282
FOUS30 KWBC 051956
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
256 PM EST THU MAR 5 2026
DAY 1
VALID 16Z THU MAR 05 2026 - 12Z FRI MAR 06 2026
...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE OHIO RIVER VALLEY AND THE SOUTHERN PLAINS...
16Z UPDATE...
SOME EXPANSION OF THE MARGINAL RISK HAS BEEN ACCOMMODATED FOR THE
LATE-MORNING UPDATE ACROSS THE EASTERN AREAS OF THE OH VALLEY AND
EXTENDING INTO PARTS OF THE CENTRAL APPALACHIANS WHERE SOME
ADDITIONAL MODERATE TO LOCALLY HEAVY RAINS WILL BE OVERLAPPING WITH
VERY LOW FFG VALUES. MUCH OF THE ADDITIONAL RAINFALL WILL BE
ASSOCIATED WITH PERSISTENT WARM AIR ADVECTION AND MOISTURE
TRANSPORT RIDING UP ACROSS THE REGION AHEAD OF THE UPSTREAM WAVE
ACTIVITY OVER THE OH VALLEY.
ACROSS THE SOUTHERN PLAINS, MORNING MCS ACTIVITY IS STILL
PERSISTING TO AN EXTENT OVER SOUTHEAST OK AND A VERY SMALL PART OF
FAR WESTERN AR, BUT THIS ACTIVITY SHOULD GRADUALLY WEAKEN GOING
INTO THE EARLY AFTERNOON HOURS. A MARGINAL RISK EXTENSION REMAINS
IN PLACE ACROSS THESE AREAS.
MEANWHILE, FARTHER BACK TO THE SOUTHWEST TOWARD THE TX HIGH PLAINS,
THERE IS EXPECTED TO BE AN OUTBREAK OF STRONG TO SEVERE THUNDERSTORMS
ALONG AND EAST OF A DRYLINE WHICH WILL INVOLVE AREAS OF NORTHWEST
TX AND THE TX PANHANDLE. THIS WILL BE FACILITATED BY A COMBINATION
OF STEEP MID-LEVEL LAPSE RATES AND THE POOLING OF ANOMALOUS LOW-
LEVEL MOISTURE AHEAD OF HEIGHT FALLS GRADUALLY PIVOTING ACROSS THE
GREAT BASIN AND PORTIONS OF THE SOUTHWEST. GIVEN THE SHEAR AND CAPE
PROFILES FORECAST ACROSS THE REGION, THE DEVELOPMENT OF SUPERCELL
THUNDERSTORMS IS EXPECTED WHICH MAY GROW UPSCALE THIS EVENING INTO
A LARGER MCS. INITIAL SEVERE CONVECTION OVER THE TX HIGH PLAINS MAY
BE CAPABLE OF PRODUCING RAINFALL RATES UP TO 2 INCHES/HOUR WHICH
MAY INDUCE SOME ISOLATED (AND MAINLY URBAN) FLASH FLOODING
CONCERNS. HOWEVER, THERE ARE A FEW CAMS (I,E, ARW/ARW2 AND RRFS)
SUGGESTING THAT MCS ACTIVITY WITH HIGH RAINFALL RATES AND
POTENTIALLY SOME CELL-TRAINING COULD IMPACT PARTS OF SOUTHWEST AND
WEST-CENTRAL OK LATER THIS EVENING. THIS MAY DRIVE SOME LOCALLY
HEAVY RAINFALL TOTALS HERE REACHING 2 TO 4 INCHES. THEREFORE, THE
MARGINAL RISK HAS BEEN EXPANDED WEST AND SOUTHWEST TO ADDRESS THESE
CONCERNS.
ORRISON
PREVIOUS DISCUSSION...
..OHIO RIVER VALLEY
POTENT MID-LEVEL SHORTWAVE PROPAGATION OVER THE CENTRAL PLAINS WILL
CONTINUE OVER THE COURSE OF THIS EVENING INTO D1 WITH A CORE AXIS
OF DIFFLUENCE CENTERED OVER THE MID-MISSISSIPPI AND OHIO VALLEYS IN
THE BEGINNING OF THE PERIOD. MULTIPLE VORTICITY MAXIMA WILL EJECT
NORTHEAST OUT OF THE OZARKS AREA WITH A STATIONARY FRONT AT THE
SURFACE BISECTING AREAS FROM NORTH TX UP THROUGH THE OHIO RIVER
BASIN. MOISTURE TRANSPORT WITH THE SETUP IS PRETTY MUCH ALIGNED
PARALLEL TO THE MEAN FLOW LEADING TO MORE ORGANIZED CONVECTIVE
CLUSTERS PROPAGATING ALONG THE FRONT, DISSEMINATING SOME RELATIVELY
SOLID QPF OUTPUT FROM DALLAS UP THROUGH THE NORTH-CENTRAL OHIO
VALLEY. MODELS ARE IN AGREEMENT ON THE SHORTWAVE PROPAGATION OUT OF
THE OZARKS THIS EVENING TO MIGRATE NORTHEAST WITH AN EVENTUAL
SECONDARY WAVE OF HEAVY PRECIP IMPACTING AREAS ALONG THE OHIO RIVER
BASIN, INCLUDING AS FAR WEST AT THE CONFLUENCE OF THE
OHIO/MISSISSIPPI RIVERS AND POINTS EAST-NORTHEAST ALONG THE OHIO
RIVER BORDERING KY/IL/IN/OH. MULTI-DAY RAINFALL OUTPUT WILL PLACE
AREAS OF IN/OH WITHIN ANOTHER PERIOD OF RAINFALL WHICH IS ALREADY
CAUSING ISSUES FOR PLACES SOUTH OF I-70 IN BOTH STATES.
HEAVIEST RAINFALL IS PROGGED TO OCCUR TO THE SOUTHWEST WITH THE
SIGNAL VIA THE LATEST 00Z HREF REALLY EMPHASIZING THE CORRIDOR AT
THE CONFLUENCE OF THE MISSISSIPPI/OHIO RIVERS UP THROUGH THE
KY/IL/IN BORDER, MUCH OF WHICH FALLING BETWEEN THE 12-21Z TIME
FRAME TODAY. NEIGHBORHOOD PROBS FOR >2" ARE BETWEEN 40-60% OVER THE
AFOREMENTIONED AREA WITH A FEW DETERMINISTIC CAMS PRODUCING
BETWEEN 3-5" OVER THE TIME FRAME. CONSIDERING THE NATURE OF THE
OVERLAP OF HEAVY RAINFALL OCCURRING TONIGHT AND THEN AGAIN IN THE
MORNING/EARLY AFTERNOON, THERE WAS ENOUGH OF A SIGNAL TO ADD A MRGL
RISK FOR THE REGION IN QUESTION.
..SOUTHERN PLAINS
STATIONARY BOUNDARY ACROSS TX WILL LIFT NORTH DURING THE MORNING
AND AFTERNOON PERIOD TODAY WITH A QUICK THETA_E ADVECTION REGIME
TAKING SHAPE ACROSS MUCH OF THE SOUTHERN PLAINS. UPSTREAM TROUGH
AXIS PUSHING THROUGH THE WEST WILL HELP TO RE-AMPLIFY THE FLOW
ACROSS THE SOUTH-CENTRAL U.S. WITH A LOW PRESSURE CENTER FORMING
ACROSS THE FRONT RANGE WITH A TRAILING DRYLINE MATURING ACROSS THE
WESTERN TX PANHANDLE UP DOWN THROUGH SOUTHWEST TX. INCREASING
ASCENT WITHIN THE DIFFLUENT AXIS DOWNSTREAM OF THE LONGWAVE TROUGH, AMPLE
INSTABILITY LOCATED DOWNSTREAM OF THE DRYLINE, AND INCREASED BULK
SHEAR PROFILES WILL PROMOTE A FAVORABLE INSTANCE OF CONVECTIVE
DEVELOPMENT AND MAINTENANCE OF PRESENT UPDRAFTS. NAEFS PWAT
PERCENTILE FORECAST IS PUSHING THE 99TH PERCENTILE VIA
CLIMATOLOGICAL NORMS ACROSS THE REGION FROM THE RED RIVER, NORTH
THROUGH THE WESTERN HALF OF OK INTO SOUTHERN KS BY LATE THIS
AFTERNOON AND BEYOND. THIS IS A TESTAMENT TO THE ANTICIPATED
PROLIFERATION OF CONVECTIVE CELLS WITHIN THE FAVORABLE ENVIRONMENT,
EACH OF WHICH WILL BE CAPABLE OF HEAVY RAIN CORES WITH HOURLY RATES
PUSHING 2-3"/HR AT PEAK INTENSITY AS NOTED VIA SOME OF THE LATEST
CAMS. DESPITE THIS AREA SIGNIFYING HIGHER FFG'S DUE TO A DEARTH OF
PRECIPITATION LATELY, THIS SETUP IS CONDUCIVE FOR STRONGER
CONVECTION AS NOTED VIA THE SPC'S SLIGHT RISK OUTLOOK FOR SEVERE
WEATHER FOCUSED WITHIN THAT AREA DOWNSTREAM OF THE DRYLINE. A LOW-
END SCENARIO FOR FLASH FLOODING IS THE FORECAST FOR THIS PARTICULAR
DOMAIN JUST GIVEN THE DEEP MOIST FAVORABILITY, AS WELL AS THE
ORGANIZED CONVECTIVE PATTERN LIKELY TO EXHIBIT SOME PRETTY HEFTY
RAINFALL IN LOCALIZED AREAS AS THE CELLS MIGRATE TO THE EAST AND
NORTHEAST. A MRGL RISK WAS ADDED FOR THE REGION ENCOMPASSING NORTH
TX UP THROUGH WESTERN OK INTO SOUTHERN KS.
KLEEBAUER
DAY 2
VALID 12Z FRI MAR 06 2026 - 12Z SAT MAR 07 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE LOWER MISSISSIPPI VALLEY, INCLUDING THE ARKLATEX...
20Z UPDATE: ONLY MINOR CHANGES MADE TO THE INHERITED RISK AREAS.
QPF HAS TRENDED UP A BIT ACROSS EASTERN IA INTO NORTHERN IL AND
SOUTHERN WI, BUT ACTIVITY LOOKS QUICK MOVING. THUS FLASH FLOOD
IMPACTS ARE STILL EXPECTED TO STAY ISOLATED.
CHENARD
..PREVIOUS DISCUSSION
..ARKLATEX TO LOWER MISSISSIPPI VALLEY
HIGHLY AMPLIFIED PATTERN ACROSS THE WESTERN CONUS WILL SHIFT
EASTWARD OVER THE COURSE OF THE END OF THE WEEK AND WEEKEND LEAVING
A BROAD AXIS OF CONVECTIVE DEVELOPMENT DOWNSTREAM OVER THE SOUTHERN
PLAINS UP INTO THE MIDWEST TO THE MISSISSIPPI VALLEY. GUIDANCE IS
BEGINNING TO COME INTO AGREEMENT ON THE AREA LOCATED FROM NORTHEAST
TX UP THROUGH THE ARKLATEX TO THE WESTERN HALF OF THE LOWER
MISSISSIPPI VALLEY A FOCAL POINT FOR HEAVY, ORGANIZED CONVECTION
CAPABLE OF FLASH FLOOD CONCERNS. INSTABILITY AND MOISTURE PRESENCE
WILL NOT BE LIMITED IN THIS SYNOPTIC EVOLUTION WITH A ROBUST
MERIDIONAL PUSH OF FAVORABLE THETA_E'S THANKS TO A FUNNELING OF
GULF MOISTURE POLEWARD DOWNSTREAM OF THE MEAN TROUGH. SLOW-MOVING
COLD FRONT ACROSS THE CENTRAL AND SOUTHERN PLAINS WILL PICK UP
SPEED BY THE END OF THE FORECAST PERIOD WITH A DEFINED WARM SECTOR
SITUATED FROM THE EASTERN HALF OF TX UP THROUGH THE MISSOURI VALLEY
WITH PWAT ANOMALIES PUSHING 2-3 STANDARD DEVIATIONS ABOVE NORMAL
FOR THE TIME FRAME. ENSEMBLE BIAS CORRECTED QPF IS NOW PUSHING OVER
2" ACROSS THE ARKLATEX WITH THE CONVERGENCE SIGNAL STRONGEST OVER
THE THREE-STATE REGION AS THE NOCTURNAL LLJ IS FORECAST TO NOSE
INTO THE AREA PROMOTING THE MOST FAVORABLE AXIS FOR ORGANIZED
CONVECTION AND EVENTUAL CELL MERGERS AFTER SUNSET. CAMS ARE STILL A
BIT OUT OF RANGE FOR THIS THREAT, HOWEVER THE SIGNALS ARE ALREADY
CREEPING INTO THE END OF THEIR TEMPORAL RANGES WITH SOME ALREADY
SHOWING 2" OF PRECIP WITH MORE TO COME ACROSS THIS AREA OF THE
CONUS. THIS SETUP IS BORDERING TEXTBOOK FOR THESE KINDS OF
CONVECTIVE EVOLUTIONS AND IMPACTS WHICH LENDS ENOUGH FAVOR TO
UPGRADE THE PREVIOUS MRGL RISK INHERITANCE TO A SLGT RISK FOR THE
HIGHLIGHTED ZONES. THIS SETUP IS ONE TO MONITOR AS SHORT TERM
CONVECTIVE TRENDS COULD ADJUST THE RISK POSITIONING FURTHER WEST
THANKS TO THE OVERALL AMPLIFIED EVOLUTION.
..MIDWEST
AMPLIFIED PATTERN TO THE WEST WILL IMPACT THE NORTH-CENTRAL CONUS,
AS WELL AS THE WAVY STATIONARY FRONT OVER THE CENTRAL PLAINS AND
MISSISSIPPI VALLEY WILL LIFT RAPIDLY TO THE NORTH AS A WARM FRONT,
ALLOWING FOR A STEADY INCREASE IN REGIONAL BUOYANCY AND DEEP
MOISTURE PRESENCE. UPPER PATTERN OUT WEST WILL EVOLVE INTO A SETUP
THAT SPLITS THE MAIN SHORTWAVE IN TWO, EJECTING A PIECE OF THE
MID-LEVEL VORTMAX RAPIDLY TO THE NORTHEAST LEADING TO LEE
CYCLOGENESIS OVER WESTERN KS, LIFTING TO THE NORTHEAST. THE
COMBINATION OF INCREASING SHEAR AND ASCENT AT BOTH THE SURFACE AND
ALOFT WILL ALLOW FOR A HEAVY CONVECTIVE CONGLOMERATION TO
MATERIALIZE OVER THE MISSOURI RIVER VALLEY AND POINTS EAST WITH
SIGHTS ON THE MIDWEST WITH A CENTROID OVER IA/SOUTHERN WI/NORTHWEST
IL. THE GOOD NEWS IS THE SETUP IS PROGGED TO BE MOVING QUICKLY, SO
ANY IMPACTS WILL BE SHORT BUT LOCALLY INTENSE. LOCALIZED FLASH
FLOOD PROSPECTS ARE FORECAST FOR THE ABOVE AREAS AS THE CONVECTIVE
PATTERN WILL PROMOTE RATES BETWEEN 1-2"/HR AT PEAK INTENSITY,
ENOUGH TO APPROACH, AND/OR ECLIPSE THE LOWER END OF THE FFG
THRESHOLDS IN PLACE. THE PREVIOUS MRGL RISK WAS MAINTAINED AS A
RESULT WITH ONLY MINOR ADJUSTMENTS MADE TO THE EAST AND NORTHEAST
FRINGES TO THE RISK AREA.
KLEEBAUER
DAY 3
VALID 12Z SAT MAR 07 2026 - 12Z SUN MAR 08 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE SOUTHERN PLAINS INTO THE LOWER MISSISSIPPI VALLEY...
20Z UPDATE: WE INTRODUCED A SLIGHT RISK ACROSS PORTIONS OF TX INTO
MS, WHERE A CORRIDOR OF HEAVY RAINFALL IS EXPECTED. THE ACTUAL
EXTENT AND MAGNITUDE OF THE FLASH FLOOD RISK REMAINS A BIT
UNCERTAIN RELATING TO HOW QUICKLY ACTIVITY PROPAGATES OFF TO THE
SOUTH AND EAST. SOME GUIDANCE SUPPORTS A RATHER QUICK SOUTHWARD
PROPAGATION OF CONVECTION, WHICH COULD KEEP THE FLASH FLOOD RISK
MORE ISOLATED IN NATURE. HOWEVER, THERE SHOULD STILL BE AN
OPPORTUNITY FOR SOME ALONG AXIS TRAINING EVEN WITH SOME SOUTHWARD
PROPAGATION. UPPER LEVEL DIVERGENCE IS STRONG, PWS HIGH AND, WHILE
WEAKENING THROUGH THE DAY, THERE IS A CORRIDOR OF LOW LEVEL
CONVERGENCE. THE CSU ML ERO ALSO INDICATES A BROAD SLIGHT RISK,
WITH EVEN SOME 25% PROBABILITIES DEPICTED. THUS THINK THERE IS
ENOUGH GOING FOR THIS EVENT TO JUSTIFY INTRODUCING A BROAD SLIGHT
RISK WITH THIS UPDATE.
A MARGINAL RISK WAS ALSO EXTENDED AS FAR NORTH AS WESTERN NY.
PLENTY OF MOISTURE WILL ADVECT NORTHWARD ALONG THIS CORRIDOR, WITH
AS MUCH AS 500-1000 J/KG OF CAPE AS WELL. THUS WHILE AREAL
AVERAGED RAINFALL IS NOT THAT IMPRESSIVE, THERE WILL BE AN
OPPORTUNITY FOR LOCALLY HEAVY RATES. WITH SATURATED CONDITIONS
OVER PORTIONS OF THE OH VALLEY, AND SOME SNOW PACK AND FROZEN
GROUND OVER NY...THESE HIGHER RATES COULD BE ENOUGH TO LOCALLY
RESULT IN EXCESS RUNOFF AND MINOR FLOOD CONCERNS.
CHENARD
...PREVIOUS DISCUSSION
AS THE LONGWAVE PATTERN ACROSS THE WESTERN HALF OF THE CONUS
MATERIALIZES AND THE SURFACE REFLECTIONS MAKE THEIR HEADWAY TO THE
EAST/NORTHEAST, THE COLD FRONT TRAILING THE PRIMARY LOW MOVING
INTO THE GREAT LAKES WILL CONTINUE ITS PROGRESS THROUGH THE
SOUTHERN PLAINS INTO THE MISSISSIPPI VALLEY LOSING LATITUDE AS IT
PROPAGATES TO THE SOUTHEAST. AS THE LOW MOVES FURTHER AWAY AND THE
SETUP BEGINS TO LOSE UPPER LEVEL FAVOR, THE COLD FRONT IS EXPECTED
TO "FAN OUT" AS IT APPROACHES THE GULF COAST LEADING TO CONVECTIVE
ALIGNMENT ALONG AND JUST AHEAD OF THE FRONT TO SLOW ITS PROGRESSION
WITH THE MEAN FLOW BECOMING A BIT MORE PARALLEL TO THE FRONTAL
ALIGNMENT. MOISTURE AND INSTABILITY WILL BE PLENTIFUL WITH THE
ENVIRONMENT PRIMED FROM A RICH GULF MOISTURE ADVECTION REGIME THAT
WILL TAKE PLACE THE PREVIOUS 48 HRS. MODELS ARE IN AGREEMENT ON AN
AXIS OF HEAVY QPF LOCATED FROM TX TO POINTS NORTHEAST OVER PORTIONS
OF AR/LA/WESTERN TN/NORTHWEST MS. THERE WILL LIKELY BE AN AREA OF
3+" OF PRECIP AS NOTED VIA MODEST NBM PROBS FOR THE THRESHOLD
(10-30%) AND 90TH PERCENTILE QPF OUTPUT PUSHING OVER 3" FOR PART OF
EAST TX INTO NORTHERN LA WITH WIDESPREAD 2+" OUTPUTS SURROUNDING.
THIS SETUP IS NOTORIOUS FOR CONDITIONS TO PRIME AND FAVOR AREAS
FURTHER SOUTHEAST JUST DUE TO THE BETTER INSTABILITY MAXIMA AND
DEEPER MOISTURE LAYER AHEAD OF THE FRONT NATURALLY POSITIONED
CLOSER TO THE GULF COAST. PENDING FORWARD PROPAGATION SPEED OF THE
COLD FRONT, HEAVY RAINFALL COULD VERY WELL MAKE A PUSH TOWARDS THE
I-10 CORRIDOR DOWN BY HOUSTON TO LAKE CHARLES, BUT THE JURY IS
STILL OUT FOR THOSE AREAS. HIGHER CONFIDENCE IN HEAVY RAINFALL IS
JUST NORTH OF THERE WITH THE AREAS OF THE PINEY WOODS IN EAST TX UP
THROUGH I-20 INTO LA AS THE MAIN TARGETS AT THIS JUNCTURE. HIGH
FFG'S WILL LIKELY THWART CONSIDERABLE FLOOD PROSPECTS, AS WELL AS
THE SETUP PROMOTING AT LEAST STEADY CONVECTIVE PROGRESS TO LOWER
TRAINING CONCERNS. THAT STILL DOESN'T MEAN THOSE CONCERNS WOULD
ALLEVIATE AT LEAST SCATTERED FLASH FLOOD CONCERNS, BUT THERE'S
STILL MORE TIME TO ASSESS LOCATION SPECIFICS BEFORE INTERJECTING AN
UPGRADE AT THIS TIME. FOR NOW, A BROAD MRGL RISK WAS MAINTAINED,
BUT THE THREAT WILL WARRANT SOME CONSIDERATION OF AN UPGRADE AS WE
MOVE CLOSER IN TIME AND GET INTO THE CAMS TEMPORAL WINDOW(S).
KLEEBAUER
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page