912
FOUS30 KWBC 070048
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
848 PM EDT MON JUL 6 2026
DAY 1
VALID 01Z TUE JUL 07 2026 - 12Z TUE JUL 07 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID ATLANTIC AND SOUTHERN NEW ENGLAND...
..MID ATLANTIC TO SOUTHERN NEW ENGLAND
PWAT ANOMALIES MAINTAIN +2 TO +3 DEVIATIONS AS WE MOVE THROUGH THE
EVENING ACROSS MUCH OF THE MID ATLANTIC AND NORTHEAST. LATEST
MESOANALYSIS INDICATES 2.0-2.4" PWAT RELEVANT ACROSS MUCH OF VA/NC
AND POINTS NORTHEAST ALONG AND EAST OF I=95. PRESENT PATTERN
INDICATES THE BEST INSTABILITY, HOWEVER, WILL RESIDE OVER VA/NC UP
THROUGH THE WESTERN HALF OF PA WITH ITS ORIENTATION DRIVEN BY THE
RESIDENCE OF A QUASI-STATIONARY FRONT OVER THE AREA. SCATTERED
THUNDERSTORMS ARE ALREADY CAUSING ISSUES ACROSS WESTERN PA DOWN
INTO WV AND VA GIVEN THE ENVIRONMENT IN PLACE WITH THE THREAT
LIKELY TO CONTINUE FOR SEVERAL MORE HOURS BEFORE DISSIPATION. THE
ACTIVITY ACROSS CENTRAL AND SOUTHEASTERN VA WILL LIKELY MAINTAIN A
PRESENCE BEYOND 06Z BEFORE FINALLY DWINDLING, BUT EVEN STILL SOME
CELLS COULD LINGER WELL INTO THE EARLY MORNING HOURS TUESDAY. LOW
FFG'S ACROSS MANY AREAS IN THE MID ATLANTIC PRECLUDED THE ACTIVITY
IN QUESTION, SO THE THREAT FOR FLASH FLOODING REMAINS MORE ELEVATED
THAN NORMAL. FOR MORE ON THE THREAT ACROSS WESTERN PA DOWN INTO THE
CENTRAL MID ATLANTIC, PLEASE SEE MPD #0632. FOR MORE INFORMATION ON
THE CURRENT THREAT INTO VA, SEE MPD #0630. GIVEN THE ABOVE, THE
SLGT RISK OVER WESTERN PA DOWN THROUGH THE CENTRAL AND SOUTHERN MID
ATLANTIC REMAINS WITH A HIGH- END SLGT FORECAST FOR THAT AREA OF
WESTERN PA BETWEEN I-80 DOWN TO THE M/D.
FOR THE NORTHEAST, SURFACE LOW WILL WANDER OFF THE NORTHERN MID
ATLANTIC COAST WITH SOME ONSHORE COMPONENT LIKELY TO MATERIALIZE
OVER PARTS OF SOUTHERN NEW ENGLAND. THE ISSUE IN SUSTAINING A MORE
APPRECIABLE THREAT FOR FLASH FLOODING IS THE LACK OF GENERAL
INSTABILITY WITH THE AREA THETA_E PATTERN RELATIVELY BENIGN FOR
AREAS INLAND, AWAY FROM THE COASTAL PLAIN. INCREASING LOW-LEVEL
CONVERGENCE WILL TRANSPIRE OVER SOUTHERN NEW ENGLAND WHICH COULD
PRODUCE SOME LOW-TOPPED CONVECTION CAPABLE OF LOCALLY HEAVY
RAINFALL GIVEN THE ANTECEDENT ENVIRONMENT. IN THIS CASE, THIS WAS
ENOUGH TO MAINTAIN THE SLGT RISK OVER THE ABOVE AREAS, BUT NOT
ENOUGH OF A RISK TO MAINTAIN THE PREVIOUS MODERATE RISK, SO THAT
WAS REMOVED WITH COORDINATION FROM THE LOCAL WFO'S.
..UPPER MIDWEST
ENERGETIC SHORTWAVE ROLLING THROUGH SOUTHERN CANADA EXTENDS INTO
THE NORTHERN TIER OF THE CONUS WITH THUNDERSTORMS MIGRATING
SOUTHEAST THROUGH THE NORTH WOODS OF MN. EXPECTATION IS FOR THE
CONVECTION TO BE HEAVY ENOUGH TO POTENTIALLY CAUSE SOME ISOLATED
FLASH FLOOD CONCERNS, BUT LIKELY TOO PROGRESSIVE TO CAUSE MORE
SIGNIFICANT PROBLEMS. WILL MONITOR THE SOUTHWESTERN EDGE OF THE
CONVECTIVE SIGNATURE FOR POSSIBLE TRAINING AS INDICATED VIA A FEW
OF THE CAMS THIS AFTERNOON/EVENING, BUT FOR NOW, THE MRGL RISK WAS
MORE THAN RELEVANT FOR THIS SETUP.
..TEXAS INTO TENNESSEE VALLEY
A FEW DISTURBANCES WILL INTERACT WITH A GENERALLY FAVORABLE
ENVIRONMENT IN PLACE TO ALLOW FOR AN ISOLATED FLASH FLOOD THREAT
FROM THE CENTRAL RGV ALL THE WAY BACK INTO THE TENNESSEE VALLEY.
A FEW MORE ORGANIZED COMPLEXES ARE MOVING THROUGH THE LOWER
MISSISSIPPI VALLEY CURRENTLY WHICH WILL BE THE ROOT OF ANY FLASH
FLOOD CONCERNS IN THAT AREA FOR THE NEXT SEVERAL HOURS. MRGL RISK
REMAINS IN THESE AREAS FOR THE LIMITED THREAT OVERNIGHT.
KLEEBAUER
DAY 2
VALID 12Z TUE JUL 07 2026 - 12Z WED JUL 08 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE NORTHERN PLAINS AND MID-ATLANTIC...
20Z UPDATE: A SLIGHT RISK WAS ADDED ACROSS PORTIONS OF THE MID-
ATLANTIC WHERE CELL MERGERS NEAR A BACKDOOR FRONT SHOULD LEAD TO
ISOLATED TO SCATTERED FLASH FLOODING. PRETTY GOOD AGREEMENT BETWEEN
THE 12Z HREF AND REFS ON THIS AXIS FROM PORTIONS OF SOUTHWEST PA
INTO CENTRAL VA AND NORTHEAST NC, WITH RAINFALL EXPECTED TO
LOCALLY EXCEED 3".
THE MARGINAL RISK WAS EXPANDED ACROSS THE TN VALLEY AND INTO
PORTIONS OF THE LOWER MS VALLEY. CONVECTION ALONG THIS CORRIDOR
SHOULD BE DISORGANIZED AND PULSE IN NATURE...HOWEVER LINGERING
HIGH MOISTURE AND INSTABILITY WILL SUPPORT HEAVY RAINFALL RATES
AND A LOCALIZED FLASH FLOOD RISK WHERE CELL MERGERS OCCUR.
THE SLIGHT RISK ACROSS PORTIONS OF THE DAKOTAS INTO MN STILL LOOKS IN
GOOD SHAPE, AND SO ONLY MINOR ADJUSTMENTS WERE MADE.
CHENARD
..PREVIOUS DISCUSSION
..NORTHERN PLAINS
DURING THIS PERIOD A SHORTWAVE ROUNDING THE RIDGE ANCHORED OVER THE
FOUR CORNERS WILL MAKE ITS WAY THROUGH CENTRAL MONTANA TO WESTERN
MINNESOTA. THIS SHORTWAVE WILL DRIVE DOWNSTREAM PVA AND HEIGHT
FALLS WHILE CONCURRENT BUT MODEST RRQ DIFFLUENCE IN THE TAIL OF A
DISTANT JET STREAK HELPS ENHANCE SYNOPTIC LIFT. AT THE SURFACE, A
WAVERING BOUNDARY WITH A WAVE OF LOW PRESSURE MOVING ALONG IT WILL
TRY TO SHIFT NORTH IN RESPONSE TO SUBTLY INCREASING SOUTHERLY LOW-
LEVEL FLOW, WITH THE RESULTING ISENTROPIC ASCENT AIDING LIFT ACROSS
THE REGION. THIS ROBUST ASCENT WILL ACT UPON PWS THAT WILL SURGE
TO 1.25 TO 1.75 INCHES, OR AROUND +2 SIGMA, COLLOCATED WITH A PLUME
OF MUCAPE EXCEEDING 2000 J/KG.
AREAL COVERAGE OF CONVECTION WILL INCREASE THROUGH THE DAY,
TRACKING FROM WEST TO EAST. THE ENVIRONMENT WILL BE FAVORABLE FOR
BACKBUILDING OR TRAINING. HOURLY RAINFALL AS MUCH AS 0.75"-1.0"+
IS LIKELY, WHICH COULD CREATE LOCALLY 2-3" OF RAINFALL AS REFLECTED
BY MODEST (5-15% CHANCE) OF 3"/24 HRS. SOILS ACROSS THIS PART OF
THE COUNTRY HAVE BEEN RECENTLY WET THUS INCREASING SENSITIVITY. A
SLIGHT RISK REMAINS IN EFFECT FROM THE EASTERN DAKOTAS TO WESTERN
WISCONSIN. A BROAD MARGINAL RISK EXTENDS FROM EASTERN MONTANA TO
NORTH-CENTRAL WISCONSIN.
..MID-ATLANTIC STATES
MUCH OF THIS REGION WILL CONTINUE TO HAVE SCATTERED TO WIDESPREAD
THUNDERSTORMS AS WEAK IMPULSES TRAVERSE THROUGH THE TROUGH
OVERHEAD. IN GENERAL, THESE STORMS SHOULD BE OF THE PULSE VARIETY
AND MOVE E/NE ON 15 KTS OF 0-6KM MEAN WIND. HOWEVER, THE IMPRESSIVE
THERMODYNAMICS IN PLACE (PWS OVER 1.75 INCHES OVERLAPPING MUCAPE
OF 1000-2000 J/KG) WILL SUPPORT RAINFALL RATES OF 1-2"/HR, THROUGH
WHICH ANY SHORT-TERM TRAINING OR REPEATING ROUNDS COULD LEAD TO
INSTANCES OF FLASH FLOODING.
..EASTERN MASSACHUSETTS & RHODE ISLAND
A WAVE OF LOW PRESSURE WILL BE TRACKING SOUTH OF RHODE ISLAND
DURING THIS PERIOD KEEPING SOME SHOWERS AND THUNDERSTORMS IN PLACE
ACROSS SOUTHERN NEW ENGLAND. ALTHOUGH NEW ACCUMULATIONS ARE
EXPECTED TO BE MODEST HOURLY RATES OF 1+ INCHES/HR WILL BE
POSSIBLE. A MARGINAL RISK AREA WAS MAINTAINED FOR THIS PERIOD.
WEISS/CAMPBELL
DAY 3
VALID 12Z WED JUL 08 2026 - 12Z THU JUL 09 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE UPPER MISSISSIPPI VALLEY/UPPER GREAT LAKES...
THE SLIGHT RISK OVER THE UPPER MIDWEST STILL LOOK PRETTY GOOD,
ALTHOUGH WE DID NUDGE IT A BIT SOUTH WITH THIS UPDATE. CONVECTION
SHOULD BE ONGOING AT 12Z WEDNESDAY MOVING FROM WEST TO EAST ACROSS
MN AND WI. WHILE THIS ACTIVITY COULD BE MOVING ALONG AND WEAKENING
DURING THE MORNING, WE SHOULD SEE RENEWED DEVELOPMENT ALONG THE
FRONT BY AFTERNOON FROM SOUTHEAST MN INTO WI. APPROACHING SHORTWAVE
ENERGY AND AN UPPER LEVEL JET WILL HELP DRIVE THIS UPTICK IN
ACTIVITY, WITH PWS ABOVE THE CLIMATOLOGICAL 90TH PERCENTILE AND
CAPE APPROACHING 2000 J/KG SUPPORTING HEAVY RAINFALL RATES. WHILE A
PROGRESSIVE SQUALL LINE SHOULD EVENTUALLY EVOLVE, THERE WILL BE AN
OPPORTUNITY FOR SOME TRAINING AND BACKBUILDING DURING THE
DEVELOPMENT AND INITIAL UPSCALE GROWTH PHASE OF CONVECTION.
RAINFALL TOTALS OF 1-2" SHOULD BE MOST COMMON, BUT LOCALIZED SWATHS
OVER 3" ARE PROBABLE AND SUPPORTED BY THE 12Z RRFS.
A MARGINAL RISK WAS ADDED ACROSS PORTIONS OF THE OH/TN VALLEY INTO
THE MID-ATLANTIC. A SHORTWAVE MOVING ACROSS KY/TN AND A LINGERING
BACKDOOR FRONT OVER WV/VA SHOULD BOTH ACT AS A FOCUS FOR
CONVECTIVE DEVELOPMENT WEDNESDAY. NOT EXPECTING ANYTHING TOO
ORGANIZED OR WIDESPREAD, BUT ENOUGH MOISTURE AND INSTABILITY WILL
BE AROUND TO SUPPORT LOCALLY HEAVY RAINFALL RATES.
CHENARD
DAY 4 AND DAY 5
VALID 12Z THU JUL 09 2026 - 12Z SAT JUL 11 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE OHIO VALLEY AND CENTRAL APPALACHIANS ON DAY 5...
20Z UPDATE: ADDITIONAL INFORMATION PROVIDED ON AN UPGRADE FOR THE
D5 PERIOD WITH A MAINTENANCE OF A BROAD MRGL FOR D4, BELOW.
STRONGER FLOW WILL INITIALLY REMAIN ALONG THE NORTHERN TIER OF THE
CONUS EARLY TO MID-WEEK WITH MEAN UPPER-RIDGING ACROSS THE WESTERN
TO CENTRAL U.S. EMBEDDED SHORTWAVES ROUNDING THE UPPER-RIDGE WILL
EVENTUALLY LEAD TO DEEPENING TROUGHING ACROSS THE THE MIDWEST AND
ADJACENT AREAS ON THURSDAY. THE SOUTHWARD SHIFT OF STRONGER FLOW
ALOFT INTO THE CENTRAL PLAINS EAST THROUGH THE MIDDLE
MISSISSIPPI/OHIO/TENNESSEE VALLEYS AND LOWER GREAT LAKES WILL BRING
MORE SCATTERED THUNDERSTORM CHANCES ACROSS THE REGION.
SEASONABLY HIGH INSTABILITY AND MOISTURE POOLING ALONG A SOUTHWARD
PROGRESSING, WAVY COLD FRONT WILL SUPPORT LOCALLY HEAVY RAINFALL
BRINGING THE THREAT FOR AT LEAST ISOLATED INSTANCES OF FLASH
FLOODING, AND A BROAD MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS
FOR D4 (THURSDAY) WITH ENOUGH CONFIDENCE TO UPGRADE A LARGE PORTION
OF THE OHIO VALLEY AND CENTRAL APPALACHIANS TO A SLGT RISK FOR D5
(FRIDAY) AS INCREASING LOW-LEVEL CONVERGENCE AMPLE MID-LEVEL ASCENT
WILL LIKELY TRIGGER WIDESPREAD CONVECTION WITH TRAINING POTENTIAL
OVER THE REGION, COMPOUNDING WITH ANY IMPACTS FROM CONVECTION THE
PREVIOUS FORECAST PERIOD. CONSENSUS GREW OVER THE PAST SERIES OF
NWP UPDATES WITH THE ENSEMBLE MEAN QPF STRUCTURE SIGNALING A LARGE
AREA OF 1-2" AREAL AVERAGE TOTALS WITH EMBEDDED HIGHER AMOUNTS
POSITIONED OVER THE SOUTHERN-THIRD OF IL/IN/OH THROUGH MUCH OF KY
INTO WV. THIS IS COINCIDENT WITH THE PROGRESSION OF BOTH THE FRONT
AND A STRENGTHENING SHORTWAVE TROUGH MIGRATING OUT OF THE CENTRAL
PLAINS INTO THE REGION AS WE MOVE INTO FRIDAY. ML OUTPUT IS ALSO
FAVORING THE OHIO RIVER BASIN INTO THE CENTRAL APPALACHIANS
EXTENDED FROM SOUTHWESTERN PA DOWN THROUGH WV AS TERRAIN INFLUENCES
ALONG WITH THE SYNOPTIC EVOLUTION WILL COUPLE INTO A TARGETED
THREAT FOR HEAVY RAINFALL AND LOCAL MAXIMA SUFFICIENT FOR SCATTERED
FLASH FLOOD PROSPECTS. PQPF FORECAST FOR AT LEAST 1" SIGNALS A
BROAD 20-40% PROBABILITY WITH A BULLSEYE OF 50-80% LOCATED OVER THE
CENTRAL APPALACHIAN FRONT IN NORTHERN WV. THIS IS A RELATIVELY
BULLISH SIGNATURE AT THIS LEAD, ENOUGH TO WARRANT AN UPGRADE TO A
SLGT RISK OVER THE AFOREMENTIONED AREAS FROM IL TO WV.
PUTNAM/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
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