374
FOUS30 KWBC 060044
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
844 PM EDT TUE MAY 5 2026
DAY 1
VALID 01Z WED MAY 06 2026 - 12Z WED MAY 06 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE MEMPHIS
METRO AND SURROUNDING AREAS...
..01Z UPDATE
THE WESTERN FLANK OF THE MARGINAL RISK AREA WAS TRIMMED DOWN GIVEN
THE WANING INSTABILITY IN WAKE OF THE COLD FRONT. THE SLIGHT RISK
AREA WAS MOVED A LITTLE FARTHER SOUTH IN SOUTHWEST TN AND NORTHERN
MS TO ALIGN WITH THE MODERATE CHANCES (40-60%) FOR >2" OF RAINFALL
BETWEEN 01-12Z DEPICTED BY THE 18Z HREF. THERE WERE ALSO SOME LOW
CHANCE PROBABILITIES (20-305) FOR LOCALIZED RAINFALL TOTALS OVER 3"
IN NORTHERN MS. THE MEMPHIS METRO AREA REMAINS MOST AT-RISK FOR
POTENTIAL FLASH FLOODING DUE TO ITS GREATER URBANIZATION, BUT WITH
SPC MESOANALYSIS SHOWING OVER 500 J/KG OF MLCAPE AVAILABLE AND PWS
OVER 1.6", RAINFALL RATES OF 2"/HR COULD OCCUR AND SUPPORT
LOCALIZED FLASH FLOODING IN POOR DRAINAGE AREAS EAST AND SOUTH OF
MEMPHIS.
MULLINAX
--PREVIOUS 16Z DISCUSSION---
IN COLLABORATION WITH MEG/MEMPHIS, TN FORECAST OFFICE, A SLIGHT
RISK UPGRADE HAS BEEN INTRODUCED WITH THIS UPDATE FOR THE MEMPHIS
METRO AND SURROUNDING AREAS. ONGOING LOCALLY HEAVY RAINFALL ON THE
SOUTHERN BOW END OF OTHERWISE LIGHT RAIN NEAR AND OVER MEMPHIS HAS
DROPPED UP TO 2 INCHES OF RAIN OVER SMALL AREAS OF NORTHEASTERN
ARKANSAS THIS MORNING. THIS MORNING RAINFALL, WHILE ALL BENEFICIAL,
IS WORKING TO SATURATE THE VERY DRY SOILS IN THE AREA, WHILE
SIMULTANEOUSLY MOISTENING THE ATMOSPHERE. BEHIND THE LINE OF RAIN
THIS MORNING, A MUCH MORE MOIST AND UNSTABLE AIR MASS MOVES IN FROM
THE SOUTH AND WEST. PWATS ACROSS WESTERN TENNESSEE AND SURROUNDING
AREAS RISE WELL ABOVE 1.5 INCHES, WHILE INSTABILITY OVER SOUTHERN
ARKANSAS COULD RISE ABOVE 2,000 J/KG OF MUCAPE.
THIS EVENING AND TONIGHT, AS A COLD FRONT APPROACHES FROM THE
NORTH AND THE NOCTURNAL LLJ TO THE SOUTH STRENGTHENS, A RENEWED
ROUND OF SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS
ARKANSAS AND SOUTHWEST TENNESSEE BEFORE MOVING INTO MISSISSIPPI. AS
THE STORMS ARE FORMING INTO A LINE, THERE WILL BE INCREASED
POTENTIAL FOR TRAINING. AS THIS APPEARS LIKELY TO OCCUR OVER THE
SAME AREAS CURRENTLY PICKING UP UP TO 2 INCHES OF RAIN, EXPECT A
SMALL AREA OF HIGHER POTENTIAL FOR FLASH FLOODING. FOR NORTHEASTERN
ARKANSAS, THERE WAS MORE RAIN THERE THIS MORNING, SO THE SOILS WILL
BE MORE PRIMED BY TONIGHT. MEANWHILE FOR SOUTHWEST TENNESSEE, IN
ADDITION TO THE ONGOING RAINFALL, URBAN CONCERNS AROUND THE MEMPHIS
METRO COULD ALSO SUPPORT MORE WIDELY SCATTERED INSTANCES OF FLASH
FLOODING.
ONCE THE LINE MOVES INTO NORTHERN MISSISSIPPI LATE TONIGHT, THE
STORMS ARE EXPECTED TO ORGANIZE INTO ONE PROGRESSIVE LINE, WHICH
SHOULD LIMIT ANY FLASH FLOODING CONCERNS TO ISOLATED INSTANCES.
ACROSS SOUTHERN ARKANSAS, THE STORMS, WHILE STRONG AND CAPABLE OF
HEAVY RAINFALL RATES, ARE LIKELY TO BE MUCH MORE WIDELY SCATTERED.
THEY WILL BE UNLIKELY TO TRAIN IN SUCH A WAY AS TO CAUSE MORE THAN
ISOLATED FLASH FLOODING, ESPECIALLY CONSIDERING THE VERY DRY SOILS
IN PLACE THERE.
WEGMAN
DAY 2
VALID 12Z WED MAY 06 2026 - 12Z THU MAY 07 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE INTERIOR SOUTHEAST...
..19Z UPDATE
A BROAD EXPANSION TO BOTH THE SLIGHT AND MARGINAL RISKS WAS
INTRODUCED WITH THIS UPDATE, IN COLLABORATION WITH BMX/BIRMINGHAM,
AL AND FFC/PEACHTREE CITY, GA FORECAST OFFICES. THE HIGH-RESOLUTION
GUIDANCE LEFT A LOT TO BE DESIRED AS TO THE EXPECTED EVOLUTION AND
CONVECTIVE FOOTPRINT WITH ALL OF THE STORMS EXPECTED ON WEDNESDAY.
GENERALLY SPEAKING, MOST OF THE GUIDANCE SUGGESTED THERE WOULD BE A
BIMODAL DISTRIBUTION TO THE HEAVY RAINFALL. THE NORTHERN PEAK IN
RAINFALL WILL OCCUR FIRST, ON WEDNESDAY MORNING, WITH THE REMNANT
CONVECTION ASSOCIATED WITH THE DIURNALLY-WEAKENING LLJ AIMED ALONG
TENNESSEE'S SOUTHERN BORDER. FAST-MOVING, BUT TRAINING CONVECTION
MAY CONTINUE FROM NORTHERN ALABAMA EAST INTO FAR WESTERN NORTH
CAROLINA THROUGH THE DAY, THOUGH THE GUIDANCE IS FAR FROM UNANIMOUS
AS TO HOW STRONG THAT CONVECTION WILL BE. ON THE SURFACE OF IT, IT
APPEARS THAT THE STEADY SUPPLY OF MOISTURE AND INSTABILITY SHOULD
FAVOR CONTINUED CONVECTIVE DEVELOPMENT THROUGH THE MIDDAY, AND ANY
CONVECTION SHOULD BE STRONG ENOUGH TO PRODUCE 1-2 INCH PER HOUR
RAINFALL RATES. FURTHER, THE TOPOGRAPHY OF THE GA/NC/TN BORDER
REGION WOULD ALSO SUPPORT THAT RUNOFF CONVERTING TO FLASH FLOODING.
A HIGHER END SLIGHT, ALBEIT AN UNCERTAIN ONE, WAS INTRODUCED FOR
THIS AREA, TO HIGHLIGHT THE POSSIBILITY OF MULTIPLE INCHES OF RAIN
IN A FEW HOURS CAUSING SCATTERED INSTANCES OF FLASH FLOODING.
IN KEEPING WITH PAST TRENDS, THE SLIGHT AND MARGINAL FURTHER SOUTH
ACROSS MISSISSIPPI, ALABAMA, AND GEORGIA CONTINUED TO EXPAND
SOUTHWARD, AS SIMULATED CONVECTION IN THE GUIDANCE CONTINUES TO
FAVOR THE REFIRING OF STORMS FURTHER SOUTH WITH THE FRONT ON
WEDNESDAY EVENING. AFTER THE MORNING AND EARLY AFTERNOON RAINS
FURTHER NORTH, THE FRONT SHOULD SINK TO THE SOUTH DURING THE
AFTERNOON, WITH SCATTERED CONVECTION STILL AROUND IN SOME AREAS. BY
WEDNESDAY EVENING, THE RESTRENGTHENING OF THE LLJ WILL ALLOW FOR A
BLOSSOMING OF STORMS IN A LINE ALONG THE FRONT, LEADING TO A
RENEWED MAXIMUM OF RAINFALL. MOST OF THE GUIDANCE SUGGESTS THIS
LINE SETS UP FROM JUST SOUTH OF BIRMINGHAM TO ABOUT MIDWAY BETWEEN
BIRMINGHAM AND MONTGOMERY, AND JUST SOUTH OF TUSCALOOSA. RAINFALL
AMOUNTS SUGGEST THIS SHOULD BE THE MORE SIGNIFICANT OF THE TWO
AREAS AS FAR AS TOTALS ARE CONCERNED, WITH MORE MOISTURE AND
INSTABILITY ADVECTING INTO THE FRONT THAN AREAS FURTHER NORTH
EARLIER IN THE DAY. THE AREA REMAINS VERY DRY SOIL-MOISTURE-WISE,
SO IT WILL TAKE A LOT OF RAINFALL TO RESULT IN SIGNIFICANT FLASH
FLOODING. WHILE THIS IS LIKELY TO OCCUR SOMEWHERE IN THIS AREA, THE
UNSURPRISING LACK OF AGREEMENT ON WHERE THIS WILL OCCUR AND THE
BUFFERING A DRY ENVIRONMENT GIVES TO THE PROSPECTS OF FLASH
FLOODING DID KEEP THE AREA FROM UPGRADING TO A MODERATE RISK FOR
NOW. HOWEVER, FURTHER INCREASES IN EXPECTED RAINFALL AND BETTER
AGREEMENT IN THE GUIDANCE WOULD RESULT IN AN UPGRADE WITH FUTURE
UPDATES.
WEGMAN
..PREVIOUS DISCUSSION
MAINTAINED THE SLIGHT SOUTHWARD SHIFT OF THE PREVIOUSLY ISSUED SLIGHT
RISK AREA INTRODUCED A COUPLE OF DAYS AGO. THE COVERAGE AND
RAINFALL INTENSITY SHOULD BE INCREASING ON WEDNESDAY AS A LARGE
SCALE TROUGH OVER THE NORTHERN PLAINS CONTINUES TO AMPLIFY AND
RESULT IN A 140 KT TO 160 KT UPPER LEVEL JET OVER THE TENNESSEE
VALLEY DURING THE LATTER PART OF THE PERIOD. THE RESULTING UPPER
DIVERGENCE, STEEPENING MID-LEVEL LAPSE RATES AND INCREASING
MOISTURE AND INSTABILITY SHOULD RESULT IN CONVECTION CAPABLE OF
PRODUCING HEAVY RAINFALL RATES AND EMBEDDED AREAS OF RAINFALL
AMOUNTS OF 3 TO 5 INCHES AS SUGGESTED BY THE LATEST RUN OF THE
RRFS. THERE IS A FAIRLY WIDE SPREAD IN THE NORTH/SOUTH PLACEMENT OF
THAT HEAVIER AXIS. AS A RESULT...THE SLIGHT AREA WAS EXPANDED
SOMEWHAT AND TENDED TO COVER THE GREATEST OVERLAP OF HIGHER QPF AND
EXCEEDANCE PROBABILITIES. THINKING IS THAT THERE ARE SOME
PROBABILITIES SUPPORTIVE OF A HIGHER-END SLIGHT RISK EMBEDDED
WITHIN THE BROADER SLIGHT. THE CONTINUED AMPLIFICATION OF THE UPPER
TROUGH SHOULD KEEP THE CONVECTION MOVING SOUTHWARD WITH TIME
DURING THE OVERNIGHT HOURS.
BANN
DAY 3
VALID 12Z THU MAY 07 2026 - 12Z FRI MAY 08 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE GULF COAST REGION INTO THE SOUTHEAST...
..19Z UPDATE
ABUNDANT MOISTURE ALONG A STALLED FRONTAL BOUNDARY ON THURSDAY WILL
SUPPORT ADDITIONAL THUNDERSTORM FORMATION ALONG THE FRONT. RAPIDLY
WEAKENING FORCING WILL GREATLY DIMINISH CONVECTIVE COVERAGE ALONG
THE GULF COAST AND INTO CENTRAL GEORGIA AND SOUTH CAROLINA AS
COMPARED WITH DAY 2/WEDNESDAY. THE ONLY SIGNIFICANT CHANGE FROM THE
PREVIOUS OUTLOOK WAS TO EXTEND THE MARGINAL BACK THROUGH HOUSTON,
DUE TO THE POTENTIAL FOR ISOLATED CONVECTION THAT WILL STILL BE
CAPABLE OF VERY HEAVY RAINFALL. SHOULD AN EVENTUAL SLIGHT BE
NEEDED, IT WOULD LIKELY FOCUS ALONG THE URBAN I-10 CORRIDOR FROM
NEW ORLEANS EAST THROUGH PENSACOLA.
WEGMAN
..PREVIOUS DISCUSSION
SHOWERS AND THUNDERSTORMS ALONG AND AHEAD OF A SURFACE COLD FRONT
WILL BE LINGERING INTO THURSDAY FROM PARTS OF THE GULF COAST REGION
NORTHEASTWARD INTO PARTS OF GEORGIA AND SOUTH CAROLINA. AT THIS
POINT...RAINFALL RATES LOOK TO BE DECREASING AS THE BETTER UPPER
LEVEL DYNAMICS PULL OFF TO THE NORTHEAST AND LOW LEVEL FLOW BECOMES
DIRECTED ALONG...RATHER THAN NORMAL...TO THE FRONT. MAINTAINED A
MARGINAL RISK AREA WHERE THERE COULD BE OVERLAP WITH AREAS SOMEWHAT
HIGHER SOIL MOISTURE CONTENT FROM RECENT RAINFALL. OVERALL THE
RAINFALL LOOKS TO BE MORE BENEFICIAL THAN NOT.
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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