568
FOUS30 KWBC 051545
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1145 AM EDT SUN JUL 5 2026
DAY 1
VALID 12Z SUN JUL 05 2026 - 12Z MON JUL 06 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FROM EASTERN
PENNSYLVANIA THROUGH SOUTHEAST NEW YORK...
..OHIO VALLEY INTO THE MID-ATLANTIC & NORTHEAST
IMPRESSIVE PLUME OF TROPICAL MOISTURE EXTENDING FROM THE GULF COAST
THROUGH SOUTHERN NEW ENGLAND WILL PRODUCE AN ENVIRONMENT FAVORABLE
FOR HEAVY RAINFALL TODAY. 12Z RAOBS FROM PIT/IAD/OKX ALL MEASURED
PWS BETWEEN 1.75 AND 1.95 INCHES, WELL ABOVE THE 90TH PERCENTILE
FOR THE DATE AND NEARING DAILY-RECORDS. THIS IS SUGGESTIVE OF THE
TROPICAL AIRMASS, AND WEAK LAPSE RATES WITHIN A SATURATED COLUMN
WITH FREEZING LEVELS NEARING 14,000 FT POINT TOWARDS AN ENVIRONMENT
WHICH WILL SUPPORT HEAVY RAINFALL IN ALL THUNDERSTORMS TODAY.
FORCING FOR ASCENT INTO THIS ENVIRONMENT WILL BECOME INCREASINGLY
ROBUST THROUGH THE DAY AS WELL. A FRONT ANALYZED BY WPC DRAPED FROM
ILLINOIS TO LONG ISLAND WILL OSCILLATE NORTH/SOUTH TODAY AS A
STATIONARY FRONT, ALONG WHICH WAVES OF LOW PRESSURE WILL RIPPLE
EASTWARD, AIDED BY SHORTWAVES PUSHING EASTWARD WITHIN THE FLOW.
THESE WAVES WILL NOT ONLY PROVIDE ENHANCED ASCENT, BUT ALSO FORCE
LOCALLY ACCELERATED MOIST INFLOW AND SHEAR TO CREATE CLUSTERS OF
MORE ORGANIZED CONVECTION WITH HEAVIER RAINFALL. THIS IS REFLECTED
BY BOTH HREF AND REFS PROBABILITIES THAT EXCEED 40% FOR 2"/HR
RAINFALL RATES, THIS MORNING/AFTN IN THE OH VLY AND THEN THIS
EVENING FOR THE MID-ATLANTIC STATES. WITH CORFIDI VECTORS ALIGNED
TO THE MEAN 0-6KM WIND, BACKBUILDING/TRAINING OF ECHOES IS LIKELY,
SO CORRIDORS OF HEAVY RAIN EXCEEDING 3" ARE LIKELY (60-80% CHANCE)
WITH MORE THAN 5" POSSIBLE (30-50%) CHANCE.
THE GREATEST RISK AREAS FOR THE HEAVIEST RAIN ARE FOCUSED IN SE
MI/NW OH AS WELL AS EASTERN PA/NORTHERN NJ/SOUTHEAST NY WHERE HREF
PROBABILITIES FOR 8"/24HRS SHOW LOW BUT MEANINGFUL (5-10%)
PROBABILITIES. WHILE SOIL MOISTURE ACCORDING TO NASA SPORT IS WELL
BELOW NORMAL IN THE FORMER (0-40CM SOIL MOISTURE IN THE 10TH
PERCENTILE), IT IS MUCH MORE SATURATED IN PA/NJ. ADDING IN THE
URBAN INFLUENCES ACROSS PA/NJ/NY, THE INHERITED MDT RISK STILL
APPEARS NEEDED, AND HAS BEEN EXPANDED NORTHEAST INTO FAR SOUTHEAST
UPSTATE NY TO ACCOUNT FOR LATEST TRENDS. AT THIS TIME, NEW YORK
CITY APPEARS TO REMAIN JUST WEST OF THE HEAVIEST RAINFALL SO WAS
EXCLUDED FROM THE MDT RISK AREA, BUT OTHERWISE, IT APPEARS LIKELY
THAT NUMEROUS IMPACTS FROM FLASH FLOODING WILL OCCUR TODAY IN THIS
AREA, WITH LOCALLY SIGNIFICANT EVENTS POSSIBLE.
..SOUTHERN PLAINS AND GULF COAST THROUGH THE TENNESSEE VALLEY
BROAD MID-LEVEL TROUGH WILL REMAIN ALIGNED SW TO NE FROM TEXAS
THROUGH KENTUCKY THROUGH TODAY. WITHIN THIS TROUGH, SEVERAL WEAK
MID-LEVEL IMPULSES ARE PROGGED TO ROTATE E/NE THROUGH THE FLOW,
PROVIDING LOCALLY ENHANCED ASCENT WITHIN AN ALREADY UNSTABLE
ATMOSPHERE CHARACTERIZED BY WIDESPREAD MUCAPE AROUND 3000 J/KG. AT
THE SURFACE, A WEAK COLD FRONT WILL DROP SOUTHEAST, REACHING ALONG
A LINE FROM KENTUCKY TO THE RED RIVER VALLEY OF THE SOUTH BY THIS
EVENING BEFORE STALLING. THE OVERLAP OF THE WEAK IMPULSES ON THIS
BAROCLINIC GRADIENT WILL HELP CREATE RIPPLES OF LOW PRESSURE, AND
THIS EXTRA LIFT WILL HELP CREATE SCATTERED THUNDERSTORMS TODAY.
PW ANOMALIES OF +1 (TO LOCALLY +1.5) SIGMA WILL SUPPORT HEAVY
RAINFALL RATES OF 1-3"/HR, WHICH THROUGH WEAK STORM MOTIONS (0-6KM
MEAN WINDS OF JUST 5-10 KTS AND VARIABLE DIRECTION) WILL CREATE
AREAS OF HEAVY RAINFALL CAPABLE OF PRODUCING AT LEAST ISOLATED
INSTANCES OF FLASH FLOODING. BOTH THE HREF AND REFS 24-HR
NEIGHBORHOOD RAINFALL PROBABILITIES SHOW SCATTERED AREAS OF GREATER
THAN 30% CHANCE FOR AT LEAST 3" OF RAIN IN A LARGE AREA, BUT THE
WEAK SHEAR TO SUPPORT GENERALLY PULSE CONVECTION SHOULD LIMIT MORE
WIDESPREAD/ORGANIZED AMOUNTS TO THIS LEVEL. IN GENERAL, THE
INHERITED MRGL RISK WAS MAINTAINED WITH ONLY COSMETIC ADJUSTMENTS.
HOWEVER, AN EXPANSION WEST OF THE MRGL WAS CREATED ALONG THE RED
RIVER VALLEY NEAR THE OK/TX BORDER FOR SOME POTENTIAL MULTI-CELL
DEVELOPMENT EXHIBITING SHORT-TERM TRAINING TONIGHT.
..FLORIDA PENINSULA
AFTER COORDINATION WITH WFOS MLB/JAX, ADDED A SMALL MRGL RISK FOR
THE EASTERN THIRD OF THE FLORIDA PENINSULA FOR TODAY. RIDGE OF HIGH
PRESSURE CENTERED JUST WEST OF THE STATE WILL PRODUCE GENERALLY
WEAK MEAN FLOW, BUT WITH SUBTLE UPPER DIFFLUENCE. GENERALLY SW
WINDS WILL HELP CONVECTION TRACK SLOWLY NORTHEAST INTO THE
AFTN/EVE, WHICH WILL LIKELY RESULT IN SEA-BREEZE COLLISIONS ON THE
ATLANTIC COAST LATER TODAY WITH STORMS STALLING/REGENERATING IN THE
PULSE ENVIRONMENT. PWS ABOVE 2" WILL SUPPORT 1-3"/HR RAIN RATES
(30-50% CHANCE FOR 2"/HR FROM BOTH THE REFS AND HREF), WHICH
THROUGH STALLING/SLOW MOTIONS COULD RESULT IN AREAS OF 3-5" OF
RAINFALL. SHOULD ANY STORMS STALL ACROSS THE MORE URBAN AREAS OR
ATOP SOILS MORE SENSITIVE FROM 24-HR RAINFALL AS MUCH AS 4",
INSTANCES OF FLASH FLOODING COULD RESULT.
WEISS
DAY 2
VALID 12Z MON JUL 06 2026 - 12Z TUE JUL 07 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID-ATLANTIC/NORTHEAST...
THE THREAT FOR EXCESSIVE RAINFALL AND SCATTERED AREAS OF FLASH
FLOODING WILL REMAIN FOR PORTION OF THE MID-ATLANTIC FOR THIS
PERIOD. RAINFALL OCCURRING DURING THE DAY 1 AND DAY 2 PERIODS MAY
LEAD TO INCREASED SOIL SATURATION AND LOWERED FLASH FLOOD GUIDANCE
FOR THIS REGION, THUS MAKING IT MORE SENSITIVE FOR ADDITIONAL HEAVY
RAINFALL. NEAR AND JUST SOUTH OF THIS FRONT INSTABILITY OF 2000
J/KG OR GREATER AND PWS OVER 2" ARE FORECAST, AN ENVIRONMENT
SUPPORTING EFFICIENT RAINFALL AND HIGH HOURLY RATES. THE INHERITED
SLIGHT RISK AREA WAS ADJUSTED TO REFLECT THE LATEST TRENDS AND WPC
QPF PLACEMENT. AS FOLLOWS, THE SOUTHERN BOUNDARY OF THE SLIGHT WAS
EXTENDED SOUTH TOWARD THE VIRGINIA AND NORTH CAROLINA BORDER TO
CAPTURE LOCATIONS WERE HI-RES GUIDANCE IS SUGGESTING LOCALIZED 3+
INCHES, PARTICULARLY ALONG I-95 AND ADJACENT URBAN AREAS.
STRONGER LOW LEVEL CONVERGENCE WILL BE CAPABLE OF PRODUCING A
BROADER AREA OF MODERATE TO LOCALLY HEAVY RAINFALL ACROSS NEW YORK
INTO SOUTHERN NEW ENGLAND. HOWEVER A LIMITING FACTOR WILL BE
REDUCED AVAILABILITY OF INSTABILITY-- RAINFALL RATES WILL LIKELY
NOT PEAK AS HIGH AS THOSE FURTHER SOUTH. THUS, THIS AREA IS COVERED
BY A BROAD MARGINAL RISK FROM PORTIONS OF UPSTATE NEW YORK TO THE
CAPE, SOUTH TO THE CAROLINAS AND THEN SOUTHWEST INTO ARKANSAS AND
NORTHERN LOUISIANA.
..MONTANA
ISOLATED INSTANCES OF HEAVY RAINFALL WILL BE POSSIBLE CAPABLE OF
PRODUCING LOCALIZED FLASH FLOODING POSSIBLE FOR AREAS AHEAD OF AND
ALONG AN APPROACHING FRONT. A SHORTWAVE TROUGH ROUNDING THE BASE
OF THE BUILDING SOUTHWESTERN RIDGE WILL TRIGGER CONVECTION. A
MARGINAL RISK WAS MAINTAINED AS WELL AS EXPANDED TO THE
WEST/SOUTHWEST TO COVER MOVER OF CENTRAL/WESTERN PARTS OF THE
STATE.
CAMPBELL
DAY 3
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...
..NORTHERN PLAINS
A SEASONABLY MOIST, UNSTABLE AIRMASS WILL BE IN PLACE ALONG THE
NORTHERN SIDE OF AN UPPER-RIDGE BUILDING OVER THE WESTERN TO
CENTRAL U.S. EARLY NEXT WEEK. AN UPPER-LEVEL WAVE ROUNDING THE
RIDGE WILL HELP TRIGGER SCATTERED TO WIDESPREAD THUNDERSTORM
DEVELOPMENT AT THE LEADING EDGE OF THE DEEPER MOISTURE OVER THE
NORTHERN HIGH PLAINS. PROPAGATION AHEAD OF A DEVELOPING SURFACE
WAVE ALONG A QUASI-STATIONARY FRONTAL BOUNDARY AND DEVELOPING LOW-
LEVEL JET WILL HELP MAINTAIN STORMS INTO THE OVERNIGHT HOURS
THROUGH THE NORTHERN PLAINS WITH THE POTENTIAL FOR AT LEAST
ORGANIZED CLUSTERS OF STORMS IF NOT A MESOSCALE CONVECTIVE SYSTEM.
GOOD CONSENSUS AMONGST THE DETERMINISTIC MODEL GUIDANCE ON AREAL
AVERAGE TOTALS IN THE 1-2" RANGE AND LOCALLY HIGHER AMOUNTS OF 3-4"
SUPPORTS THE THREAT FOR SCATTERED FLASH FLOODING. A SLIGHT RISK IS
IN EFFECT FOR PORTIONS OF THE DAKOTAS AND INTO WEST/CENTRAL
MINNESOTA. A MARGINAL RISK AREA SPANS FROM EASTERN MONTANA, MOST OF
THE DAKOTAS AND MINNESOTA, FAR NORTHWEST IOWA AND NORTHWEST
WISCONSIN.
..MID-ATLANTIC TO CAROLINAS
PERSISTENT TROUGHING OVER THE REGION ALONG ADEQUATE INSTABILITY AND
PW VALUES AROUND 2 INCHES WILL KEEP CONVECTION ACROSS THE AREA FOR
THIS PERIOD. ISOLATED TO SCATTERED CONVECTION CAPABLE OF HEAVY
RAINFALL RATES WILL MAINTAIN A MARGINAL RISK FOR EXCESSIVE RAINFALL
IN PLACE FOR THIS PERIOD.
PUTNAM/CAMPBELL
DAY 4 AND DAY 5
VALID 12Z WED JUL 08 2026 - 12Z FRI JUL 10 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE UPPER GREAT LAKES WEDNESDAY...
A SEASONABLY MOIST, UNSTABLE AIRMASS WILL BE IN PLACE ALONG THE
NORTHERN SIDE OF AN UPPER-RIDGE BUILDING OVER THE WESTERN TO
CENTRAL U.S. EARLY NEXT WEEK. AN UPPER-LEVEL WAVE ROUNDING THE TOP
OF THE RIDGE WILL HELP TRIGGER SCATTERED TO WIDESPREAD THUNDERSTORM
DEVELOPMENT ALONG A FRONTAL BOUNDARY THROUGH THE NORTHERN
PLAINS/UPPER MIDWEST TUESDAY WITH ONGOING/ADDITIONAL STORMS
SPREADING INTO THE UPPER GREAT LAKES WEDNESDAY. STORMS WILL LIKELY
FOCUS AHEAD OF AN EASTWARD MOVING SURFACE WAVE ALONG THE BOUNDARY
WITH CLUSTERING/UPSCALE GROWTH POTENTIALLY LEADING TO A MORE
ORGANIZED SYSTEM. TYPICAL UNCERTAINTY ON THE EXACT LOCATION AND
COVERAGE OF CONVECTIVE DEVELOPMENT REMAINS A CONCERN PARTICULARLY
AS THE STORM EVOLUTION TUESDAY WILL LIKELY IMPACT STORM
DEVELOPMENT/EVOLUTION WEDNESDAY. HOWEVER, THERE REMAINS GOOD
CONSENSUS AMONGST THE DETERMINISTIC MODEL GUIDANCE ON AREAL AVERAGE
RAINFALL TOTALS IN THE 1-2" RANGE, LOCALLY 3"+, SUPPORTING THE
THREAT FOR SCATTERED FLASH FLOODING. A SLIGHT RISK OF EXCESSIVE
RAINFALL IS IN PLACE FROM EAST-CENTRAL MN INTO NORTHERN WI AND THE
UP/NORTHERN LP MI, WITH THE POTENTIAL FOR AREAL ADJUSTMENT OF THE
RISK IN SUBSEQUENT OUTLOOKS.
THE EMBEDDED SHORTWAVE ENERGY WILL HELP TO SUBTLY DEEPEN/EXPAND
TROUGHING MORE BROADLY ACROSS THE THE MIDWEST AND ADJACENT AREAS ON
THURSDAY. THE SOUTHWARD SHIFT OF STRONGER UPPER-FLOW ALOFT INTO
THE CENTRAL PLAINS EAST THROUGH THE MIDDLE MISSISSIPPI/OHIO VALLEYS
AND LOWER GREAT LAKES WILL BRING MORE SCATTERED THUNDERSTORM
CHANCES ACROSS THE REGION. SEASONABLY HIGH INSTABILITY AND MOISTURE
POOLING ALONG A SOUTHWARD PROGRESSING 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 HAS BEEN OUTLINED. A TARGETED SLIGHT RISK MAY EVENTUALLY
BE NECESSARY WITH MORE CONFIDENCE IN THE FRONTAL POSITION AS STORM
MOTIONS MAY TEND TO RUN GENERALLY PARALLEL TO THE BOUNDARY HELPING
TO LEAD TO PROLONGED/REPEATED ROUNDS OF RAINFALL.
PUTNAM
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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