431
FOUS30 KWBC 200108
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
908 PM EDT SAT SEP 19 2026
DAY 1
VALID 01Z SUN SEP 20 2026 - 12Z SUN SEP 20 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL IN PORTIONS OF
THE MIDWEST...PARTICULARLY EASTERN IOWA, NORTHERN ILLINOIS, AND
NORTHERN INDIANA...
..01Z UPDATE
..CENTRAL PLAINS TO THE CENTRAL APPALACHIANS
A MODERATE RISK REMAINS IN PLACE ACROSS PORTIONS OF THE MIDWEST,
EXTENDING FROM EASTERN IOWA TO SOUTHWESTERN MICHIGAN AND
NORTHWESTERN INDIANA. IT IS EXPECTED THAT SCATTERED SHOWERS AND
STORMS WILL CONTINUE ALONG THIS AXIS THROUGH THE REMAINDER OF THE
EVENING, FOLLOWED BY MORE ORGANIZED ACTIVITY THAT IS ALREADY
DEVELOPING OVER THE CENTRAL PLAINS AND LOWER MISSOURI VALLEY AND IS
EXPECTED TO PROPAGATE NORTHEAST THROUGH THE REMAINDER OF THE
EVENING. THIS LATEST ROUND OF DEVELOPING ACTIVITY IS SUPPORTED BY A
WELL-DEFINED SHORTWAVE AND A STEADY TRANSPORT OF MOISTURE FROM THE
SOUTH.
THE NORTH-SOUTH GRADIENT OF THE MODERATE RISK AND SURROUNDING
SLIGHT AND MARGINAL RISKS WAS TIGHTENED SOME. HOWEVER, THE SLIGHT
RISK WAS ELONGATED A LITTLE FARTHER EAST AND WEST. THERE HAS BEEN
SOME MODEL SIGNAL FOR SHOWER AND STORMS TO PROPAGATE EAST AND
PRODUCE LOCALLY HEAVY AMOUNTS WITHIN THE TYPICALLY MORE RUNOFF SENSITIVE
AND LOWER FFG PARTS OF WEST VIRGINIA.
THERE HAS ALSO BEEN SOME SIGNAL FOR LOCALLY HEAVY AMOUNTS
DEVELOPING BACK ALONG THE AXIS OF DEEPER MOISTURE AND STRONGER
SOUTHWESTERLY INFLOW EXTENDING BACK ACROSS SOUTHERN IOWA INTO
NORTHWESTERN MISSOURI AND EASTERN KANSAS, WHERE ACTIVITY IS NOW
FIRING.
WITHIN THE MODERATE RISK AREA ITSELF, BOTH THE 18Z
HREF/REFS SUPPORT LOCALIZED ADDITIONAL AMOUNTS OF 2-3 INCHES
OVERNIGHT -- WHICH GIVEN THE VERY MOIST SOILS FROM PREVIOUS HEAVY
RAINS IS LIKELY TO PRODUCE ADDITIONAL RUNOFF CONCERNS.
..NORTHERN TO CENTRAL HIGH PLAINS
ANOMALOUS MOISTURE INTERACTING WITH A CLOSED LOW WILL CONTINUE TO
PRODUCE WIDESPREAD PRECIPITATION ACROSS THE REGION, WITH
ADDITIONAL LOCALIZED HEAVY AMOUNTS POSSIBLE THROUGH THE REMAINDER
OF THE EVENING AND INTO THE OVERNIGHT. INSTABILITY HAS BEEN LIMITED
ACROSS MUCH OF MONTANA, KEEPING RATES IN CHECK. WITH INSTABILITY
EXPECTED TO REMAIN A LIMITING FACTOR, THE MODERATE RISK WAS REMOVED
WITH THIS UPDATE. A SLIGHT RISK WAS MAINTAINED FOR PARTS OF SOUTH-
CENTRAL TO SOUTHEASTERN MONTANA WHERE LOW LEVEL EASTERLY INFLOW
OVERLAPPED BY MID-TO-UPPER LEVEL FORCING MAY HELP PRODUCE SOME
LOCALLY HEAVIER AMOUNTS OVERNIGHT, WHICH MAY PRODUCE LOCALIZED
RUNOFF CONCERNS GIVEN THE LOW FFGS PRODUCED IN PART BY EARLIER
RAINS.
SOME OF THE HEAVIEST AMOUNTS OVERNIGHT MAY OCCUR FARTHER SOUTH,
SUPPORTED BY THE GREATER INSTABILITY EXTENDING NORTH FROM THE
CENTRAL HIGH PLAINS INTO PARTS OF WESTERN SOUTH DAKOTA AND EASTERN
WYOMING. A SLIGHT RISK WAS MAINTAINED WHERE THE HI-RES ENSEMBLE
SUITES SHOW SOME POTENTIAL FOR LOCALIZED AMOUNTS OVER 2 INCHES IN
THIS REGION.
..SOUTHWEST INTO THE SOUTHERN PLAINS
MADE SOME MINOR ADJUSTMENTS BASED IN LARGE PART ON MESOANALYSIS
AND RADAR TRENDS, INCLUDING EXTENDING THE MARGINAL RISK
NORTHEASTWARD ACROSS THE TEXAS PANHANDLE AND WESTERN OKLAHOMA --
REFLECTING ONGOING ACTIVITY THAT IS BEING SUPPORTED BY AN AXIS OF
DEEPER MOISTURE AND LOW LEVEL CONVERGENCE.
PEREIRA
DAY 2
VALID 12Z SUN SEP 20 2026 - 12Z MON SEP 21 2026
...THERE ARE SLIGHT RISKS OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MIDWEST AND OHIO VALLEY AS WELL AS THE NORTHERN HIGH PLAINS...
..2030Z UPDATE
..MIDWEST AND OHIO VALLEY
A MODEST ADJUSTMENT WAS MADE TO THE INHERITED SLIGHT RISK BASED ON
EXPECTED PROGRESSION OF THE FRONTAL BOUNDARY OVER THE MIDWEST.
MOST GUIDANCE INDICATES THE WESTERN PORTION OF THE FRONT WILL PUSH
FURTHER SOUTHWARD FROM THE GREAT LAKES TOWARDS THE MIDDLE
MISSISSIPPI VALLEY, LIKELY AIDED BY GROWING OUTFLOW DUE TO REPEATED
ROUNDS OF STORMS TO THE NORTH SATURDAY AND THROUGH SATURDAY NIGHT.
THIS WOULD SET UP THE AXIS OF HIGHEST INSTABILITY/FORCING AND
POTENTIAL FOR TRAINING ALONG THE FRONT FROM NORTHEASTERN MISSOURI
EAST THROUGH CENTRAL ILLINOIS AND INDIANA. THE RRFS MAINTAINED AN
AXIS FURTHER TO THE NORTHWEST BUT THIS SEEMS MORE UNREALISTIC BASED
ON THE ONGOING CONVECTION. GIVEN THE INFLUENCE OF ONGOING
CONVECTION, ADDITIONAL CHANGES ARE POSSIBLE. THERE IS HIGHER
CONFIDENCE IN BOTH THE PLACEMENT AND POTENTIAL FOR HEAVIER
RAINFALL/FLASH FLOODING FURTHER EAST ACROSS THE UPPER OHIO VALLEY.
STORMS MAY BE ONGOING AT THE START OF THE PERIOD BEFORE A RENEWED
ROUND IN THE AFTERNOON, AND RAINFALL OVERALL FROM SATURDAY WILL
LEAD TO MORE SENSITIVE ANTECEDENT CONDITIONS COMPARED TO FURTHER
WEST WHERE STORM COVERAGE WILL BE FURTHER SOUTH THAN THE DAY
BEFORE. A BIT HIGHER/ANOMALOUS MOISTURE POOLING IN THE VALLEY WILL
ALSO BRING A GREATER CHANCE OF HEFTIER TOTALS IN THE 2-5" RANGE.
..NORTHERN HIGH PLAINS
MINIMAL AREAL ADJUSTMENTS WERE MADE TO THE INHERITED SLIGHT RISK
OVER PORTIONS OF THE NORTHERN HIGH PLAINS BASED ON THE NOW
AVAILABLE CAM GUIDANCE. A SLOW MOVING UPPER-LOW OVER THE ROCKIES
WILL BEGIN TO PROGRESS EASTWARD AS AN OPEN WAVE LATER SATURDAY AND
INTO THE DAY SUNDAY ENCOURAGING A RENEWED ROUND OF STORM
DEVELOPMENT. ANOMALOUSLY MOIST UPSLOPE FLOW (PWS REMAINING 2 TO 2.5
STANDARD DEVIATIONS ABOVE THE MEAN) WILL CONTINUE TO PROMOTE
EFFICIENT RAINFALL WITH RAIN RATES OF 1-1.5"+ PER HOUR. THE CAM
GUIDANCE SHOWS THE POTENTIAL FOR LOCALIZED TOTALS IN THE 2-4" RANGE
PARTICULARLY WITHIN THE BLACK HILLS AND VICINITY. THE REGION WILL
ALSO BE MORE SENSITIVE TO ADDITIONAL RAINFALL FOLLOWING A PRIOR
BOUT OF STORMS AND HEAVY RAINFALL ON SATURDAY.
ELSEWHERE, THE BROADER MARGINAL RISK ACROSS THE PLAINS WAS
MAINTAINED AS IS. THERE LIKELY IS A LOWER POTENTIAL FOR EVEN
ISOLATED FLASH FLOODING ACROSS THE CENTRAL PLAINS NORTHEAST INTO
THE MIDDLE MISSOURI VALLEY AND UPPER MIDWEST GIVEN MORE LIMITED
INSTABILITY NORTH OF THE FRONT AND AWAY FROM TERRAIN INDUCED
UPSLOPE FLOW. HOWEVER, THERE WAS STILL ENOUGH OF A SIGNAL FOR SOME
MULTI-INCH TOTALS IN THE GUIDANCE PARTICULARLY INTO THE MISSOURI
VALLEY SO LEFT THE MARGINAL RISK AS IS FOR NOW. SIMILAR TO
SATURDAY, AFTERNOON THUNDERSTORMS FUELED BY A PLUME OF ANOMALOUSLY
HIGH MOISTURE WILL LEAD TO SOME VERY HEAVY DOWNPOURS AND ISOLATED
FLOODING/PONDING CONCERNS FOR SOUTH FLORIDA.
PUTNAM
..PREVIOUS DISCUSSION
..OHIO VALLEY/SOUTHERN GREAT LAKES
VERY FEW CHANGES WERE MADE TO THE PLACEMENT OF THE DAY 3 EXCESSIVE
RAINFALL OUTLOOK AS IT PROPAGATED INTO THE DAY 2 PERIOD. THERE WAS
A TIGHTENING OF THE EAST-WEST LENGTH AND A SUBTLE SOUTHWARD SHIFT
TO MATCH THE LATEST GUIDANCE BUT MAINTAINED THE FOCUS FOR HEAVY
RAINFALL IN THE OHIO VALLEY, THERE REMAINED SOME POTENTIAL FOR
BACKBUILDING AND TRAINING CONVECTIVE BANDS AFFECTING THOSE AREAS
FROM LATE TONIGHT INTO SUNDAY. CONFIDENCE IS LOW ON PLACEMENT OR
CONVECTIVE EVOLUTION BEYOND THE FIRST 36 HOURS OF THE FORECAST, SO
THIS IS BEING NOTED AS A POSSIBILITY FOR NOW. ANYONE WITHIN THE
SLIGHT RISK AREA SHOULD BE MONITORING THE POTENTIAL FOR FLASH
FLOODING, HOWEVER, GIVEN JUST HOW ANOMALOUSLY HIGH THE MOISTURE
LEVELS ARE.
FARTHER TO THE EAST, THE SLIGHT RISK WAS REMOVED AS MODEL AND
ENSEMBLE QPF DWINDLED. COOL, STABLE AIR BEING FED OUT OF CANADA
BY A SPRAWLING AREA OF HIGH PRESSURE WILL OVERSPREAD THE AREA AND
LIMIT RAINFALL RATES OVER AN INCREASING AMOUNT OF NEW ENGLAND AND
THE NORTHEAST STATES. A BOUNDARY SEPARATING THIS AIRMASS WITH
MOISTER AND MORE UNSTABLE CONDITIONS (STILL FAIRLY MODEST MAGNITUDE
OF INSTABILITY) TO THE SOUTH MAY STILL PROVE TO BE THE FOCUS FOR
CONVECTION CAPABLE OF PRODUCING MODERATE TO HEAVY RAINFALL RATES
BUT THE SIGNALS FOR HEAVY RAINFALL HAVE BECOME WEAKER AND MORE
ISOLATED IN NATURE.
ROCKIES TO THE CENTRAL PLAINS...
THERE CONTINUES TO BE A MARGINAL RISK OF EXCESSIVE RAINFALL FROM
THE SOUTHERN HIGH PLAINS NORTHWARD TO THE WESTERN HIGH PLAINS
ADJACENT TO THE NORTHERN ROCKIES AS DEEP MOISTURE REMAINS IN PLACE
WITH WEAK SHORTWAVE ENERGY EMBEDDED HELPING TO FUEL SCATTERED
CONVECTION.
..ELSEWHERE
A LARGE MARGINAL RISK AREA WAS MAINTAINED FROM THE NORTHERN ROCKIES
THROUGH MUCH OF THE PLAINS AND INTO WESTERN TEXAS. SCATTERED
THUNDERSTORMS EMBEDDED WITHIN A LARGE PLUME OF ANOMALOUSLY HIGH
MOISTURE WILL POSE THE THREAT FOR LOCALIZED HEAVY RAINFALL AND HIGH
INSTANTANEOUS RAIN RATES. HOWEVER, CONFIDENCE IS LOW ON PLACEMENT,
SO A MARGINAL RISK SEEMS APPROPRIATE.
BANN
DAY 3
VALID 12Z MON SEP 21 2026 - 12Z TUE SEP 22 2026
...THERE IS A BROAD MARGINAL RISK AREA FROM PARTS OF THE SOUTHERN
MID-ATLANTIC STATES AND NEW MEXICO...
..2030Z UPDATE
COVERAGE OF THE INHERITED MARGINAL RISK ACROSS THE SOUTHERN MID-
ATLANTIC STATES WAS REDUCED GIVEN A COLD AIR DAMMING PATTERN
SETTING UP THROUGHOUT THE REGION EARLY NEXT WEEK. THE LATEST
GUIDANCE SHOWS THAT THE COLD FRONT WILL PUSH SOUTHWARD THROUGH THE
DAY SUNDAY OVER MARYLAND AND NORTHERN VIRGINIA AND INTO SOUTHERN
VIRGINIA AND NORTH CAROLINA BY MONDAY MORNING. RAIN CHANCES AFTER
THIS FURTHER NORTH WILL BE MUCH MORE LIMITED WITH LOWER RATES.
HOWEVER, FORCING AND MOISTURE CONVERGENCE ALONG THE FRONT AS IT
STALLS ALONG THE CENTRAL APPALACHIANS WILL KEEP HEAVIER RAIN
CHANCES AND ISOLATED FLASH FLOODING A CONCERN HERE. OTHERWISE, THE
PREVIOUS FORECAST FOR THE SOUTHERN HIGH PLAINS REMAINS ON TRACK. A
MARGINAL RISK REMAINS IN PLACE FOR SOUTH FLORIDA AS ANOTHER DAY OF
THUNDERSTORMS FUELED BY A PLUME OF ANOMALOUSLY HIGH MOISTURE WILL
BRING SOME VERY HEAVY DOWNPOURS AND THE RISK OF SOME ISOLATED
FLOODING/PONDING FOR URBAN AREAS.
PUTNAM
..PREVIOUS DISCUSSION
SOUTHERN MID-ATLANTIC STATES... AN UPPER LEVEL LOW/TROUGH MOVING
FROM THE UPPER MIDWEST INTO THE GREAT LAKES WHILE AN UPPER LOW IN
THE EASTERN GULF SHEARS NORTHWARD AHEAD OF THE CLOSED LOW WILL SET
THE STAGE FOR SHOWERS AND THUNDERSTORMS ON MONDAY. MODEL SPREAD
INCREASED WHILE THE OVERALL SIGNAL FOR HEAVY AMOUNTS DIMINISHED
DURING THE PAST 24 HOURS. GIVEN THE INCREASED UNCERTAINTY COMBINED
WITH RELATIVELY DRY ANTECEDENT CONDITIONS, WAS NOT INCLINED TO
REINTRODUCE A SLIGHT RISK AREA. HOWEVER...ISOLATED INSTANCES OF
EXCESSIVE RAINFALL ARE POSSIBLE
SOUTHERN HIGH PLAINS...
INCREASING LOW-LEVEL GULF MOISTURE WITH TIME COULD LEAD TO AN
INCREASING THREAT FOR EXCESSIVE RAINFALL IN AND NEAR THE SOUTHERN
HIGH PLAINS AS MID-LEVEL FLOW INCREASES OVER THE CENTRAL US AND
STARTS TO PUSH A SURFACE FRONT EASTWARD. PRECIPITABLE WATER VALUES
SHOULD GENERALLY BE AROUND 1.75 INCHES FROM TEXAS NORTHWARD INTO
THE MID-MISSISSIPPI VALLEY WITH ENOUGH EFFECTIVE BULK SHEAR AND
INSTABILITY TO RESULT IN ORGANIZED CONVECTION CAPABLE OF PRODUCING
HEAVY RAINFALL WITH THE ASSOCIATED RISK OF FLASH FLOODING.
MIDWEST/SOUTHERN APPALACHIANS...
THE MIDWEST ISN'T SHOWING A UNIFIED/COHESIVE SIGNAL FOR HEAVY
RAINFALL MONDAY/MONDAY NIGHT BUT ENOUGH EFFECTIVE BULK SHEAR,
MOISTURE, AND INSTABILITY SHOULD EXIST NEAR AN INCOMING UPPER
LOW/TROUGH FOR ORGANIZED THUNDERSTORMS. THE AREA AROUND IN/OH/WV
NEEDS TO BE WATCHED FOR A POSSIBLY UPGRADE TO THE SLIGHT RISK
SHOULD THE GUIDANCE SHOW A MORE COHESIVE/AGREEABLE HEAVY RAINFALL
SIGNAL CONSIDERING THE EXPECTED RAINFALL IN THE DAY 1 PERIOD AND
HOW MUCH OF THAT LINGERS INTO DAY 2.
BANN
DAY 4 AND DAY 5
VALID 12Z TUE SEP 22 2026 - 12Z THU SEP 24 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF THE
APPALACHIANS AND NEW MEXICO...
20Z UPDATE...
NO MAJOR CHANGES FOR MOST OF THE PREVIOUS OUTLOOK AREAS. GIVEN THE
LINGERING AXIS OF DEEP MOISTURE (PWS ~2.0 INCHES) -- FUELING THE
POTENTIAL FOR ADDITIONAL HEAVY RAINFALL -- CONTINUED A MARGINAL
RISK INTO DAY 5 ACROSS PARTS OF SOUTH FLORIDA. OTHERWISE, MADE
MINOR ADJUSTMENTS BASED ON THE 12Z GUIDANCE.
PEREIRA
PREVIOUS DISCUSSION...
..OHIO VALLEY AND MID-ATLANTIC
MID LEVEL TROUGHING WITH MULTIPLE EMBEDDED SHORTWAVES WILL SLOWLY
TRACK EASTWARD INTO THE OH VALLEY AND MID-ATLANTIC, INTERACTING
WITH A BACKDOOR FRONT. SHOULD BE PLENTY OF MOISTURE OVERRUNNING
THIS FRONT, RESULTING IN WHAT SHOULD BE A BROAD AREA OF STEADY
RAINFALL. HOWEVER, QUITE A BIT OF UNCERTAINTY WITH THE DETAILS, AS
A COASTAL LOW SHOULD EVENTUALLY DEVELOP OFFSHORE, HELPING ADVECT
DRIER AIR IN FROM THE NORTH OVER PORTIONS OF THE MID-ATLANTIC.
THIS TREND HAS RESULTED IN A SOUTHWARD TREND IN THE RAINFALL AXIS
ON DAY 4. ALSO OF QUESTION IS THE DEGREE OF INSTABILITY, WITH THE
BACKDOOR FRONT LIKELY MAKING A PUSH ALL THE WAY INTO THE CAROLINAS,
LEAVING A MORE STABLE AIRMASS TO ITS NORTH. GIVEN THESE
UNCERTAINTIES WE OPTED TO DROP THE CENTRAL/SOUTHEAST VA SLIGHT RISK
WITH THIS UPDATE. OVERALL JUST ENOUGH UNCERTAINTY ON PLACEMENT,
AND QUESTIONABLE PEAK RAINFALL RATES GIVEN THE LIMITED INSTABILITY,
TO BE CONFIDENT IN A SCATTERED FLASH FLOOD RISK. WE WILL KEEP A
MARGINAL THOUGH, AS PLENTY OF MOISTURE IS IN PLACE, SO EVEN JUST A
BIT OF CAPE COULD DRIVE SOME LOW TOPPED CONVECTION AND LOCALLY
HIGHER RATES. WE WILL CONTINUE TO MONITOR AND POSSIBLE A SLIGHT
RISK IS REINTRODUCED SOMEWHERE OVER THE REGION AS WE GET CLOSER AND
CONFIDENCE INCREASES.
THE SLIGHT RISK OVER PA AND WV ON DAY 4 (TUE) WAS MAINTAINED. AN
INVERTED TROUGH SHOULD HELP FOCUS CONVECTION HERE, AND WHILE STILL
WEAK, UP TO ~500-1000 J/KG OF CAPE COULD DEVELOP. IN ADDITION, THIS
AREA HAS LOWER FFG THAN THE COASTAL PLAIN, AND SHOULD SEE
ADDITIONAL RAIN IN THE DAYS LEADING UP TO TUESDAY, POTENTIALLY
LOWERING FFG FURTHER.
SIMILAR SETUP ON DAY 5 (WED), JUST WITH EVEN MORE UNCERTAINTY AS
MODEL SPREAD INCREASES. THE DEGREE OF MODEL SPREAD SUPPORTS KEEPING
THE RISK LEVEL AT MARGINAL, WITH THE UNDERSTANDING AN EMBEDDED
SLIGHT RISK IS POSSIBLE AS WE GET CLOSER. THE BEST CHANCE APPEARS
TO BE FROM TN/KY INTO OH AND WV AS THE UPPER LOW MOVES OVERHEAD AND
DECENT INSTABILITY IS FORECAST. IF THE 00Z EC AND AIFS ARE
CORRECT, A SLIGHT RISK WILL BE NEEDED ON FUTURE UPDATES. HOWEVER,
MODEL SPREAD IS HIGH AND RUN TO RUN CONTINUITY IS LOW. THE GFS IS
MORE AGGRESSIVE ALONG THE COASTAL PLAIN WITH AN OFFSHORE LOW
BRINGING HEAVY RAIN INLAND. HOWEVER, IT GENERALLY SEEMS LIKE AN
OUTLIER AT THIS TIME, WITH BOTH THE GEFS MEAN AND AIGFS MORE
OFFSHORE (ALTHOUGH STILL MORE AGGRESSIVE THAN THE NON-NCEP
GUIDANCE).
..NEW MEXICO
A FAVORABLE SETUP FOR HEAVY RAIN AND SCATTERED TO NUMEROUS
INSTANCES OF FLASH FLOODING APPEARS TO BE SETTING UP FOR NEW
MEXICO ON DAYS 4 AND 5, AND PROBABLY CONTINUING INTO DAYS 6 AND 7
AS WELL. CONDITIONS WILL LIKELY GET MORE SENSITIVE WITH TIME AS WE
SEE MULTIPLE DAYS IN A ROW WITH AREAS OF HEAVY RAINFALL, AND THIS
MAY VERY WELL END UP BEING A MDT RISK EVENT AT SOME POINT DURING
THE TUE-FRI TIMEFRAME. BROAD TROUGHING IN THE WEST WILL PLACE NM
PERSISTENTLY WITHIN THE RIGHT ENTRANCE REGION OF A STRONG UPPER
JET. ONE STRONGER WAVE WILL MOVE TO THE NORTH TUESDAY, HELPING
ENHANCE LIFT, WITH A FEW MORE SUBTLE WAVES ON WEDNESDAY PROVIDING
ASCENT. WE WILL ALSO HAVE EASTERLY UPSLOPE FLOW IN THE LOW LEVELS,
SUFFICIENT INSTABILITY, AND EVENTUALLY A POSSIBLE PW CONNECTION TO
AN EASTERN PACIFIC TROPICAL SYSTEM. THIS COMBINATION OF FORCING,
INSTABILITY AND WELL OVER 90TH PERCENTILE PWS FOR SEPTEMBER,
SUGGEST HEAVY RAINFALL AND A GROWING FLASH FLOOD RISK. WE WILL
CARRY SLIGHT RISKS FOR NOW GIVEN WE ARE SEVERAL DAYS OUT AND SOME
UNCERTAINTIES CONTINUE WITH THE DETAILS, BUT OVERALL THIS SEEMS TO
BE AN ABOVE AVERAGE CONFIDENCE FORECAST FOR THIS LEAD TIME, AND
WOULD EXPECT TO SEE SOME FLASH FLOOD ISSUES ARISE. CAN NOT RULE OUT
THE POTENTIAL FOR LOCALLY SIGNIFICANT FLASH FLOODING IN THAT TUE-
FRI TIMEFRAME GIVEN THE SETUP, SO WE WILL NEED TO CLOSELY MONITOR
TRENDS.
CHENARD
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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