500
FOUS30 KWBC 250011
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
811 PM EDT FRI OCT 24 2025
DAY 1
VALID 01Z SAT OCT 25 2025 - 12Z SAT OCT 25 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS...
..SOUTHERN PLAINS
AN UPPER LEVEL LOW NEAR THE NM/CO BORDER IS LEADING TO A BROAD AREA
OF UPPER DIVERGENCE ACROSS THE SOUTHERN PLAINS. SPC MESOANALYSES
SHOW 40-50 KTS OF EFFECTIVE BULK SHEAR ACROSS CENTRAL AND EASTERN TX.
BOTH THE 12Z REFS AND 18Z HREF GUIDANCE INDICATE THAT A FEW
POSSIBLE CONVECTIVE MAXIMA ARE EXPECTED OVERNIGHT WHERE 3"+ IS
POSSIBLE THROUGH 12Z...NEAR TO NORTHWEST OF THE DALLAS/FORT WORTH
METRO AREA (WHICH HAS ALREADY PARTIALLY EVOLVED), NORTH OF EAGLE
PASS TX (WHICH WOULD EVOLVE OVER THE NEXT SEVERAL HOURS), AND
ACROSS SOUTHEAST TX (WHOSE TIMING WOULD BE EARLY SATURDAY MORNING),
ALL DOWNWIND OF MU CAPE POOLS OF 2000+ J/KG. THE BIGGEST INITIAL
IMPACT IS NEAR AND NORTHWEST OF DALLAS/FORT WORTH WHERE A
BROADENING AREA OF CONVECTION'S FORWARD PROPAGATION IS BEING HELD
UP NORTHEAST OF A COUPLE CONVECTIVE ARCS/BOWS/MESOSCALE CYCLONES.
THERE SHOULD BE SOME ATTEMPT FOR THE CONVECTIVE PATTERN TO SOLIDIFY
AND FORM A LEWP/QLCS WITH TIME. WHEREVER CONVECTIVE PROGRESSION
CAN BE HELD UP FOR A COUPLE OF HOURS, 2.5" AMOUNTS IN AN HOUR AND
LOCAL AMOUNTS OF 5" ARE POSSIBLE. MAINTAINED THE SLIGHT RISK AREA
BUT MADE ADJUSTMENTS PER RADAR REFLECTIVITY TRENDS, AS WELL AS THE
MOST RECENT HREF AND REFS GUIDANCE, WHICH APPEAR A LITTLE SLOW.
SCATTERED AREAS OF FLASH FLOODING, ESPECIALLY FOR MORE URBANIZED
LOCATIONS, WILL BE A CONCERN.
..PACIFIC NORTHWEST INTO NORTHWEST CALIFORNIA
AS THE HEAVY RAIN THREAT ACROSS THE PACIFIC NORTHWEST IS WINDING
DOWN, THE MARGINAL RISK AREA WAS REMOVED.
ROTH
DAY 2
VALID 12Z SAT OCT 25 2025 - 12Z SUN OCT 26 2025
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS INTO CENTRAL ARKANSAS AND WESTERN MISSISSIPPI...
..2030Z UPDATE
THE SLIGHT RISK AREA OVER THE SOUTH WAS EXPANDED EASTWARD INTO
PORTIONS OF SOUTHEASTERN LOUISIANA AND WESTERN MISSISSIPPI, WHERE A
NOTABLE NEIGHBORHOOD PROBABILITY SIGNAL OF EXCEEDING 3" EXISTS. THE
HIGH QPF SIGNAL SHIFTED SOUTH AND EAST SINCE THE PREVIOUS ISSUANCE
AS A RESULT. A ROUND OF CONVECTION IN THE MORNING COULD PRIME
SOILS FOR ANOTHER ROUND IN THE EVENING, WHICH WOULD CARRY HIGHER
RAIN RATES DUE TO A RECHARGED INSTABILITY AND MOISTURE PLUME. ERO
FIRST GUESS FIELDS INDICATE A 15-40% PROBABILITY OF ARI EXCEEDANCE
OR UFVS-VERIFIED FLASH FLOODING ACROSS MUCH OF THE HIGHLIGHTED
AREAS.
THE MARGINAL RISK OVER THE NORTHWEST REMAINS IN PLACE WITHOUT ANY
CHANGES DUE TO A LACK OF SIGNIFICANT CHANGES IN THE QPF GUIDANCE.
THE HEAVIEST RAIN ASSOCIATED WITH AN ATMOSPHERIC RIVER EVENT WILL
OCCUR LATE SATURDAY MORNING INTO THE AFTERNOON.
KEBEDE
..PREVIOUS DISCUSSION
MULTIPLE ROUNDS OF HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED TO
IMPACT THE BROADER NORTHWEST GULF COAST REGION THIS PERIOD, WITH
ONE INITIAL AXIS OF CONVECTION LIKELY ONGOING SATURDAY MORNING
ACROSS AREAS OF SOUTHEAST TO EAST-CENTRAL TX AND ADVANCING ACROSS
WESTERN LOUISIANA AND SOUTHERN ARKANSAS. THIS WILL BE THE
CARRYOVER OF ORGANIZED CONVECTION FROM THE DAY 1 PERIOD WHICH
SHOULD BE INTERACTING AT LEAST INITIALLY WITH A 40+ KT SOUTHERLY
LOW-LEVEL JET OFF THE WESTERN GULF. PRECIPITABLE WATER VALUES AT OR
ABOVE 1.75 INCHES AND MUCAPE VALUES LOCALLY OF 2000+ J/KG WILL
SUPPORT HIGH RAINFALL RATES POTENTIALLY EXCEEDING 2 INCHES/HOUR
WITH THE STRONGER STORMS.
THE ARRIVAL OF AN UPPER- LEVEL JET STREAK IN THE SUBTROPICAL
STREAM COMBINED WITH THE INTERACTION WITH THE SOUTHERN STREAM
CLOSED LOW/TROUGH AXIS CROSSING THE SOUTHERN PLAINS WILL FAVOR A
RENEWED CONVECTIVE OUTBREAK ACROSS AREAS OF EASTERN TEXAS THROUGH
PORTIONS OF WESTERN AND SOUTHERN LOUISIANA SATURDAY AFTERNOON
THROUGH EARLY SUNDAY. EVEN THOUGH ANTECEDENT CONDITIONS ARE QUITE
DRY, THE CONCERN FOR MULTIPLE ROUNDS OF CONVECTION WHICH COMBINED
MAY YIELD SOME 3 TO 5+ INCH TOTALS, WILL PROBABLY BE ENOUGH TO
SUPPORT A THREAT FOR SCATTERED AREAS OF FLASH FLOODING. THE MORE
SENSITIVE URBANIZED LOCATIONS WILL BE AT GREATEST RISK FOR IMPACTS.
FOR THIS UPDATE, THE SLIGHT RISK AREA WAS EXPANDED GIVEN THE
FOOTPRINT OF 2+ INCH RAINFALL AMOUNTS WITHIN A BROADENED REGION OF
INSTABILITY SHOWN BY THE MODELS. THIS IS ALSO CONSISTENT WITH THE
LATEST DETERMINISTIC QPF FROM WPC.
..PACIFIC NORTHWEST AND NORTHWEST CALIFORNIA
MULTIPLE ROUNDS OF MOISTURE TRANSPORT INTO THE COASTAL RANGES WILL
CONTINUE FOR THE PERIOD AS ATMOSPHERIC RIVER ACTIVITY CONTINUES.
LOCALLY A FEW ADDITIONAL INCHES OF RAIN WILL BE POSSIBLE FOR THE
WINDWARD SLOPES OF THE TERRAIN, BUT GIVEN THE EARLY-SEASON AND
RELATIVELY MODEST NATURE OF THIS ATMOSPHERIC RIVER ACTIVITY, ANY
FLOODING CONCERNS ARE EXPECTED TO BE ISOLATED AT BEST. THEREFORE,
THE MARGINAL RISK AREA IS MAINTAINED WITH NO CHANGES FOR THIS
UPDATE CYCLE.
BANN
DAY 3
VALID 12Z SUN OCT 26 2025 - 12Z MON OCT 27 2025
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID-AND LOWER-MISSISSIPPI VALLEY, TENNESSEE VALLEY, SOUTHERN
APPALACHIANS AND SOUTHEAST...
..2030Z UPDATE
SEPARATE AXES OF PRECIPITATION WILL IMPACT DIFFERENT PARTS OF THE
MARGINAL RISK AREA ON SUNDAY. CONVECTION ASSOCIATED WITH THE MID-
LEVEL LOW WILL SPREAD ACROSS THE TENNESSEE VALLEY GENERATING
QUARTER TO HALF INCH RAIN RATES WITHIN A WEAKLY DESTABILIZED
ENVIRONMENT (200-400J/KG MUCAPE). ANOTHER LINE OF STORMS WILL
SPREAD ACROSS THE CENTRAL GULF COAST BENEATH RIPPLES OF SHORTWAVE
ENERGY BREAKING AWAY FROM THE PARENT MID-LEVEL LOW TO ITS NORTH.
PWATS OF 1-2" MAY SUPPORT ANY ISOLATED INSTANCES OF EXCESSIVE
RAINFALL/FLASH FLOODING WITHIN THE MARGINAL RISK AREA. MODELS ARE
TRENDING TOWARD A HIGHER QPF SOLUTION ALONG THE CENTRAL GULF COAST,
BUT THERE'S STILL ENOUGH UNCERTAINTY ON THE EXACT PLACEMENT (READ:
EURO OUTLIER) TO MITIGATE ANY UPGRADES AT THIS TIME.
KEBEDE
..PREVIOUS DISCUSSION
MAINTAINED A MARGINAL RISK AREA ACROSS PORTIONS OF THE SOUTHERN AND
MIDDLE MISSISSIPPI VALLEY. THE RISK ACROSS THE SOUTHERN SHOULD
DIMINISH ONCE A COLD FRONT PASSES THROUGH THE AREA EARLY IN THE
PERIOD AND THE DEEPER MOISTURE/INSTABILITY GET SHUNTED EASTWARD.
FARTHER NORTH WHERE THE MOISTURE IS NOT AS DEEP...CONCERN IS MORE
FROM MID-LEVEL FRONTOGENESIS AND UPPER LEVEL DIVERGENCE LEADING TO
LOCALLY ENHANCED RAINFALL RATES WHERE ANTECEDENT CONDITIONS HAVE
BEEN SOMEWHAT WETTER THAN OTHER LOCATIONS. THERE IS PLENTY
UNCERTAINTY AS TO WHETHER THERE WILL BE A SECOND ROUND OF STORMS
CAPABLE OF PRODUCING LOCALLY HEAVY RAINFALL...SO OVERALL CONFIDENCE
IS BELOW AVERAGE WHICH PRECLUDES ANYTHING HIGHER THAN A MARGINAL
RISK.
BANN
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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