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FOUS30 KWBC 010835
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
435 AM EDT SAT AUG 1 2026
DAY 1
VALID 12Z SAT AUG 01 2026 - 12Z SUN AUG 02 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE UPPER
MIDWEST TO THE GULF COAST AND FOR NEW MEXICO INTO THE SOUTHERN
HIGH PLAINS...
..UPPER MIDWEST
A POTENT AND UNSEASONABLY DEEP LOW PRESSURE SYSTEM WILL CONTINUE TRACKING
ACROSS THE UPPER MIDWEST AS ITS PARENT MID/UPPER LOW DIGS AND
DEEPENS OVER THE REGION. A STEADY INFLUX OF DEEP GULF MOISTURE WILL
BE POOLING AHEAD OF THE SYSTEM WITH PW VALUES AROUND 2-2.25
INCHES/150-175% OF NORMAL. STRONG FORCING, LARGE SCALE ASCENT,
AND SUFFICIENT INSTABILITY WILL ALL BE PRESENT TO LEAD TO
EFFICIENT,HEAVY RAINFALL ESPECIALLY WITHIN THE PIVOTING COMMA HEAD
DUE NORTH OF THE LOW TRACK ACROSS PARTS OF ILLINOIS AND INDIANA
WHERE GUIDANCE HAS BEEN SUGGESTING A CONCENTRATION OF 3 TO 5
INCHES. AS A RESULT, THE EXISTING SLIGHT RISK SPANS THE MIDWEST TO
THE TENNESSEE VALLEY AND THE PORTION OVER EAST-CENTRAL ILLINOIS TO
NORTHERN INDIANA CAN BE CONSIDERED AN ENHANCED SLIGHT.
..PARTS OF THE SOUTHEAST TO THE GULF COAST
A MID/UPPER IMPULSE EMBEDDED WITHIN NORTHWESTERLY FLOW ON THE
SOUTHERN PERIPHERY OF THE DEEPENING LOW OVER THE UPPER MIDWEST WILL
DIVE INTO THE SOUTHEAST BEFORE SLOWING DOWN NEAR THE FLORIDA
PANHANDLE DURING THE DAY. ANOMALOUSLY HIGH PW VALUES OF 2.25-2.75
INCHES (125-150% OF NORMAL) ALONG WITH 1000-2000+ J/KG OF MUCAPE
WILL SUPPORT NUMEROUS CLUSTERS OF SLOW-MOVING SHOWERS AND
THUNDERSTORMS CONTAINING INTENSE RAINFALL RATES. SOME OF THE HI-RES
GUIDANCE IS FAVORING PARTS OF GEORGIA AND FLORIDA FOR VERY
LOCALIZED POCKETS OF 3+ INCHES (VERY ISOLATED AREAS OF 5+ INCHES).
A SLIGHT RISK COVERS MUCH OF THE FLORIDA PANHANDLE, EASTERN
ALABAMA, MOST OF GEORGIA, WESTERN HALF OF SOUTH CAROLINA, AND WESTERN
NORTH CAROLINA.
..SOUTHERN ROCKIES/HIGH PLAINS TO THE TEXAS HILL COUNTRY
MONSOONAL MOISTURE AND INSTABILITY INTERACTING WITH UPSLOPE FLOW
AND A SOUTHWARD PROGRESSING COLD FRONT WILL SUPPORT SCATTERED
SHOWERS AND THUNDERSTORMS FROM THE SOUTHERN ROCKIES AND HIGH
PLAINS TO THE TEXAS HILL COUNTRY. INDIVIDUAL STORMS COULD
POTENTIALLY DROP 1+ INCH/HR RAINFALL RATES THAT MAY LEAD TO
ISOLATED TO SCATTERED INSTANCES OF FLASH FLOODING. THE MOST
FAVORABLE LOCATIONS FOR THIS WILL BE ACROSS EASTERN NEW MEXICO
INTO FAR WESTERN PORTIONS OF TEXAS. A SLIGHT RISK AREA REMAINS IN
EFFECT FOR THIS PART OF THE REGION. THERE CONTINUES TO BE AN
INCREASING SIGNAL FOR MULTIPLE INCHES OF RAINFALL TO FOCUS ACROSS
THE HILL COUNTRY. A BROAD MARGINAL RISK SPANS FROM SOUTHEAST
ARIZONA NORTHWARD TO SOUTHERN COLORADO AND TO THE EAST OF THE TEXAS
HILL COUNTRY.
CAMPBELL/MILLER
DAY 2
VALID 12Z SUN AUG 02 2026 - 12Z MON AUG 03 2026
..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE FLORIDA BIG
BEND REGION, AND OVER PORTIONS OF THE NORTHEAST...
..GULF COAST INTO THE SOUTHEAST
ONSHORE FLOW WILL CONTINUE TO FOCUS HEAVY RAINFALL OVER NORTHERN
FLORIDA AND PARTS OF THE SOUTHEAST. THE MID-LEVEL LOW OVER INDIANA
IS FORECAST TO MOVE EAST/SOUTH ALLOWING FOR HEIGHT FALLS TO REACH
THE GULF COAST AND MAINTAINING S/SW FLOW DOWNSTREAM. AN IMPRESSIVE
PLUME OF PWS ABOVE 2.25" OVERLAPPED WITH MUCAPE OF AROUND 2000
J/KG WILL BE POOLED AHEAD OF THE APPROACHING SURFACE COLD FRONT,
AND IT IS THIS IMPRESSIVE ENVIRONMENT THAT WILL SHIFT NORTHEAST
THUNDERSTORMS WILL BE WIDESPREAD; TRAINING AND BACKBUILDING CAN BE
EXPECTED WITH HOURLY RATES REACHING 2 OR MORE INCHES/HOUR. SEVERAL
LOCATIONS MAY ACCUMULATE 3+ INCHES/24 HOURS THUS MAINTAINING AN
ELEVATED THREAT FOR FLASH FLOODING.
..UPPER MIDWEST TO NORTHEAST AND MID-ATLANTIC REGION
A SLOW MOVING OCCLUDED FRONT WILL BE ADVANCING EASTWARD INTO THE
OHIO VALLEY. IMPRESSIVE THERMODYNAMIC ADVECTION WITHIN THE WARM
SECTOR WILL SURGE NORTHWARD AS 30-40 KTS OF WIND AT 850MB TRANSPORT
PW VALUES OF 1.75 TO 2.0 INCHES ALL THE WAY TO THE CANADIAN BORDER
OVERLAPPING 500-1000 J/KG OF MUCAPE. THIS WILL SUPPORT WIDESPREAD
THUNDERSTORMS WITH RAINFALL RATES OF 1-2"/HR, WITH ORGANIZATION
INTO CLUSTERS FOSTERED VIA 30-35 KTS OF BULK SHEAR.
WITH TIME, WINDS WILL BECOME MORE PARALLEL TO THE FRONT WHICH WILL
INCREASE THE THREAT FOR TRAINING OF CELLS FROM THE MID-ATLANTIC
STATES NORTHWARD INTO UPSTATE NEW YORK. THE CURRENT SLIGHT RISK IS
FOCUSED FROM EASTERN LOWER MICHIGAN NORTHEAST TOWARDS THE
ADIRONDACKS WHERE AN IMPRESSIVE DEFORMATION AXIS WILL DEVELOP AND
LAY BENEATH A RARE AUGUST-TROWAL TO ENHANCE BOTH ASCENT AND
INSTABILITY. HERE, MEAN WINDS BECOME ANTI-PARALLEL TO THE
PROPAGATION VECTORS, AND IT IS LIKELY THAT SOME SLOW
MOVING/BACKBUILDING CELLS WILL BRING HEAVY RAINFALL TO AREAS
INCLUDING DETROIT, CLEVELAND, AND BUFFALO. THIS IS WHERE THE
GREATEST EXCESSIVE RAINFALL RISK EXISTS AND WHERE THE HIGHEST
PROBABILITIES FOR RAINFALL EXCEEDING 3"/24HRS.
..SOUTHWEST
FAVORABLE INSTABILITY AND MOISTURE WILL BE A BIT SUPPRESSED DURING
THIS PERIOD THANKS TO THE WITH THE SOMEWHAT FLATTENED RIDGE
DOWNSTREAM. THE ANOMALOUS PW VALUES AND SBCAPE ABOVE 1000 J/KG WILL
GENERALLY BE CONFINED TO THE MOGOLLON RIM AND SOUTHERN VICINITY.
CONVECTION IS STILL LIKELY TO BLOSSOM ACROSS ARIZONA AND NEW MEXICO
AND STORMS THAT DEVELOP MAY ORGANIZE SLIGHTLY TO MOVE SOUTHWEST
OFF THE TERRAIN. A MARGINAL RISK AREA REMAINS IN EFFECT FOR THIS
PERIOD.
CAMPBELL/WEISS
DAY 3
VALID 12Z MON AUG 03 2026 - 12Z TUE AUG 04 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE NORTHERN
MID-ATLANTIC INTO SOUTHERN NEW YORK STATE AND SOUTHERN NEW
ENGLAND...
..PORTIONS OF THE EAST COAST AND OHIO VALLEY
AN AXIS OF ANOMALOUS PW VALUES, 2+ STANDARD DEVIATIONS ABOVE THE
MEAN, 2 TO 2.25" PW VALUES, WILL STRETCH FROM NORTH FLORIDA,
NORTHEASTWARD ACROSS THE COASTAL SOUTHEAST, MID- ATLANTIC AND FROM
EASTERN NEW YORK STATE INTO NEW ENGLAND WILL SUPPORT LOCALLY HEAVY
RAINFALL. A SLIGHT RISK REMAINS OVER PORTIONS OF THE NORTHERN MID-
ATLANTIC (INCLUDING PORTIONS OF NY) INTO SOUTHWEST NEW ENGLAND
WHERE RECENT HEAVY RAINS HAVE LOWERED FFG VALUES/SATURATED SOILS.
DURING THE DAY THE CLOSED LOW IS FORECAST TO SLOW/STALL WHILE
MAINTAINING AN AREA OF ANOMALOUS PW VALUES EAST OF THIS CLOSED
LOW, ACROSS THE UPPER OHIO VALLEY INTO THE MID- ATLANTIC, SOUTHERN
NEW ENGLAND AND SOUTH INTO THE COASTAL SOUTHERN MID-ATLANTIC. A
BROAD MARGINAL RISK AREA WAS DEPICTED IN THIS ANOMALOUS PW AXIS FOR
LOCALLY HEAVY RAINS AND ISOLATED RUNOFF ISSUES.
..SOUTHWEST/SOUTHERN HIGH PLAINS
CONVECTION WILL BECOME LESS SUPPRESSED AS THE RIDGE BUILDS TO THE
EAST ALLOWING FOR MORE MONSOONAL MOISTURE AND INSTABILITY TO REACH
THE SOUTHERN ROCKIES/ADJACENT HIGH PLAINS. LOCALLY HEAVY RAINFALL
WITH ISOLATED RUNOFF ISSUES POSSIBLE FOR THIS PERIOD. A MARGINAL
RISK SPANS FROM SOUTHEAST ARIZONA INTO NEW MEXICO AND SOUTH-
CENTRAL COLORADO.
..PORTIONS OF THE CENTRAL/NORTHERN PLAINS AND MIDWEST
AREAL AVERAGE OF 1-2 INCHES EXPECTED AS A SURFACE FRONT ADVANCES
SOUTHEASTWARD FROM THE UPPER MISSISSIPPI VALLEY INTO THE UPPER
LAKES AND SOUTH THROUGH THE CENTRAL PLAINS. MOIST SOUTHERLY LOW
LEVEL INFLOW INTO THE FRONT AT THIS TIME MAY SUPPORT ORGANIZED
CONVECTION, HEAVY RAINS AND ISOLATED RUNOFF ISSUES. A MARGINAL RISK
IS IN AFFECT FOR NORTHERN MINNESOTA, EASTER NORTH DAKOTA AND
NORTHEAST SOUTH DAKOTA.
CAMPBELL/ROTH
DAY 4 AND DAY 5
VALID 12Z TUE AUG 04 2026 - 12Z THU AUG 06 2026
...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL FROM THE UPPER
OHIO VALLEY/EASTERN LAKES INTO THE NORTHEAST, FROM THE CENTRAL
PLAINS IN THE MID TO UPPER MISSISSIPPI VALLEY AND OVER THE
SOUTHWEST...
...UPPER OH VALLEY, CENTRAL APPALACHIANS, LOWER LAKES, MID-ATLANTIC
INTO THE NORTHEAST...
VERY LITTLE MOVEMENT EXPECTED DAY 4 TO THE CLOSED LOW IN THE
VICINITY OF EASTERN KY/EASTERN TN, WITH THEN A NORTHEASTWARD PUSH
INTO THE EASTERN LAKES ON WEDNESDAY AS IT BEGINS TO WEAKEN. A BROAD
REGION OF ANOMALOUS PW VALUES WILL PERSIST DAY 4 AND DAY 5 TO THE
EAST OF THIS CLOSED LOW FROM THE UPPER OH VALLEY, CENTRAL
APPALACHIANS, EASTWARD INTO THE MID- ATLANTIC, MUCH OF NY STATE AND
SOUTHERN NEW ENGLAND. CONFIDENCE IS LOW WITH QPF DETAILS, BUT
THERE WILL LIKELY BE AREAS OF HEAVY RAINS BOTH DAY 4 AND 5 ACROSS
THESE AREAS WITH ISOLATED RUNOFF ISSUES POSSIBLE. GIVEN THE
UNCERTAINTIES WITH DETAILS, THE RISK LEVEL WAS KEPT AT MARGINAL FOR
BOTH DAY 4 AND 5.
..SOUTHWEST/SOUTHERN HIGH PLAINS
FOR BOTH DAY 4 AND 5, 1200 UTC TUESDAY TO 1200 UTC THURSDAY, A
MARGINAL RISK WAS DEPICTED FOR MONSOONAL CONVECTION ACROSS SOUTHERN
ARIZONA INTO NEW MEXICO. NOT A LOT OF CONFIDENCE WITH QPF DETAILS
HERE, BUT LOCALLY HEAVY RAINS AND ISOLATED RUNOFF ISSUES POSSIBLE
IN THE ABOVE AVERAGE PW VALUES EXPECTED ACROSS THIS AREA.
..CENTRAL PLAINS INTO THE MID TO UPPER MS VALLEY
A SURFACE FRONTAL BOUNDARY IS EXPECTED TO REMAIN NEARLY STATIONARY
DURING THE DAY 4 AND DAY 5 TIME PERIOD FROM THE CENTRAL PLAINS,
EAST-NORTHEASTWARD INTO THE MID TO UPPER MS VALLEY REGION. THIS
FRONT WILL BE SITUATED ALONG THE SOUTHERN EDGE OF THE WESTERLIES
WHERE SHORTWAVE ENERGY PUSHING EAST NORTHEASTWARD ALONG THE FRONTAL
ZONE WILL SUPPORT POTENTIAL FOR ORGANIZED CONVECTION BOTH DAY 4 AND
DAY 5. PW VALUES EXPECTED TO BE SLIGHTLY ABOVE AVERAGE...1.5 TO
1.75"+ IN THE VICINITY OF THIS FRONT, SUPPORTING HEAVY PRECIP
TOTALS WHERE CONVECTION DOES ORGANIZE AND ISOLATED RUNOFF ISSUES.
ORAVEC
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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