301
FOUS30 KWBC 312013
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
413 PM EDT FRI JUL 31 2026
DAY 1
VALID 16Z FRI JUL 31 2026 - 12Z SAT AUG 01 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
MID TO UPPER MISSISSIPPI VALLEY, AND THE UPPER PENINSULA OF
MICHIGAN...
..CENTRAL US SYSTEM
A POTENT SHORTWAVE DIVING ACROSS THE NORTHERN PLAINS THIS MORNING
WILL DEEPEN AS IT EJECTS SOUTHEAST INTO THE UPPER MIDWEST BY
SATURDAY MORNING. THIS DEEPENING WILL CREATE AN EXTREMELY ANOMALOUS
MID-LEVEL LOW FOR LATE JULY, REFLECTED BY NAEFS HEIGHT ANOMALIES
FALLING TO BELOW THE MINIMUM CLIMATOLOGICAL VALUES AT 700MB, AND TO
BELOW THE 10TH PERCENTILE AT 500MB. AN IMPRESSIVELY DEEP SYSTEM
OVERLAPPING LATE JULY THERMODYNAMICS IS A CLEAR INDICATOR OF
EXCESSIVE RAINFALL POTENTIAL, AND THIS EVENT IS NO DIFFERENT.
AS THE MID-LEVEL LOW DIVES SOUTHEAST, IT WILL DRIVE INCREASING
DOWNSTREAM ASCENT THROUGH DIVERGENCE AND HEIGHT FALLS, WITH THE
SUBSEQUENT SURFACE LOW OCCLUDING ACROSS IOWA. WITHIN THIS
OCCLUSION (AND FARTHER DOWNSTREAM WARM SECTOR) PWS WILL CLIMB TO
1.75 TO 2.00 INCHES, ABOVE THE 90TH PERCENTILE FOR THE DATE, AND
OVERLAP WITH MUCAPE AROUND 1000 J/KG. THE ACCOMPANYING 850MB INFLOW
WILL BE LOCALLY ACCELERATED TO 30-40 KTS, DRAWING THESE PRONOUNCED
THERMODYNAMICS NORTHWARD TO SUPPORT HEAVY RAIN PRODUCTION WITHIN
THUNDERSTORMS. AT THE SAME TIME, THE ASSOCIATED THETA-E RIDGE IS
PROGGED TO LIFT CYCLONICALLY, CREATING AN IMPRESSIVE (ESPECIALLY
FOR THE END OF JULY) TROWAL WHICH WILL PIVOT ATOP THE UPPER
MIDWEST. THIS WILL NOT ONLY RESULT IN ENHANCED ELEVATED
INSTABILITY, BUT ALSO SUPPORT ADDITIONAL MOISTURE TO FUEL HEAVY
RAINFALL.
BOTH THE HREF AND REFS NEIGHBORHOOD PROBABILITIES INDICATE A 40-70%
CHANCE FOR AT LEAST HOURLY RAINFALL OF 1", AND ALTHOUGH THERE
CONTINUES TO BE SOME LATITUDINAL UNCERTAINTY TO THE PLACEMENT, THE
CONSENSUS OF THE AVAILABLE HIGH-RES CAMS IS FOR LOCALLY HEAVY RAIN
RATES WITHIN A PROGRESSIVE BAND THIS MORNING, BECOMING MORE ALIGNED
FOR TRAINING LATER TODAY. THIS IS MOST LIKELY BENEATH THE TROWAL
WHERE CORFIDI VECTORS AND MEAN 0-6KM WINDS BECOME ANTI-PARALLEL
LEADING TO BACKBUILDING/REPEATING HEAVY RAIN RATES. THE GREATEST
RISK FOR 3"/24HRS FROM THE HIGH-RES ENSEMBLES IS FROM NEAR ST.
LOUIS, MO NORTHWARD THROUGH SOUTHERN WI, WHICH IS ALSO WHERE THERE
ARE NOTABLE PROBABILITIES FOR 5"/24 HRS (30-60%), ESPECIALLY NEAR
THE QUAD CITIES OF IA. THIS IS ALSO WHERE THE CSU FIRST-GUESS ERO
FIELD IS MOST AGGRESSIVE, SO DESPITE SOME DRYNESS IN THE ANTECEDENT
SOILS, AN ELEVATED SLGT RISK IS WARRANTED FOR THIS REGION.
OTHERWISE, COSMETIC ADJUSTMENTS WERE MADE TO BOTH THE SLGT AND MRGL
RISKS ACROSS THE REGION.
..UPPER PENINSULA OF MICHIGAN
THE IMPRESSIVE SYSTEM MOVING THROUGH THE UPPER MIDWEST WILL RESULT
IN INCREASED DEFORMATION BETWEEN 700-500MB PIVOTING INTO THE UPPER
PENINSULA THIS AFTN/EVE. THIS WILL ENCOURAGE ENHANCED ASCENT ACROSS
THE REGION, DESPITE A SLOW WANE IN MUCAPE NOTED VIA THE VARIOUS
MODELS. THE ACCOMPANYING ASCENT WITHIN THIS PERSISTENT DEFORMATION
AXIS WILL SUPPORT WIDESPREAD SHOWERS AND THUNDERSTORMS TODAY, WHICH
DESPITE THE WANING INSTABILITY WILL BE FUELED BY PWS AS HIGH AS
1.5 INCHES, OR ABOVE THE 90TH CLIMATOLOGICAL PERCENTILE. THIS WILL
SUPPORT RAINFALL RATES THAT ARE PROGGED BY BOTH HREF AND REFS
NEIGHBORHOOD PROBABILITIES TO HAVE A 30-60% CHANCE OF EXCEEDING
1"/HR, WHICH WILL OCCUR WITHIN ALIGNED CORFIDI VECTORS/MEAN 0-6KM
WINDS TO SUPPORT TRAINING.
3-HR FFG ACROSS THE AREA IS GENERALLY 1.5 TO 2.5 INCHES WHICH HAS
20-40% CHANCE OF EXCEEDANCE. THIS SUGGESTS AT LEAST SCATTERED
INSTANCES OF FLASH FLOODING ARE POSSIBLE, BUT WILL BE MOST LIKELY
WHERE ANY MORE PROLONGED TRAINING CAN RESULT IN 3 INCHES (50-60%
CHANCE) TO AS MUCH AS 5 INCHES (10-20% CHANCE) OF RAIN. AFTER
COORDINATION WITH WFO MQT, A SLGT RISK WAS ADDED FOR THE INCREASED
EXCESSIVE RAINFALL POTENTIAL TODAY AND TONIGHT.
..NORTHERN FLORIDA THROUGH THE CENTRAL GULF COAST
ROBUST LATE-JULY THERMODYNAMICS CHARACTERIZED BY PWS OF 2-2.25
INCHES AND MUCAPE ABOVE 2000 J/KG WILL SPREAD ACROSS THE AREA TODAY
AND TONIGHT AHEAD OF A QUASI-STATIONARY FRONT. THIS WILL LIKELY
RESULT IN TWO PERIODS OF CONVECTION CAPABLE OF PRODUCING HEAVY
RAINFALL.
THE FIRST WILL BE DURING PEAK HEATING WHEN AIRMASS
THUNDERSTORMS WILL DEVELOP, AIDED BY A MODEST VORTICITY IMPULSE
DIGGING INTO MS/AL AROUND THE LARGE MID-LEVEL RIDGE TO THE WEST.
WEAK SHEAR (LESS THAN 20 KTS) DURING THIS TIME SUGGESTS STORMS THAT
DEVELOP WILL BE GENERALLY OF THE PULSE VARIETY WITH LIMITED
ORGANIZATION AND LIFESPANS, BUT STORM MERGERS, BOUNDARY
COLLISIONS, AND ANY LOCALLY ENHANCED ASCENT IN THE VICINITY OF THIS
SHORTWAVE COULD INCREASE THE OVERAGE AND INTENSITY OF STORMS DURING
THE AFTN/EVE.
THESE STORMS SHOULD WANE WITH CONVECTIVE OVERTURNING DURING THE
EVENING, BUT A SECONDARY SIGNAL HAS SHOWN UP IN THE GUIDANCE FOR
LATE TONIGHT INTO EARLY SATURDAY, ESPECIALLY ACROSS THE FLORIDA
PANHANDLE AND INTO THE BIG BEND AREA. HERE, THE AFOREMENTIONED
SHORTWAVE WILL SLOW WITHIN AN AREA OF THICKNESS DIFFLUENCE, LEADING
TO A LONGER PERIOD OF ENHANCED SYNOPTIC LIFT AIDED BY MODEST JET-
LEVEL DIFFLUENCE. THIS ASCENT ACTING UPON ANY RESIDUAL BOUNDARIES
AND THE LAND BREEZE COULD REIGNITE THUNDERSTORMS AS THE LLJ
ATTEMPTS TO BACK SUBTLY MORE TO THE WSW FROM W AS THE FRONT
APPROACHES, DRAWING EVEN MORE IMPRESSIVE PWS ALONG THE COAST.
DURING THIS TIME, CORFIDI VECTORS ARE PROGGED TO COLLAPSE TO 5 KTS
OR LESS AND BECOME INCREASINGLY ANTI-PARALLEL TO THE MEAN WIND
SUGGESTING SOME GREATER BACKBUILDING/TRAINING POTENTIAL WITH RAIN
RATES POTENTIALLY REACHING 3"/HR (10-20% CHANCE). BOTH THE HREF AND
REFS INDICATE A 20-40% CHANCE FOR 5" OF RAINFALL FROM THIS
NOCTURNAL EVENT, BUT THE DETERMINISTIC MODELS ARE QUITE DIFFERENT
IN THE COVERAGE AND PLACEMENT. AT THIS TIME, AFTER COORDINATION
WITH WFO TAE, THE MRGL RISK WAS LEFT UNCHANGED FOR THIS AREA, BUT
AN UPGRADE TO A TARGETED SLGT RISK MAY BE NEEDED WITH LATER
UPDATES, WITH THE SLGT POTENTIALLY EXTENDING (OR BEING MORE NEEDED)
THROUGH D2.
..FOUR CORNERS STATES INTO THE SOUTHERN-CENTRAL HIGH PLAINS
THE MONSOON RIDGE WILL GET SUPPRESSED TO THE SOUTH AND WEST IN
RESPONSE TO THE POTENT SYSTEM MOVING THROUGH THE PLAINS/MIDWEST,
WITH A SECONDARY PIECE OF VORTICITY ENERGY DROPPING ACROSS THE
SOUTHERN HIGH PLAINS INTO THE TEXAS PANHANDLE. THIS WILL HELP PUSH
A COLD FRONT THROUGH THE SOUTHERN PLAINS AND BANK AGAINST THE
TERRAIN OF NEW MEXICO LATER THIS EVENING. THE OVERLAPPING ASCENT
FROM THE COLD FRONT AND SHORTWAVE WILL ACT UPON FAVORABLE
THERMODYNAMICS AS A RIBBON OF PWS ABOVE 1.5 INCHES AND POOLED
MUCAPE OF 1000-1500 J/KG GET DRAWN WESTWARD AHEAD OF THE FRONT.
COVERAGE OF MONSOONAL THUNDERSTORMS MAY BE SOMEWHAT LESS THAN
PREVIOUS DAYS TODAY DUE TO THE RE-CENTEREING OF THE RIDGE. BUT AT
LEAST SCATTERED DIURNAL THUNDERSTORMS ARE EXPECTED FROM EASTERN AZ,
THROUGH NM, AND INTO EASTERN CO WITH HOURLY RAINFALL UP TO 1 INCH
AT TIMES. THE FOCUS FOR HEAVIEST RAIN IS LIKELY WHERE THE
SHORTWAVE/FRONT MOVE INTO NM/TX PANHANDLE WHERE SOME ORGANIZED
CLUSTERS AND BETTER TRAINING POTENTIAL EXISTS. THIS IS REFLECTED BY
BOTH HREF AND REFS EXCEEDANCE PROBABILITIES REACHING 15-25% (FFG)
AND 30-50% (3"/24HRS). THIS STILL SUPPORTS THE INHERITED MRGL RISK,
AND ONLY COSMETIC ADJUSTMENTS WERE MADE BASED ON THE NEW GUIDANCE.
WEISS/MILLER
DAY 2
VALID 12Z SAT AUG 01 2026 - 12Z SUN AUG 02 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE THE UPPER
MIDWEST TO THE GULF COAST AND THE SOUTHERN HIGH PLAINS...
..UPPER MIDWEST
A POTENT AND UNSEASONABLY DEEP LOW PRESSURE SYSTEM (ENSEMBLE MEAN
FORECAST MSLP VALUES BELOW THE MINIMUM CFSR CLIMATOLOGICAL) WILL
CONTINUE TO PIVOT ACROSS THE UPPER MIDWEST AS ITS PARENT MID/UPPER
LOW DIGS AND DEEPENS OVER THE REGION. AHEAD OF THE SYSTEM, STRONG
LOW-LEVEL SOUTH AND SOUTHWESTERLY FLOW WILL ADVECT DEEP GULF
MOISTURE (PWS 2-2.25 INCHES/150-175% OF NORMAL) NORTHWARD. COMBINED
WITH IMPRESSIVE DYNAMICS, LARGE SCALE ASCENT, AND SUFFICIENT
INSTABILITY, THE THREAT OF CONVECTIVELY DRIVEN HEAVY RAIN IS
EXPECTED TO CONTINUE INTO DAY 2/SATURDAY, ESPECIALLY WITHIN THE
PIVOTING COMMA HEAD DUE NORTH OF THE LOW TRACK ACROSS PARTS OF
ILLINOIS AND INDIANA. THERE, THE 12Z HREF/RRFS GUIDANCE IS
HIGHLIGHTING THE POTENTIAL FOR SIGNIFICANT QPF, WITH NOTABLE
PROBABILITIES OF EXCEEDING 3"/24 HRS (60-80%) AND 5"/24 HRS
(25-50%). AS A RESULT, THE EXISTING SLGT RISK CAN BE CONSIDERED AN
ENHANCED SLGT FROM EAST-CENTRAL ILLINOIS TO NORTHWEST INDIANA.
ELSEWHERE ACROSS THE OHIO AND TENNESSEE VALLEYS, ONLY COSMETIC
ADJUSTMENTS WERE MADE TO THE SLGT AND MRGL RISKS.
..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 ON SATURDAY. ANOMALOUSLY HIGH PWS 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. THE 12Z HREF/RRFS
SHOW FAIRLY WIDESPREAD PROBABILITIES OF 40-90% FOR QPF GREATER THAN
3"/24 HOURS AND 20-60% FOR GREATER THAN 5"/24 HOURS ACROSS PARTS
OF THE SOUTHEAST, ESPECIALLY FOR PORTIONS OF GEORGIA AND THE
FLORIDA PANHANDLE. GIVEN THIS INCREASED SIGNAL FOR POTENTIALLY
SIGNIFICANT RAINFALL, THE SLGT RISK WAS EXPANDED SOUTHWARD TO
INCLUDE SOUTHWEST ALABAMA, SOUTHERN GEORGIA, AND MOST OF THE
FLORIDA PANHANDLE.
..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 ON DAY 2/SATURDAY. THIS ACTIVITY WILL
HAVE THE POTENTIAL TO PRODUCE HEAVY RAINFALL RATES IN EXCESS OF 1"
PER HOUR, LEADING TO ISOLATED AND SCATTERED INSTANCES OF FLASH
FLOODING. 12Z HREF/RRFS PROBABILITIES FOR QPF GREATER THAN 3"/24
HOURS ARE 20-50% AND MOSTLY CONCENTRATED ACROSS THE SOUTHERN HIGH
PLAINS OF NEW MEXICO. THE EXISTING SLGT RISK COVERING THAT AREA
LOOKED ON TRACK SO MINIMAL CHANGES WERE MADE. HOWEVER, THE
HREF/RRFS IS ALSO BEGINNING TO HIGHLIGHT THE TEXAS HILL COUNTRY
WITH A 10-40% CHANCE FOR QPF GREATER THAN 3"/24 HOURS. ALSO NOTABLE
ARE THE VERY LOW BUT NON-ZERO PROBABILITIES FOR GREATER THAN 5"/24
HRS (5-10%). AS A RESULT, THE MRGL RISK WAS EXPANDED EASTWARD FROM
FAR WESTERN TEXAS WITH THIS UPDATE, AND A FUTURE UPGRADE TO A SLGT
RISK CAN'T BE RULED OUT.
MILLER
DAY 3
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
LONG DURATION ONSHORE FLOW EVENT FROM THE GULF CONTINUES INTO D3
BRINGING HEAVY RAIN TO THE BIG BEND AREA OF FLORIDA AND PORTIONS OF
THE SOUTHEAST.
A POTENT CLOSED MID-LEVEL LOW CENTERED OVER INDIANA SUNDAY MORNING
WILL ROTATE E/SE THROUGH D3 BRINGING HEIGHT FALLS TO THE GULF
COAST, AND KEEPING PRONOUNCED S/SW FLOW DOWNSTREAM. AS THIS CLOSED
LOW ELONGATED TO BECOME AT LEAST SUBTLY MORE N-S ORIENTED, ONSHORE
FLOW FROM THE GULF WILL LOCALLY BACK AND INTENSIFY, DRAWING ROBUST
THERMODYNAMICS NORTHWARD INTO FLORIDA/GEORGIA. 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 THROUGH D3.
WITHIN THIS SETUP, WIDESPREAD THUNDERSTORMS ARE LIKELY, AND WITH
MEAN 0-6KM WINDS ALIGNED PARALLEL TO THE FRONT ONSHORE, AND ANTI-
PARALLEL TO THE CORFIDI VECTORS, THE SETUP APPEARS TO SUGGEST A
HIGH THREAT FOR BACKBUILDING AND TRAINING CONVECTION WITH HEAVY
RAINFALL RATES OF 2"/HR OR MORE. THIS WILL RESULT IN LOCALLY MORE
THAN 3" OF RAINFALL (SREF/GEFS/ECENS PROBABILITIES FOR 3"/24 HRS AS
HIGH AS 10%) FALLING ATOP SATURATED SOILS FROM ANTICIPATED HEAVY
RAIN ON D2. FOR THIS REASON A SLGT WAS ADDED NEAR THE FLORIDA BIG
BEND REGION, WITH THE MRGL EXPANDED NORTHEAST FROM INHERITED.
..UPPER MIDWEST TO NORTHEAST AND MID-ATLANTIC REGION
THE ANOMALOUS MID-LEVEL LOW WILL CONTINUE TO TRACK SLOWLY EASTWARD
FROM THE MIDWEST INTO THE OHIO VALLEY ON SUNDAY AND SUNDAY NIGHT.
BENEATH THIS UPPER LOW, AN OCCLUDED SURFACE CYCLONE WILL TRACK
EASTWARD IN TANDEM, WITH THE ACCOMPANYING FRONTS PRODUCING LOCALLY
ENHANCED ASCENT WITHIN THEIR VICINITY DUE TO OVERRUNNING AND/OR
CONVERGENCE. AS THE WAVE PUSHES EAST, IMPRESSIVE THERMODYNAMIC
ADVECTION WITHIN THE WARM SECTOR WILL SURGE NORTHWARD AS 30-40 KTS
OF WIND AT 850MB TRANSPORT PWS 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.
WITHIN THIS WARM SECTOR, PROPAGATION VECTORS AND MEAN 0-6KM WINDS
WILL BECOME INCREASINGLY PARALLEL AND ALIGNED TO THE APPROACHING
FRONT, WHICH SUGGESTS AN INCREASING TRAINING THREAT FROM THE MID-
ATLANTIC STATES NORTHWARD INTO UPSTATE NY. THE GUIDANCE HAS TRENDED
UPWARD IN QPF FOR THIS AREA, AND AN UPGRADE TO A SLGT RISK IN PARTS
OF THIS AREA MAY BE NEEDED WITH LATER ISSUANCES. HOWEVER, THE
CURRENT SLGT 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 ON D3. THIS IS WHERE THE
GREATEST EXCESSIVE RAINFALL RISK EXISTS, AND THE INHERITED SLGT
RISK WAS MODIFIED TO ACCOUNT FOR RECENT GUIDANCE AND HIGHEST
(ALBEIT STILL MODEST) PROBABILITIES FOR RAINFALL EXCEEDING
3"/24HRS.
..SOUTHWEST
THE MID-LEVEL RIDGE RESPONSIBLE FOR THE MONSOON WILL REMAIN
SOMEWHAT FLATTENED SUNDAY INTO MONDAY /D3/ BUT BEGIN TO EXPAND
EASTWARD ONCE AGAIN AS THE DOWNSTREAM TROUGH ADVECTS EAST INTO THE
MID-ATLANTIC STATES. THIS WILL KEEP MUCH OF THE FAVORABLE
INSTABILITY AND MOISTURE SUPPRESSED TO THE SOUTHERN EDGE OF THE
TYPICAL MONSOON REGION, WITH BOTH ANOMALOUS PWS AND SBCAPE ABOVE
1000 J/KG CONFINED TO GENERALLY THE MOGOLLON RIM AND POINTS SOUTH.
CONVECTION IS STILL LIKELY TO BLOSSOM ACROSS AZ/NM, AND STORMS THAT
DEVELOP MAY ORGANIZE SLIGHTLY WITHIN 25 KTS OF BULK SHEAR TO MOVE
SW OFF THE TERRAIN AT 10-15 KTS. HOWEVER, THE COVERAGE AND SPEED OF
CONVECTION SHOULD LIMIT EXCESSIVE RAINFALL POTENTIAL TO BE
ISOLATED, SO THE MRGL RISK WAS MAINTAINED WITH ONLY SUBTLE COSMETIC
ADJUSTMENTS.
WEISS
DAY 4 AND DAY 5
VALID 12Z MON AUG 03 2026 - 12Z WED AUG 05 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/GREAT LAKES/OH VALLEY
THE WELL-DEFINED UPPER LEVEL TROUGH MOVING THROUGH THE OHIO VALLEY
WILL BEGIN TO FRACTURE ON THURSDAY. THERE IS AGREEMENT THAT 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 NY STATE INTO NEW ENGLAND. GENERALLY FAVORABLE RIGHT
ENTRANCE REGION JET DYNAMICS WILL ACCENTUATE LIFT IN THIS ANOMALOUS
PW AXIS, SUPPORTING POTENTIAL FOR LOCALLY HEAVY RAINFALL TOTALS. 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.
THE CLOSED LOW OVER THE UPPER OH VALLEY WILL BECOME NEARLY
STATIONARY ON FRIDAY. AN AREA OF ANOMALOUS PW VALUES WILL REMAIN
TO THE EAST OF THIS CLOSED LOW, ACROSS THE UPPER OH 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. THE SURFACE FRONT MOVING THROUGH NEW ENGLAND THURSDAY MAY
BECOME STATIONARY AND WEST TO EAST ORIENTED ACROSS SOUTHERN NEW
ENGLAND INTO THE NORTHERN MID-ATLANTIC FRIDAY. A FEW MODELS ARE
SHOWING MORE DEFINED HEAVY RAINS IN THE VICINITY OF THIS FRONT
WHERE THERE IS POTENTIAL FOR PERSISTENT SOUTH SOUTHWESTERLY INFLOW.
STILL A LOT OF SPREAD WITH QPF DETAILS, WARRANTING ONLY A MARGINAL
RISK AT THIS TIME, WITH CHANGES POSSIBLE WITH FUTURE UPDATES.
..SOUTHWEST/SOUTHERN HIGH PLAINS
FOR THURSDAY AND FRIDAY, 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.
..PORTIONS OF THE CENTRAL/NORTHERN PLAINS & MIDWEST
A SURFACE FRONT EXPECTED TO PUSH SOUTHEASTWARD FROM THE UPPER MS
VALLEY INTO THE UPPER LAKES AND SOUTH THROUGH THE CENTRAL PLAINS.
ON THURSDAY, THERE IS A DECENT MODEL SIGNAL FOR 1-2" OF RAIN WHICH
COULD FALL IN A SHORT PERIOD OF TIME, SO ADDED A MARGINAL RISK AREA
FOR PORTIONS OF THE DAKOTAS AND NORTHERN MN -- IT WOULD NOT BE A
SURPRISE IF THE GUIDANCE TRENDED UPWARD ON AMOUNTS. FOR FRIDAY, A
MODEL CONSENSUS EXISTS FOR AN AXIS OF POTENTIALLY HEAVY RAINS FROM
NEBRASKA, EASTWARD INTO IOWA AND SOUTHERN MN WHERE THE FRONT MAY
BECOME MORE WEST TO EAST ORIENTED. MOIST SOUTHERLY LOW LEVEL
INFLOW INTO THE FRONT AT THIS TIME MAY SUPPORT ORGANIZED
CONVECTION, HEAVY RAINS AND ISOLATED RUNOFF ISSUES.
ROTH/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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