107
FXUS02 KWBC 191855
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 PM 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
THE LATEST MODELS AND ENSEMBLES STILL SHOW 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 LIKELY TO EVOLVE 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.
THE 00Z/06Z GUIDANCE AVAILABLE FOR THIS FORECAST UPDATE ALONG WITH
INCOMING 12Z DATA SHOW SOME DETAIL REFINEMENTS EARLY IN THE PERIOD
AND THEN MAINTAIN RECENT SPREAD FOR OTHER EMBEDDED FEATURES. MOST
SOLUTIONS NOW SHOW MORE SEPARATION BETWEEN MIDWEST AND SOUTHERN
ROCKIES SHORTWAVE ENERGY AS OF EARLY SATURDAY. THIS TREND FOR THE
SOUTHERN SHORTWAVE HAS INCREASED RAINFALL POTENTIAL OVER PARTS OF
THE GULF COAST STATES. GFS RUNS ARE A BIT EXTREME ON THE DEPTH
THOUGH. THERE IS FAIR AGREEMENT IN CONCEPT WITH A SOUTHERN
CANADA/GREAT LAKES-NEW ENGLAND SYSTEM EARLY-MID WEEK AS SHORTWAVE
ENERGY CROSSES THE REGION, BUT SPREAD PERSISTS FOR TIMING WITH NO
PROMINENT CLUSTER EMERGING YET. FOR THE FAIRLY VIGOROUS SYSTEM
REACHING THE PACIFIC NORTHWEST/VANCOUVER ISLAND EARLY NEXT WEEK,
LATEST MACHINE LEARNING (ML) MODELS JOIN MOST OTHER GUIDANCE IN
SUGGESTING FASTER PROGRESSION THAN LATEST GFS RUNS BY NEXT
TUESDAY. THE UPPER SHORTWAVE SHOULD SUPPORT PLAINS/MIDWEST LOW
PRESSURE BY WEDNESDAY, WITH THE GFS STILL LEANING ON THE SLOW SIDE.
ML MODELS HINT AT THE POTENTIAL FOR A MORE AMPLIFIED SHORTWAVE
THAN THE DYNAMICAL MODEL AVERAGE, ALONG WITH A SURFACE PATTERN
CLOSEST TO ECMWF RUNS AND THE ENSEMBLE MEANS (ESPECIALLY THE BETTER
DEFINED GEFS/CMCENS). NEW 12Z DYNAMICAL MODELS GENERALLY SUPPORT
THE ML MODEL IDEAS OF SLIGHTLY LOWER PRESSURES WITH THE SURFACE
SYSTEM THAN WHAT MOST 00Z/06Z MODELS/MEANS WERE OFFERING.
A COMPOSITE OF 00Z/06Z OPERATIONAL MODELS PROVIDED A REASONABLE
STARTING POINT EARLY-MID PERIOD, REFLECTING LATEST DETAIL TRENDS OR
A REASONABLE INTERMEDIATE SOLUTION DEPENDING ON THE FEATURE. AFTER
MONDAY THE FORECAST TRANSITIONED TOWARD PHASING OUT THE 00Z/06Z
GFS AND THEN THE 00Z CMC, IN FAVOR OF THE PAST TWO ECMWF RUNS (00Z
AND PRIOR 12Z/18 CYCLES) AND INCREASING 06Z GEFS/00Z ECENS/00Z
CMCENS INPUT.
..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. SATURDAY WILL STILL BE COLD OVER PARTS OF THE
CENTRAL/EASTERN U.S., AND ESPECIALLY SOUTHERN TEXAS WHERE HIGHS
COULD BE 20-30 DEGREES BELOW NORMAL. ABOVE AVERAGE 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 TO ABOVE NORMAL BY THE EARLY-MIDDLE PART OF NEXT
WEEK.
GUIDANCE CONTINUES TO OFFER A STRONG SIGNAL FOR A PATTERN FAVORING
A LONGER FETCH MOISTURE FEED TO FUEL ROUNDS OF MODERATE TO HEAVY
LOWER ELEVATION RAIN AND HIGH ELEVATION/MOUNTAIN SNOW INTO THE
PACIFIC NORTHWEST FROM SATURDAY INTO EARLY NEXT WEEK. ENHANCED
SNOWS WILL 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 DAYS 4/5 WPC
EXCESSIVE RAINFALL OUTLOOK (ERO) BOTH SHOW A SIMILAR FOCUSED
MARGINAL RISK AREA, WITH MINIMAL CHANGE IN THIS AFTERNOON'S
UPDATE. THE NORTHWEST SHOULD TREND DRIER BY MIDWEEK AS A MONDAY-
TUESDAY SYSTEM DEPARTS AND UPPER RIDGING BUILDS IN.
FARTHER EAST, STRONGLY ORGANIZED STORM SYSTEMS GENERALLY APPEAR
UNLIKELY OVER THE CENTRAL TO EASTERN U.S. DESPITE MULTIPLE
UNCERTAIN IMPULSES RIDING INTO THE ERODING ARCTIC AIRMASS AND WITH
FLOW TRANSITION. A MEDIUM TO SMALLER SCALE SHORTWAVE EJECTING FROM
THE SOUTHERN ROCKIES DURING THE WEEKEND MAY SUPPORT PERIODIC
MODERATE RAINFALL OVER THE GULF AND POSSIBLY INLAND INTO THE GULF
COAST STATES TO THE NORTH OF SLOW MOVING AND WAVY FRONTAL ZONES.
RECENT TRENDS HAVE BEEN HEAVIER WITH THIS ACTIVITY BUT SO FAR THE
MODELS ARE KEEPING INSTABILITY OVER THE GULF. THUS THE ERO
CONTINUES TO SHOW NO RISK AREA FOR THIS REGION. MOST PRECIPITATION
SHOULD BE RAIN, THOUGH A LITTLE WINTRY WEATHER COULD BE POSSIBLE
IN THE NORTHERN FRINGE OF THE MOISTURE SHIELD IF IT EXTENDS FAR
ENOUGH NORTH. SURFACE WAVE/FRONTAL DETAILS OVER THE GULF INTO THE
WESTERN ATLANTIC ARE STILL SOMEWHAT MURKY FROM LATE WEEKEND INTO
EARLY NEXT WORK WEEK. HOWEVER FEATURES MAY EVOLVE, ANY WAVES
SHOULD BE WEAK AND MOST PRECIPITATION SHOULD STAY OFFSHORE THE
MID-ATLANTIC/NEW ENGLAND COAST. 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. 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. ANOTHER SYSTEM MAY DEVELOP OVER THE
PLAINS/MISSISSIPPI VALLEY AROUND NEXT WEDNESDAY. THE WARMER
PATTERN BY THEN SHOULD FAVOR MOSTLY LIGHT TO MODERATE RAIN ASIDE
FROM PERHAPS A LITTLE WINTRY WEATHER ON THE COOL SIDE OF THE
SURFACE LOW.
RAUSCH/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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page