760
FOUS30 KWBC 182030
QPFERD
EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
430 PM EDT THU JUN 18 2026
DAY 1
VALID 16Z THU JUN 18 2026 - 12Z FRI JUN 19 2026
...THERE IS A HIGH RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL GULF
COAST...
...WIDESPREAD AND LIFE THREATENING FLASH FLOODING LIKELY TODAY FOR
THE CENTRAL GULF COAST...
..1600 UTC UPDATE
A WIDESPREAD AND LIFE-THREATENING FLASH FLOOD EVENT IS UNDERWAY
ACROSS THE CENTRAL GULF COAST AND WILL CONTINUE TO EXPAND
NORTHEASTWARD DEEPER INTO THE SOUTHEAST THROUGHOUT THE DAY. FLASH
FLOOD EMERGENCIES HAVE ALREADY BEEN ISSUED BOTH IN SOUTHEASTERN AND
CENTRAL LA AS WELL AS SOUTHERN MISSISSIPPI WHERE BANDS OF
BACKBUILDING, TRAINING THUNDERSTORMS HAVE ALREADY LEAD TO MRMS
ESTIMATED RAINFALL TOTALS OF 9-11" (SEE WPC MPD #450 FOR MORE
DETAILS). TORRENTIAL RAINFALL IS EXPECTED TO CONTINUE THROUGHOUT
THE DAY WITH THESE ONGOING STORMS AS WELL AS ADDITIONAL BANDS OF
THUNDERSTORMS SUPPORTED BY A SURFACE LOW ASSOCIATED WITH THE
REMNANTS OF TROPICAL STORM ARTHUR, AN IMPRESSIVE ~40-50 KT LOW
LEVEL JET OFF THE GULF, AND DAILY-RECORD LEVEL PWATS OVER 2". SOME
MODEST ADJUSTMENTS WERE MADE TO THE INHERITED OUTLOOK BASED ON
ONGOING THUNDERSTORMS AND THE LATEST 12Z HI-RES GUIDANCE INCLUDING
A WESTWARD EXPANSION OF THE HIGH RISK TO CENTRAL LOUISIANA WHERE
ONGOING LIFE-THREATENING FLASH FLOODING IS OCCURRING. A SLIGHT
NORTHEASTWARD EXPANSION WAS ALSO INCLUDED ACROSS SOUTHERN
MISSISSIPPI AND ALABAMA GIVEN MODERATE TO HIGH PROBABILITIES FROM
THE HREF OF 5-8"+ OF RAINFALL. GUIDANCE IN GENERAL HAS SUGGESTED A
NORTHEASTWARD EXPANSION OF THE FLASH FLOOD RISK BRINGING HEIGHTENED
CONCERN TO SOUTHWESTERN TO CENTRAL GEORGIA AS WELL AS FURTHER
NORTH INTO THE SOUTHERN APPALACHIANS.
ELSEWHERE, THE SLIGHT RISK OVER PORTIONS OF THE SOUTHERN
PLAINS/TEXAS WAS ALSO EXPANDED BASED ON THE LATEST 12Z HI-RES
GUIDANCE. THUNDERSTORMS ARE EXPECTED TO DEVELOP LATER THIS EVENING
AND INTO THE OVERNIGHT HOURS IN VICINITY OF A WAVE OF LOW PRESSURE
ALONG AN APPROACHING COLD FRONT AND SOUTHWARD ALONG THE DRYLINE.
SPORADIC/SLOW STORM MOTIONS AND CLUSTERING OF STORMS WILL SUPPORT
LOCALLY HEAVY RAINFALL, ESPECIALLY IF THE COLLECTIVE
CLUSTERING/MERGING OF COLD POOLS CAN RESULT IN MORE ORGANIZED
COMPLEXES AS SUGGESTED BY SOME OF THE HI-RES GUIDANCE. THIS
INCLUDES BOTH ALONG THE RED RIVER VALLEY, WHERE A SLIGHT RISK IS
ALREADY IN PLACE, AS WELL AS FURTHER SOUTH ALONG THE DRYLINE INTO
THE TEXAS HILL COUNTRY WHERE THE SLIGHT RISK HAS BEEN EXPANDED.
SOME OF THE LATEST HI-RES GUIDANCE (INCLUDING THE RRFS) IS MORE
BULLISH ON THE POTENTIAL FOR HEAVIER RAINFALL SPREADING SOUTHWARD
GIVEN EXPECTED STORM MOTIONS AND POTENTIAL FOR A MORE ORGANIZED
COMPLEX TO DEVELOP.
ANOTHER ROUND OF THUNDERSTORMS IS EXPECTED TODAY OVER PORTIONS OF
ARIZONA AND NEW MEXICO WHERE SOME LOCALLY HEAVY RAINFALL/ISOLATED
FLASH FLOODING WILL BE POSSIBLE GIVEN HEIGHTENED MOISTURE IN PLACE.
MOST STORMS WILL LIKELY BE DIURNALLY DRIVEN ALONG THE MORE COMPLEX
TERRAIN. INCREASED MOIST SOUTHERLY FLOW OFF THE ATLANTIC INTO
INTERIOR NEW ENGLAND/UPSTATE NEW YORK AHEAD OF AN APPROACHING LOW
PRESSURE SYSTEM WILL ALSO BRING THE THREAT FOR SOME LOCALLY HEAVY
RAINFALL (1-3" TOTALS) AND ISOLATED FLASH FLOODING.
PUTNAM
..PREVIOUS DISCUSSION
..SOUTHEAST
THE REMNANTS OF POST TROPICAL CYCLONE ARTHUR ARE MOVING INTO THE
CENTRAL GULF COAST THIS MORNING. WHILE THE CYCLONE CENTER MAY HAVE
DISSIPATED, THE MOISTURE PLUME AND ASSOCIATED RAINFALL SHIELD MOST
CERTAINLY HAVE NOT. RAINFALL MOVING INTO SOUTHEASTERN LOUISIANA
RIGHT NOW ARE PRODUCING RATES TO 3 INCHES PER HOUR. THESE KINDS OF
RAINFALL RATES ARE EXPECTED TO CONTINUE WITH THE STRONGEST CELLS
FOR MUCH OF THE DAY TODAY ACROSS THE CENTRAL GULF COAST. AN
IMPRESSIVE 50 KT LOW LEVEL JET AT 850 IS ADVECTING VERY DEEP
TROPICAL MOISTURE INTO THE COAST. THIS IS PUSHING PWATS TO OVER 2.6
INCHES. MEANWHILE INSTABILITY OVER THE GULF IS UP TO 4,000 J/KG.
THIS IS SUPPORTING VERY EFFICIENT CELLS CAPABLE OF MULTIPLE INCH
PER HOUR RATES TO THE EAST OF THE REMNANT CIRCULATION CENTER.
MULTIPLE WAVES OF STORMS WILL TRACK SOUTH TO NORTH ACROSS EASTERN
LOUISIANA INTO SOUTHERN MISSISSIPPI THIS MORNING. THE AREA HAS BEEN
HARD HIT WITH HEAVY RAIN IN RECENT DAYS, SO LARGER RIVERS ARE
ALREADY FLOODING, AND SOILS ARE NEARLY SATURATED, SO NEARLY ALL OF
THE HEAVY RAINFALL IS EXPECTED TO CONVERT TO RUNOFF, RESULTING IN
MORE SIGNIFICANT RIVER, STREAM, AND CREEK RISES THOUGH THE MORNING.
THE EASTERN SIDE OF THE PLUME OF MOISTURE WILL SPAWN ADDITIONAL
NUMEROUS THUNDERSTORMS INTO SOUTHERN ALABAMA AND THE FLORIDA
PANHANDLE THROUGH MIDDAY. THE STORM ORGANIZATION IS EXPECTED TO
CHANGE A BIT INTO THE AFTERNOON WITH PEAK HEATING. TO THE WEST
ACROSS MISSISSIPPI AND LOUISIANA, BACKBUILDING AND TRAINING
CONVECTION IS EXPECTED TO FORM INTO 1 OR 2 NEARLY STATIONARY LINES,
AS THE INDIVIDUAL CELLS EMBEDDED WITHIN TRAIN TOWARDS THE EAST
ALONG THE LINE. MEANWHILE, OVER ALABAMA, MULTIPLE LINES OF EASTWARD
MOVING LINES OF STORMS WILL GET THE FLOODING AND HEAVY RAINFALL
STARTED AS EARLY AS MID-MORNING. THE WESTERN END OF THE LINE IN
LA/MS WILL BECOME THE TRAILING STORMS ON THE SOUTHWEST END OF THE
MCS ASSOCIATED WITH POST TROPICAL CYCLONE ARTHUR. THIS LINE WILL
VERY SLOWLY DRIFT SOUTHEASTWARD TOWARDS THE GULF COAST, LIKELY
IMPACTING MOBILE AND EVENTUALLY THE PENSACOLA AREA, AS WELL AS
POINTS NORTH. THIS WILL RESULT IN MULTIPLE HOURS FROM MID-AFTERNOON
INTO THE EVENING WHERE TRAINING STORMS TRACK OVER THE SAME AREAS.
THE EASTWARD MOVING CONVECTION IS EXPECTED TO MOVE FASTER TOWARDS
THE EAST THAN THE STORMS CAN BACKBUILD, SO THE TRAILING LINE
RESPONSIBLE FOR THE WORST FLOODING SHOULD GRADUALLY SHIFT EAST AS
WELL. THE STORMS COULD PERSIST AS LONG AS UNTIL MIDNIGHT IN THE
FLORIDA PANHANDLE, BUT MOST GUIDANCE HAS IT MOVING ON AND
DISSIPATING EARLIER IN THE EVENING. REGARDLESS, WITH POTENTIAL FOR
MULTIPLE INCH PER HOUR RAINFALL RATES WITH NUMEROUS STORMS THROUGH
THE DAY TRACKING OVER THE SAME AREAS, THE STORM TOTAL RAINFALL IN
THESE AREAS IS LIKELY TO PILE UP VERY QUICKLY. GUIDANCE SUGGESTS
RAINFALL TOTALS IN MANY AREAS OF THE HIGH RISK COULD EXCEED 12
INCHES, THOUGH LOCAL AMOUNTS COULD APPROACH 20 INCHES.
WIDESPREAD AND POTENTIALLY LIFE THREATENING FLASH FLOODING IS
LIKELY AS A RESULT OF THESE DOUBLE-DIGIT RAINFALL NUMBERS. URBAN
AREAS THAT COULD BE IMPACTED FROM NEW ORLEANS (IN A HIGHER-END
MODERATE RISK), MOBILE, AND PENSACOLA COULD SEE LIFE-THREATENING
FLASH FLOODING OCCUR AS A RESULT. EVERYONE SHOULD HEED THE ADVICE
OF LOCAL AUTHORITIES AS WARNINGS ARE ISSUED.
ACROSS CENTRAL ALABAMA INTO NORTHERN GEORGIA, STORM COVERAGE AND
INTENSITY OF THE STRONGEST CELLS ARE EXPECTED TO BE A BIT LOWER,
BUT ANTECEDENT SOIL CONDITIONS REMAIN NEARLY SATURATED. MULTIPLE
HOURS OF MODERATE TO AT TIMES HEAVY RAIN ARE EXPECTED UP AS FAR
NORTH AS BIRMINGHAM AND NORTHEAST AS ATLANTA. THE MODERATE RISK FOR
THESE AREAS REMAINS IN PLACE WITH FEW CHANGES. AN EASTWARD
EXPANSION OF THE MODERATE RISK IN WEST-CENTRAL GEORGIA WAS ALSO
MADE.
..OHIO/TENNESSEE VALLEYS
A COLD FRONT PUSHING SOUTH ACROSS THE OHIO VALLEY TODAY WILL RUN
INTO THE NORTHERN EXTENT OF THE DEEP PLUME OF TROPICAL MOISTURE
ASSOCIATED WITH THE REMNANTS OF ARTHUR. WITH DAYTIME HEATING, THE
CLASHING OF AIR MASSES ALONG THE FRONT WILL RESULT IN NUMEROUS
SHOWERS AND THUNDERSTORMS DEVELOPING ALONG THE FRONT, WHICH WILL
LIKELY BE ALONG THE KY/TN BORDER, EXTENDING ENE INTO EASTERN
KENTUCKY AND SOUTHERN WEST VIRGINIA. THE STORMS WILL BE IN A
FAVORABLE ENVIRONMENT FOR TRAINING AS THE PLUME OF MOISTURE TRACKS
PARALLEL TO THE FRONT AS WELL. A SHORTWAVE TROUGH WILL HELP THE
FRONT ADVANCE SOUTH AND EAST ACROSS THE AREA MORE QUICKLY THIS
EVENING THROUGH TONIGHT, WHICH SHOULD END ANY BACKBUILDING AND
TRAINING FROM THE AFTERNOON AND ALLOW EVERYTHING TO PROGRESS
EASTWARD, ENDING THE FLOODING THREAT.
..SOUTHWESTERN OKLAHOMA INTO NORTH TEXAS
OVERNIGHT TONIGHT, AN MCS IS EXPECTED TO DEVELOP ACROSS
SOUTHWESTERN OKLAHOMA AND NORTH TEXAS IN RESPONSE TO BOTH PROXIMITY
TO THE DRY LINE, DEEP TROPICAL MOISTURE WITH PWATS APPROACHING 2
INCHES, AND A DEVELOPING LOW OVER WEST TEXAS, ENCOURAGING THE
FORMATION OF A LOW LEVEL JET INTO THE STORMS. GIVEN THIS IS A
SMALLER FEATURE THAN THE REMNANTS OF ARTHUR TO THE EAST, THE CAMS
ARE STRUGGLING MUCH MORE WITH WHERE AND HOW LONG THE STORMS IN THE
AREA WILL FORM, AND WHERE THEY WILL TRACK. MOST LIKELY THE STORMS
WILL REMAIN ALONG THE RED RIVER/OK-TX BORDER. THE INHERITED SLIGHT
COVERING MOST OF THE REST OF OKLAHOMA INTO ARKANSAS WAS DROPPED TO
A MARGINAL AS THIS MCS SHOULD REMAIN WELL SEPARATED FROM THE RAINS
WITH ARTHUR TO THE EAST, WITH LITTLE RAIN IN BETWEEN.
WEGMAN
DAY 2
VALID 12Z FRI JUN 19 2026 - 12Z SAT JUN 20 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
GULF COAST...
..2030 UTC UPDATE
THE PRIOR FORECAST REASONING REMAINS ON TRACK WITH THE GREATEST
CONCERN FOCUSED ON WHERE ADDITIONAL RAINFALL FRIDAY MAY OVERLAP
SOME OF THE TORRENTIAL TOTALS SEEN ACROSS THE CENTRAL GULF COAST
INTO THE SOUTHEAST ON THURSDAY. SOME INSTANCES OF FLASH FLOODING
MAY REMAIN ONGOING AS WELL. THE NOW AVAILABLE 12Z HI-RES GUIDANCE
SUPPORTS THE GREATEST RISK OF ADDITIONAL RAINFALL OF 1-3", LOCALLY
4-6", ACROSS MUCH OF THE INHERITED MODERATE RISK AREA. SOME MINOR
AREAL EXPANSIONS WHERE MADE TO THE NORTHERN EXTENT OF THE MODERATE
ACROSS SOUTHERN ALABAMA AND MISSISSIPPI BASED ON THE LATEST
GUIDANCE, AS WELL AS TO THE SOUTHWEST FROM COASTAL MISSISSIPPI
INTO SOUTHEASTERN LOUISIANA WHERE SOME OF THE HEAVIEST 24 HOUR
TOTALS (MRMS ESTIMATED 6-10") HAD OCCURRED THROUGH THURSDAY
AFTERNOON. THERE WAS ALSO A SIGNAL IN THE GUIDANCE FOR SOME SIMILAR
HEAVIER TOTALS FURTHER WEST ACROSS PORTIONS OF WESTERN LOUISIANA.
HOWEVER, MOST OF THIS REGION DID NOT SEE RAINFALL OVER THE PAST DAY
AND THUS FEEL COMFORTABLE RETAINING THE RISK AS A HIGHER-END
SLIGHT FOR NOW. ANOTHER MORE ISOLATED BUT SIGNIFICANT AREA OF
CONCERN WILL BE IF ANY RAINFALL OVERLAPS PORTIONS OF EAST-CENTRAL
LOUISIANA WHERE EXTREME RAINFALL OF OVER 24" IN THE PAST 24 HOURS
HAS BEEN ESTIMATED BY MRMS.
PUTNAM
..PREVIOUS DISCUSSION
..SOUTHEAST
WHILE THE PLUME OF EXTREME MOISTURE ASSOCIATED WITH THE REMNANTS OF
ARTHUR WILL BE EXITING THE CAROLINA COAST AT THE START OF THE
PERIOD, DEEP TROPICAL MOISTURE WILL REMAIN ENTRENCHED OVER MUCH OF
THE SOUTHEAST ON FRIDAY. A COLD FRONT THAT TRACKED OVER THE OHIO
VALLEY ON DAY 1/THURSDAY WILL CONTINUE EDGING SOUTHWARD INTO THE
SOUTHEAST, BRINGING MUCH DRIER AIR AND RELIEF TO AREAS BEHIND IT.
UNFORTUNATELY AHEAD OF IT, THE AIR MASS WILL REMAIN SOUPY. THE
MOISTURE OFF THE GULF WILL HAVE TURNED EASTWARD ALONG THE FRONT ON
FRIDAY, WHICH WILL DO A COUPLE THINGS: 1) IT WILL NOT PREVENT THE
FRONT FROM MAKING MORE SOUTHWARD PROGRESS, AS OPPOSED TO A
SOUTHERLY LOW LEVEL JET WHICH WOULD ACTIVELY WORK AGAINST A
SOUTHWARD MOVING FRONT. 2) IT WILL CREATE A MORE UNIDIRECTIONAL
WIND FLOW THROUGH THE DEPTH OF THE ATMOSPHERE, WHICH WILL SUPPORT
FASTER-MOVING, BUT TRAINING STORMS ALONG THE FRONT. IN ADDITION TO
ANY MCSS WHICH COULD FORM IN THE SOUPY AIR MASS EARLY IN THE
MORNING, POTENTIALLY MULTIPLE LINES OF STORMS WILL TRACK
SOUTHEASTWARD ALONG THE FRONT INTO THE AREA THAT JUST WAS HIT WITH
ARTHUR'S REMNANTS THE PREVIOUS DAY. THUS, THE MODERATE RISK FOR
THIS AREA REMAINS IN EFFECT. EXPECTED RAINFALL FOR MOST AREAS WILL
GENERALLY STAY BETWEEN 1-3 INCHES ON AVERAGE, SO THE RAINFALL
AMOUNTS EXPECTED ON FRIDAY WILL PALE IN COMPARISON TO TODAY.
HOWEVER, GIVEN THE EXPECTED FLOODING THAT WILL VERY MUCH STILL BE
ONGOING ON FRIDAY, THE ADDITION OF 1-3 INCHES OF RAIN WITH LOCALLY
HIGHER AMOUNTS WHERE STORM TRAINING PERSISTS LONGEST OVER THESE
SAME AREAS STILL RAISED THE FLOODING THREAT IN THE AREA TO THE
MODERATE RISK CATEGORY. CHANGES IN WHERE THE HEAVIEST RAINS
TODAY/DAY 1 OCCUR MAY RESULT IN SHIFTS OF THE MODERATE RISK,
PARTICULARLY IF THE HEAVIEST EXPECTED RAINS OCCUR FURTHER SOUTH AND
WEST INTO MISSISSIPPI AND EASTERN LOUISIANA. A FEW OF THE CAMS
MODELS ARE HINTING AT THAT POSSIBILITY.
..SOUTHERN PLAINS
ACROSS A LARGE SWATH OF TEXAS ON FRIDAY, MULTIPLE MCSS MAY IMPACT
MUCH OF THE STATE. ON FRIDAY MORNING, LINGERING MCSS FROM OKLAHOMA
AND THE SLIGHT RISK ON DAY 1 MAY BE ONGOING INTO NORTH-CENTRAL
TEXAS FRIDAY MORNING, INCLUDING INTO THE METROPLEX. WIDELY
SCATTERED INSTANCES OF FLASH FLOODING WILL BE POSSIBLE WITH THAT.
MORE COVERAGE OF STORMS ARE EXPECTED FRIDAY NIGHT. THE TYPICAL
STRENGTHENING MCS WILL ADVECT EXTREME INSTABILITY AND MOISTURE OVER
ALL OF THE EASTERN HALF OF THE STATE. AS STORMS FORM AND ORGANIZE
INTO MCSS, THE POTENTIAL FOR ADDITIONAL INSTANCES OF FLASH FLOODING
WILL INCREASE. THERE IS CONSIDERABLE UNCERTAINTY AS TO WHERE THEY
FORM AND HOW THEY TRACK, SO A LARGE SWATH OF EASTERN TEXAS WAS
INCLUDED IN A SLIGHT RISK, ESPECIALLY DOWN TOWARDS SAN ANTONIO AND
HOUSTON, WHICH HAVE BEEN IMPACTED WITH HEAVY RAINS IN RECENT DAYS,
AND SOILS REMAIN WETTER THAN NORMAL.
WEGMAN
DAY 3
VALID 12Z SAT JUN 20 2026 - 12Z SUN JUN 21 2026
...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL PLAINS AND MISSOURI VALLEY...
..CENTRAL PLAINS AND MISSOURI VALLEY
A LARGE AREA OF HEAVY RAIN ASSOCIATED WITH A DEVELOPING MCS
STARTING SATURDAY AFTERNOON AND CONTINUING INTO SATURDAY NIGHT IS
EXPECTED TO BRING WIDESPREAD HEAVY RAINFALL ACROSS PORTIONS OF THE
CENTRAL PLAINS INTO THE MISSOURI VALLEY WITH THE GREATEST THREAT
CURRENTLY EXPECTED ACROSS SOUTHEASTERN NEBRASKA, NORTHEASTERN
KANSAS, AND FAR NORTHWESTERN MISSOURI/SOUTHWESTERN IOWA. STORMS
ARE EXPECTED TO INITIATE SATURDAY AFTERNOON WITH PEAK HEATING. AN
LLJ OF SOUTHEASTERLY FLOW WILL PUMP DEEP GULF MOISTURE UP THE
PLAINS THROUGH THE DAY. A DEVELOPING SURFACE LOW AND UPPER LEVEL
SHORTWAVE STRENGTHENING THE LOW OVER COLORADO WILL EJECT INTO THE
PLAINS. THIS WILL FORCE THE DRYLINE TO RACE EASTWARD IN RESPONSE.
THE WARM FRONT ASSOCIATED WITH THE LOW AND THE DRY LINE WILL UPLIFT
THE DEEP MOISTURE, RESULTING IN WIDESPREAD SHOWER AND THUNDERSTORM
DEVELOPMENT. THESE STORMS ARE EXPECTED TO GROW UPSCALE INTO AN
EXPANSIVE, ORGANIZED CONVECTIVE SYSTEM INTO THE EVENING AND
OVERNIGHT HOURS THAT WILL THEN TRACK SOUTHEASTERLY ACROSS THE RISK
AREA. THE LATEST DETERMINISTIC GUIDANCE SHOWS AREAL AVERAGE
RAINFALL TOTALS ALONG THE EXPECTED PATH OF THE MCS IN THE 2-3"
RANGE WITH LOCALLY HIGHER AMOUNTS OF 4-6", MORE THAN SUFFICIENT TO
LEAD TO SCATTERED AND POTENTIALLY WIDESPREAD FLASH FLOODING, WHICH
HAS PROMPTED AN UPGRADE TO A MODERATE RISK. AS IS USUALLY THE CASE
WITH CONVECTIVE SYSTEMS THE EXACT PATH AND DURATION WILL BE
DETERMINED BY MORE MESOSCALE DETAILS THAN THE GUIDANCE CAN
TYPICALLY PIN DOWN AT THIS TIME FRAME, SO SOME AREAL MODIFICATION
AND POSSIBLE EXPANSION OF THE MODERATE RISK WILL BE LIKELY OVER THE
NEXT COUPLE OF DAYS. THE MOST LIKELY AREA FOR EXPANSION WOULD BE
FURTHER TO SOUTHEAST INTO MORE OF WESTERN MISSOURI AND EAST-
CENTRAL/SOUTHEASTERN KANSANS. HOWEVER, GIVEN THE NOTED UNCERTAINTY
WITH THE EVOLUTION OF THESE TYPES OF SYSTEMS AT THIS TIMEFRAME,
HAVE LIMITED THE EXTENT OF THE RISK AREA TO ALSO OVERLAP WHERE THE
GREATEST SUPPORT/CONFIDENCE IS SHOWN BY THE ENSEMBLE
MEAN/PROBABILISTIC GUIDANCE.
..SOUTHEAST
AN MCS TRACKING FROM THE OZARKS FOLLOWING THE SAME FRONT THAT
ENTERED INTERIOR PORTIONS OF THE SOUTHEAST AS A COLD FRONT ON
FRIDAY WILL HELP THAT SAME FRONT NOW RETREAT AS A WARM FRONT ON
SATURDAY. HEAVY RAINS ARE EXPECTED SATURDAY MORNING OVER THE SLIGHT
RISK AREA FROM NORTHERN MISSISSIPPI TO SOUTHERN ALABAMA AS STORMS
TRACK SOUTHEASTWARD ALONG THE RETREATING FRONT. DAYTIME HEATING
WILL LIKELY SUPPORT ADDITIONAL CLUSTERS OF STORMS INTO THE
AFTERNOON IN THESE AREAS. THE HEAVIEST RAINS OVER THE MOST
WIDESPREAD AREA WILL BE SATURDAY MORNING IN NORTHERN MISSISSIPPI.
THEY WILL BE LESS ORGANIZED AS THEY MOVE INTO SOUTHERN ALABAMA
SATURDAY AFTERNOON, BUT GIVEN THE PRIOR DAY'S EXPECTED RAINS IN
THESE SAME AREAS, THE SLIGHT RISK INCLUDES SOUTHERN ALABAMA AS
WELL. RAINFALL TOTALS WILL LIKELY BE MORE LIMITED THAN THEY HAVE
COMPARED TO THE PRIOR DAYS BUT THE REGION WILL REMAIN MORE
SUSCEPTIBLE TO ADDITIONAL INSTANCES OF FLASH FLOODING GIVEN THE
HEAVY RAINFALL RECEIVED FROM PRECIPITATION ASSOCIATED WITH THE
REMNANTS OF T.S. ARTHUR.
PUTNAM/WEGMAN
DAY 4 AND DAY 5
VALID 12Z SUN JUN 21 2026 - 12Z TUE JUN 23 2026
...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE OZARKS THROUGH THE MIDWEST AND INTO THE UPPER OHIO VALLEY...
2030Z UPDATE...
MAINTAINED THE SLIGHT RISK IN THE DAY 4 PERIOD AND THE MARGINAL
RISK ON DAY 5 WITH FEW CHANGES. THE WAVE COMING OUT OF THE PLAINS
AND CROSSING INTO THE MIDWEST REMAINS THE PRIMARY FOCUS FOR HEAVY
TO EXCESSIVE RAINFALL ON SUNDAY INTO EARLY MONDAY. SOME DIFFERENCES
LINGER IN LATITUDE OF THE AXIS OF HEAVIEST RAINFALL...BUT
PROBABILITIES WERE COMPARABLE WITH THE OVERNIGHT GUIDANCE.
LIKEWISE...THE PREVIOUSLY ISSUED OUTLOOK WAS STILL GENERALLY
CAPTURED THE AXIS OF HEAVIER RAINFALL THAT COULD RESULT IN HEAVY TO
POTENTIALLY EXCESSIVE RAINFALL ON MONDAY. SO CHANGES TENDED TO BE
FEW.
BANN
PREVIOUS DISCUSSION...
DAY 4...
BY THE START OF THE DAY 4 FORECAST PERIOD A POTENT SHORTWAVE AND
RELATED SURFACE LOW ARE EXPECTED TO EJECT EASTWARD OUT OF THE
CENTRAL PLAINS INTO THE MIDWEST. THERE WILL ALSO BE A TRAILING
FRONTAL BOUNDARY EXTENDING INTO THE SOUTHERN PLAINS TO ADD A FOCUS
FOR ADDITIONAL THUNDERSTORMS. THERE REMAINS SOME UNCERTAINTY
REGARDING THE SPEED AND LATITUDE OF THESE FEATURES, BUT PWS ABOVE
THE 90TH CLIMATOLOGICAL PERCENTILE (PER THE 00Z GEFS) OVERLAPPING
WITH SOILS LIKELY STILL RECOVERING FROM RECENT HEAVY RAIN IN THE
MIDWEST WILL LEAD TO AT LEAST SCATTERED FLASH FLOODING CONCERNS.
NBM PROBABILITIES FOR AT LEAST 2" ARE BETWEEN 30-55% AND COVER MUCH
OF THE SLGT RISK AREA. LOCALLY HIGHER TOTALS ARE LIKELY GIVEN THE
CONVECTIVE ENVIRONMENT. THE PROGRESSIVE NATURE OF THESE STORMS MAY
END UP LIMITING THE SEVERITY OF FLASH FLOOD IMPACTS, BUT A MDT RISK
UPGRADE IS POSSIBLE SHOULD TRAINING/BACK-BUILDING ELEMENTS BECOME
MORE OBVIOUS IN THE SHORT RANGE UPDATES. THIS IS ESPECIALLY THE
CASE GIVEN THE SENSITIVITY OF THE AFFECTED REGIONS TO ADDITIONAL
RAINFALL.
DAY 5...
THE SHORTWAVE AND LOW PRESSURE ON DAY 4 IS
FORECAST TO CONTINUE EAST TOWARDS THE MID-ATLANTIC AND NORTHEAST,
WITH ADDITIONAL UNCERTAINTIES IN LATITUDE AND SPEED. ADDITIONALLY,
THUNDERSTORMS SHOULD REFORM ALONG THE ATTACHED FRONTAL BOUNDARY
EXTENDING WESTWARD ACROSS THE TENNESSEE VALLEY AND INTO THE
SOUTHERN PLAINS. AT THE MOMENT MOST CONVECTION APPEARS SCATTERED IN
NATURE AND LOW CONFIDENCE IN PLACEMENT OF HEAVIER QPF. THEREFORE,
A MRGL RISK IS HIGHLIGHTED AND WILL BE REFINED IN FUTURE UPDATES.
ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY INTO THE HIGH PLAINS,
WITH UNCERTAINTY SURROUNDING THE IMPACT OF A NEARBY SOUTHERN CANADA
UPPER LOW ON THUNDERSTORM ACTIVITY IN THE NORTHERN HIGH PLAINS.
SNELL
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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