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FOUS30 KWBC 051115 AAA
QPFERD
EXCESSIVE RAINFALL DISCUSSION...UPDATED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
715 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 IN EASTERN
PENNSYLVANIA INTO NORTHERN NEW JERSEY...
A MCV IS EXPECTED TO CONTINUE ITS EASTWARD PROGRESSION INTO/ACROSS
OHIO MAINTAINING AN ELEVATED THREAT FOR LOCALIZED FLASH FLOOD
ALONG ITS PATH. A BIT FURTHER DOWNSTREAM SCATTERED TO WIDESPREAD
HEAVY RAINFALL WILL BE FOCUSING ALONG THE WAVY, EAST-WEST
ORIENTATED FRONTAL BOUNDARY DRAPED OVER SOUTHERN PORTIONS OF THE
NORTHEAST. BACK BUILDING/TRAINING OF SLOW MOVING STORMS CAPABLE OF
HOURLY RATES RATES GREATER THAN 2 INCHES/HOUR WILL TRACK ACROSS
EASTERN PENNSYLVANIA AND NEW JERSEY. GUIDANCE IS SIGNALING AREAL
AVERAGES OF 3 TO 6 INCHES WITH LOCAL MAXIMUMS OF 8+ POSSIBLE ALONG
THIS CORRIDOR.
THE LATEST GUIDANCE MAINTAINS FOCUS OF THE HIGHEST PROBABILITIES
FOR THE INTENSE RAIN RATES AND HIGHER QPF OVER CENTRAL TO EASTERN
PA, PORTIONS OF CENTRAL TO NORTHERN NJ, AND FAR NORTHERN MARYLAND.
THE COMBINATION OF SOME TERRAIN AREAS AND THE HIGHLY URBANIZED
CORRIDOR MAKES THIS AREA MUCH MORE VULNERABLE TO FLASH FLOODING.
WHILE THERE REMAINS SOME SPATIAL UNCERTAINTY TO EXACTLY WHERE THE
GREATEST RAINFALL WILL OCCUR, THE SETUP FAVORS SOME LOCALLY
SIGNIFICANT FLASH FLOODING WILL BE POSSIBLE. THE SLIGHT RISK SPANS
FROM NORTHEAST INDIANA TO THE MID-ATLANTIC COAST WITH AN EMBEDDED
MODERATE RISK AREA OVER EASTERN PENNSYLVANIA AND NORTH/CENTRAL NEW
JERSEY.
A BROAD MARGINAL RISK AREA SPANS FROM THE OHIO VALLEY TO THE LOWER
MISSISSIPPI VALLEY FOR ISOLATED FLASH FLOOD CONCERNS DUE TO EXCESS
GULF MOISTURE.
CAMPBELL
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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