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FOUS30 KWBC 251921
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
321 PM EDT WED MAR 25 2026
DAY 1
VALID 16Z WED MAR 25 2026 - 12Z THU MAR 26 2026
THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS LESS
THAN 5 PERCENT.
HURLEY
DAY 2
VALID 12Z THU MAR 26 2026 - 12Z FRI MAR 27 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE MIDWEST AND UPPER OHIO VALLEY...
2100 UTC UPDATE...
THE 1200 UTC MODEL SUITE CONTINUES TO SHOW ENHANCING CONVECTION
LATE THURSDAY AFTERNOON, CONTINUING THURSDAY NIGHT INTO EARLY
FRIDAY MORNING, ALONG AND AHEAD OF THE STRONG COLD FRONT SINKING
SOUTH FROM THE LOWER LAKES INTO THE MID-ATLANTIC/OH VALLEY/MID MS
VALLEY BY 1200 UTC FRIDAY. FAVORABLE UPPER DIFLUENCE IN THE RIGHT
ENTRANCE REGION OF THE UPPER JET, IN AN AXIS OF MUCH ABOVE AVERAGE
PW VALUES, 2 TO 3+ STANDARD DEVIATIONS ABOVE THE MEAN, ALONG AND
AHEAD OF THIS FRONT, WILL SUPPORT POTENTIAL FOR WIDESPREAD MODERATE
TO HEAVY PRECIP TOTALS ALONG AND AHEAD OF THE FRONT. CHANGES TO THE
PREVIOUS MARGINAL RISK WERE TO EXPAND IT NORTHEASTWARD INTO THE
SOUTHERN TIER OF NY STATE/NORTHERN PA WHERE FFG VALUES ARE LOWER.
OTHERWISE, MODELS CONTINUE TO EMPHASIZE AREAS BETWEEN THE LOWER
LAKES AND THE OH RIVER FOR THE HEAVIEST TOTALS DAY 2, BUT THE LOWER
FFG VALUES FARTHER NORTHEAST INTO THE SOUTHERN TIER OF NY
STATE/NORTHERN PA, WARRANT THE MARGINAL RISK EXPANSION. OVERALL,
THE MARGINAL RISK AREA FITS WELL WHERE THE HREF AND RRFS
PROBABILITIES FOR 3 HOUR PRECIP EXCEEDING 3 HOUR FFG ARE THE
HIGHEST. THESE PROBABILITIES ARE NOT UNIFORM ALONG AND AHEAD OF THE
FRONT, BUT DO SHOW POTENTIAL FOR ISOLATED RUNOFF ISSUES, WITH AREAS
OF PROBABILITIES IN THE 20-40% RANGE.
ORAVEC
PREVIOUS DISCUSSION:
ONLY MINOR TWEAKS WERE NEEDED FOR THE NEW DAY 2 FORECAST THIS
MORNING. THE LATEST GUIDANCE, INCLUDING SOME OF THE LONGER-RANGE
CAMS, SUGGESTS THAT THERE IS A GREATER CHANCE FOR TRAINING SHOWERS
AND THUNDERSTORMS THURSDAY EVENING AND THURSDAY NIGHT ACROSS
PORTIONS OF NORTHERN INDIANA AND OHIO. A SERIES OF WAVES OF SHOWERS
AND STORMS WILL RACE EASTWARD ALONG THE INTERFACE OF A VERY STRONG
SOUTHWARD-MOVING COLD FRONT. A ZONAL UPPER LEVEL JET STREAK ACROSS
LAKE SUPERIOR WILL MAX OUT AROUND 150 KT 00Z FRIDAY. MEANWHILE
MOISTURE ADVECTION WILL ALLOW PWATS TO CREEP ABOVE 1.25 INCHES AND
DEW POINTS TO SPIKE INTO THE 60S. INSTABILITY IN THE LONGER-RANGE
GUIDANCE HAS ALSO NUDGED HIGHER, INTO THE 1,000 TO 1,500 J/KG RANGE
OF MUCAPE. WHILE ORGANIZED CONVECTION APPEARS LIKELY GIVEN
FAVORABLE INSTABILITY AND SHEAR PROFILES, THE FAST MOTION OF THE
STORMS WILL REMAIN THE PRIMARY FACTOR LIMITING THE FLASH FLOODING
THREAT. THUS, AS REGARDS FLOODING POTENTIAL, WITH SOMEWHAT BETTER
ENVIRONMENTAL PARAMETERS THAN 24 HOURS AGO BUT STILL DRY SOILS IN
MOST AREAS, ESPECIALLY INTO ILLINOIS, THE AREA REMAINS UNDER A
SOLID MARGINAL RISK. THE GREATEST THREAT OF ISOLATED INSTANCES OF
FLASH FLOODING REMAINS INTO THE URBAN CENTERS. SINCE MOST OF THE
SHOWERS AND STORMS WILL BE OCCURRING OVERNIGHT THURSDAY NIGHT IN
THE MARGINAL RISK AREA, ANY FLOODING WILL POSE A HEIGHTENED DANGER
DUE TO LACK OF VISIBILITY.
WEGMAN
DAY 3
VALID 12Z FRI MAR 27 2026 - 12Z SAT MAR 28 2026
THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS LESS
THAN 5 PERCENT.
ORAVEC
DAY 1 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/94EPOINTS.TXT
DAY 2 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/98EPOINTS.TXT
DAY 3 THREAT AREA: HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/99EPOINTS.TXT
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