428
FOUS30 KWBC 242000
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 PM EDT SUN MAY 24 2026
DAY 1
VALID 16Z SUN MAY 24 2026 - 12Z MON MAY 25 2026
...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL FROM THE CENTRAL
GULF COAST INTO NORTH GEORGIA AND ACROSS THE UPPER OHIO VALLEY...
16Z UPDATE...
THE FORECAST OVERALL REMAINS ON TRACK WITH SOME TWEAKS MADE TO
REFLECT THE LATEST TRENDS ON 12Z CAMS. SATELLITE SHOWS MOSTLY
CLOUDY AND OVERCAST SKIES ACROSS A LARGE PORTION OF THE EASTERN
THIRD OF THE CONUS. LARGE SUMS OF ANOMALOUS MOISTURE REMAIN IN
PLACE IN THE SOUTH AND INTO BOTH THE OH VALLEY AND MID-ATLANTIC.
HOWEVER, IT IS WHERE THERE ARE BREAKS IN THE CLOUDS THAT WILL
PROMOTE A MORE UNSTABLE ATMOSPHERE OVER SOILS THAT ARE HIGHLY
SATURATED (WV, EASTERN OH, WESTERN PA) OR NEAR THE REMNANT MCV IN
APPROACHING CENTRAL AL THAT REMAIN THE FOCUS AS SHOWING THE BEST
POTENTIAL FOR SCATTERED AREAS OF FLASH FLOODING. THE SLIGHT RISK IN
THE OH VALLEY WAS EXPANDED SOUTH MORE INTO EASTERN KY WHERE 12Z
HREF PROBABILITIES SHOW LOW CHANCES (20-35%) FOR LOCALIZED RAINFALL
TOTALS >3". SOME ZONES IN EASTERN KY SPORT 3-HR FFGS <2", AND NASA
SPORT-LIS 0-10CM SOIL PERCENTILES ARE >80% IN SOME CASES.
12Z SOUNDINGS ARE PAINTING A BUSY PICTURE IN THE MID-SOUTH AND OHIO
VALLEY. THE BMX SOUNDINGS SHOW A WEAK CAPPING INVERSION WITH OVER
1,500 MUCAPE AND A 1.87" PW AHEAD OF THE APPROACHING MCV. FARTHER
NORTH, THE BNA SOUNDING IS HIGHLY SATURATED AND SHOWS AN EVEN
WEAKER CAPPING INVERSION. THIS AIR-MASS IN THE TN VALLEY WILL
ADVECT NORTH AND EAST INTO THE OH VALLEY THIS AFTERNOON, SETTING
THE STAGE FOR HIGHLY EFFICIENT THUNDERSTORMS FROM CENTRAL TN TO AS
FAR NORTH AND EAST AS THE CENTRAL APPALACHIANS AND WESTERN PA.
STRONG DIFFERENTIAL HEATING IS ALSO UNDERWAY IN CENTRAL GA AND
SOUTHERN SC ALONG THE STATIONARY FRONT, WHICH WILL ONCE AGAIN BE
ANOTHER TRIGGER FOR ADDITIONAL STRONG THUNDERSTORMS THIS AFTERNOON.
LATEST 12Z HREF BROUGHT QPF UP IN THE WINDWARD SIDE OF THE CENTRAL
APPALACHIANS IN EASTERN WV, WITH SOME LOW-TO-MODERATE CHANCE
PROBABILITIES (30-50%) FOR >3" OF RAINFALL THIS AFTERNOON AND
EVENING. THERE ARE ALSO MODERATE CHANCE PROBABILITIES (40-60%) FOR
RAINFALL TOTALS >3" FROM THE SC/GA BORDER TO THE COASTAL PLAIN OF
NC. LOCALIZED FLASH FLOODING IS POSSIBLE IN THESE AREAS THIS
AFTERNOON AND EVENING.
..CENTRAL TX
A MARGINAL RISK WAS INTRODUCED FOR THE MIDDAY UPDATE. 12Z HREF
PROBABILITIES SHOW LOW CHANCES (10-30%) FOR LOCALIZED RAINFALL
TOTALS TOPPING 3" THIS AFTERNOON AND LINGERING INTO THIS EVENING.
THERE IS A REMNANT MID-UPPER LEVEL CIRCULATION OVER THE HEART OF TX
THAT COINCIDES WITHIN AN AREA SEEING STRONG SURFACE-BASED HEATING
AND PWS APPROACHING 1.5". STORM MOTIONS WILL BE VERY SLOW WITH
ECMWF AREA-AVERAGED SOUNDINGS SHOWING MEAN CLOUD-LAYER WINDS WITHIN
THE MARGINAL RISK AREA LESS THAN 5 KTS. THE LACK OF SHEAR SHOULD
MAKE THESE STORMS MORE PULSE LIKE IN NATURE AND SHORTER IN DURATION,
BUT GIVEN THE SATURATED SOILS IN THE REGION (NASA SPORT-LIS SHOWS
>80 PERCENTILE 0-10CM SOIL MOISTURE THE FARTHER SOUTH YOU GO IN
CENTRAL TX) AND THESE STORMS POTENTIALLY PACKING A PUNCH IN A BRIEF
PERIOD OF TIME (1-HR HREF PMM PRECIP RATES UP TO 1.5"), THE
POTENTIAL EXISTS FOR ISOLATED CASES OF FLASH FLOODING THIS
AFTERNOON AND EVENING.
MULLINAX
---PREVIOUS DISCUSSION---
THE WELL DEFINED MCV MOVING FROM SOUTHEAST LA INTO FAR SOUTHERN MS
EARLY THIS MORNING EXPECTED TO CONTINUE TO PUSH NORTHWARD DAY 1
ACROSS CENTRAL AL AND INTO NORTH GA. WHILE THE ORGANIZED CONVECTION
ASSOCIATED WITH THIS MCV MAY WEAKEN EARLY DAY 1, THERE IS POTENTIAL
FOR CONVECTION TO RE-FIRE AHEAD OF THIS MCV LATER THIS AFTERNOON
IN THE AXIS OF MUCH ABOVE AVERAGE PW VALUES, 2 TO 2.5+ STANDARD
DEVIATIONS ABOVE THE MEAN EXPECTED TO STRETCH FROM THE CENTRAL GULF
COAST, NORTHEASTWARD THROUGH THE SOUTHERN TO CENTRAL APPALACHIANS,
SOUTHEAST AND MID-ATLANTIC. WE ADDED A SLIGHT RISK FROM CENTRAL AL
INTO NORTH GA TO ACCOUNT FOR THIS CONVECTIVE POTENTIAL.
FARTHER TO THE SOUTHWEST...WE MADE SOME SIGNIFICANT CHANGES TO THE
PREVIOUS SLIGHT RISK AREA ACROSS SOUTHERN MS AND SOUTHERN LA. WE
SUPPRESSED THE SLIGHT, KEEPING IT JUST FOR FAR SOUTHEAST LA. THE
BEST INSTABILITY IN THE WAKE OF THE NORTHEASTWARD MOVING MCV WILL
BE OVER THE NORTHERN GULF, SUGGESTING THE HEAVIEST PRECIP WITH THE
NEXT ROUND OF CONVECTION ALSO BEING OFFSHORE. WE KEPT THE NEW
ORLEANS METRO AREA IN THE SLIGHT AS MODEL CONSENSUS IS FOR A NARROW
AXIS OF HEAVY RAINS TO EXTEND INTO FAR EASTERN LA.
ACROSS FL...THE MARGINAL RISK WAS EXTENDED SOUTH INTO PORTIONS OF
NORTH CENTRAL TO SOUTHWEST FL. MODEL CONSENSUS IS FOR ANOTHER ROUND
OF ACTIVE CONVECTION FORMING SUNDAY AFTERNOON IN A GENERAL NORTH TO
SOUTH AXIS. SLOW MOVING CELLS WILL AGAIN HAVE POTENTIAL FOR PRODUCE
LOCALLY HEAVY RAINFALL AMOUNTS AND ISOLATED RUNOFF ISSUES. THERE
WILL BE POTENTIAL FOR OVERLAP OF YESTERDAY'S HEAVY RAINFALL AMOUNTS
WITH SUNDAY AFTERNOON'S. THE BIGGEST RUNOFF THREAT WILL CONTINUE TO
BE IN MORE URBANIZED REGIONS.
OVER THE UPPER OHIO VALLEY...ADDED A SLIGHT RISK AREA FROM
NORTHEAST KY INTO EASTERN OH, NORTHWEST WV AND FAR SOUTHWEST PA.
BOTH THE HREF AND RRFS ARE SHOWING FAIRLY HIGH PROBABILITIES,
25-50%+ FOR 3 HOUR PRECIP AMOUNTS EXCEEDING FFG VALUES THIS
AFTERNOON INTO EARLY EVENING. FAVORABLE RIGHT ENTRANCE REGION JET
DYNAMICS IN THE ABOVE MENTIONED AXIS OF ANOMALOUS PW VALUES WILL
SUPPORT POTENTIAL FOR HEAVY PRECIP AND LOCALIZED RUNOFF ISSUES.
ORAVEC
DAY 2
VALID 12Z MON MAY 25 2026 - 12Z TUE MAY 26 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
GULF COAST TOWARD THE SOUTHERN APPALACHIANS...
20Z UPDATE...
SOME ADJUSTMENTS WERE MADE TO THE EASTERN PERIPHERY OF BOTH THE
INHERITED MARGINAL AND SLIGHT RISKS IN THE SOUTH WITH THE LATEST
QPF BEING A LITTLE WETTER IN SOUTHERN AL, SOUTHERN GA, AND THE FL
PANHANDLE. THIS ALIGNS WELL WITH WHERE THE GREATEST SOURCE OF
INSTABILITY IS LIKELY TO BE.
BIGGEST CHANGE WAS TO INTRODUCE A MARGINAL RISK IN EASTERN NM AND
WESTERN TX. ECMWF SATS SHOW A NARROW 200 KG/M/S SOUTHERLY IVT IN
ADVANCE OF THE APPROACHING UPPER LOW OVER AZ. PWS JUMP TO 1" OVER
THE PLAINS OF EASTERN NM, BUT APPROACH 0.75" IN THE SACRAMENTO,
GUADALUPE, AND DAVIS MOUNTAINS. ALL PWS IN THESE AREAS ARE LIKELY
TO SURPASS THE 90TH CLIMATOLOGICAL PERCENTILE. ON TOP OF THE
SYNOPTIC SCALE FORCING AND AMPLE MOISTURE, SUFFICIENT MUCAPE >500
J/KG WILL SUPPORT RAINFALL RATES THAT COULD RANGE BETWEEN
1-1.5"/HR. THERE IS A FLOOD WATCH FOR AREAS DOWNSTREAM OF THE SOUTH
FORK AND SEVEN CABINS BURN SCARS IN THE SACRAMENTO, INDICATING THE
FLASH FLOOD POTENTIAL THAT COULD OCCUR NEAR BURN SCARS AS WELL.
LATEST HREF PROBABILITIES DO SHOW LOW CHANCE PROBABILITIES (20-35%)
FOR RAINFALL TOTALS >2" WITHIN THE MARGINAL RISK AREA, PARTICULARLY
JUST EAST OF THE SACRAMENTO MOUNTAINS.
MULLINAX
---PREVIOUS DISCUSSION---
AN AXIS OF ANOMALOUS PW VALUES, 2 TO 2.5+ STANDARD DEVIATIONS
ABOVE THE MEAN, WILL PERSIST FROM THE CENTRAL GULF COAST,
NORTHEASTWARD ACROSS THE SOUTH, SOUTHEAST AND SOUTHERN MID-ATLANTIC
DAY 2. THE CLOSED LOW OVER THE EASTERN PORTIONS OF THE SOUTHERN
PLAINS TOWARD THE LOWER MS VALLEY WILL MOVE ONLY VERY SLOWLY NORTH
NORTHEASTWARD DAY 2, KEEPING A FAVORABLE BROADLY UPPER DIFFLUENT
PATTERN TO ITS EAST IN THIS ANOMALOUS PW AXIS. THIS WILL SUPPORT
WIDESPREAD SCATTERED CONVECTION AND POTENTIAL FOR WIDESPREAD
MODERATE TO HEAVY PRECIP TOTALS. THERE IS A TYPICAL AMOUNT OF MODEL
QPF SPREAD, BUT CONSENSUS FOR POTENTIAL FOR WIDESPREAD MODERATE TO
HEAVY TOTALS. THERE WILL LIKELY BE OVERLAP BETWEEN THE DAY 1 AND
DAY 2 HEAVY PRECIP AREAS, ALTHOUGH LOW CONFIDENCE AT THE MOMENT
WITH DETAILS. NO SIGNIFICANT CHANGES MADE TO THE PREVIOUS OUTLOOKS
AREAS. MINOR ADJUSTMENTS MADE TO FIT THE LATEST MODEL QPF
CONSENSUS.
ORAVEC
DAY 3
VALID 12Z TUE MAY 26 2026 - 12Z WED MAY 27 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
GULF COAST TOWARD THE SOUTHERN APPALACHIANS AND ACROSS THE SOUTH
CENTRAL TEXAS...
20Z UPDATE...
THE RATIONALE WITH THE INHERITED SLIGHT RISK IN THE SOUTHERN PLAINS
REMAINS IN GOOD SHAPE. THERE WAS AN INCREASED NUMBER OF MODEL
MEMBERS THAT SHOWED EXCESSIVE RAINFALL POTENTIAL JUST OUT AHEAD OF
THE NEGATIVELY-TILTING 200-500MB TROUGH AXIS EJECTING OUT OF NM.
THIS PLACES MORE OF NORTHWEST TX (ENCROACHING UPON THE TX
PANHANDLE) WITHIN AN AXIS STRONG FORCING ALOFT WITHIN A NARROW
CORRIDOR OF >1.25" PWS, WHICH IS ABOVE THE 90TH CLIMATOLOGICAL
PERCENTILE. LATEST GUIDANCE ALSO SHOW THE POTENTIAL FOR UP TO 1,000
J/KG OF MUCAPE AS FAR NORTH AS THE TX PANHANDLE. SOME PORTIONS OF
WEST TX, EVEN AS FAR NORTH AS THE CAP ROCK, HAVE DEALT WITH
LOCALIZED FLASH FLOODING IN RECENT DAYS, AND SENSITIVE SOILS IN THE
AREA ARE UNLIKELY TO RECOVER FAST ENOUGH FOR A SETUP THAT COULD
FEATURE 1.5-2.0"/HR RAINFALL RATES AT THEIR PEAK. FOR THESE
REASONS, THE SLIGHT RISK WAS EXTENDED FARTHER NORTH INTO NORTHWEST
TX.
THE SETUP CONTINUES TO BE ONE THAT RESIDENTS IN THE TX HILL COUNTRY
WILL WANT TO MONITOR IN THE COMING DAYS. WHILE THERE REMAINS SOME
UNCERTAINTY IN THE EXACT LOCATION OF THE HEAVIEST PRECIPITATION,
RAINFALL RATES TOPPING 2"/HR ARE POSSIBLE AS FAR SOUTH AS LAREDO
AND SOUTH OF SAN ANTONIO. SOILS REMAIN MOST SENSITIVE ALONG THE
I-35 CORRIDOR ON NORTH TO THE EDWARDS PLATEAU. THE FLASH FLOOD
THREAT COULD START AS EARLY AS TUESDAY AFTERNOON, BUT LATEST
ENSEMBLE GUIDANCE IS INDICATING THE HEAVIEST RAINFALL RATES ARE
FAVORED TO OCCUR OVERNIGHT TUESDAY.
MULLINAX
---PREVIOUS DISCUSSION---
NOT A LOT OF CHANGES TO THE WET PATTERN FROM THE CENTRAL GULF
COAST, NORTHEASTWARD ACROSS THE SOUTH, SOUTHEAST AND SOUTHERN
APPALACHIANS. THE AXIS OF ANOMALOUS PW VALUES, 2 TO 2.5+ STANDARD
DEVIATIONS ABOVE THE MEAN, WILL PERSIST ACROSS THIS AREA IN A
REGION OF PERSISTENT SOUTH SOUTHWESTERLY MID TO UPPER LEVEL FLOW ON
THE EAST SIDE OF THE WEAK MID TO UPPER LOW MOVING NORTH THROUGH THE
LOWER MS VALLEY. EXPECT ANOTHER DAY OF WIDESPREAD SCATTERED
CONVECTION AND WIDESPREAD MODERATE TO HEAVY RAINFALL TOTALS. WITH
NOT MUCH CHANGES OVERALL TO THE LARGE SCALE PATTERN, A SLIGHT RISK
WAS MAINTAINED IN A SIMILAR REGION AS DURING THE DAY 2 PERIOD.
THERE MAY AGAIN BE OVERLAP IN HEAVY RAIN AREAS DAY 3 WITH DAY 1 AND
2, WHICH MAY LEAD TO A UPGRADE IN THREAT CATEGORIES IN FUTURE
ISSUANCES.
MID TO UPPER LEVEL TROFFING DEVELOPING ACROSS THE SOUTHWEST DURING
DAY 2 WILL BE PUSHING HEIGHT FALLS INTO THE SOUTHERN PLAINS DAY 3.
INCREASINGLY ACTIVE CONVECTION LIKELY ACROSS THE SOUTHERN PLAINS
DAY 3, WITH MODEL CONSENSUS FOR WIDESPREAD MODERATE TO HEAVY
TOTALS. NOT A LOT OF CHANGES MADE TO THE PREVIOUS SLIGHT RISK AREA
OVER SOUTH CENTRAL TX. THIS REGION HAS SEEN SEVERAL ROUNDS OF
HEAVY PRECIP OVER THE PAST WEEK, LOWERING FFG VALUES AND INCREASING
THREAT OF ADDITIONAL RUNOFF ISSUES. THERE IS A LOT OF SPREAD WITH
QPF DETAILS, BUT A STRONG SIGNAL FOR HEAVY RAINFALL TOTALS DAY 3
ACROSS THIS AREA.
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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