517
FXUS02 KWBC 250631
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
231 AM EDT SAT APR 25 2026
VALID 12Z TUE APR 28 2026 - 12Z SAT MAY 02 2026
...POTENTIAL FOR HEAVY RAIN AND SEVERE WEATHER FROM THE ARKLATEX
TO THE TENNESSEE VALLEY ON TUESDAY...
..OVERVIEW
AN ACTIVE PATTERN CONTINUES ACROSS THE CONUS NEXT WEEK AS A QUASI-
ZONAL MID-LEVEL PATTERN BECOMES INCREASINGLY AMPLIFIED WITH TIME.
A DEVELOPING WAVE ALONG THE TAIL END OF AN SOUTH/EASTWARD
PROGRESSING COLD FRONT WILL SUPPORT THE THREAT OF HEAVY RAIN AND
POSSIBLE SEVERE WEATHER FROM THE ARKLATEX THROUGH THE TENNESSEE
VALLEY ON TUESDAY. THIS WAVE TRACKS NORTHEASTWARD WEDNESDAY INTO
THURSDAY, SPREADING MUCH NEEDED RAIN INTO THE MID-ATLANTIC AND
NORTHEAST. MEANWHILE, A PACIFIC SYSTEM WILL SLIDE ACROSS SOUTHERN
CALIFORNIA AND THE SOUTHWEST MID TO LATE WEEK, BRINGING INCREASING
CHANCES FOR LOW ELEVATION RAIN AND MOUNTAIN SNOW ACROSS THE WINDY
INTERMOUNTAIN WEST, CENTRAL/SOUTHERN ROCKIES AND PLAINS. THERE
CONTINUES TO BE A GROWING GUIDANCE SIGNAL FOR POTENTIALLY HEAVY
RAIN AND STRONG THUNDERSTORMS ACROSS THE SOUTH-CENTRAL U.S.
THURSDAY INTO FRIDAY, WITH EASTWARD EXPANSION HEADING INTO
SATURDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
A QUASI-ZONAL MID-LEVEL PATTERN REMAINS REASONABLY DEPICTED BY THE
LATEST GUIDANCE THROUGH ABOUT MIDWEEK BEFORE BECOMING INCREASINGLY
AMPLIFIED AND BLOCKY WITH SMALLER SCALE DETAILS MORE UNCERTAIN
LATER IN THE PERIOD. BROAD TROUGHING GRADUALLY EXPANDS FROM THE
CENTRAL TO EASTERN U.S. NEXT WEEK, WITH GUIDANCE HINTING AT THE
POSSIBLE DEVELOPMENT OF A LARGE, POTENTIALLY CUT-OFF UPPER LOW
LATER ON. IN THE WESTERN U.S., MODELS CONTINUES TO FAVOR THE SLOWER
TRENDS OF THE INLAND PROGRESSION OF THE SOUTHERN STREAM PACIFIC
LOW, THOUGH THE 12Z AND LATEST 00Z CMC REMAINS ON THE FASTER END OF
THE GUIDANCE ENVELOPE. BY THE END OF THE PERIOD, IN CONJUNCTION
WITH THE POSSIBLE LARGE UPPER LOW IN THE EAST, THE WESTERN HALF OF
THE U.S. LOOKS INCREASINGLY BLOCKY, WITH POSSIBLE DEVELOPMENT OF AN
OMEGA OR REX BLOCK.
GIVEN THE ABOVE, THE WPC PRODUCT SUITE WAS DERIVED FAVORING THE
DETERMINISTIC RUNS OF THE 18Z/12Z GFS/ECMWF ALONG WITH THE
GEFS/ECMWF ENSEMBLE MEANS. THE WEIGHTING OF ENSEMBLE MEANS
INCREASED TO 40% BY DAY 6/FRIDAY AND 50% FOR DAY 7/SATURDAY.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT TRAILING IN THE WAKE OF STRONG LOW PRESSURE ADVANCING
INTO SOUTHERN CANADA WILL SLIDE TO THE SOUTH AND EAST ON TUESDAY,
BRINGING A FEW SCATTERED SHOWERS AND THUNDERSTORMS TO THE EASTERN
U.S. A WAVE OF LOW PRESSURE DEVELOPING ON THE TAIL END OF THE FRONT
WILL BECOME THE GREATER FOCUS FOR ANOTHER ROUND OF HEAVY RAIN AND
POSSIBLE SEVERE WEATHER ON TUESDAY FROM THE ARKLATEX TO THE
TENNESSEE VALLEY. SIGNIFICANT MOISTURE AND INSTABILITY POOLING
ALONG THE BOUNDARY AND FRONTAL WAVE WILL LIKELY LEAD TO CLUSTERS OF
STRONG THUNDERSTORMS WITH HIGH RAINFALL RATES, SUPPORTING THE
POTENTIAL FOR ISOLATED INSTANCES OF FLASH FLOODING. A MARGINAL RISK
ERO REMAINS IN PLACE FOR DAY 4/TUESDAY AS A RESULT. ADDITIONAL
SHOWERS AND STORMS LIKELY LINGER ALONG AND JUST NORTH OF THE GULF
COAST ON DAY 5/WEDNESDAY, BUT ANY FLOODING RISK SHOULD BE MINOR AND
FAIRLY LOCALIZED. THE FRONTAL WAVE TRACKS EASTWARD TO THE EASTERN
SEABOARD WEDNESDAY INTO THURSDAY, SPREADING MUCH NEEDED RAIN INTO
THE MID-ATLANTIC AND NORTHEAST. A BIT OF SNOW ISN'T RULED OUT WITH
THIS ACTIVITY FOR PARTS OF THE HIGHER ELEVATIONS OF NORTHERN NEW
ENGLAND AND THE INTERIOR NORTHEAST.
FARTHER WEST, A SOUTHERN STREAM PACIFIC LOW WILL SLOWLY ADVANCE
INLAND ACROSS SOUTHERN CALIFORNIA, THE SOUTHWEST, AND THE FOUR
CORNERS STATES LATE WEDNESDAY INTO THURSDAY, SPREADING LIGHT TO
MODERATE LOW ELEVATION RAIN AND HIGHER ELEVATION MOUNTAIN SNOW INTO
THE REGION. AS THIS FEATURE CONTINUES EASTWARD, A GROWING SIGNAL
FOR SIGNIFICANT RAINFALL AND POSSIBLE SEVERE WEATHER WILL DEVELOP
AND EXPAND/INTENSIFY OVER THE SOUTH-CENTRAL U.S. THURSDAY INTO
FRIDAY, WITH EASTWARD PROGRESSION ON SATURDAY.
WARMER THAN AVERAGE TEMPERATURES ARE LIKELY FROM THE SOUTHERN
PLAINS INTO THE MID-SOUTH AND OHIO VALLEY THROUGH EARLY NEXT WEEK.
TEMPERATURES WELL INTO THE 90S AND LOW 100S WILL BE COMMON ACROSS
THE SOUTHERN PLAINS, ESPECIALLY SOUTHERN TEXAS. MEANWHILE, COOLER
THAN AVERAGE TEMPERATURES WILL EXPAND FROM THE NORTH-CENTRAL U.S.
TO THE SOUTH AND EAST IN THE WAKE OF A STRONG COLD FRONT MID TO
LATE WEEK. HIGH TEMPERATURES FROM THE NORTHEAST TO THE SOUTHERN
PLAINS WILL BE AS MUCH AS 10 TO 15 DEGREES BELOW NORMAL BY FRIDAY
AND SATURDAY. AS THE EASTERN HALF OF THE U.S. COOLS DOWN, THE
WESTERN U.S. WILL START WARMING UP. IN FACT, PARTS OF THE DESERT
SOUTHWEST WILL TURN A BIT MORE SUMMERLIKE WITH HIGHS CLIMBING TO
NEAR THE CENTURY MARK HEADING INTO NEXT WEEKEND.
MILLER
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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