324
FXUS61 KILN 110729
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
329 AM EDT TUE AUG 11 2026
WHAT HAS CHANGED
DUE TO THE HIGHER POTENTIAL FOR IMPACTS, THE DAMAGING WIND AND FLASH
FLOOD THREAT HAVE BEEN SEPARATED INTO SECTIONS.
KEY MESSAGES
1) INCREASED THREAT FOR A SIGNIFICANT DAMAGING WIND EVENT ACROSS THE
AREA THIS AFTERNOON AND EVENING.
2) INCREASED THREAT FOR FLASH FLOODING ACROSS THE AREA TODAY THROUGH
TUESDAY NIGHT.
3) ADDITIONAL CHANCES FOR THUNDERSTORMS AND HEAVY RAIN ARE POSSIBLE
THROUGH THE END OF THE WEEK WITH DRIER WEATHER ATTEMPTING TO RETURN
LATE FRIDAY AND INTO THE WEEKEND.
DISCUSSION
KEY MESSAGE 1)
NOW THAT THE LATE EVENING AND EARLY OVERNIGHT THUNDERSTORM COMPLEX
HAS SHIFTED SOUTHEAST OF THE REGION, THE NORTHERN HALF OF THE AREA
IS CURRENTLY IN A STABLE COLD POOL AIR MASS, WHILE THE SOUTHERN HALF
IS STILL CONSIDERABLE UNSTABLE. THUNDERSTORMS ARE BEGINNING TO FORM
ALONG A STALLED BOUNDARY CURRENTLY PLACED ACROSS NORTHERN INDIANA.
IF THESE THUNDERSTORMS ATTEMPT TO MOVE SOUTHEAST, THEY WILL ENCOUNTER
THE COLD POOL AIR MASS PREVIOUSLY MENTIONED. THESE STORMS WOULD
STRUGGLE TO ORGANIZE AS A RESULT. TRENDS WILL BE MONITORED OVER THE
NEXT FEW HOURS, BUT THIS IS FIRST FEATURE WHICH COULD PLAY AN
IMPORTANT ROLE IN TODAY'S SIGNIFICANT WIND THREAT POTENTIAL.
THE SECOND FEATURE IS ACROSS SOUTHERN WISCONSIN AND NORTHERN
ILLINOIS. NEAR THE NORTHERN TIP OF THE LOW-LEVEL JET, THUNDERSTORMS
ARE BEGINNING TO DEVELOP. TO THE EAST AND SOUTH OF THESE STORMS,
UNDISTURBED ENERGY REMAINS. WHILE THIS IS AHEAD OF THE BETTER FORCING
ASSOCIATED WITH THE SHORTWAVE, THE AVAILABLE ENERGY TO THE SOUTH
WOULD GIVE IT A MUCH BETTER CHANCE TO EVOLVE INTO A MORE ORGANIZED
STORM COMPLEX INTO THE MORNING HOURS.
IF THESE TWO FEATURES REMAIN ON THE WEAKER SIDE, CONFIDENCE WOULD
BECOME VERY HIGH THAT THE LOCAL AREA WOULD SEE A WIDESPREAD,
SIGNIFICANT DAMAGING WIND EVENT LATER THIS AFTERNOON AND EVENING. THE
SECOND FEATURE HAS THE BETTER CHANCE OF ORGANIZING, THEREFORE IT
WOULD LIKELY HAVE THE BIGGEST ROLE TO PLAY IN ALTERING LOCAL IMPACTS
FROM THE HIGHER-END SCENARIO. THERE IS ALSO THE POTENTIAL WHERE THIS
FEATURE AND THE MAIN EVENT COMBINE AS THEY APPROACH THE LOCAL AREA.
AS SPC NOTES IN THEIR DISCUSSION, ALL ENVIRONMENTAL PARAMETERS ARE
IN PLACE FOR A WIDESPREAD, POTENTIALLY SIGNIFICANT DAMAGING WIND
EVENT ACROSS THE AREA. THE TIMING IS ALSO OPTIMAL FOR THE LOCAL AREA,
MOVING THROUGH DURING THE PEAK OF THE DIURNAL INSTABILITY (AFTERNOON
INTO EVENING). DAMAGING WIND GUSTS OF 75+ MPH ARE LIKELY IF A WELL-
ORGANIZED MCS CAN DEVELOP AND THEN MOVE THROUGH THE AREA. THE MAJOR
LIMITING FACTOR WOULD BE ANY EARLIER DEVELOPMENT AHEAD OF THIS MAIN
EVENT. DESPITE THE FOCUS BEING ON THE MORE WIDESPREAD DAMAGING WIND
EVENT, EMBEDDED TORNADOES WITHIN THE SQUALL-LINE WOULD ALSO BE
POSSIBLE, ESPECIALLY ON THE NORTHERN SEGMENT OF THE MCS. LARGE HAIL
COULD ALSO OCCUR IN THE DEEPEST THUNDERSTORMS.
KEY MESSAGE 2)
THE BEST CHANCE FOR FLASH FLOODING ACROSS THE NORTHERN PORTION OF
THE AREA WOULD BE IF MULTIPLE ROUNDS OF THUNDERSTORMS OCCUR LATER
THIS MORNING AND THROUGH THE AFTERNOON. THEN, IF AN ORGANIZED MCS
MOVES THROUGH, MULTIPLE INCHES WOULD HAVE ACCUMULATED OVER THIS
REGION.
OF MORE INCREASING CONCERN, AFTER THE MCS MOVES THROUGH, MOISTURE
WILL CONTINUE TO MOVE INTO THE REGION FROM THE SOUTHWEST. BACK
BUILDING OF THUNDERSTORMS ALONG THE STRETCHED OUTFLOW WILL FOCUS A
FLASH FLOOD THREAT OVER A PORTION OF THE AREA. THIS ACTIVITY COULD
CONTINUE WELL INTO WEDNESDAY AS THE FRONT STALLS OVER SOUTHERN
PORTIONS OF THE AREA. SPC HREF LPMM DOES SUPPORT THIS POTENTIAL OVER
SOUTH-CENTRAL AND SOUTHERN OHIO, BUT THERE IS A GROWING SIGNAL FOR
SOUTHEAST INDIANA, SOUTHWEST OHIO AND NORTHERN KENTUCKY (SOME OF
THESE COUNTIES ARE OUTSIDE THE FLOOD WATCH). BECAUSE THIS THREAT MAY
NOT EVOLVE UNTIL LATER TONIGHT AND INTO WEDNESDAY, THE FLOOD WATCH
HAS NOT BEEN EXTENDED TO INCLUDE THESE AREAS QUITE YET. HOWEVER, IT
MAY BE NEEDED LATER TODAY AS CONFIDENCE INCREASES. IF A BACK-BUILDING
SCENARIO CAN DEVELOP, LOCALIZED AMOUNTS OF 5-7" ARE PLAUSIBLE AS SEEN
FROM EARLIER EVENTS IN PERRY COUNTY OH THIS EVENING.
KEY MESSAGE 3)
THURSDAY AND THROUGH THE WEEKEND, LONG-RANGE GUIDANCE CONTINUES TO
SUGGEST AN ACTIVE PATTERN WILL CONTINUE OVER THE OHIO VALLEY, BUT
SOME BREAKS ARE POSSIBLE. THIS IS LARGELY DUE TO A RIDGE OF HIGH
PRESSURE OVER THE MIDDLE AND LOWER MISSISSIPPI RIVER VALLEY FEEDING
MOISTURE NORTHWARD. THE TROUGH OVER SOUTHEAST CANADA IS SUPPLYING A
STEADY AMOUNT OF NORTHWESTERLY UPPER LEVEL FLOW, INCREASING WIND
SHEAR OVER THE REGION. THERE ARE SIGNS THIS MAY BREAKDOWN AS THE
RIDGE BUILDS NORTHWARD OVER THE UPPER MIDWEST INTO THE WEEKEND. THIS
WOULD BRING A SURGE OF LOWER PWATS SOUTHWARD REDUCING RAINFALL
CHANCES FRIDAY INTO SATURDAY. CHANCES FOR THUNDERSTORMS INCREASE TO
ROUND OUT THE WEEKEND.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
MUCH OF THE THUNDERSTORM ACTIVITY HAS DIMINISHED ACROSS THE AREA.
SEVERAL ROUNDS OF THUNDERSTORMS ARE POSSIBLE TODAY, WITH AN INCREASED
POTENTIAL FOR A LINE OF SIGNIFICANT WINDS GUSTS (75+ MPH) THIS
AFTERNOON AND EVENING. BECAUSE THERE IS A THREAT FOR EARLIER ROUNDS
OF THUNDERSTORMS, PROB30 GROUPS BEGIN LATE THIS MORNING AND INTO THE
EARLY AFTERNOON. BECAUSE OF THE HIGHER CONFIDENCE LATE THIS AFTERNOON
AND EVENING, TEMPO GROUPS HAVE BEEN ADDED. EXPECT TIMING ADJUSTMENTS
THROUGHOUT THE DAY.
OTHERWISE WINDS ARE OUT OF THE SOUTHWEST AROUND 10 KNOTS BEFORE
THUNDERSTORM ACTIVITY POTENTIALLY INFLUENCES THEM. WINDS BECOME MORE
WESTERLY AFTER 00Z AS A FRONT SLIDES THROUGH THE AREA.
OUTLOOK...THUNDERSTORMS ARE POSSIBLE AT TIMES THROUGH FRIDAY.
ILN WATCHES/WARNINGS/ADVISORIES
OH...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR OHZ026-034-035-042>046-
051>056-060>065-070>074-077>082-088.
KY...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR KYZ091>093-096>100.
IN...FLOOD WATCH THROUGH WEDNESDAY MORNING FOR INZ050-058-059-066-074.
DISCUSSION...MCGINNIS
AVIATION...MCGINNIS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page