640
FXUS02 KWBC 210754
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
354 AM EDT THU MAY 21 2026
VALID 12Z SUN MAY 24 2026 - 12Z THU MAY 28 2026
...HEAVY RAIN AND THUNDERSTORMS EXPECTED TO CONTINUE ACROSS
EASTERN TEXAS INTO THE LOWER MISSISSIPPI RIVER VALLEY...
..GENERAL OVERVIEW
AN ACTIVE WEATHER PATTERN WILL CONTINUE TO REMAIN IN PLACE ACROSS
THE SOUTH-CENTRAL U.S. GOING INTO THE UPCOMING WEEKEND AND INTO
EARLY NEXT WEEK, WITH MULTIPLE SHORTWAVE DISTURBANCES AND A WEAK
FRONTAL BOUNDARY PRODUCING MULTIPLE ROUNDS OF HEAVY RAIN AND
STORMS. AN UPPER TROUGH OVER THE GREAT LAKES THIS WEEKEND SHOULD
REACH NORTHERN NEW ENGLAND BY MONDAY NIGHT, WITH WIDESPREAD SHOWERS
FROM THE OHIO VALLEY TO THE NORTHEAST AHEAD OF THIS FEATURE.
OUT WEST, A MORE AMPLIFIED LEVEL PATTERN STARTS TO EMERGE AS A
STRONGER UPPER TROUGH AND THEN CLOSED LOW ENTER THE PACIFIC
NORTHWEST AND ENVELOPING MORE OF THE INTERMOUNTAIN WEST BY THE
MIDDLE OF THE WEEK, AND A DOWNSTREAM UPPER RIDGE DEVELOPS OVER THE
OHIO VALLEY AND WESTERN GREAT LAKES WITH ABOVE AVERAGE TEMPERATURES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE HAS A GOOD SOLIDIFIED DEPICTION OF
THE AMPLIFYING TROUGH ACROSS THE WEST LATE IN THE PERIOD, AND
FORECAST CONFIDENCE HAS INCREASED IN THIS PATTERN CHANGE EVOLVING,
EVEN THOUGH THE GFS IS A LITTLE WEAKER WITH THIS TROUGH BY NEXT
THURSDAY. ACROSS THE SOUTHERN TIER STATES, THE GUIDANCE CONTINUES
TO SHOW A WEAK CLOSED SOUTHERN STREAM LOW OVER TEXAS AND OKLAHOMA
FOR THE BEGINNING OF THE FORECAST PERIOD.
THE NBM IS LIKELY TOO WARM WITH TEMPERATURES ACROSS THE
NORTHWESTERN QUADRANT OF THE COUNTRY GOING INTO THE TUESDAY TO
THURSDAY TIME PERIOD, SO THE WPC FORECAST REFLECTS A COOLER
SCENARIO MORE IN LINE WITH THE LATEST DETERMINISTIC GUIDANCE, AND
ALSO A SLIGHT INCREASE IN QPF ACROSS THIS SAME GENERAL REGION
GIVEN BETTER ASCENT. THE ENSEMBLE MEANS WERE INCREASED TO ABOUT 50%
BY NEXT THURSDAY FOR FRONTS AND PRESSURES.
..WEATHER/HAZARDS HIGHLIGHTS
HEAVY RAIN WILL CONTINUE TO MAKE WEATHER HEADLINES GOING INTO
SUNDAY AND MEMORIAL DAY FROM EASTERN TEXAS TO THE DEEP SOUTH WITH
MULTIPLE MESOSCALE CONVECTIVE SYSTEMS DEVELOPING. THESE WILL BE IN
RESPONSE TO ENHANCED ASCENT FROM A WEAK UPPER TROUGH IN THE
SOUTHERN STREAM FLOW, COUPLED WITH A WEAK FRONT IN THE REGION AND
PLENTY OF MOISTURE AND INSTABILITY. A SLIGHT RISK FOR EXCESSIVE
RAINFALL WILL BE VALID ON SUNDAY FROM EASTERN TEXAS TO WESTERN
LOUISIANA, WHERE THE POTENTIAL EXISTS FOR A FEW INCHES OF RAINFALL
WITH THE MOST PERSISTENT STORMS OVER SOILS THAT WILL BE BECOMING
INCREASINGLY SATURATED. THE COVERAGE BECOMES LESS CONCENTRATED
GOING INTO THE DAY 5/MONDAY TIME PERIOD, SO A BROAD MARGINAL RISK
AREA IS VALID ACROSS MUCH OF THE SOUTH AND EXTENDING EASTWARD TO
INCLUDE PORTIONS OF SOUTHERN VIRGINIA. SCATTERED SHOWERS AND
THUNDERSTORMS ARE LIKELY TO DEVELOP, AND SOME OF THESE COULD BE
LOCALLY HEAVY. MORE PRECIPITATION RETURNS TO THE PACIFIC NORTHWEST
TO START NEXT WEEK WITH A COLD FRONT MOVING IN AND A BUILDING UPPER
LEVEL TROUGH, AND THIS MOVES INLAND THROUGH THE MIDDLE OF THE WEEK.
A GRADUAL WARMING TREND CAN BE EXPECTED FOR THE MID-ATLANTIC AND
THE NORTHEAST TO START NEXT WEEK AFTER A FEW DAYS OF COOLER
WEATHER FROM COLD AIR DAMMING. SLIGHTLY BELOW AVERAGE TEMPERATURES
ARE LIKELY ACROSS THE GULF COAST REGION GIVEN THE WIDESPREAD
RAINFALL THAT IS EXPECTED. WITH THE UPPER LOW DEVELOPING OVER THE
NORTHWESTERN U.S., A RETURN TO COLDER CONDITIONS IS ALSO LIKELY
HERE GOING INTO TUESDAY AND WEDNESDAY, WITH SOME HIGHER ELEVATION
SNOW LIKELY FOR PORTIONS OF THE NORTHERN ROCKIES. THE GREATEST
POSITIVE ANOMALIES WILL LIKELY BE OVER THE NORTHERN PLAINS AND
UPPER MIDWEST WITH THE UPPER RIDGE AXIS MONDAY THROUGH WEDNESDAY,
WITH READINGS UP TO 20 DEGREES ABOVE AVERAGE.
HAMRICK
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC
MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS,
QUANTITATIVE PRECIPITATION FORECAST, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
ARE AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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