015
FXUS02 KWBC 281848
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
248 PM EDT THU MAY 28 2026
VALID 12Z SUN MAY 31 2026 - 12Z THU JUN 04 2026
...HEAVY RAIN AND THUNDERSTORM THREATS CONTINUE FOR THE SOUTHEAST
AND THE NORTHERN ROCKIES LATE WEEKEND INTO NEXT WEEK...
..OVERVIEW
IT REMAINS THE CASE THAT AN AMPLIFIED UPPER-LEVEL SYNOPTIC PATTERN
WILL REMAIN IN PLACE INTO EARLY NEXT WEEK, BEFORE TURNING MORE
ZONAL LATE NEXT WEEK. OVERALL, THE GENERAL UPPER PATTERN WILL
FEATURE TROUGHING OVER BOTH THE WEST AND THE EASTSANDWICHING
CENTRAL U.S. RIDGING. THE TROUGH OVER THE WEST WILL CLOSE OFF INTO
A BROAD UPPER LOW AND SPIN OVER THE NORTHERN ROCKIES, BRINGING LOW
ELEVATION HEAVY RAIN AND MOUNTAIN SNOW SUNDAY INTO MONDAY.
UNSEASONABLY LOW HEIGHTS OVER THE EAST WILL BE REINFORCED THROUGH
MIDWEEK AS SEVERAL DISTURBANCES ROTATE WITHIN AND AROUND A MAIN
TROUGH/CLOSED LOW OVER EASTERN CANADA. THE RELATIVELY COOL AIR MASS
ACROSS THE NORTHEAST AND EAST- CENTRAL U.S. WILL KEEP HEAT AND
HUMIDITY SUPPRESSED TO THE SOUTH. THE RESULTING FRONTAL BOUNDARY
DRAPED ACROSS THE SOUTHEAST COMBINED WITH SOUTHERN STREAM ENERGY
WILL ALLOW FOR THE PERSISTENCE OF A GENERALLY WET AND STORMY
PATTERN ACROSS MUCH OF THE REGION. LATER IN THE PERIOD, STORMY
WEATHER FROM PARTS OF THE WEST/ROCKIES BUILDS INTO THE PLAINS
BEFORE ADVANCING SLUGGISHLY EASTWARD WITH TIME, BUMPING INTO A
MOISTURE FEED ON THE WESTERN PERIPHERY OF DOWNSTREAM RIDGING.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST MODELS ARE IN DECENT AGREEMENT OF THEIR DEPICTIONS OF THE
LARGE SCALE PATTERN THROUGH THE MEDIUM RANGE PERIOD, HIGHLIGHTING
AN AMPLIFIED SOLUTION THAT SLOWLY BECOMES MORE ZONAL. SMALLER
SPATIAL AND TEMPORAL DIFFERENCES, PARTICULARLY WITH RESPECT TO THE
TRANSITION AWAY FROM A BLOCKY PATTERN MID TO LATE NEXT WEEK, LEADS
TO SOME LINGERING UNCERTAINTY WITH SYSTEM/FRONTAL PLACEMENT AND
SENSIBLE WEATHER IMPACTS. HOWEVER, FOR THE MOST PART, A BLEND OF
THE DETERMINISTIC MODELS AND ENSEMBLE MEANS SEEMED TO PROVIDE A
SOLID FORECAST BASIS THAT RETAINED DECENT CONTINUITY AND ACTED TO
MITIGATE DIFFERENCES AS CONSISTENT WITH INDIVIDUAL PREDICTABILITY.
THIS SOLUTION IS GENERALLY IN LINE WITH THE NBM AND ALSO FITS WITH
NATIONAL HURRICANE CENTER INSIGHT THAT CONTINUES TO DISCOUNT
TROPICAL MOISTURE FEED AND DEVELOPMENT POTENTIAL BY RECENT BUT
CYCLE TO CYCLE QUITE VARIED GFS/ECMWF RUNS OUT FROM THE CARIBBEAN.
..WEATHER/HAZARDS HIGHLIGHTS
A VERY WARM, HUMID, AND UNSTABLE AIRMASS SOUTH OF A WAVY FRONTAL
BOUNDARY WILL KEEP MUCH OF THE SOUTH AND SOUTHEAST ACTIVE WITH
DAILY RAIN AND THUNDERSTORM CHANCES THIS WEEKEND INTO NEXT WEEK.
THE POTENTIAL FOR SCATTERED CLUSTERS OF THUNDERSTORMS CONTAINING
HIGH RAINFALL RATES COMBINED WITH WHAT HAS ALREADY BEEN A WET
PATTERN ACROSS THIS REGION INDICATES THAT ISOLATED FLASH FLOODING
COULD BE A CONCERN, PARTICULARLY FOR FLOOD PRONE AREAS. AS A
RESULT, FOR DAY 4/SUNDAY AND DAY 5/MONDAY, MARGINAL RISK AREAS HAVE
BEEN INTRODUCED FOR PARTS OF THE SOUTHEAST INTO FLORIDA.
MEANWHILE, AN UPPER TROUGH THAT IS FORECAST TO CLOSE OFF INTO A
CUT-OFF LOW OVER THE NORTHERN ROCKIES WILL BRING WIDESPREAD LOW
ELEVATION HEAVY RAIN AND SOME HIGH ELEVATION MOUNTAIN SNOW FROM
LATE WEEKEND INTO EARLY NEXT WEEK. THE SIGNAL FOR HEAVY RAINFALL
REMAINS ROBUST ENOUGH TO MAINTAIN THE DAY 4/SUNDAY MARGINAL RISK
ACROSS A LARGE PORTION OF MONTANA AND A PART OF NORTHERN WYOMING,
WITH INTENSITY WANING HEADING INTO MONDAY AND TUESDAY. RAINFALL AND
THUNDERSTORM CHANCES ALSO INCREASE ACROSS THE PLAINS MID TO LATE
WEEK AS THE CUT-OFF LOW OPENS BACK UP INTO A WAVE AND EJECTS OUT.
MODERATING TEMPERATURES ARE EXPECTED ACROSS THE WEST INTO NEXT
WEEK FOLLOWING A PERIOD OF COOLER THAN NORMAL TEMPERATURES
ASSOCIATED WITH INCREASED CLOUD COVER AND PRECIPITATION. ABOVE
NORMAL PRE-FRONTAL WARMTH WILL GENERALLY BE CONFINED TO THE
CENTRAL U.S. WHERE UPPER LEVEL RIDGING IS MOST PERSISTENT. IN
CONTRAST, NEAR TO SLIGHTLY BELOW NORMAL TEMPERATURES ARE EXPECTED
ACROSS THE NORTHEAST AND MID-ATLANTIC AS PERIODIC SYSTEMS BRING
RAIN CHANCES AND REINFORCING PUSHES OF COOL AIR.
MILLER/SCHICHTEL
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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