638
FXUS63 KIWX 150644
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
244 AM EDT FRI MAY 15 2026
KEY MESSAGES
- A WARMING TREND STARTS TODAY WITH HIGHS IN THE UPPER 60S TO
LOW 70S. HIGHS IN THE LOW 80S SATURDAY THEN MID TO UPPER 80S
SUNDAY THROUGH TUESDAY.
- 20-30% CHANCES FOR LIGHT RAIN SHOWERS TODAY SOUTH OF US 24.
- INCREASING HUMIDITY AND MOISTURE THROUGH THE WEEKEND ALLOW FOR
DAILY PERIODIC RAIN AND STORM CHANCES.
- STRONG TO SEVERE STORMS POSSIBLE SATURDAY AND AGAIN MONDAY.
DISCUSSION
ISSUED AT 244 AM EDT FRI MAY 15 2026
INFRARED SATELLITE IMAGERY SHOWS HIGH LEVEL CLOUDS BUILDING IN THIS
MORNING AHEAD OF LOW CHANCES FOR LIGHT RAIN SHOWERS TODAY. A
DECAYING COMPLEX OF SHOWERS AND STORMS COMING OUT OF MISSOURI AND
ILLINOIS AIDED BY AN INCOMING WEAK 500MB SHORTWAVE WILL LEAD TO
20- 30% CHANCES FOR LIGHT RAIN MAINLY SOUTH OF US 24 LATER THIS
MORNING AND EARLY AFTERNOON. A WARMING TREND BEGINS TODAY AND
CONTINUES INTO THE WEEKEND. SOUTHERLY WINDS RAMP UP ALONGSIDE
DIURNAL HEATING WITH GUSTS AS HIGH AS 25 TO 30 MPH. ALTHOUGH
SKIES WILL BE PARTLY TO MOSTLY CLOUDY TODAY, SOUTHERLY WINDS AND
MODEST WAA WILL LEAD TO HIGHS IN THE UPPER 60S TO LOW 70S BY
THE AFTERNOON.
A STRONGER 500MB SHORTWAVE MOVES IN SATURDAY MORNING AND AS A WARM
FRONT LIFTS NORTHWARD ACROSS THE AREA, MOISTURE AND INSTABILITY WILL
INCREASE. SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP, SOME OF
WHICH MAY BE STRONG TO SEVERE. THERE IS A MARGINAL RISK (LEVEL 1 OF
5) FOR SEVERE WEATHER ON SATURDAY. A GULF CONNECTION STARTS TO
DEVELOP SATURDAY WITH SOUTHERLY WINDS. HIGHS IN THE UPPER 70S TO LOW
80S AND DEWPOINTS RISING TO AROUND 60 WILL PROVIDE AN INCREASINGLY
FAVORABLE ENVIRONMENT FOR MARGINALLY SEVERE STORMS. SHOULD ANY
STRONG TO SEVERE STORMS DEVELOP, THE MAIN THREAT WILL BE DAMAGING
WIND GUSTS AS MUCAPE INCREASES TO 1000-2000 J/KG THROUGHOUT THE DAY.
WINDS PARALLEL TO THE WARM FRONT COULD ALSO YIELD BACKBUILDING OR
TRAINING ALONGSIDE POTENTIAL FOR HEAVY RAINFALL IN ANY STORMS.
WHILE DAILY PERIODIC CHANCES FOR RAIN AND STORMS EXIST THROUGH EARLY
NEXT WEEK, SUNDAY HAS THE LOWEST CHANCES. AS THE WARM FRONT LIFTS
NORTHWARD, IT MAY STALL NEAR OR JUST NORTH OF THE INDIANA-MICHIGAN
STATE LINE AND COULD SPARK A FEW ISOLATED STORMS SUNDAY IN THE
VICINITY OF I-80/I-90 (20-30% CHANCES). MUCAPE WILL BE 1000-2000
J/KG ONCE AGAIN DURING PEAK HEATING WITH AROUND 30 KTS OF BULK
SHEAR. HIGHS CLIMB INTO THE LOW TO MID 80S WITH SOUTHWEST WINDS
PULLING IN MORE MOISTURE INTO THE OHIO RIVER VALLEY AND UPPER GREAT
LAKES REGIONS.
MUCH BETTER SURGES OF MOISTURE ARRIVE MONDAY WITH DEWPOINTS INTO THE
UPPER 60S AND PWATS OF 1.5" TO 2". OUR FORECAST AREA WILL BE WELL
INTO THE WARM SECTOR BY MONDAY WITH BREEZY SOUTHERLY WINDS ALLOWING
FOR A STRENGTHENING GULF CONNECTION. SCATTERED STRONG TO SEVERE
THUNDERSTORMS MAY DEVELOP, ESPECIALLY IN THE EVENING INTO THE EARLY
OVERNIGHT HOURS. FORECAST SOUNDINGS SHOW ~40 KTS OF BULK SHEAR AS
THE LLJ RAMPS UP IN THE EVENING. SPC CURRENTLY HAS OUR AREA IN A 15%
SLIGHT RISK ON MONDAY, ALTHOUGH CONSIDERABLE SPREAD IN MODEL
GUIDANCE AND UNCERTAINTY REMAINS. SBCAPE OF 1500-2000 J/KG WILL BE
PRESENT DURING PEAK HEATING, ALTHOUGH THERE IS UNCERTAINTY IN HOW
MUCH AND HOW QUICKLY IT COULD WANE. ADDITIONALLY, MEAGER LOW TO MID
LEVEL LAPSE RATES MONDAY EVENING AREN'T AS FAVORABLE FOR SEVERE
WEATHER. WITH A COLD FRONT LAGGING UNTIL TUESDAY TO SWEEP THROUGH,
LIFT MAY ALSO BE A LIMITING FACTOR.
DEPENDING ON WHAT HAPPENS MONDAY AND HOW MUCH THE ATMOSPHERE CAN
RECOVER TUESDAY, THE COLD FRONTAL PASSAGE THEN MAY ALSO SPARK
ANOTHER OPPORTUNITY FOR STRONG TO SEVERE STORMS. THE TIMING OF
THE COLD FRONT IS UNCERTAIN AND SIGNIFICANT SPREAD IN MODEL
GUIDANCE EXISTS IN TEMPERATURES ON TUESDAY. COOLER, DRIER
WEATHER FOLLOWS MIDWEEK IN THE WAKE OF THE COLD FRONTAL PASSAGE.
AVIATION /06Z TAFS THROUGH 06Z SATURDAY/
ISSUED AT 113 AM EDT FRI MAY 15 2026
WINDS REMAIN LIGHT AND VARIABLE AS HIGH PRESSURE SLOWLY DRIFTS
EASTWARD. INFRARED SATELLITE IMAGERY SHOWS HIGH LEVEL CLOUDS
DRIFTING IN FROM THE WEST AHEAD OF A WEAK UPPER LEVEL
DISTURBANCE THAT WILL BRING LIGHT RAIN SHOWERS MAINLY SOUTH OF
US 24 TODAY. ALTHOUGH ADDITIONAL MID AND HIGH LEVEL CLOUDS WILL
BUILD IN THROUGHOUT THE MORNING, KSBN AND KFWA ARE EXPECTED TO
REMAIN DRY WITH VFR CEILINGS THROUGHOUT THE TAF FORECAST PERIOD.
SOUTHERLY WINDS WILL RAMP UP IN ACCORDANCE WITH DIURNAL
HEATING; BY MIDDAY INTO THE AFTERNOON, EXPECT SOUTHWEST WINDS TO
BE SUSTAINED AROUND 12 KTS WITH GUSTS AS HIGH AS 20-25 KTS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...JOHNSON
AVIATION...JOHNSON
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