661
FXUS02 KWBC 301943
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
343 PM EDT THU APR 30 2026
VALID 12Z SUN MAY 03 2026 - 12Z THU MAY 07 2026
..OVERVIEW
SEVERAL DISTURBANCES ROTATING AROUND A PERSISTENT UPPER LEVEL
CLOSED LOW CENTERED OVER ONTARIO AND QUEBEC WILL HELP TO REINFORCE
BROADLY DEEP TROUGHING ACROSS THE EASTERN U.S. FROM LATE THIS
WEEKEND THROUGH MUCH OF NEXT WEEK. THIS PATTERN WILL KEEP
CONDITIONS COOL AND UNSETTLED AT TIMES ACROSS PARTS OF THE UPPER
MIDWEST, GREAT LAKES, MID-ATLANTIC, AND NORTHEAST AS MULTIPLE
FRONTAL SYSTEMS MOVE THROUGH. MEANWHILE, WHAT'S LEFT OF A FRONTAL
BOUNDARY WILL CONTINUE TO BE A FOCUS FOR SHOWERS AND THUNDERSTORMS
ACROSS CENTRAL AND SOUTHERN FLORIDA SUNDAY INTO MONDAY. THEN
ANOTHER PACIFIC CLOSED LOW PUSHES INLAND EARLY NEXT WEEK, BRINGING
LOW ELEVATION SHOWERS AND THUNDERSTORMS ALONG WITH MOUNTAIN SNOW
SHOWERS TO PARTS OF THE WEST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE 12Z MODEL GUIDANCE SUITE IS IN ABOVE AVERAGE AGREEMENT ON THE
LARGE SCALE PATTERN ACROSS THE COUNTRY THROUGH THE FIRST HALF OF
NEXT WEEK, WITH MODEST DIFFERENCES ON THE MESOSCALE DETAILS AND
FRONTAL TIMING. THEREFORE, A MULTI-MODEL BLEND WAS USED FOR FRONTS
AND PRESSURES, WITH THE ENSEMBLE MEANS INCREASED TO ABOUT 30-40% BY
THE END OF THE FORECAST PERIOD NEXT THURSDAY.
..WEATHER/HAZARDS HIGHLIGHTS
AS A LARGE UPPER LEVEL LOW SPINS OVER SOUTHEAST CANADA, MULTIPLE
DISTURBANCES ROTATING AROUND THE LOW ARE LIKELY TO PUSH A FEW COLD
FRONTS AND CHANCES FOR SHOWERS AND THUNDERSTORMS INTO THE UPPER
MIDWEST, GREAT LAKES, OHIO VALLEY, AND NORTHEAST SUNDAY INTO THE
MIDDLE OF NEXT WEEK. A LITTLE SNOW MAY EVEN MIX IN WITH THE RAIN
CLOSER TO THE U.S./CANADA BORDER. IN ADDITION TO SHOWER CHANCES,
THE FRONTS WILL BRING REINFORCING SURGES OF COOL AIR, KEEPING
TEMPERATURES NEAR TO BELOW SEASONAL NORMS. CHILLY NIGHTTIME LOWS
MAY ALSO LEAD TO FROST AND FREEZE CONCERNS OVER PARTS OF THE OHIO
VALLEY, MID-ATLANTIC, AND THE CENTRAL APPALACHIANS SUNDAY NIGHT
INTO EARLY MONDAY MORNING.
A COLD FRONT SAGGING SOUTHWARD ACROSS CENTRAL AND SOUTHERN FLORIDA
WILL BE A FOCUS FOR HEAVY RAIN ON SUNDAY. ANOMALOUS MOISTURE
POOLING ALONG THE FRONT COMBINED WITH INCREASING INSTABILITY WILL
LEAD TO THE DEVELOPMENT OF SCATTERED TO NUMEROUS CLUSTERS OF
SHOWERS AND THUNDERSTORMS, MAINLY DURING THE AFTERNOON AND EVENING.
THIS ACTIVITY MAY CONTAIN HEAVY RAINFALL RATES WHICH COULD LEAD TO
LOCALIZED POOR DRAINAGE AND URBAN FLOODING. AS A RESULT, THE DAY
4/SUNDAY MARGINAL RISK ERO REMAINS IN PLACE, ALTHOUGH IT WAS
TRIMMED BACK ON THE WESTERN EDGE TO NOW COVER MAINLY EAST-CENTRAL
PORTIONS OF THE FLORIDA PENINSULA. WHILE SOME SHOWERS AND STORMS
ARE LIKELY TO LINGER INTO MONDAY, WANING COVERAGE AND INTENSITY
SHOULD KEEP ANY REMAINING FLOODING THREAT TO A MINIMUM, AND
THEREFORE NO AREAS ARE CURRENTLY NECESSARY FOR THE DAY 5/MONDAY
ERO NATIONWIDE.
A SLOW-MOVING PACIFIC LOW SPINNING OFF THE COAST OF CALIFORNIA
WILL BEGIN TO PUSH INLAND ACROSS CALIFORNIA AND THE GREAT BASIN
DURING THE FIRST HALF OF NEXT WEEK. INCREASING MOISTURE AND
INSTABILITY AHEAD OF THIS LOW WILL SUPPORT SCATTERED LOW ELEVATION
SHOWERS AND STORMS ALONG WITH MOUNTAIN SNOW SHOWERS ACROSS PORTIONS
OF THE WEST MONDAY AND TUESDAY. AFTER SEVERAL DAYS OF UNSEASONABLE
WARMTH, TEMPERATURES TREND COOLER FOR THE FIRST HALF OF THE WEEK
GIVEN PLENTY OF SHOWERS AND CLOUDS AROUND. ONCE THE LOW MOVES OUT
MID TO LATE WEEK, A RIDGE BUILDS IN AND TEMPERATURES REBOUND BACK
ABOVE SEASONAL NORMS ONCE AGAIN.
MILLER/HAMRICK
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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