571
FXUS02 KWNH 210805
PREEPD
PRELIMINARY EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
404 AM EDT SAT MAR 21 2026
VALID 12Z TUE MAR 24 2026 - 12Z SAT MAR 28 2026
...ANOMALOUS EARLY SEASON HEAT WAVE ACROSS THE SOUTHWEST ABATING
SOMEWHAT EARLY NEXT WEEK BUT WILL REBUILD MIDWEEK...
..OVERVIEW
A SERIES OF SHORTWAVES WILL PROPAGATE THROUGH THE SOUTHERN TIER OF
CANADA AND NORTHERN TIER OF THE CONUS NEXT WEEK. ONE OF THESE WAVES
WILL PRODUCE PRECIPITATION OVER PORTIONS OF THE PACIFIC NORTHWEST,
GREAT LAKES AND NORTHEAST/MID-ATLANTIC BETWEEN TUESDAY AND FRIDAY.
MEANWHILE, AN UPPER RIDGE WILL BE RESPONSIBLE FOR A PROLONGED
HEATWAVE FROM THE SOUTHWEST TO THE GREAT PLAINS BEFORE A PACIFIC
TROUGH SHOVES THE RIDGE TOWARD THE SOUTHEAST LATE NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS TEND TO AGREE ON THE OVERALL SYNOPTIC EVOLUTION ACROSS THE
CONUS OUTLINED IN THE OVERVIEW SECTION. HOWEVER, THERE'S REMAINS
SOME UNCERTAINTY AROUND THE AMPLITUDE OF THE RIDGE TROUGH AXES IN
THE WEST AND EAST RESPECTIVELY BEGINNING NEXT WEDNESDAY.
A GENERAL MODEL BLEND CONSISTING OF THE DETERMINISTIC
EURO/GFS/CANADIAN,
ECAIFS AND GEFS MODELS WERE UTILIZED ON DAY 3 DUE TO RUN-TO-RUN
CONSISTENCY AND REASONABLE AGREEMENT ON THE TIMING OF THE EAST
PACIFIC TROUGH APPROACHING THE PACIFIC NORTHWEST. THE CANADIAN IS
REPLACED BY THE UKMET DUE TO TIMING DIFFERENCES WITH THE PAC NW
ENERGY. CLUSTER ANALYSIS REVEALS BETTER CLUSTERING BETWEEN THE EURO
AND CANADIAN ENSEMBLE MEMBERS COMPARED TO GEFS MEMBERS BEYOND DAY
4. THEREFORE, THE EURO, WITH SOME DETERMINISTIC/ENSEMBLE CANADIAN,
WAS FAVORED IN THE DAYS 5-7 BLENDS.
..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 ON TUESDAY AND WEDNESDAY.
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.
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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