125
FXUS02 KWBC 201945
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
345 PM EDT FRI MAR 20 2026
VALID 12Z MON MAR 23 2026 - 12Z FRI MAR 27 2026
...ANOMALOUS EARLY SEASON HEAT WAVE ACROSS THE SOUTHWEST ABATING
SOMEWHAT EARLY NEXT WEEK BUT WILL REBUILD MIDWEEK...
..OVERVIEW
THE MEDIUM RANGE PERIOD WILL FEATURE AN ACTIVE NORTHERN STREAM,
SUPPLIED BY A CLOSED GULF OF ALASKA LOW SHEDDING LOBES OF SHORTWAVE
VORTICITY ACROSS DOWNSTREAM PORTIONS OF SOUTHERN CANADA/NORTHERN
CONUS. THESE TRANSIENT WAVES WILL OCCASIONALLY ERODE RIDGING IN THE
NORTHWEST AND GENERATE PRECIPITATION. MEANWHILE, THE PREDOMINANT
WESTERN RIDGE WILL REBUILD OVER THE SOUTHWEST WHILE GRADUALLY
EXPANDING INTO THE SOUTHEAST BY MID-WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST 00/06Z MODEL GUIDANCE REMAINS FAIRLY AGREEABLE ON THE
LARGE-SCALE PATTERN HEADING INTO NEXT WEEK. AFTER A BRIEF PERIOD OF
MORE ZONAL FLOW ALOFT OVER THE WEEKEND, THE PATTERN WILL BEGIN TO
AMPLIFY AGAIN WITH MEAN RIDGING OVER THE WESTERN U.S. AND MEAN
TROUGHING OVER THE EASTERN U.S. MEANWHILE, SHORTWAVES/SURFACE
SYSTEMS WITHIN A MAINTAINED ACTIVE NORTHERN STREAM STILL PRESENT
CHALLENGES TIMING AND EVOLUTION WISE. EARLY NEXT WEEK, THE
ECMWF/ECMWF AIFS/CMC ALONG WITH THE MEANS ARE BETTER CLUSTERED
WITH A SYSTEM DEPARTING THE EAST COAST FASTER WHILE THE GFS SHOWS
A SLOWER PROGRESSION. THE GFS ALSO SHOWS A WEAKER UPPER-RIDGE/HIGH
BUILDING OVER THE WESTERN U.S. COMPARED TO THE OTHER GUIDANCE.
UNCERTAINTY REMAINS WITH THE ORIENTATION/COVERAGE OF A POTENTIAL
ATMOSPHERIC RIVER AROUND TUESDAY IN THE PACIFIC NORTHWEST WITH THE
GFS/GEFS MEAN FAVORING A MORE SOUTHERLY ORIENTATION WITH HEAVIER
PRECIPITATION AND POTENTIAL FOR FLOODING CONCERNS WHILE THE
ECMWF/ECENS MEAN FAVOR A MORE NORTHERN ORIENTATION WITH MUCH LESS
PRECIPITATION. THEN, MID- TO LATE WEEK, THE GFS ALONG WITH THE
ECMWF AIFS/CMC AND GEFS/CMC MEANS ARE BETTER CLUSTERED REGARDING A
CLIPPER-LIKE SYSTEM PROGRESSING ALONG THE U.S./CANADIAN BORDER. THE
OTHER GUIDANCE FROM THE EC (DETERMINISTIC AND MEAN) HAVE REMAINED
SLOWER AND WEAKER DEVELOPING A SYSTEM, WITH THE ECMWF AIFS, GEFS
MEAN, AND CMC PROVIDING THE MOST AGREED UPON SOLUTION BY THE END
OF THE PERIOD.
THE UPDATED WPC FORECAST USED A BROAD BLEND OF THE ECMWF AIFS/ECMWF
(FAVORING THE AIFS) AND CMC ALONG WITH THE ENSEMBLE MEANS FOR THE
FIRST PART OF THE PERIOD WHEN THE GFS WAS AN OUTLIER. THEREAFTER,
THE BLEND FOCUSED ON THE ECMWF AIFS ALONG WITH THE CMC AND A MUCH
GREATER CONTRIBUTION FROM THE GEFS MEAN WHICH WERE NOTABLY BETTER
CLUSTERED COMPARED TO THE REST OF THE EC SUITE AND ALSO MAINTAINED
GOOD FORECAST CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
WHILE NOT QUITE AS ANOMALOUS AS THIS PAST WEEK, THE MAIN STORY
DURING THE MEDIUM RANGE PERIOD NEXT WEEK WILL REMAIN ANOTHER PERIOD
OF WELL ABOVE AVERAGE, WIDESPREAD DAILY-RECORD LEVEL WARMTH ACROSS
PORTIONS OF THE WESTERN AND CENTRAL U.S. A PROMINENT UPPER-LEVEL
RIDGE WILL SUPPORT MAXIMUM TEMPERATURES THAT ARE 20-40 DEGREES
ABOVE AVERAGE, AND WIDESPREAD MAXIMUM AND MINIMUM TEMPERATURE
RECORDS ARE POSSIBLE FROM THE SOUTHWEST EARLY NEXT WEEK TO THE
PLAINS BY MIDWEEK. THIS HEATWAVE, COMBINED WITH DRY CONDITIONS AND
DAILY BOUTS OF GUSTY, DOWNSLOPING WINDS ACROSS THE HIGH PLAINS MAY
LEAD TO POTENTIAL FIRE WEATHER CONCERNS. A MORE CONCENTRATED AREA
OF VERY STRONG WINDS IS EXPECTED ACROSS THE NORTHERN ROCKIES AND
ADJACENT HIGH PLAINS WEDNESDAY AS A DEEPENING LOW IN THE LEE OF THE
CANADIAN ROCKIES PASSES BY.
A POTENT MID-LATITUDE CYCLONE WILL MOVE FROM THE NORTHWEST TO THE
CANADIAN MARITIME NEXT WEEK. THIS SYSTEM WILL BRING MODERATE TO
HEAVY RAIN OVER THE PACIFIC NORTHWEST TUESDAY. MOST OF THE
PRECIPITATION FROM THIS WILL BE IN THE FORM OR RAIN SINCE THE
SHORTWAVE ALOFT WILL BE EMBEDDED WITHIN THE BROADER WESTERN RIDGE.
TOTAL AMOUNTS REMAIN A BIT UNCERTAIN BUT AN UPWARD TREND WOULD
SIGNAL POTENTIAL FOR AT LEAST ISOLATED FLOODING CONCERNS. HIGHER
ELEVATIONS OF THE OLYMPIC AND CASCADE MOUNTAINS WILL RECEIVE SOME
SNOWFALL, ESPECIALLY ON THE BACKSIDE OF THE ASSOCIATED COLD FRONT.
THE LOW PRESSURE SYSTEM WILL WEAKEN WHILE IT TRACKS ACROSS THE
CENTRAL U.S., BEFORE REINVIGORATING OVER THE EAST AND PRODUCING
SOME RAIN SOUTH/SNOW NORTH FOR PARTS OF THE GREAT LAKES/OHIO
VALLEY/NORTHEAST BY LATE NEXT WEEK.
PUTNAM/KEBEDE
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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