591
FXUS02 KWBC 160800
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
400 AM EDT THU OCT 16 2025
VALID 12Z SUN OCT 19 2025 - 12Z THU OCT 23 2025
..GUIDANCE/PREDICTABILITY ASSESSMENT
TWO MAIN UPPER TROUGHS/LOWS AND ASSOCIATED WEATHER FOCUSING
WAVY FRONTAL SYSTEMS REMAIN SLATED TO IMPACT OUR NATION DURING
THIS MEDIUM RANGE FORECAST PERIOD. A LEAD SYSTEM WILL WORK FROM THE
EAST-CENTRAL U.S. SUNDAY TO THE EAST/NORTHEAST COAST BY TUESDAY.
MEANWHILE UPSTREAM. A SECOND SYSTEM BREACHING THE WEST/NORTHWEST
COAST SUNDAY SHOULD CROSS THE COUNTRY TO THE EAST AROUND NEXT
MIDWEEK. GUIDANCE SOLUTIONS HAVE BEEN REASONABLY WELL CLUSTERED
WITH THE LARGER SCALE FLOW EVOLUTION EARLY INTO MEDIUM RANGE TIME
SCALES, BOLSTERING FORECAST CONFIDENCE, BUT HAVE SHOWN STEADILY
INCREASING FORECAST SPREAD AND UNCERTAINTY BY DAY 5. BOTH SYSTEMS
ARE HAVING STILL UNRESOLVED GUIDANCE CYCLE TO CYCLE CONTINUITY
ISSUES INCLUDING LATEST 00 UTC GUIDANCE, MAINLY WITH RESPECT TO
TIMING AND PHASING. ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE
WAS MAINLY DERIVED FROM A COMPOSITE BLEND OF BEST CLUSTERED
GUIDANCE AT TIME OF PRODUCTION OF THE 18 UTC GFS/GEFS MEAN AND 12
UTC ECMWF/ECMWF ENSEMBLE MEANS ALONG WITH THE COMPATIBLE 01 UTC
NATIONAL BLEND OF MODELS, ALL WITH AN EYE ON WPC CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
A LEAD MAIN UPPER TROUGH AND DEEPENED SURFACE LOW PUSHING ACROSS
THE GREAT LAKES REGION THIS WEEKEND WILL DRAW ANOMALOUS MOISTURE
AND INSTABILITY NORTHWARD IN ADVANCE OF A COLD FRONT. THE SLOWLY
PROGRESSIVE NATURE OF THE UPPER-LEVEL AND SURFACE FEATURES WILL
THEN SPREAD ORGANIZED RAINFALL EASTWARD INTO THE EAST/NORTHEAST
SUNDAY INTO EARLY NEXT WEEK. ACTIVITY WILL ALSO FOCUS WITH
DEVELOPMENT OF A DEEPENING/CONSOLIDATING COASTAL LOW PRESSURE
SYSTEM. A WPC DAY 4/SUNDAY EXCESSIVE RAINFALL OUTLOOK MARGINAL
RISK AREA WAS SHIFTED NORTHWARD TO EXTEND FROM THE CENTRAL
APPALACHIANS TO THE EASTERN GREAT LAKES/OHIO VALLEY.
OUT WEST, A MAIN/COMPLEX UPPER TROUGH AND SURFACE LOW/FRONTAL
SYSTEM WILL APPROACH AND PUSH ACROSS THE PACIFIC NORTHWEST AND
NORTHERN ROCKIES OVER THE WEEKEND TO PRODUCE A PERIOD OF MODERATELY
HEAVY COASTAL AND VALLEY RAINS ALONG WITH HIGHER MOUNTAIN SNOW.
THE WPC DAY WINTER WEATHER OUTLOOK SHOWS MOUNTAIN SNOW POTENTIAL
INLAND TO THE NORTHERN ROCKIES INTO MONDAY. DOWNSTREAM SYSTEM
TRANSLATION AND SOME LEAD RETURN FLOW LOOKS TO SUPPORT MODERATE
RAINFALL EMERGENCE IN AN EXPANDING PATTERN OVER THE NORTH-CENTRAL
TO EAST CENTRAL U.S. INTO NEXT WEDNESDAY/THURSDAY TO MONITOR.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page