817
FXUS02 KWBC 151748
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
148 PM EDT SAT MAR 15 2025
VALID 12Z TUE MAR 18 2025 - 12Z SAT MAR 22 2025
..ANOTHER ROCKIES TO GREAT LAKES SNOWSTORM THREAT NEXT WEEK
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST OVERNIGHT 00/06Z GUIDANCE REMAINS GENERALLY WELL
CLUSTERED FOR NEARLY ALL OF THE MEDIUM RANGE FORECAST PERIOD (TUES
MAR 18 - SAT MAR 22) AND PRESENTS THREE MAIN SYSTEMS TRACKING
ACROSS THE CONUS IN A CONTINUED PROGRESSIVE PATTERN. GUIDANCE SHOWS
AN INITIAL UPPER-TROUGH OVER THE WESTERN U.S. MOVING EASTWARD AND
OFF THE EAST COAST THROUGH MID- TO LATE NEXT WEEK WITH ACCOMPANYING
SURFACE CYCLOGENESIS/SYSTEM DEVELOPMENT IN THE LEE OF THE ROCKIES
AND LIFTING NORTHEASTWARD ACROSS THE PLAINS INTO THE MIDWEST/GREAT
LAKES. THE 00Z/06Z GFS IS INITIALLY MORE AGGRESSIVE IN LIFTING THIS
SYSTEM NORTHEASTWARD INTO THE MIDWEST/GREAT LAKES FASTER THAN THE
OTHER GUIDANCE (A TREND AWAY FROM PREVIOUSLY BEING IN AGREEMENT
WITH THE OTHER GUIDANCE), THOUGH COMES BACK INTO THE GENERAL
CLUSTER AS THE LOW OCCLUDES OVER SOUTHEASTERN CANADA AND THE
NORTHEAST. THEREFORE, THE UPDATED WPC BLEND FAVORED OTHER GUIDANCE
(00Z ECMWF/ECENS MEAN, CMC, UKMET) THROUGH THE FIRST HALF OF THE
PERIOD. THIS ALSO FAVORS A MORE PROLONGED, HEAVIER QPF AXIS ACROSS
THE CENTRAL PLAINS TO UPPER MIDWEST NORTHWEST OF THE LOW TRACK MID-
NEXT WEEK WITH POTENTIAL WINTER STORM IMPLICATIONS. THEN, TOWARDS
THE END OF NEXT WEEK, ANOTHER UPPER-WAVE/SURFACE FRONTAL SYSTEM
ENTERS THE PACIFIC NORTHWEST WITH THE UPPER-WAVE AGAIN LEADING TO
LEE CYCLOGENESIS AND FRONTAL SYSTEM REINFORCEMENT/CONSOLIDATION
EAST OF THE ROCKIES. IN THIS CASE, THE CMC DIVERGES FROM THE
GFS/ECMWF, LIFTING THIS SYSTEM NORTHEAST ACROSS THE PLAINS FASTER.
FINALLY, A THIRD SYSTEM UPSTREAM OVER THE NORTHEASTERN PACIFIC IS
FORECAST TO ENTER SOUTHWESTERN CANADA/THE PACIFIC NORTHWEST BY NEXT
WEEKEND, WITH INCREASING DIFFERENCES IN THE GUIDANCE WITH UPPER-
WAVE PROGRESSION BUT STILL GENERALLY GOOD AGREEMENT WITH RESPECT TO
THE ACCOMPANYING SURFACE SYSTEM PROGRESSING EASTWARD ACROSS THE
NORTHERN U.S./SOUTHERN CANADIAN ROCKIES. THE UPDATED BLEND FOR THE
LATTER HALF OF THE PERIOD THUS FAVORS THE ECMWF/GFS OVER THE CMC
AND INCLUDES A LARGER CONTRIBUTION FROM THE ECENS/GEFS/CMC ENSEMBLE
MEANS GIVEN INCREASING UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
THE WEATHER STORY FOR NEXT WEEK WILL HIGHLIGHT AN EMERGING SIGNAL
FOR A MAIN WINTER STORM SET TO SPREAD ORGANIZED PRECIPITATION
INCLUDING TERRAIN ENHANCED HEAVY SNOWS ACROSS THE INTERIOR WEST TO
THE ROCKIES TUESDAY. DOWNSTREAM CYCLOGENESIS OVER THE PLAINS
TUESDAY WILL FOLLOW WITH A WINDY LOW TRACK OVER THE MIDWEST/GREAT
LAKES MIDWEEK AND TO EASTERN CANADA BY THURSDAY. THIS WILL COMBINE
WITH SECONDARY COLD FRONTAL COOLING TO ENHANCE UPSLOPE IN AN
EMERGING WRAP-AROUND HEAVY SNOW THREAT FROM THE NORTH-CENTRAL
ROCKIES/PLAINS TO THE UPPER MIDWEST AND NORTHERN GREAT
LAKES/NORTHEAST TUESDAY-THURSDAY. A WAVY TRAILING COLD FRONT WILL
HAVE LESS MOISTURE THAN AN EARLIER NEXT WEEK SYSTEM, BUT WILL ALIGN
AND SWEEP AN AXIS OF SHOWERS AND THUNDERSTORMS THROUGH THE CENTRAL
TO EASTERN U.S. THURSDAY/FRIDAY WITH A WINTRY MIX/SNOWS POSSIBLE
FOR INTERIOR NORTHEAST LOCATIONS. MOST ACTIVITY EXITS THE EAST
COAST BY NEXT WEEKEND. MEANWHILE WELL UPSTREAM, STEADILY
PROGRESSIVE AND MODERATELY AMPLIFIED PACIFIC SYSTEMS WILL POOL
MOISTURE TO SPREAD PRECIPITATION INLAND FROM THE WEST/NORTHWEST
THROUGH THE ROCKIES. MODERATELY HEAVY RAINS AND TERRAIN FOCUSING
SNOWS ARE MOST LIKELY VIA CHANNELED MOISTURE INTO THE PACIFIC
NORTHWEST IN THIS PATTERN. SUBSEQUENT DOWNSTREAM RAIN CHANCES MAY
EMERGE NEXT WEEKEND OVER THE CENTRAL U.S. WITH UNCERTAIN SYSTEM
DETAILS AND RETURN FLOW DEVELOPMENTS.
WELL-ABOVE AVERAGE TEMPERATURES BY AS MUCH AS 15-20 DEGREES WILL
PROCEED THE THE INITIAL MID-WEEK SYSTEM OVER THE MIDWEST AND
CENTRAL/SOUTHERN PLAINS, WITH TEMPERATURES INTO THE 90S POSSIBLE IN
THE SOUTHERN PLAINS TUESDAY. THE FOCUS WILL SHIFT EASTWARD WITH
THE SYSTEM TO THE NORTHEAST WEDNESDAY, POSSIBLY LINGERING INTO
THURSDAY DEPENDING ON PROGRESSION OF THE FOLLOWING COLD FRONT.
TEMPERATURES FROM THE CENTRAL TO EASTERN U.S. WILL BE BRIEFLY BELOW
AVERAGE FOLLOWING COLD FRONT PASSAGE THEN TREND BACK TOWARDS JUST
ABOVE AVERAGE CONDITIONS (5-10 DEGREES) INTO NEXT WEEKEND. IN
CONTRAST, CONDITIONS WILL BEGIN BELOW TO WELL BELOW AVERAGE ACROSS
MUCH OF THE WEST MID-NEXT WEEK BEFORE TRENDING CLOSER TOWARDS
AVERAGE BY NEXT WEEKEND.
PUTNAM/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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