652
FXUS02 KWBC 201909
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
209 PM EST THU FEB 20 2025
VALID 12Z SUN FEB 23 2025 - 12Z THU FEB 27 2025
..WET PACIFIC NORTHWEST PATTERN THIS WEEKEND/EARLY NEXT WEEK
..OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
THE MEDIUM RANGE PERIOD (SUNDAY, 2/23) BEGINS WITH AN UPPER RIDGE
IN THE WEST AND SHORTWAVE ENERGY DIVING THROUGH THE SOUTHERN
PLAINS. THE 00Z EURO AND 06Z GFS WERE HEAVILY FAVORED AT THIS
TIMESTEP GIVEN THE 00Z CMC AND UKMET'S NOTICEABLY DIVERGENT
SOLUTIONS TIMING-WISE WITH RESPECT TO THE SHORTWAVE ENERGY IN THE
PLAINS. ON MONDAY, WE HAVE RIDGING IN THE WEST AND MEAN TROUGHING
IN THE EAST WITH SHORTWAVE ENERGY PROPAGATING THROUGH THE UPPER
MIDWEST/ONTARIO AS WELL AS A POSITIVELY TILTED SHORTWAVE EXTENDING
FROM THE MID-ATLANTIC TO THE GULF COAST/SOUTHERN PLAINS. THE
CANADIAN ATTEMPTS TO OVER AMPLIFY A CLOSED LOW OVER THE GULF,
WHICH IS WHY IT AND THE UKMET REPRESENTED A MINORITY OF THE DAY 4
BLEND, AS WELL.
SHORTWAVE ENERGY SLIDES ACROSS THE MIDWEST ON TUESDAY, WHILE SOME
UPPER-LEVEL ENERGY PUSHES ONSHORE IN THE NORTHWEST. A MORE
CONSENSUS APPROACH WAS TAKEN ON THIS DAY DUE TO SOME MORE VARIANCE,
PARTICULARLY IN THE 00Z EURO'S MORE PROGRESSIVE SOLUTION COMPARED
TO THE REST OF THE GUIDANCE. BY WEDNESDAY, ANOTHER SHORTWAVE
EMERGES OVER THE PLAINS AND DEEPENS AS IT MOVES INTO THE MIDWEST.
THE 12Z GFS APPEARS TO BE THE ONLY PIECE OF GUIDANCE THAT WEAKENS
THE TROUGH THROUGHOUT THE DAY WHILE ALL OF THE OTHER GUIDANCE,
INCLUDING THE ENSEMBLE MEANS AND AIFS STRENGTHEN IT. JUST ABOUT ALL
OF THE AVAILABLE GUIDANCE AGREE ON AMPLIFIED MEAN TROUGHING IN THE
WEST AND MEAN TROUGHING IN THE EAST ON DAY 7. A RUN-OF-THE-MILL
BLEND CONSISTING OF THE AVAILABLE ENSEMBLE MEANS AND 06Z GFS WERE
USED DESPITE SOME MINOR TIMING DETAILS. NOT IN THE BLEND, BUT
WORTH NOTING THAT THE LATEST AIFS RUN HAS A NOTICEABLY OVER
AMPLIFIED CLOSED LOW (COMPARED TO OTHER GUIDANCE) OVER THE
MISSISSIPPI VALLEY AT THE START OF DAY 7.
..WEATHER/HAZARDS HIGHLIGHTS
IT REMAINS THE CASE THAT ABOVE AVERAGE TEMPERATURES WILL DEVELOP
OVER THE WEST THEN FOR MUCH OF CENTRAL U.S. WHERE BY EARLY NEXT
WEEK MOST LOCATIONS WEST OF THE MISSISSIPPI RIVER WILL WARM TO MUCH
ABOVE NORMAL WITH DECENT COVERAGE OF PLUS 10-25 DEGREE ANOMALIES.
BEST POTENTIAL FOR HIGHEST ANOMALIES WILL BE NEAR THE NORTHERN
PLAINS. THE EAST SHOULD ALSO WARM TO ABOVE NORMAL NEXT WEEK.
GUIDANCE CONTINUES TO OFFER A STRONG SIGNAL FOR A PATTERN FAVORING
A LONGER FETCH MOISTURE FEED TO FUEL MODERATE TO HEAVY LOWER
ELEVATION RAIN AND HIGH ELEVATION/MOUNTAIN SNOW INTO THE PACIFIC
NORTHWEST THIS WEEKEND INTO EARLY NEXT WEEK. ENHANCED SNOWS WILL
ALSO WORK INLAND OVER THE NORTHERN INTERMOUNTAIN WEST/ROCKIES WITH
DOWNSTREAM SYSTEM TRANSLATION. EXPECT HIGHEST PRECIPITATION TOTALS
EXISTS OVER THE FAVORED TERRAIN AND COASTAL AREAS OF WESTERN
WASHINGTON/OREGON AND INTO NORTHWEST CALIFORNIA. THE DAYS 4/5 WPC
EXCESSIVE RAINFALL OUTLOOKS VALID FOR SUNDAY AND MONDAY EACH SHOW A
MARGINAL RISK THREAT AREA GIVEN THE CUMULATIVE EFFECT OF THE
MULTI-DAY EPISODE. THE NORTHWEST SHOULD TREND DRIER MIDWEEK AS A
DYNAMIC MONDAY- TUESDAY SYSTEM DEPARTS AND UPPER RIDGING BUILDS
IN.
DOWNSTREAM, SHORTWAVE ENERGY EJECTING FROM THE SOUTHERN ROCKIES
OUT FROM THE WEEKEND AND MAY SUPPORT PERIODS OF MODERATE RAINFALL
OVER THE GULF AND POSSIBLY INLAND INTO THE GULF COAST STATES AND
SOUTHEAST TO THE NORTH OF A WAVY FRONTAL ZONES. MOST GUIDANCE HOLDS
MAIN INSTABILITY OVER THE GULF. MOST PRECIPITATION SHOULD BE RAIN,
THOUGH A LITTLE WINTRY WEATHER COULD BE POSSIBLE IN THE NORTHERN
FRINGE OF THE MOISTURE SHIELD EARLY PERIOD IF IT EXTENDS FAR
ENOUGH NORTH BEFORE THE AIRMASS MODERATES. SURFACE WAVE/FRONTAL
DETAILS OVER THE GULF AND THE WESTERN ATLANTIC REMAIN QUITE
UNCERTAIN FOR DETAILS INTO NEXT WEEK. HOWEVER FEATURES MAY EVOLVE,
WAVES SHOULD BE RELATIVELY WEAK AND MOST PRECIPITATION SHOULD STAY
OFFSHORE THE MID- ATLANTIC/NEW ENGLAND. DIGGING OF NORTHERN STREAM
SHORTWAVE ENERGY THIS WEEKEND INTO EARLY NEXT WEEK WILL SPREAD
LIGHT-SIDE PRECIPITATION (MOSTLY SNOW) FROM THE GREAT LAKES REGION
THROUGH NEW ENGLAND. LATEST GUIDANCE IS NOT TOO ENTHUSIASTIC ABOUT
POTENTIAL FOR WRAPBACK COASTAL LOW LINKAGE OVER THE NORTHEAST TO
ENHANCE ACTIVITY EARLY- MID NEXT WEEK, BUT IT REMAINS WORTH
MONITORING IN FUTURE RUNS. MODERATE CYCLOGENESIS AND FRONTOGENESIS
MAY DEVELOP OVER THE PLAINS/MISSISSIPPI VALLEY NEXT WEDNESDAY AND
WORK OVER THE EAST- CENTRAL U.S. BY THURSDAY. THE WARMER PATTERN BY
THEN SHOULD MOSTLY FAVOR AN EMERGING AREA OF MODERATE WRAPPING
RAINS WITH RETURN GULF MOISTURE FLOW ASIDE FROM A LITTLE WINTRY
WEATHER ON THE FAR NORTH COOL SIDE OF THE LOW.
KEBEDE/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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