459
FXUS63 KIWX 152206
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
606 PM EDT THU MAY 15 2025
KEY MESSAGES
- STRONG TO SEVERE STORMS ARE LIKELY THIS EVENING INTO THE EARLY
OVERNIGHT (8 PM THROUGH 2 AM EDT). ALL HAZARDS POSSIBLE.
- ANOTHER ROUND OF SHOWERS AND STORMS IS EXPECTED LATE FRIDAY
AFTERNOON INTO FRIDAY EVENING. A FEW STORMS COULD BECOME
SEVERE.
- WARM TEMPERATURES THROUGH FRIDAY WILL GIVE WAY TO COOLER AND
DRIER CONDITIONS THIS WEEKEND.
DISCUSSION
ISSUED AT 218 PM EDT THU MAY 15 2025
HIGH END SEVERE THREAT (ALL HAZARDS) REMAINS IN PLAY THIS EVENING
INTO THE EARLY OVERNIGHT (8P-2A EDT) AS ANY CONVECTION ALONG AN
INCOMING DRYLINE WILL HAVE 35-40 KNOTS OF DEEP LAYER SHEAR AND 2000-
3000 J/KG OF MLCAPE TO WORK WITH. THE LOW LEVEL JET ALSO INCREASES
THIS EVENING WITH 0-3 KM STORM-RELATED HELICITY PUSHING 250-300
M2/S2 FOR A TORNADO THREAT. THERE WILL ALSO BE SUFFICIENT CAPE IN
THE HAIL GROWTH ZONE/EML WITH SUPERCELLS FOR LARGE HAIL, WITH ANY
ORGANIZATION INTO SEGMENTS SUPPORTING A WIND DAMAGE THREAT MID-LATE
EVENING.
EXPECTATIONS ARE STILL FOR CONVECTIVE INITIATION (SCATTERED DISCRETE
SUPERCELLS) IN NE IL BETWEEN 21-00Z, LIKELY CONGEALING INTO
QUASI-LINEAR SEGMENTS OR CLUSTERS WITH EASTWARD PROGRESSION
INTO THE LOCAL AREA THEREAFTER. CAPPING AT THE BASE OF AN EML,
AND MORE FAVORABLE DEEP ASCENT AND LOW LEVEL CONVERGENCE LIFTING
THROUGH WI AND MI, BRINGS INTO QUESTION STORM EVOLUTION/CHANCES
FOR AREAS SOUTH OF THE US 30 CORRIDOR. MUCH HIGHER CONFIDENCE
IN STRONG TO SEVERE STORMS BREAKING THROUGH THE CAP AND TRACKING
EAST THROUGH NORTHERN ZONES AS WEAK HEIGHT FALLS/COOLING ALOFT
CLIPS THE LOWER GREAT LAKES.
DRIER AIR BRIEFLY FILTERS IN BEHIND THE FRONT LATER TONIGHT INTO
MOST OF THE DAY FRIDAY WITH HIGHS ONCE AGAIN WELL INTO THE 80S.
MOISTURE DOES RETURN NORTHWARD LATE FRIDAY INTO FRIDAY EVENING IN
ADVANCE OF A SECONDARY COLD FRONT AND MID LEVEL SHORTWAVE (70-80 KT
500 MB JET) ARRIVING FROM THE MID MS VALLEY. THIS SHOULD BE ENOUGH
TO GENERATE A ROUND OF SHOWERS AND STORMS MAINLY FRIDAY EVENING WITH
DEEP FORCING, MOISTURE QUALITY, AND DEEP LAYER SHEAR MAGNITUDES
FAVORABLE FOR SCATTERED STRONG TO SEVERE STORMS. INSTABILITY
MAGNITUDES ARE LACKING WHEN COMPARED TO THIS EVENING HOWEVER WITH
THE PRIMARY MOISTURE/INSTABILITY RESERVOIR LIKELY SUPPRESSED CLOSER
TO THE OH RIVER. DRY AIR ON LEADING EDGE WITH A SUB-CLOUD INVERTED-V
PROFILE AND HIGH DCAPE VALUES MAY SUPPORT GOOD DOWNDRAFT POTENTIAL
AND LOCALIZED WIND DAMAGE IF MORE ROBUST CELLS DEVELOP, ALONG WITH A
HAIL THREAT GIVEN LINGERING STEEP MID LEVEL RATES.
DRY AND COOLER WEATHER WILL FILTER IN BEHIND FRIDAY NIGHT'S WAVE IN
TIME FOR THE WEEKEND, WITH SATURDAY ALSO BREEZY. RAIN CHANCES
EVENTUALLY RETURN TOWARD THE MIDDLE OF AS THE NEXT WESTERN CONUS
UPPER TROUGH SLOWS OR CUT-OFF OVER THE MIDWEST.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 601 PM EDT THU MAY 15 2025
MINIMAL CHANGES NEEDED FOR THE 00Z TAFS. THE FORECAST IS IN
GREAT SHAPE AS WE CONTINUE TO MONITOR CONVECTION FIRING ACROSS
THE NORTHERN HALF OF ILLINOIS. WE ARE EXPECTING STORMS TO ENTER
INDIANA AROUND 00-01Z TONIGHT AND QUICKLY MOVE
EAST/NORTHEAST. GIVEN MODERATE TO STRONG INSTABILITY AND AMPLE
SHEAR, THESE STORMS WILL LIKELY BE STRONG TO SEVERE WITH A
POTENTIAL OF SOME LARGE HAIL AND THUNDERSTORM WIND GUSTS IN
EXCESS OF 45 TO 50 KNOTS. A FEW TORNADOES ARE ALSO POSSIBLE.
CEILINGS REMAIN VFR FOR NOW BUT WILL LIKELY DROP TO MVFR THIS
EVENING AS CLOUDS INCREASE AND STORMS MOVE THROUGH THE AREA.
THINKING 01-04Z IS THE BEST TIMING FOR STORMS AT KSBN AND 03-05Z
AT KFWA. STORMS DEPART BY 06Z, WITH DECREASING WINDS AND PARTLY
CLOUDY SKIES AHEAD FOR THE OVERNIGHT HOURS. TOMORROW, SOUTHERLY
WINDS WILL ONCE AGAIN INCREASE, WITH GUSTS TO 20 TO 25 KNOTS.
STORMS ARE POSSIBLE FRIDAY AFTERNOON, WITH THE BEST CHANCES
SOUTH OF US 24.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...STEINWEDEL
AVIATION...JOHNSON
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page