718
FXUS63 KIWX 160600
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
200 AM EDT SUN AUG 16 2026
KEY MESSAGES
- THUNDERSTORMS ARE LIKELY THIS MORNING. THE SEVERE RISK IS VERY
LOW BUT ISOLATED GUSTY WINDS AND BRIEF HEAVY RAIN ARE
POSSIBLE. A FLOOD WATCH REMAINS IN EFFECT UNTIL 11AM EDT FOR
AREAS SOUTH OF US-30.
- ADDITIONAL STORMS ARE POSSIBLE THIS AFTERNOON AND EVENING BUT
COVERAGE WILL REMAIN LOW. A FEW STRONG STORMS CAPABLE OF GUSTY
WINDS MAY BE POSSIBLE SOUTH OF US-24.
- MONDAY AND TUESDAY WILL BE DRY BUT ADDITIONAL RAIN IS EXPECTED
TUESDAY NIGHT INTO WEDNESDAY. THE RISK FOR HEAVY RAIN AND
SEVERE WEATHER CURRENTLY APPEARS LOW.
DISCUSSION
ISSUED AT 200 AM EDT SUN AUG 16 2026
LATEST WATER VAPOR IMAGERY SHOWS ONE MORE POTENT MCV EJECTING OUT OF
IOWA EARLY THIS MORNING. REGIONAL RADAR MOSAIC CURRENTLY SHOWS A
BOWING SEGMENT BUT MESOANALYSIS INDICATES VERY LIMITED SHEAR AND
THEREFORE UNLIKELY TO POSE A SEVERE RISK. ONCE AGAIN OUR CURRENT
ENVIRONMENT IS VERY STABLE BUT ANOTHER ROUND OF STRENGTHENING
NOCTURNAL LLJ WILL ADVECT HIGHER THETA-E AIR BACK INTO THE AREA EARLY
THIS MORNING. THIS SHOULD SUPPORT AT LEAST SOME ELEVATED CONVECTION
ROUGHLY 08-15Z THIS MORNING. CONVECTION WILL LIKELY TEND TO OUTPACE
BETTER SURFACE-BASED INSTABILITY BUT THERE'S AT LEAST SOME LOW
CHANCES THAT A SLIGHTLY LATER PASSAGE COULD ALLOW SOME DIURNAL
CONTRIBUTION IN THE 14-17Z TIMEFRAME THAT WOULD YIELD A GUSTY WIND
THREAT FOR OUR FAR E/NE COUNTIES. THIS IS SUGGESTED BY SOME RUNS OF
THE HRRR BUT STILL THINK IT WILL BE DIFFICULT TO GET SUFFICIENT
INSTABILITY THAT FAR NE THAT EARLY TO SUPPORT SEVERE STORMS. AS FOR
THE HYDRO THREAT...BEST OVERALL RAIN CHANCES LOOK TO BE IN OUR
NORTHERN CWA AND STORMS WILL LIKELY BE MUCH MORE PROGRESSIVE AND
SCATTERED THAN IN RECENT DAYS DUE TO THE CURRENT SYNOPTIC SETUP. THE
THREAT OF TRUE "HEAVY" RAIN IS VERY LOW BUT SUSCEPTIBILITY TO EVEN
MODERATE RAIN IN OUR SOUTHERN CWA IS STILL HIGH. GIVEN THIS AND SOME
LINGERING UNCERTAINTY ON WHERE EXACTLY STORMS TRACK LATER THIS
MORNING PLAN TO JUST LET THE EXISTING FLOOD WATCH RIDE FOR NOW.
ATTENTION THIS AFTERNOON AND EVENING THEN TURNS TO VERY BROAD/
DIFFUSE COLD FRONTAL PASSAGE. AMPLE LOW LEVEL MOISTURE AND SOME
STEEPENING MIDLEVEL LAPSE RATES GENERATE OVER 2000 J/KG OF SBCAPE IN
OUR SOUTHERN ZONES THIS AFTERNOON AND 25-30KTS OF DEEP-LAYER SHEAR
WOULD SUGGEST A THREAT FOR ORGANIZED CONVECTION. THE PROBLEM IS THE
FORCING IS JUST VERY WEAK. WE ACTUALLY HAVE SOME SHORTWAVE RIDGING
IN THE WAKE OF THIS MORNING MCV THAT PERSISTS WELL INTO THE EVENING
AND LOW LEVEL CONVERGENCE IS VIRTUALLY NIL. HI-RES CAM'S
SUBSEQUENTLY SHOW VERY ISOLATED CONVECTION THIS AFTERNOON AND
EVENING. CAN'T ENTIRELY RULE OUT A STRAY STRONG STORM IN OUR
SOUTH GIVEN THE INSTABILITY AND SHEAR PARAMETERS BUT RISK
APPEARS VERY LOW AT THIS POINT.
FINALLY WE RETURN TO QUIET WEATHER FOR MONDAY AND TUESDAY. THE NEXT
CHANCE OF STORMS ARRIVES TUE NIGHT. A DEEP UPPER LOW IS FORECAST TO
CROSS NORTHERN ONTARIO WITH MODEST HEIGHT FALLS EXTENDING INTO THE
GREAT LAKES REGION. ASSOCIATED FAST MIDLEVEL FLOW YIELDS SOME
IMPRESSIVE SHEAR BUT INSTABILITY WILL BE IN DOUBT FOR OUR AREA.
GENERAL WNW FLOW AHEAD OF THE FRONT LIMITS THETA-E RECOVERY AND
NIGHTTIME ARRIVAL LIMITS THE DIURNAL CONTRIBUTION. AN EARLIER
ARRIVAL COULD YIELD A THREAT FOR STRONGER STORMS IN OUR FAR NW TUE
EVENING BUT CHANCES FOR THAT CURRENTLY APPEAR LOW. THIS FRONT WILL
BE SLOW MOVING AND RAIN CHANCES EXTEND THROUGH THE DAY WED BUT
LACKLUSTER MIDLEVEL LAPSE RATES AND LOW LEVEL MOISTURE RETURN
SUGGEST A LOW RISK FOR BOTH SEVERE WEATHER AND HEAVY RAIN GIVEN THE
CURRENT TIMING.
FORECAST CONFIDENCE ISN'T HIGH FOR THE END OF THE WEEK GIVEN SOME
FAIRLY LARGE MODEL DIFFERENCES BUT THERE IS A GENERAL LEAN TOWARD
COOLER, DRIER, AND MORE TRANQUIL WEATHER.
AVIATION /06Z TAFS THROUGH 06Z MONDAY/
ISSUED AT 200 AM EDT SUN AUG 16 2026
MCV CURRENTLY APPROACHING THE AREA AND WILL BRING OUR NEXT CHANCE OF
STORMS AND LOWER CEILINGS ROUGHLY 09-15Z. LOCAL ENVIRONMENT IS
CURRENTLY DRY/STABLE IN THE LOW LEVELS. INCREASING LLJ WILL MODULATE
THAT SOME BUT CONFIDENCE IN MODEL GUIDANCE SHOWING IFR CEILINGS IS
LOW BASED ON LACK OF OBSERVATIONAL SUPPORT. WILL LEAN MORE TOWARD
MVFR THOUGH SOME BRIEF IFR IS POSSIBLE AT KSBN. CONFIDENCE IN
THUNDERSTORMS IS EQUALLY LOW FOR THE SAME REASON SO WILL HOLD WITH
PROB30'S FOR NOW. ADDITIONAL SHOWERS/STORMS THEN POSSIBLE AT KFWA
DURING THE AFTERNOON BUT LACK OF GOOD FORCING WILL LIKELY KEEP
COVERAGE LOW AND WILL THEREFORE HOLD OFF ON ANY THUNDER MENTION.
SLOW RETURN TO VFR CEILINGS EXPECTED BY LATE AFTERNOON WITH TRANQUIL
WEATHER TO END THE PERIOD.
IWX WATCHES/WARNINGS/ADVISORIES
IN...FLOOD WATCH UNTIL 11 AM EDT /10 AM CDT/ THIS MORNING FOR
INZ012-013-015-020-022>027-032>034.
OH...FLOOD WATCH UNTIL 11 AM EDT THIS MORNING FOR OHZ024-025.
MI...NONE.
MARINE...NONE.
DISCUSSION...AGD
AVIATION...AGD
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