335
FXUS02 KWBC 180703
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
203 AM EST TUE FEB 18 2025
VALID 12Z FRI FEB 21 2025 - 12Z TUE FEB 25 2025
...INTENSE CENTRAL TO EASTERN U.S. ARCTIC BLAST THIS WEEK TO
MODERATE BY THE WEEKEND...
..WET PACIFIC NORTHWEST PATTERN THIS WEEKEND/EARLY NEXT WEEK
..OVERVIEW AND GUIDANCE/PREDICTABILITY ASSESSMENT
GUIDANCE CONTINUES TO OFFER A REASONABLY SIMILAR LARGER SCALE FLOW
EVOLUTION OVER THE NEXT WEEK, ALBEIT LADEN WITH NUMEROUS SMALLER
SCALE EMBEDDED SYSTEM DIFFERENCES. MODERATE PROGRESSION OF THESE
INDIVIDUAL SHORTWAVES ALOFT IN SPLIT STREAMS OVER THE LOWER 48 THIS
WEEK IS EXPECTED TO LEAD AN EVOLUTION TOWARD A LARGER SCALE MEAN
UPPER PATTERN HIGHLIGHTED BY A WESTERN RIDGE AND EASTERN TROUGH 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 OVER ESPECIALLY THE WESTERN-CENTRAL U.S. IN STARK
CONTRAST TO THE ONGOING ARCTIC AIRMASS THIS WEEK.
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. THIS SOLUTION MAINTAINS GOOD CONTINUITY AND MESSAGING
AND IS BROADLY IN LINE WITH THE 01 UTC NATIONAL BLEND OF MODELS,
MACHINE LEARNING MODELS AND LATEST 00 UTC CYCLE ENSEMBLE GUIDANCE.
..WEATHER/HAZARDS HIGHLIGHTS
QUITE THE IMPRESSIVE ARCTIC AIRMASS IS SETTLING OVER THE CENTRAL
AND EASTERN U.S. THIS WEEK. AN EXTREME COLD THREAT WITH WIDESPREAD
RECORD TEMPERATURES FOR MORNING LOWS/COLD DAYTIME HIGHS WILL LINGER
INTO FRIDAY OVER THE SOUTH-CENTRAL TO SOUTHERN U.S., BUT THE BROAD
AIRMASS WILL CONTINUE TO STEADILY MODERATE 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.
FROM SATURDAY ONWARD THE PATTERN BECOMES INCREASINGLY FAVORABLE
FOR LONGER FETCH MOISTURE FEED TO FUEL ROUNDS OF MODERATE TO HEAVY
LOWER ELEVATION RAIN AND HIGH ELEVATION/MOUNTAIN SNOW PRIMARILY
INTO THE PACIFIC NORTHWEST, BUT ALSO INLAND TO THE NORTHERN
ROCKIES. THE BEST POTENTIAL FOR HIGHEST TOTALS CURRENTLY EXISTS
OVER THE FAVORED TERRAIN AND COASTAL AREAS OF WESTERN WASHINGTON
AND NORTHWESTERN OREGON WHERE A DAY 5/SATURDAY WPC EXCESSIVE
RAINFALL OUTLOOK (ERO) MARGINAL THREAT AREA HAS BEEN INTRODUCED TO
BEGIN A MULTI-DAY PERIOD OF VERY WET WEATHER TO CONTINUE TO MONITOR.
FARTHER EAST, NO CONSENSUS EXISTS FOR ANY STRONGLY ORGANIZED STORM
SYSTEM OVER THE CENTRAL TO EASTERN U.S. DURING THIS MED-RANGE
PERIOD DESPITE MULTIPLE UNCERTAIN IMPULSES RIDING INTO THE ERODING
ARCTIC AIRMASS AND WITH FLOW TRANSITION. ONE FEATURE TO NOTE IS
EMERGING WESTERN U.S. ENERGY THAT MAY SUPPORT PERIODIC MODERATE
RAINFALL OVER THE GULF AND POSSIBLY EXTENDING INTO THE GULF COAST
STATES IN ASSOCIATION WITH A PERSISTENT AND SLOW MOVING WAVY
FRONTAL ZONE. 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
LOW REGARDING HOW THE WAVINESS MAY EVOLVE OVER THE GULF DURING THE
WEEKEND, AND WHAT THE SURFACE PATTERN MAY LOOK LIKE OFF THE EAST
COAST INTO EARLY NEXT WEEK. THE MAJORITY (THOUGH NOT ALL) OF
GUIDANCE STILL SUGGESTS MOST PRECIPITATION SHOULD STAY OFFSHORE
THE MID-ATLANTIC/NEW ENGLAND COAST. MEANWHILE, A SERIES OF WAVES
MAY SPREAD LIGHT PRECIPITATION (MOSTLY SNOW) ACROSS PARTS OF THE
GREAT LAKES INTO NEW ENGLAND FROM THE WEEKEND INTO EARLY 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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