138
FXUS02 KWBC 052002
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
402 PM EDT TUE MAY 5 2026
VALID 12Z FRI MAY 08 2026 - 12Z TUE MAY 12 2026
..GENERAL OVERVIEW
A BROAD UPPER-LEVEL CLOSED LOW OVER EASTERN CANADA WILL CONTINUE
TO DRIVE BROAD CYCLONIC FLOW AND REPEATED TROUGH REINFORCEMENT
THROUGH THE PERIOD. THIS PATTERN WILL BRING UNSETTLED WEATHER
ACROSS THE CENTRAL/EASTERN U.S. THE SERIES OF FRONTAL PASSAGES WILL
CONTINUE TO MOVE ACROSS THE CENTRAL U.S. INTO EASTERN U.S THROUGH
MONDAY, BRINGING SHOWERS AND THUNDERSTORMS ALONG THE BOUNDARIES.
THE REMNANTS OF A PRIOR FRONT WILL LINGER ACROSS THE LOWER
MISSISSIPPI VALLEY INTO THE SOUTHEAST, BRINGING ADDITIONAL RAINFALL
TO THE AREA. BELOW NORMAL TEMPERATURES WILL CONTINUE ACROSS THE
GREAT LAKES INTO THE NORTHEAST THROUGH THE WEEKEND, WHILE A WARMING
TREND ENSUES ACROSS MUCH OF THE WESTERN U.S.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST MODEL GUIDANCE REMAINS WELL CLUSTERED THROUGH MOST OF
THE FORECAST PERIOD WITH A GOOD HANDLE ON THE LARGE-SCALE FEATURES.
THESE MAIN FEATURES INCLUDE MEAN UPPER-TROUGHING OVER THE CENTRAL
TO EASTERN U.S. BELOW AN UPPER-LOW ANCHORED OVER HUDSON BAY WITH
PERIODIC SHORT-WAVE/FRONTAL PASSAGES. TYPICAL SMALLER-SCALE
DIFFERENCES EMERGE WITH RESPECT TO THESE SHORT-WAVE/FRONTAL
PASSAGES BUT EVEN THE FRONTAL PROGRESSION IS GENERALLY WELL AGREED
UPON. MEANWHILE, AN UPPER-RIDGE WILL BUILD OVER THE WESTERN U.S.
LATE THIS WEEKEND AND INTO EARLY NEXT WEEK. THE GUIDANCE DOES BEGIN
TO DIVERGE A BIT BY THE END OF THE PERIOD PARTICULARLY WITH
RESPECT TO A POTENTIAL CLIPPER-LIKE SYSTEM DROPPING INTO THE NORTH-
CENTRAL U.S. EARLY NEXT WEEK, WITH THE GFS/CMC AND ECMWF AIFS
TRENDING MORE AGGRESSIVE WITH THIS FEATURE COMPARED TO THE ECMWF,
THOUGH ALONG WITH THE MEANS ALL GUIDANCE HAS TRENDED TOWARDS THE
POTENTIAL FOR A SYSTEM. THE UPDATED WPC FORECAST USED A COMPOSITE
BLEND OF THE 06Z GFS AND 00Z ECMWF/ECMWF AIFS/CMC THROUGH MOST OF
THE PERIOD GIVEN THE GOOD AGREEMENT AMONGST THE DETERMINISTIC
GUIDANCE. A CONTRIBUTION FROM THE MEANS WAS ADDED FOR THE LATTER
PART OF THE PERIOD EARLY NEXT WEEK AS DETAILS BEGIN TO NATURALLY
DIVERGE OVERALL AS WELL AS WITH RESPECT TO THE NOTED PATTERN
EVOLUTION OVER THE NORTH-CENTRAL U.S.
..WEATHER/HAZARDS HIGHLIGHTS
THE BROAD UPPER-LEVEL LOW HOVERING OVER EASTERN CANADA WILL SERVE
AS AN ANCHOR FOR CYCLONIC FLOW AND MULTIPLE SHORTWAVE ENERGIES NEAR
THE BASE OF THE MEAN TROUGH. THE TRAILING END OF A PREVIOUS COLD
FRONT WILL STALL OVER/NEAR THE GULF COAST AND SOUTHEAST AND WILL
INTERACT WITH WARM GULF MOISTURE EARLY IN THE PERIOD. THIS WILL
BRING ADDITIONAL SHOWERS AND THUNDERSTORMS ACROSS PARTS OF THE
SOUTHERN PLAINS AND SOUTHEAST THROUGH THE WEEKEND. ON FRIDAY, THERE
IS A SIGNAL FOR SOME INSTABILITY THAT MAY CAUSE MOMENTS OF HEAVY
RAINFALL. A MARGINAL RISK WAS CONSIDERED FOR SOUTHERN PORTIONS OF
THE SOUTHEAST, BUT THERE IS LOW CONFIDENCE AT THIS MOMENT DUE TO
MODEL SPREAD AND CONDITIONS NOT MEETING FLASH FLOODING GUIDANCE.
FURTHERMORE, AS THE FRONT EXITS OFF THE COAST, WRAPAROUND MOISTURE
AND EMBEDDED SHORTWAVES WILL BRING OCCASIONAL SHOWERS ACROSS THE
GREAT LAKES, INTERIOR NORTHEAST, AND CENTRAL APPALACHIANS THROUGH
THE WEEKEND. IN ADDITION, A FEW FRONTAL PASSAGES WILL MOVE THROUGH
THE CENTRAL U.S. INTO THE EASTERN U.S. THROUGH MONDAY, BRINGING
WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE NORTHEAST AS WELL
AS THROUGH THE LOWER MISSISSIPPI VALLEY/SOUTHERN PLAINS ALONG THE
FRONTAL BOUNDARIES.
MEANWHILE, BELOW AVERAGE TEMPERATURES WILL CONTINUE ACROSS THE
EASTERN U.S. BEHIND THE COLD FRONT THROUGH FRIDAY. FROST/FREEZE
CONDITIONS WILL CONTINUE ACROSS THE UPPER MIDWEST/GREAT LAKES AND
NORTHEAST THROUGH SATURDAY MORNING. WITH THE COLD TEMPERATURES,
THERE IS A SLIGHT CHANCE FOR SOME MIXED PRECIPITATION OVER ISOLATED
HIGH- ELEVATION AREAS OVER THE NORTHEAST, BUT IMPACTS WILL BE
MINIMAL. HIGH TEMPERATURES MODERATE ACROSS MUCH OF EASTERN U.S. BY
SATURDAY AFTERNOON THROUGH THE REST OF THE PERIOD.
OVER THE WESTERN U.S., A SHORTWAVE ENERGY WILL PUSH A FRONTAL
BOUNDARY INTO THE NORTHERN-CENTRAL ROCKIES/PLAINS EARLY IN THE
PERIOD, BRINGING A CHANCE FOR SHOWERS, THUNDERSTORMS, AND HIGH-
ELEVATION SNOW THROUGH THE WEEKEND. IN ADDITION, DEEP BOUNDARY
LAYER MIXING WILL BRING GUSTY WINDS ACROSS THE AREA THROUGH THE
WEEKEND. THE FRONT WILL CONTINUE TO STRENGTHEN AS THE SURFACE LOW
MOVES INTO THE GREAT LAKES AND THE COLD FRONT PASSES THROUGH THE
PLAINS/ROCKIES INTO THE SOUTHWEST. THIS WILL EXPAND THE CHANCES FOR
PRECIPITATION ACROSS THE CENTRAL U.S. THROUGH SUNDAY. A RIDGING
PATTERN WILL CONTINUE TO MOVE FURTHER INLAND OVER THE WESTERN U.S.
BRINGING INCREASINGLY WELL ABOVE AVERAGE HIGHS THROUGH THE PERIOD.
SOME RECORD-TYING/BREAKING HIGHS WILL BE POSSIBLE AS HEAT REACHES
POTENTIALLY HAZARDOUS LEVELS ACROSS PORTIONS OF THE CENTRAL
CALIFORNIA VALLEYS AND THE DESERT SOUTHWEST BY SUNDAY.
PUTNAM/OUDIT
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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