223
FXUS02 KWBC 290700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM EST THU FEB 29 2024
VALID 12Z SUN MAR 03 2024 - 12Z THU MAR 07 2024
...HEAVY SNOW AND HIGH WIND THREAT FOR THE WESTERN AND
NORTH-CENTRAL U.S...
..WET PATTERN FOR THE WEST COAST AND THE SOUTH
..GUIDANCE/PREDICTABILITY ASSESSMENT
GFS/ECMWF/UKMET/CANADIAN MODEL GUIDANCE SOLUTIONS SEEM REASONABLY
WELL CLUSTERED ONLY FOR SUNDAY. A MODEL COMPOSITE LOOKS
REASONABLE. HOWEVER, MODEL SOLUTIONS THEN QUICKLY DIVERGE. MODEL
CYCLE TO CYCLE CONTINUITY AND FORECAST CONFIDENCE HAS DECREASED
SIGNIFICANTLY OVER THE PAST TWO DAYS WITH BOTH THE AMPLITUDE AND
TIMINGS OF LOCAL WEATHER/HAZARD FOCUSING SYSTEMS IN MULTIPLE UPPER
STREAM FLOWS. ACCORDINGLY, THE BEST FORECAST MAY BE DERIVED FROM A
BROAD GEFS/ECMWF ENSEMBLE MEAN COMPOSITE ALONG WITH THE COMPATIBLE
NATIONAL BLEND OF MODELS IN AN EFFORT TO MAINTAIN THE MOST
PREDICTABLE FORECAST COMPONENTS AND LARGER SCALE HAZARDS/THREATS
SIGNALS UNTIL THE PATTERN BECOMES LESS SENSITIVE TO INITIALIZATION
DATA.
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
A MAIN WEATHER STORY CONCERNS THE EVOLUTION OF AMPLIFIED UPPER
TROUGHING DIGGING INTO THE EASTERN PACIFIC THAT WILL SHIFT
EARNESTLY OVER THE WEST THIS WEEKEND. THIS AND SUBSEQUENT/HIGHLY
UNCERTAIN AND VARIED ADDITIONAL PACIFIC SYSTEMS WILL SUPPORT
MULTIPLE CHANCES FOR PERIODS OF MODERATE TO LOCALLY HEAVIER
PRECIPITATION THROUGH THE WEST COAST NEXT WEEK. THE WPC DAY
5/MONDAY EXCESSIVE RAINFALL OUTLOOK (ERO) INTRODUCES A MARGINAL
RISK AREA FOR COASTAL OREGON/NORTHERN CALIFORNIA. THERE ARE ALSO
THREATS FOR HIGH WINDS AND HEAVY SNOW TO SPREAD FROM THE WEST
COAST STATES INLAND ACROSS THE INTERMOUNTAIN WEST TO THE ROCKIES,
ESPECIALLY FOR FAVORED TERRAIN/MOUNTAINS AS HIGHLIGHTED IN THE WPC
WINTER WEATHER OUTLOOK (WWO). VALLEY SNOWFALLS MAY DEVELOP MORE
OVER TIME AS SNOW LEVELS DECREASE WITH UPPER SYSTEM AND WAVY
FRONTAL COOLING. THIS TRANSLATION SHOULD ALSO FAVOR WINDY
WRAP-BACK SNOW DEVELOPMENT FROM THE NORTHERN PLAINS SUNDAY TO OVER
THE UPPER MIDWEST MONDAY WITHIN COLD CANADIAN AIR DUG ON THE
BACKSIDE OF THE SYSTEM. RUN TO RUN GUIDANCE CONTINUITY HAS BEEN
LESS THAN STELLAR WITH THE EVOLUTION OF THE WEATHER PATTERN
DOWNSTREAM OVER TIME, BUT PROTRACTED MOISTURE RETURN WITH WAVY AND
NOW SLOWER TO PROPAGATE MAIN FRONTS AND A LINGERING/WAVY COASTAL
FRONTS UP THE EAST COAST ALL POINT TO DEVELOPMENT OF WIDESPREAD
SHOWERS/THUNDERSTORMS FROM THE MISSISSIPPI VALLEY MONDAY THROUGH
THE EASTERN SEABOARD WEDNESDAY INTO THURSDAY, BUT WITH POSSIBLE
MAIN FOCUS OVER THE LOWER MISSISSIPPI VALLEY/CENTRAL GULF COAST
STATES MONDAY/TUESDAY. THE WPC DAY 5/MONDAY ERO INTRODUCES A
MARGINAL RISK AREA.
PACIFIC UPPER TROUGH AMPLIFICATION AND INLAND PROGRESSION THIS
WEEKEND WILL COOL TEMPERATURES OVER MUCH OF THE WEST, LEADING TO
THE SPREADING OF VALUES AS COLD AS 15 DEGREES BELOW NORMAL, WILL
COOLED CONDITIONS LINGERING NEXT WEEK. EXPECT MUCH ABOVE NORMAL
WARMTH WILL SPREAD ACROSS MUCH OF THE CENTRAL AND EASTERN U.S.
THIS WEEKEND INTO EARLY NEXT WEEK BEFORE MODERATING. YET ANOTHER
RECENT ONSET OF PRE-FRONTAL SPRINGLIKE CONDITIONS WILL BE
HIGHLIGHTED BY TEMPERATURES RANGING UPWARDS TO 20-30+ DEGREES
ABOVE NORMAL TO SPREAD FROM THE MISSISSIPPI VALLEY/MIDWEST/GREAT
LAKES INTO THE NORTHEAST TO AGAIN CHALLENGE RECORD VALUES.
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES ARE AT:
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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