159
FXUS02 KWBC 221943
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
343 PM EDT FRI MAY 22 2026
VALID 12Z MON MAY 25 2026 - 12Z FRI MAY 29 2026
...HEAVY RAIN AND THUNDERSTORMS EXPECTED TO CONTINUE ACROSS MUCH
OF THE SOUTHERN U.S...
..OVERVIEW
A COUPLE OF SOUTHERN STREAM UPPER TROUGHS WILL PASS THROUGH THE
SOUTHWESTERN AND SOUTH-CENTRAL U.S. NEXT WEEK, PROVIDING LIFT FOR
WIDESPREAD RAIN AND THUNDERSTORMS IN A MOIST AND UNSTABLE
ENVIRONMENT. THE HEAVIEST RAIN SHOULD GENERALLY AFFECT THE LOWER
MISSISSIPPI VALLEY AND SOUTHEAST INTO MEMORIAL DAY, AND POTENTIALLY
GET RENEWED IN TEXAS AND VICINITY INTO THE WORKWEEK OVER AREAS
THAT WILL ALREADY HAVE WET ANTECEDENT CONDITIONS. OUT WEST, A MORE
AMPLIFIED PATTERN STARTS TO EMERGE AS A STRONGER UPPER TROUGH
LIKELY BECOMING A CLOSED LOW ENTERS THE PACIFIC NORTHWEST AND
ENVELOPS MORE OF THE INTERMOUNTAIN WEST BY MID TO LATE WEEK,
YIELDING COOLER TEMPERATURES AND PRECIPITATION. AN UPPER RIDGE
SHOULD DEVELOP DOWNSTREAM IN THE EAST-CENTRAL U.S., REACHING INTO
THE UPPER MIDWEST/GREAT LAKES AND BRINGING ABOVE AVERAGE
TEMPERATURES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODELS AND GUIDANCE SHOW GOOD AGREEMENT ON THE OVERALL
PATTERN EVOLUTION THROUGH THE PERIOD, WHICH SHOULD GRADUALLY TREND
MORE AND MORE AMPLIFIED THROUGH NEXT WEEK. GFS AND GEFS RUNS FROM
TODAY (FRIDAY) HAVE FORTUNATELY CAUGHT BACK ONTO A SOLUTION OF
SHOWING A DEEPER AND SLOWER UPPER LOW MOVING ACROSS THE WEST LIKE
THE NON-NCEP GUIDANCE HAS SHOWN, UNLIKE YESTERDAY'S GFS/GEFS RUNS.
THERE REMAINS SOME MINOR SPREAD WITH JUST HOW FAR SOUTH THE LOW
WILL GET, WITH THE 12Z CMC THE FARTHEST SOUTH BY LATE WEEK WHILE
OTHER GUIDANCE HAS THE LOW CENTROID FARTHER NORTH. THERE IS GOOD
AGREEMENT FOR UPPER RIDGING DOWNSTREAM, ORIENTED FROM THE SOUTHEAST
NORTHWESTWARD INTO THE MIDWEST, AS SOUTHERN STREAM ENERGY CUTS
INTO IT IN THE SOUTH-CENTRAL U.S., WITH TYPICAL MODEL DIFFERENCES
IN THE DETAILS. MEANWHILE, THERE IS SOME UNCERTAINTY BY THURSDAY
AND FRIDAY WITH A POTENTIAL UPPER LOW RETROGRADING INTO THE
NORTHEAST AND THE POTENTIAL FOR MULTIPLE WAVES OF TROUGHING. THE
DETAILS ARE YET TO BE DETERMINED BUT WILL CONTINUE TO BE MONITORED
AS IT DOES AFFECT SENSIBLE WEATHER FOR TEMPERATURES AND QPF.
A MULTI-MODEL BLEND WORKED WELL FOR THE MEDIUM RANGE FORECAST
EARLY ON. AS THE WEEK PROGRESSED, USED MORE OF THE ENSEMBLE MEANS
FOR THE FRONTS/PRESSURES TO MITIGATE INDIVIDUAL MODEL DIFFERENCES,
WITH THE MEANS REACHING ABOUT HALF BY DAY 7.
..WEATHER/HAZARDS HIGHLIGHTS
ON MONDAY, NORTHERN STREAM TROUGHING OVER THE NORTHEAST AND
SOUTHERN STREAM TROUGHING OVER THE SOUTHERN PLAINS/LOWER
MISSISSIPPI VALLEY WILL ALLOW FOR A LARGE SWATH OF RAIN AND
THUNDERSTORMS THROUGH THE SOUTH-CENTRAL U.S. STRETCHING ACROSS THE
EAST. AREAS FARTHER SOUTH SHOULD SEE HEAVIER RAIN IN A MORE
UNSTABLE ENVIRONMENT, SO A MARGINAL RISK REMAINS IN PLACE IN THE
DAY 4/MONDAY ERO FROM EASTERN TEXAS THROUGH MUCH OF THE MID-SOUTH
AND SOUTHEAST FOR POTENTIAL FLASH FLOODING FROM HEAVY RAIN RATES.
ADDITIONALLY, THE NEXT SOUTHERN STREAM UPPER LOW MOVING ACROSS THE
SOUTHWEST WILL HELP SPARK CONVECTION IN THE FOUR CORNERS REGION,
ESPECIALLY NEW MEXICO, ON MONDAY. THESE STORMS SHOULD HAVE GOOD
DYNAMICAL LIFT BUT LESS INSTABILITY AND FASTER MOVEMENT THAN WOULD
LIKELY CAUSE FLOODING ISSUES, SO WILL KEEP THIS AREA OUT OF A
MARGINAL RISK. AS THE SOUTHERN STREAM UPPER LOW MOVES EAST, THIS
SHOULD RENEW CONVECTION WITH HEAVY RAIN POTENTIAL IN TEXAS AND
VICINITY, AND MAINTAIN RAIN/STORM CHANCES FARTHER EAST. A BROAD
MARGINAL RISK IS ALSO IN PLACE FOR DAY 5/TUESDAY. IT IS POSSIBLE
EMBEDDED SLIGHT RISKS MAY BE NEEDED AS MODELS CONVERGE ON BETTER
POTENTIAL FOR WHERE HEAVY RAINFALL MAY OCCUR. THIS IS ESPECIALLY
TRUE FOR PARTS OF TEXAS AND VICINITY (TUESDAY AND BEYOND) WHERE
RECENT RAINS AND SHORT TERM RAINFALL HAS LEAD TO RATHER SATURATED
GROUNDS. THE WET PATTERN LOOKS TO REMAIN IN PLACE ACROSS THE
SOUTHEAST QUADRANT OF THE COUNTRY THROUGH THE REST OF THE WEEK AS
THE OVERALL PATTERN ALOFT STAGNATES.
UPPER TROUGHING MOVING INTO THE NORTHWEST EARLY NEXT WEEK AND A
FRONTAL SYSTEM AHEAD OF IT WILL ALLOW FOR INCREASED PRECIPITATION
REACHING THE PACIFIC NORTHWEST AND SPREADING SOUTH AND EASTWARD
WITH TIME THROUGH THE WEEK. SNOW IS POSSIBLE AT THE HIGHEST
ELEVATIONS OF THE CASCADES TO ROCKIES.
WITH A DEEPENING TROUGH OVER THE WEST, TEMPERATURES SHOULD TREND
COOLER IN THIS REGION THROUGH ABOUT WEDNESDAY, WITH SOME MODERATING
BACK TOWARDS NORMAL AS THE TROUGH WEAKENS AND DRIFTS. THE UPPER
RIDGE TO ITS EAST WILL ALLOW FOR WARMER THAN AVERAGE TEMPERATURES
ACROSS THE NORTH-CENTRAL U.S. THROUGH MUCH OF NEXT WEEK, WITH
DAYTIME HIGHS 10-20 DEGREES ABOVE NORMAL, ESPECIALLY FOR THE EARLY
PART OF THE WEEK.
TATE/SANTORELLI
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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