035
FXUS02 KWBC 190654
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 AM EST WED FEB 19 2025
VALID 12Z SAT FEB 22 2025 - 12Z WED FEB 26 2025
..WET PACIFIC NORTHWEST PATTERN THIS WEEKEND/EARLY NEXT WEEK
..OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT GUIDANCE HAS OFFERED A REASONABLY SIMILAR LARGER SCALE FLOW
EVOLUTION OVER THE NEXT WEEK, ALBEIT LADEN WITH NUMEROUS SMALLER
SCALE EMBEDDED SYSTEM DIFFERENCES THAT OFTEN DO NOT HAVE GOOD CYCLE
TO CYCLE CONTINUITY. MODERATE PROGRESSION OF THESE INDIVIDUAL
SHORTWAVES ALOFT IN SPLIT STREAMS OVER THE LOWER 48 THIS WEEK IS
STILL EXPECTED TO LEAD AN EVOLUTION TOWARD A LARGER SCALE MEAN
UPPER PATTERN HIGHLIGHTED BY A WESTERN RIDGE AND EASTERN TROUGH
POSITIONS BY THE START OF NEXT WEEK. THIS TRANSITION WILL BRING THE
BEST POTENTIAL FOR MEANINGFUL PRECIPITATION TO THE PACIFIC
NORTHWEST FROM THE WEEKEND INTO EARLY NEXT WEEK, ALONG WITH A
PRONOUNCED WARMING TREND FROM WEST TO EAST OVER THE LOWER 48.
ACCORDINGLY, THE WPC MEDIUM RANGE PRODUCT SUITE WAS MAINLY DERIVED
FROM A COMPOSITE BLEND OF THE GENERALLY COMPATIBLE 18 UTC GEFS
MEAN AND 12 UTC ECMWF/CANADIAN ENSEMBLE MEANS THROUGH MEDIUM-RANGE
TIME SCALES. WHILE PREDICTABILITY FOR FLOW EMBEDDED WEATHER
FEATURES IS BELOW NORMAL, THE BROADER OVERALL SOLUTION OFFERS
REASONABLY GOOD CONTINUITY AND MESSAGING IN LINE WITH THE 01 UTC
NATIONAL BLEND OF MODELS AND FAVORABLE 00 UTC GUIDANCE TRENDS.
..WEATHER/HAZARDS HIGHLIGHTS
AN IMPRESSIVE ARCTIC AIRMASS HAS SETTLED OVER THE CENTRAL AND
EASTERN U.S., BUT WILL STEADILY WARM THROUGH THE WEEKEND INTO NEXT
WEEK. ABOVE NORMAL TEMPERATURES WILL DEVELOP OVER THE WEST AND
EVENTUALLY THE CENTRAL U.S. WHERE BY EARLY NEXT WEEK MOST LOCATIONS
WEST OF THE MISSISSIPPI RIVER WILL WARM TO ABOVE NORMAL WITH
DECENT COVERAGE OF PLUS 10-25 DEGREE ANOMALIES. BEST POTENTIAL FOR
HIGHEST ANOMALIES WILL BE OVER AND NEAR THE NORTHERN PLAINS.
TEMPERATURES OVER THE EAST SHOULD REACH NEAR NORMAL TO SLIGHTLY
WARMER INTO EARLY NEXT WEEK.
THE SIGNAL REMAINS STRONG THAT FROM SATURDAY ONWARD THE PATTERN
WILL BECOME FAVORABLE FOR LONGER FETCH MOISTURE FEED TO FUEL
ROUNDS OF MODERATE TO HEAVY LOWER ELEVATION RAIN AND HIGH
ELEVATION/MOUNTAIN SNOW INTO THE PACIFIC NORTHWEST, WITH ENHANCED
SNOWS TO WORK INLAND OVER THE NORTHERN INTERMOUNTAIN WEST/ROCKIES.
THE BEST POTENTIAL FOR HIGHEST PRECIPITATION TOTALS EXISTS OVER
THE FAVORED TERRAIN AND COASTAL AREAS OF WESTERN WASHINGTON/OREGON
AND INTO NORTHWEST CALIFORNIA. THE DAY 4/5 WPC EXCESSIVE RAINFALL
OUTLOOK (ERO) BOTH SHOW A SIMILAR FOCUSED MARGINAL RISK AREA.
FARTHER EAST, IT GENERALLY REMAINS THE CASE THAT STRONGLY
ORGANIZED STORM SYSTEMS GENERALLY DO NOT LOOK LIKELY OVER THE
CENTRAL TO EASTERN U.S. DESPITE MULTIPLE UNCERTAIN IMPULSES RIDING
INTO THE ERODING ARCTIC AIRMASS AND WITH FLOW TRANSITION. ONE
PATTERN FEATURE TO NOTE IS HOW EJECTING WESTERN U.S. ENERGY MAY
SUPPORT PERIODIC MODERATE RAINFALL OVER THE GULF AND POSSIBLY
INLAND INTO THE GULF COAST STATES IN ASSOCIATION WITH SLOW MOVING
AND WAVY FRONTAL ZONES. MOST PRECIPITATION SHOULD BE RAIN, BUT
THOUGH A LITTLE WINTRY WEATHER COULD BE POSSIBLE IN THE NORTHERN
FRINGE OF THE MOISTURE SHIELD IF IT EXTENDS FAR ENOUGH NORTH.
CONFIDENCE IS STILL LOW REGARDING HOW THE WAVINESS MAY EVOLVE OVER
THE GULF DURING THE WEEKEND, AND WHAT THE SURFACE PATTERN MAY LOOK
LIKE UP OFF THE EAST COAST INTO EARLY NEXT WEEK. THE MAJORITY OF
GUIDANCE STILL SUGGESTS MOST PRECIPITATION SHOULD STAY OFFSHORE
THE MID-ATLANTIC/NEW ENGLAND COAST. HOWEVER, DIGGING OF NORTHERN
STREAM SHORTWAVE ENERGY THIS WEEKEND INTO EARLY NEXT WEEK WILL SPREAD
LIGHT PRECIPITATION (MOSTLY SNOW) FROM THE GREAT LAKES REGION
THROUGH NEW ENGLAND WHERE ANY UNCERTAIN WRAPBACK COASTAL LOW
LINKAGE COULD ENHANCE ACTIVITY EARLY-MID NEXT WEEK.
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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