028
FXUS02 KWBC 251901
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 PM EST SUN FEB 25 2024
VALID 12Z WED FEB 28 2024 - 12Z SUN MAR 03 2024
..HEAVY PRECIPITATION PATTERN EMERGING AGAIN FOR THE WEST
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL ENSEMBLE MEANS SHOW RATHER GOOD AGREEMENT ON THE OVERALL
SYNOPTIC PATTERN EVOLUTION ACROSS THE MAINLAND U.S. THROUGH THE
MEDIUM-RANGE FORECAST PERIOD. AS THE FORECAST PERIOD BEGINS ON
WEDNESDAY, MODELS HAVE SLIGHTLY SLOWED DOWN THE EASTWARD
PROGRESSION OF THE DEEPENING UPPER TROUGH AND A SHARP COLD FRONT
TOWARD THE EASTERN U.S., WHICH HAS BEEN THE GENERAL MODEL TREND
SINCE YESTERDAY. THE MAIN UNCERTAINTY IS NORTH OF THE BORDER
ACROSS THE CANADIAN PRAIRIES WHERE MODELS HAVE BEEN EJECTING MORE
ENERGETIC PIECES OF SHORTWAVES EASTWARD ALONG A FRONT. MEANWHILE,
MODEL AGREEMENT ON THE TIMING OF THE DEEP UPPER TROUGH THAT IS
FORECAST TO DIVE INTO THE WESTERN U.S. REMAINS SURPRISINGLY GOOD
THROUGH NEXT SUNDAY WHEN A LOW PRESSURE SYSTEM IS FORECAST TO
DEEPEN OVER THE CENTRAL HIGH PLAINS. ALSO DURING NEXT WEEKEND,
THE DETERMINISTIC GUIDANCE IS INDICATING A SMALLER SCALE LOW
PRESSURE WAVE TO FORM NEAR THE COAST OF THE SOUTHEASTERN U.S.,
ALTHOUGH THE ENSEMBLE MEANS ARE NOT SUPPORTIVE OF THIS FEATURE YET.
THEREFORE, THE WPC MEDIUM RANGE PRODUCT SUITE WAS DERIVED FROM THE
CONSENSUS OF THE 06Z GFS/GEFS, 00Z ECMWF/EC MEAN, AND THE 00Z
CMC/CMC MEAN. WPC CONTINUITY IS WELL MAINTAINED WITH THIS BLEND.
..OVERVIEW AND WEATHER/HAZARDS HIGHLIGHTS
A DYNAMIC/AMPLIFIED NORTHERN STREAM UPPER TROUGH WILL RACE FROM
THE PLAINS TO THE APPALACHIANS WEDNESDAY TO OFF THE EAST COAST
EARLY THURSDAY. AN EMERGING AREA OF SHOWERS AND THUNDERSTORMS WILL
SWEEP ACROSS THE EAST-CENTRAL THROUGH EASTERN U.S. WITH
PROGRESSION OF A WAVY/WELL DEFINED FRONTAL SYSTEM INTO A
MOIST/UNSTABLE PRE-FRONTAL ENVIRONMENT TO INCLUDE LINGERING
MIDWEEK MUCH ABOVE NORMAL TO RECORD WARMTH OVER THE EAST. SPC
SHOWS SOME RISK FOR SEVERE WEATHER WITH FOCUS ACROSS THE TENNESSEE
VALLEY AND VICINITY. A MARGINAL RISK OF EXCESSIVE RAINFALL HAS
BEEN INTRODUCED FOR THE OHIO VALLEY ON WEDNESDAY IN ANTICIPATION
OF BRIEF HEAVY RAINFALL ASSOCIATED WITH LINES OF THUNDERSTORMS
FORMING AHEAD OF THE SHARP COLD FRONT POSSIBLY DURING THE
AFTERNOON INTO THE EARLY EVENING, AND TO BE CONSISTENT WITH THE
DAY 3 MARGINAL. A POST-FRONTAL SURGE OF COLD CANADIAN HIGH
PRESSURE OFFERS TRANSITION FOR WRAP-BACK SNOWS FROM THE UPPER OHIO
VALLEY/GREAT LAKES TO THE INTERIOR NORTHEAST.
LESS PROGRESSIVE SOUTHERN STREAM SYSTEM ENERGY EJECTION OUT
THROUGH NORTHERN MEXICO MIDWEEK MAY SUPPORT LIGHT PRECIPITATION UP
INTO SOUTHERN ARIZONA/NEW MEXICO/SOUTHWESTERN TEXAS WEDNESDAY.
DOWNSTREAM TRANSLATION AND ADDITIONAL IMPULSES SUPPORT SYSTEM
GENESIS AND FOCUS, WITH LEAD RETURN MOISTURE TO FUEL AN EXPANDING
AREA WITH RAIN/CONVECTIVE CHANCES ACROSS THE SOUTH/SOUTHEAST LATER
WEEK INTO NEXT WEEKEND.
FARTHER UPSTREAM, A GROWING GUIDANCE SIGNAL IN SUPPORT OF
AMPLIFYING UPPER TROUGH DEVELOPMENT/HEIGHT FALLS OVER THE EAST
PACIFIC AND GRADUALLY SHIFT INTO THE WEST WILL INCREASINGLY
SUPPORT CHANCES FOR A MODERATE TO HEAVIER RAIN FOCUS INTO THE
PACIFIC NORTHWEST MID-LATER WEEK THAT SEEMS SET TO SHIFT EARNESTLY
DOWN THE COAST THROUGH CALIFORNIA LATER WEEK INTO NEXT WEEKEND TO
MONITOR. THE WPC DAY 4/WEDNESDAY AND DAY 5/THURSDAY EXCESSIVE
RAINFALL OUTLOOKS OFFER MARGINAL RISK AREAS FOR COASTAL AREAS OF
THE PACIFIC NORTHWEST/NORTHERN CALIFORNIA. THERE IS ALSO A
SIGNIFICANT THREAT FOR HEAVY SNOW TO SPREAD FARTHER INLAND ACROSS
THE WEST, ESPECIALLY FOR FAVORED TERRAIN/MOUNTAINS AS HIGHLIGHTED
IN THE WPC WINTER WEATHER OUTLOOK.
KONG/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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