063
FXUS02 KWBC 260700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT MON MAY 26 2025
VALID 12Z THU MAY 29 2025 - 12Z MON JUN 02 2025
..OVERVIEW
THIS MEDIUM RANGE PERIOD BEGINS LATER WEEK WITH A SLOW TO PROGRESS
UPPER LEVEL PATTERN OVER THE LOWER 48, WITH SPLIT FLOW TO INCLUDE
A COUPLE OF EMBEDDED CUTOFF LOWS. A NORTHERN STREAM LOW WILL
MEANDER OVER THE NORTH-CENTRAL U.S. AND MIDWEST THIS WEEK WHILE AN
OFFSHORE SOUTHERN STREAM LOW WILL ONLY GRADUALLY APPROACH THE
SOUTHWEST U.S. AS UPPER RIDGING BUILDS HEAT OVER THE WEST. THE
NORTHERN STREAM LOW SHOULD GAIN MOMENTUM HEADING INTO NEXT WEEKEND
AS IT TENDS TO SYNC INTO AMPLIFIED UPPER LEVEL TROUGHING. THIS
PATTERN WILL RESULT IN A PERIOD WITH AREAS OF WET UNSETTLED WEATHER
TO FOCUS FROM THE SOUTH-CENTRAL U.S. TO THE EAST/SOUTHEAST U.S.
THIS PERIOD. MEANWHILE, A SERIES OF PACIFIC FRONTAL APPROACHES
SLUGGISHLY TOWARD THE PACIFIC NORTHWEST MAY OFFER SOME MODEST
COASTAL RAINS CHANCES LATE WEEK INTO NEXT.
..GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE STILL OFFERS A REASONABLY SIMILAR MEDIUM RANGE LARGER
SCALE PATTERN EVOLUTION FOR THE ONGOING SLOW TO TRANSITION FLOW.
HOWEVER, COMPLEX SYSTEM AND STREAM PHASING INTERACTIONS HAVE AGAIN
LED TO AN INCREASE IN SMALLER SCALE VARIANCES THROUGH MEDIUM RANGE
TIME SCALES, ESPECIALLY EMINATING FROM ENERGY TRANSFERS FROM A
NORTH-CENTRAL U.S./MIDWEST CLOSED LOW TO AN UPPER TROUGH OVER THE
EAST. ACCORDINGLY, FAVOR A COMPATIBLE 12 UTC NAEFS/ECMWF ENSEMBLE
MEANS BLEND AS MANUALLY AUGMENTED TO RESTORE SYSTEM DEFINITION AS
WARRANTED WHEN INHERENTLY SMOOTHED BY THIS BROAD BLEND PROCESS.
WPC PRODUCT CONTINUITY IS DECENTLY MAINTAINED WITH THIS STRATEGY,
WITH A SOLUTION IN LINE WITH A COMPOSITE OF LATEST 00 UTC GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
A MAIN SURFACE LOW SET TO SLOWLY EJECT OUT OF THE GREAT LAKES LATER
THIS WEEK AND FRONTAL AND SECONDARY BOUNDARIES TRAILING DOWN OVER
THE EAST AND BACK ACROSS THE SOUTH WILL CONTINUE TO FOCUS DEEP
MOISTURE WITH POTENTIAL TO FUEL HEAVY RAINS LOCALLY. WHILE THERE
IS UNCERTAINTY IN THE DETAILS AND LOCATIONS OF IMPACTFUL/HAZARDOUS
RAINFALL, THREAT POTENTIAL SHOULD REMAIN THE GREATEST FROM THE
SOUTHERN PLAINS AND GULF COAST STATES TO THE SOUTHEAST/EAST, AREAS
THAT MAY ALSO EXPERIENCE PERIODS OF ENHANCED SHORT-RANGE RAINFALL.
THIS ACTIVITY SHOULD PERIODICALLY PERSIST LATER WEEK INTO THE
WEEKEND AS BOUNDARIES LINGER AND WEAKEN AND AS UPPER TROUGHING
BECOMES MORE ESTABLISHED OVER THE EAST INTO THE WEEKEND. RAINS MAY
LINGER LONGER OVER PARTS OF THE SOUTHERN HIGH PLAINS ASSOCIATED
WITH RETURN FLOW AHEAD OF A BUILDING UPPER RIDGE UP OVER THE
SOUTHWEST. TO THE NORTH, A SECONDARY COLD FRONT AND LOW WILL
SPREAD RAIN OVER THE NORTHEAST PORTION OF THE NATION LATE WEEK.
IN THE WEST, A BUILDING UPPER RIDGE WILL LEAD TO AN EXPANDING AREA
OF HEAT FROM THE INTERMOUNTAIN WEST INTO THE WEST COAST STATES
THIS WEEK, WITH TEMPERATURES RISING UPWARDS TO 10 TO 15+ DEGREES
ABOVE NORMAL. THIS IN PARTICULAR MAY LEAD TO A HAZARDOUS HEAT FOCUS
FOR THE CALIFORNIA CENTRAL VALLEY LATE WEEK/NEXT WEEKEND.
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 (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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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