SHOULD LEAD
TO ABOVE NORMAL TEMPS BACK INTO LOW-MID 70S FOR MOST LOCATIONS.
A SOUTHWARD SAGGING FRONTAL BOUNDARY TUESDAY NIGHT AND SOME
POOLING OF MOISTURE IN PRE-FRONTAL ZONE SHOULD LEAD TO SOME
LIGHT RAIN SHOWERS SHIFTING NORTH TO SOUTH ACROSS THE AREA
TUESDAY EVENING, BUT PRECIP AMOUNTS SHOULD BE LESS THAN ONE
QUARTER OF AN INCH.
FOR THE REMAINDER OF THE WORK WEEK, MEDIUM RANGE GUIDANCE DOES
SUGGEST MORE SIGNIFICANT WESTERN CONUS TROUGHING DEVELOPING BUT
THIS WILL OCCUR IN THE BACKDROP OF A SOMEWHAT STABLE LONGWAVE
PATTERN WITH ONLY A SLOW EASTERN PROGRESSION OF CENTRAL CONUS
UPPER RIDGE. THIS EVOLUTION SHOULD KEEP PRIMARY
MOISTURE/INSTABILITY AXIS WEST OF THE LOCAL AREA ON THURSDAY
WITH LIKELY COLD FRONTAL PASSAGE AS SYSTEM OCCLUDES WELL TO THE
NORTHWEST ACROSS NORTHERN PLAINS/SOUTH CENTRAL CANADA. RAIN
SHOWERS AND PERHAPS A FEW STORMS MAY ACCOMPANY THIS FRONT. MUCH
ABOVE NORMAL TEMPS THURSDAY AND FRIDAY WILL GIVE WAY TO MORE
SEASONABLE TEMPERATURES BY EARLY NEXT WEEKEND.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 607 PM EDT SUN APR 19 2026
SHOWERS AND GUSTY NW WINDS ASSOCIATED WITH A POTENT UPPER LEVEL
VORT MAX WILL TAPER OFF NEAR ISSUANCE TIME. VFR/DRY WITH WINDS
BECOMES LIGHT AND VARIABLE OTHERWISE TONIGHT INTO MONDAY AS
SURFACE HIGH PRESSURE BUILDS IN.
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...NONE.
DISCUSSION...MARSILI
AVIATION...STEINWEDEL
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