819
FXUS61 KILN 010809
AFDILN
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WILMINGTON OH
409 AM EDT TUE APR 1 2025
SYNOPSIS
HIGH PRESSURE WILL BUILD EAST ACROSS THE GREAT LAKES TODAY. STRONG
LOW PRESSURE WILL THEN BRING THE CHANCE OF SEVERE STORMS AND HEAVY
RAIN LATE WEDNESDAY INTO WEDNESDAY NIGHT. ADDITIONAL WAVES OF LOW
PRESSURE WILL CAUSE MORE ROUNDS OF STORMS WITH HEAVY RAIN THURSDAY
NIGHT INTO SATURDAY.
NEAR TERM /UNTIL 6 PM THIS EVENING/
RIDGE OF HIGH PRESSURE WILL EXTEND FROM THE GREAT LAKES SOUTH INTO
THE MIDDLE OHIO VALLEY TODAY, THEN WILL EXIT TO THE EAST BY EARLY
EVENING. DRIER AIR WILL SCATTER OUT THE LOW CLOUDS THROUGH THE
MORNING BEFORE HIGH CLOUDS START TO STREAM OVER OUR WESTERN COUNTIES
LATE. HIGH TEMPERATURES WILL REACH THE 50S TODAY.
SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/
STRONG LOW PRESSURE WILL BEGIN TO LIFT NORTHEAST FROM THE CENTRAL
PLAINS TONIGHT INTO THE UPPER MIDWEST ON WEDNESDAY. A WARM FRONT
AHEAD OF THE LOW WILL LIFT THROUGH OUR AREA WEDNESDAY MORNING IN
ADVANCE OF A 50- TO 60-KNOT LOW LEVEL JET. WHILE A FEW CAMS SHOW
ONLY ISOLATED SHOWERS/STORMS DEVELOPING ALONG AND AHEAD OF THE WARM
FRONT, BELIEVE THERE WILL BE AMPLE FRONTAL LIFT IN CONJUNCTION WITH
500J OF MUCAPE TO CAUSE PRETTY DECENT COVERAGE OF SHOWERS AND
STORMS... ESPECIALLY ACROSS OUR NORTHERN AND WESTERN COUNTIES. THE
VERTICAL TEMPERATURE PROFILE, ALONG WITH COOL SURFACE TEMPERATURES,
SIGNAL POTENTIAL FOR SMALL HAIL IN THIS WEDNESDAY MORNING ACTIVITY.
BY AFTERNOON, THE WARM FRONT WILL BE WELL TO OUR NORTHEAST. DEWPOINTS
IN THE OPEN WARM SECTOR WILL RISE QUICKLY THROUGH THE 50S INTO THE
60S AS TEMPERATURES RISE INTO THE 70S AND EVEN A FEW 80S SOUTHEAST OF
INTERSTATE 71. SOUTH TO SOUTHWEST WINDS ARE LIKELY TO GUST ABOVE 35
MPH AT TIMES IN THE WELL-MIXED ATMOSPHERE. DEPENDING ON THE COVERAGE
AND TIMING OF THE MORNING STORMS, WE MAY HAVE ENOUGH TIME TO
DESTABILIZE; AS SOME MODELS (INCLUDING SOME RECENT RUNS OF THE HRRR)
SHOW A FEW STORMS DEVELOPING IN THE LATE AFTERNOON FOR OUR
WHITEWATER AND MIAMI VALLEY ZONES. BY THIS TIME, VERTICAL WIND
PROFILES ARE LIKELY TO CREATE LONG, CURVING HODOGRAPHS, SO WILL NEED
TO KEEP A WATCHFUL EYE FOR POTENTIAL ISOLATED SUPERCELLS HEADING
INTO THE LATE AFTERNOON. HOWEVER, THE HIGHEST RISK OF HAZARDOUS
WEATHER WILL AFFECT OUR CWA IN THE LONG TERM PERIOD...
LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/
A VERY ACTIVE LONG TERM PERIOD IS ON TAP FOR THE AREA, STARTING
RIGHT OUT OF THE GATES ON WEDNESDAY NIGHT AS STORMS, SOME OF THEM
LIKELY SEVERE, WILL BE WORKING THEIR WAY INTO THE ILN FA LATE
WEDNESDAY EVENING THROUGH WEDNESDAY NIGHT.
THE BOTTOM LINE IS THAT THE SETUP FOR SEVERE WEATHER LOCALLY,
PRIMARILY LATE WEDNESDAY EVENING THROUGH THE FIRST PART OF THE
OVERNIGHT, IS QUITE CONCERNING FOR LOCALES NEAR/W OF I-75. THIS IS
WHERE THE BEST OVERLAP OF MODEST TO STRONG INSTBY (EXPANDING IN FROM
THE SW) AMIDST VERY STRONG LL/DEEP-LAYER WIND FIELDS SUGGEST
NUMEROUS INGREDIENTS WILL BE IN PLACE FOR SCT SEVERE STORMS. THIS
ACTIVITY WILL BE WORKING IN FROM THE W NEAR/PAST SUNSET, INITIALLY
IN ONE OR MORE CLUSTERS, BEFORE CONGEALING INTO A LARGE LINEAR
COMPLEX OVER TIME. ALL HAZARDS WILL BE POSSIBLE WITHIN THE AREA OF
GREATEST CONCERN LATE WEDNESDAY EVENING INTO EARLY IN THE OVERNIGHT,
WITH A MIXED STORM MODE OF SUPERCELLS AND CLUSTERS EXPECTED
(ESPECIALLY ACROSS FAR WRN ILN FA) BEFORE UPSCALE GROWTH LATE INTO
THE EVENING/OVERNIGHT.
THE LATEST GUIDANCE SUGGESTS THAT THE BEST SEVERE THREAT LOCALLY MAY
END UP FOCUSING ACROSS THE W/SW PART OF THE LOCAL AREA, PARTICULARLY
NEAR/W OF I-75/I-71 AS THERE ARE UNCERTAINTIES ABOUT INSTBY
AVAILABILITY FURTHER TO THE E, ESPECIALLY WITH THE PROSPECT OF
DEWPOINTS BEING MIXED DOWN LATE IN THE AFTERNOON ACROSS NE KY AND
THE LOWER SCIOTO VALLEY WITHIN AN INCREASINGLY WELL-MIXED
ENVIRONMENT. THIS MAY CREATE A SOMEWHAT SIZABLE INSTBY GRADIENT
LOCALLY, RANGING FROM LESS THAN 500 J/KG MLCAPE IN THE ERN 1/3 OF
THE ILN FA TO MORE THAN 1000 J/KG MLCAPE IN THE WRN 1/3 BY 00Z
THURSDAY. THIS WILL BE INCREDIBLY IMPORTANT FOR DETERMINING HOW FAR
E THE SEVERE THREAT WILL EXTEND INTO THE NIGHTTIME HOURS, ESPECIALLY
WITH A SLOWING OF THE BOUNDARY AND THE LOSS OF THE STEEPER MIDLEVEL
LAPSE RATES (AND DEEP LAYER INSTBY) INTO THE OVERNIGHT. EITHER WAY,
STORM COVERAGE WILL BE INCREASING FROM THE W AT THE START OF THE
LONG TERM PERIOD, WITH ALL HAZARDS POSSIBLE (PARTICULARLY NEAR/W OF
I-71) THROUGH MIDNIGHT BEFORE THE SEVERE THREAT WANES THEREAFTER
WITH A SLOWING OF THE OVERALL CONVECTIVE PROGRESSION TO THE
SOUTHEAST.
IN FACT, THE GREATEST THREAT WILL LIKELY QUICKLY TRANSITION FROM A
SEVERE FOCUS TO A HYDRO FOCUS AS WIDESPREAD STORM ACTIVITY PIVOTS TO
THE SE THROUGH THE LATTER HALF OF THE OVERNIGHT AS THE PARENT S/W
EJECTS TO THE NE, ESSENTIALLY ABANDONING ITS FRONT/BOUNDARY IN ITS
WAKE EXTENDING TO THE SW ACROSS THE OH VLY. PROLONGED AND STRONG
MOISTURE AND MASS CONVERGENCE ALONG THIS STALLING/SLOWING BOUNDARY
LENDS ITSELF TO A PRONOUNCED CONCERN FOR A WIDESPREAD HYDRO/FLOODING
SETUP INTO EARLY THURSDAY MORNING. WITH PWATS ON THE ORDER OF 250-
300% OF SEASONAL NORMS (APPROACHING 2") COINCIDENT WITH BOUNDARY-
PARALLEL FORCING/LIFT, THE POTENTIAL FOR TRAINING CONVECTION WITH
VERY HEAVY RAIN RATES WILL LIKELY UNFOLD WEDNESDAY NIGHT INTO EARLY
THURSDAY. IT REMAINS TO BE SEEN EXACTLY WHERE THE GREATEST HYDRO
THREAT WILL UNFOLD DURING INITIAL ROUND, BUT EARLY INDICATIONS FAVOR
LOCALES NEAR/W OF I-71 THROUGH THURSDAY MORNING BEFORE THE BOUNDARY
SLOWLY PIVOTS TO THE SE INTO THE DAY THURSDAY TO NEAR/S OF THE OH
RVR. THIS MAY OFFER A BRIEF REPRIEVE IN HEAVY RAIN/STORMS NW OF I-71
BY DAYBREAK.
THE CONCERNS ONLY CONTINUE INTO THURSDAY/NIGHT AS ANOTHER S/W
DIGGING INTO THE SOUTH-CENTRAL PLAINS WILL ACT TO FURTHER SLOW THE
SE PROGRESSION OF THE LL BAROCLINIC ZONE THROUGH THE SRN OH VLY AND
NRN TN VLY, WITH ADDITIONAL LIFT GENERATED FROM CONTINUED
MOISTURE/MASS CONVERGENCE ALONG THE SW-TO-NE AXIS EXPECTED TO ALLOW
FOR NEARLY-CONTINUOUS REDEVELOPMENT OF CONVECTION ACROSS SOUTHERN
PARTS OF THE LOCAL AREA, PARTICULARLY WITH THE ARRIVAL OF MORE S/W
ENERGY INTO THURSDAY NIGHT. THE CORRIDOR OF PWATS IN EXCESS OF 200%
SEASONAL NORMS WILL REMAIN NEARLY STATIONARY FROM THURSDAY MORNING
THROUGH FRIDAY MORNING, WITH ADDITIONAL WIDESPREAD HEAVY
RAIN/FLOODING LIKELY TO UNFOLD ACROSS AT LEAST PARTS OF THE LOCAL
AREA. THERE IS ALSO THE POTENTIAL FOR SOME STRONG/SEVERE STORMS
ACROSS THE SE THIRD OF THE LOCAL AREA THURSDAY AFTERNOON/EVENING IF
ENOUGH LL INSTBY IS ABLE TO DEVELOP ON THE SRN SIDE OF THE CORRIDOR
OF CONVECTION. THIS CERTAINLY SEEMS POSSIBLE GIVEN THE NEARLY-
CONTINUOUS FEED OF MOISTURE-RICH LL FLOW IN FROM THE SSW DURING THIS
TIME.
AFTER A POTENTIAL BRIEF RESPITE DURING THE DAY FRIDAY, YET ANOTHER
S/W WILL EJECT E INTO THE SOUTH-CENTRAL PLAINS FRIDAY NIGHT INTO
SATURDAY, SETTING THE STAGE FOR ADDITIONAL ROUNDS OF SHOWERS,
STORMS, AND HEAVY RAIN LOCALLY. FROM A CONCEPTUAL MODEL, THE SETUP
FOR SUSTAINED HEAVY RAIN/FLOODING ACROSS THE REGION IS CONCERNING.
THE OH VLY WILL FIND ITSELF WITHIN, OR NEAR, THE RIGHT ENTRANCE
REGION OF AN ANOMALOUSLY STRONG MID/UPPER LEVEL JET (SUPPORTING
PROLONGED LARGE-SCALE ASCENT) ALONGSIDE SUSTAINED STRONG LL
MOISTURE/MASS CONVERGENCE ALONG THE SLOWLY-OSCILLATING BAROCLINIC
ZONE FROM WEDNESDAY NIGHT THROUGH SATURDAY NIGHT. THIS WILL OCCUR ON
THE NW PERIPHERY OF AN H5 RIDGE PARKED OVER THE CAROLINAS ON THE
ORDER OF THE 99TH CLIMATOLOGICAL PERCENTILE. ENSEMBLE PROBS FROM
MULTIPLE SUITES SUGGEST GREATER THAN 70% CHANCE OF AT LEAST 4" OF
RAIN FROM WEDNESDAY EVENING THROUGH SATURDAY NIGHT ACROSS A LARGE
PORTION OF THE REGION, WITH THE HIGHEST PROBS FOCUSING NEAR THE OH
RVR FROM SRN IL/IN INTO N KY AND SW OH AND ALONG/NEAR THE OH RVR.
EVEN AFTER A POTENTIALLY SIGNIFICANT SEVERE EVENT LOCALLY WEDNESDAY
INTO WEDNESDAY NIGHT, THE SETUP FOR A HIGH-IMPACT/WIDESPREAD HEAVY
RAIN AND AREAL/RIVER FLOODING EVENT IS EVEN MORE CONCERNING.
AS WITH ANY EVENT THAT AFFECTS THE REGION, THE DETAILS ARE
INCREDIBLY IMPORTANT IN DETERMINING THE LOCATIONS OF GREATEST
IMPACTS, AS WELL AS THE SCOPE OF THOSE IMPACTS. AND THAT INFORMATION
WILL BECOME CLEARER IN THE COMING DAYS. BUT CONFIDENCE IS FAIRLY
HIGH IN A POTENTIALLY SIGNIFICANT SEVERE (LATE WED/WED NIGHT) AND
HEAVY RAIN/FLOODING EVENT (WED NIGHT THROUGH SAT NIGHT) TO CONTEND
WITH IN THE ILN FA THROUGH THE LONG TERM PERIOD. DRIER CONDITIONS
RETURN BY LATE SUNDAY AS THE FRONT FINALLY MOVES E THROUGH THE
REGION AND MUCH COOLER/DRIER CONDITIONS RETURN BY EARLY NEXT WEEK.
AVIATION /07Z TUESDAY THROUGH SATURDAY/
WEAK HIGH PRESSURE WILL SHIFT THROUGH THE GREAT LAKES DURING THE TAF
PERIOD. USING SATELLITE AND OBSERVATION TRENDS ALONG WITH UPDATED
GUIDANCE, TRIED TO SET THE TIMING FOR SLOW EROSION OF THE
STRATOCUMULUS DECK. WHILE THE TAFS CALL FOR THE MARGINAL CEILINGS TO
BECOME SCATTERED THIS MORNING, IT IS ALSO POSSIBLE IT COULD PERSIST
UNTIL AROUND NOON.
OTHERWISE, WINDS WILL SHIFT FROM NORTHERLY TO EASTERLY OVER THE NEXT
24 HOURS. HIGH AND MID-LEVEL CLOUDS WILL BEGIN TO STREAM INTO THE
REGION AFTER 00Z AHEAD OF THE NEXT LOW PRESSURE SYSTEM ORGANIZING
OVER THE CENTRAL PLAINS.
OUTLOOK...SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE AT TIMES
WEDNESDAY THROUGH SATURDAY. MVFR/IFR CONDITIONS WILL BE POSSIBLE AT
TIMES DURING THIS PERIOD.
ILN WATCHES/WARNINGS/ADVISORIES
OH...FLOOD WATCH FROM WEDNESDAY EVENING THROUGH SUNDAY MORNING FOR
OHZ026-034-035-042>046-051>056-060>065-070>074-077>082-088.
KY...FLOOD WATCH FROM WEDNESDAY EVENING THROUGH SUNDAY MORNING FOR
KYZ089>100.
IN...FLOOD WATCH FROM WEDNESDAY EVENING THROUGH SUNDAY MORNING FOR
INZ050-058-059-066-073>075-080.
SYNOPSIS...
NEAR TERM...
SHORT TERM...
LONG TERM...KC
AVIATION...
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