472
FOUS30 KWBC 130805
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
405 AM EDT SAT SEP 13 2025
DAY 1 VALID 12Z SAT SEP 13 2025 - 12Z SUN SEP 14 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR EASTERN NEW
MEXICO INTO FAR WEST TEXAS AS WELL AS FOR WESTERN NORTH DAKOTA...
..CENTRAL HIGH PLAINS THROUGH SOUTHERN ROCKIES/WEST TX
UPPER TROUGH OVER THE GREAT BASIN THIS MORNING WILL CONTINUE
SLOWLY EASTWARD AND TAKE ON A NEGATIVE TILT, WITH A CONTINUED
INFLUX OF MOISTURE (PW ANOMALIES +2 SIGMA) INTO THE SOUTHERN
ROCKIES AND POINTS NORTHWARD. AS THE TROUGH AXIS CROSSES THE FOUR
CORNERS REGION AROUND 00Z TONIGHT, LLJ INCREASE WILL SUPPORT
CONVECTION OVER EASTERN NM LATE AFTERNOON THAT WILL PUSH INTO WEST
TEXAS IN THE EVENING. STORMS MAY HAVE ENOUGH FORWARD SPEED TO LIMIT
FLASH FLOODING POTENTIAL, BUT 00Z CAMS CONTINUE TO SHOW POTENTIAL
FOR 1-4" AMOUNTS. FOCUSED THE SLIGHT RISK OUTLINE FURTHER FROM THE
PREVIOUS SHIFTS TO THE BEST ENSEMBLE AGREEMENT.
..NORTHERN PLAINS
SOUTHERLY FLOW THROUGH THE COLUMN WILL MAINTAIN A SURGE OF
MOISTURE (PW ANOMALIES +3 SIGMA / 1.50") INTO THE NORTHERN PLAINS
AS WEAKER SHORTWAVES RACE NORTHWARD AHEAD OF THE MAIN UPPER LOW
OVER MT. RECENT CAM GUIDANCE STILL SHOWS SOME EAST-WEST
DISPLACEMENT OF HEAVER NORTH-TO-SOUTH QPF MAXIMA, OWING TO SMALL
DIFFERENCES IN SHORTWAVE/SFC BOUNDARY INTERACTIONS AND ANY MORNING
CONVECTION. MAINTAINED THE SLIGHT RISK OUTLINE OVER WESTERN ND BUT
THE EVENTUAL QPE FOOTPRINT WILL LIKELY BE MUCH NARROWER.
..NORTHEASTERN ILLINOIS AND SURROUNDING AREAS
SHORTWAVE DIVING SOUTHEASTWARD OUT OF WISCONSIN THIS MORNING AT
THE NOSE OF A JET STREAK WILL HELP ORGANIZE A SMALL AREA OF AT
LEAST MODEST RAINFALL AROUND THE CHICAGOLAND AREA THAT CONTINUES
SSE-WARD THIS AFTERNOON. SOME 00Z CAM GUIDANCE REMAINS RATHER
BULLISH WITH 2-3" AMOUNTS WHICH MAY BE ENOUGH TO CAUSE SOME URBAN
RUNOFF ISSUES.
..SOUTH FLORIDA
FRONTAL BOUNDARY WILL REMAIN JUST TO THE SOUTHEAST OF FLORIDA, BUT
PRECIPITABLE WATER VALUES WILL START THE DAY AROUND 2 INCHES.
DRIER AIR WILL SLOWLY WORK SOUTHEASTWARD THROUGH THE ENTIRETY OF
THE PENINSULA BY THE END OF THE DAY, AND HAVE TARGETED THE MARGINAL
RISK OUTLINE TO AROUND THE URBAN AREAS BETWEEN PALM BEACH AND
MIAMI.
FRACASSO
DAY 2 VALID 12Z SUN SEP 14 2025 - 12Z MON SEP 15 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE WESTERN DAKOTAS...
..CENTRAL AND NORTHERN PLAINS
UPPER TROUGH EXITING THE ROCKIES WILL SPLIT OFF ITS SOUTHERN
PORTION INTO AN UPPER LOW OVER WESTERN NEBRASKA MIDDAY SUNDAY, WITH
SOUTHERLY FLOW CONTINUING ACROSS THE NORTHERN PLAINS (AND AMPLE
MOISTURE -- PW ANOMALIES STILL +2 TO +3 SIGMA). THIS MID-LEVEL LOW
WILL LIFT NORTHWARD AND ACT AS A FOCUS FOR CONVERGENCE TOWARD THE
NOSE OF THE SFC- BASED INSTABILITY GRADIENT JUST TO THE EAST.
STORMS MAY REPEAT OVER THE SAME AREA AS D1, WITH THE POTENTIAL FOR
ANOTHER 1-2"+ OF RAIN. MAINTAINED THE SLIGHT RISK OUTLINE HERE WITH
A BROADER MARGINAL RISK EXTENDING TO THE SOUTH WHERE THE GUIDANCE
SHOWS POTENTIAL FOR 2-4" OF RAINFALL, BUT OVER AREAS WITH HIGHER
FFG VALUES (ESP. THE SAND HILLS).
FRACASSO
DAY 3 VALID 12Z MON SEP 15 2025 - 12Z TUE SEP 16 2025
THE PROBABILITY OF RAINFALL EXCEEDING FLASH FLOOD GUIDANCE IS LESS
THAN 5 PERCENT.
FRACASSO
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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