603
FXUS02 KWBC 050659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 AM EST WED MAR 5 2025
VALID 12Z SAT MAR 08 2025 - 12Z WED MAR 12 2025
..GENERAL OVERVIEW
ANOTHER LOW PRESSURE SYSTEM WILL DEVELOP ACROSS THE WEST AND EJECT
INTO THE CENTRAL PLAINS BY FRIDAY AS THE LEADING SYSTEM EXITS THE
EAST COAST. GUIDANCE SUGGESTS THIS SYSTEM WILL EVOLVE INTO TWO
SEPARATE SHORTWAVES, WITH ONE QUICKLY TRACKING TOWARD THE OHIO
VALLEY FOLLOWED BY A SOUTHERN STREAM WAVE IN ITS WAKE TO TRACK
GENERALLY NEAR OR JUST NORTH OF THE GULF COAST WITH UNCERTAIN
DOWNSTREAM DEVELOPMENT ALONG THE EAST COAST EARLY NEXT WEEK.
MEANWHILE, A PACIFIC COLD FRONT WILL APPROACH THE WEST COAST ON
MONDAY WITH RAIN AND MOUNTAIN SNOW RETURNING TO THE REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LARGE SCALE PATTERN CONTINUES TO BE IN GOOD AGREEMENT WITH THE
EVOLUTION WITH THE NORMAL DEGREE OF UNCERTAINTY IN REGARDS TO THE
PLACEMENT, INTENSITY AND QPF AMOUNTS FOR THE LATTER PERIODS. THE
GUIDANCE IS SIGNALING FOR LOW SURFACE LOWS TO SPIN UP, THE FIRST
ONE OVER THE CENTRAL PLAINS AND THE SECOND NEAR THE GULF COAST AND
INTO THE WESTERN ATLANTIC EARLY NEXT WEEK. BY MONDAY-TUESDAY WITH
THE NEXT TROUGH REACHING THE WEST COAST, THE GFS IS STRONGER WITH A
CLOSED UPPER LOW, WHEREAS THE CMC AND ECMWF FAVOR MORE OF AN OPEN
WAVE ALOFT (OR BRIEF CLOSING OF A LOW).WPC UTILIZED A MULTI- MODEL
APPROACH WITH INCREASING WEIGHTS AND INCLUSION OF ENSEMBLE MEANS BY
THE LATTER PART OF THE FORECAST. THIS APPROACH MAINTAINED
CONTINUITY WHILE REDUCING NOISE FOR DAYS 6 AND 7.
..WEATHER/HAZARDS HIGHLIGHTS
THERE WILL BE STRONG AND GUSTY WINDS LINGERING ACROSS THE NORTHEAST
AS THE LEADING LOW PRESSURE SYSTEM TRACKS FURTHER OFFSHORE. RAIN
AND MOUNTAIN SNOW WILL BE ONGOING ACROSS SOUTHERN CALIFORNIA, AND
THE SOUTHWEST/FOUR CORNERS REGION THROUGH FRIDAY. MODERATE TO HEAVY
SNOWS ARE POSSIBLE FOR THE HIGHEST TERRAIN OF UTAH, ARIZONA, AND
THE SOUTHERN ROCKIES WITH SOME GUSTY WINDS AS WELL. STRONG WINDS
AND LOW RELATIVE HUMIDITY BEHIND A DRY LINE, WILL INCREASE THE
CONDITIONS CONDUCIVE FOR WILDFIRES TO DEVELOP AND SPREAD RAPIDLY.
SHOWERS AND THUNDERSTORMS WILL INCREASE IN COVERAGE AND INTENSITY
NEAR THE GULF COAST AS THE SURFACE LOW EVOLVES WITH UNCERTAIN
DOWNSTREAM CYCLOGENESIS NEAR THE MID-ATLANTIC. A DAY 4 MARGINAL
RISK FOR EXCESSIVE RAINFALL WAS INTRODUCED FOR PORTIONS OF THE
LOWER MISSISSIPPI VALLEY, GULF COAST AND INTO THE SOUTHEAST.
LINGERING MODEL DIFFERENCES FACTORED INTO KEEPING DAY 5 WITHOUT AN
EXCESSIVE RAINFALL OUTLOOK.
BY SUNDAY ANOTHER ROUND OF RAIN AND MOUNTAIN SNOW IS ANTICIPATED
TO REACH THE WEST COAST AS A STRONG UPPER TROUGH AND COLD FRONT
APPROACHES THE COAST AND MOVES INLAND. THERE IS A GROWING POTENTIAL
FOR AN ATMOSPHERIC RIVER EVENT TO YIELD HEAVIER RAIN TO PORTIONS OF
CENTRAL AND SOUTHERN CALIFORNIA THIS WEEKEND INTO MONDAY, ALONG
WITH HEAVY SNOW FOR THE SIERRA AND EVENTUALLY MOVING INLAND ACROSS
THE HIGHER TERRAIN OF THE INTERMOUNTAIN WEST. THIS LOOKS TO SET UP
A PARTICULARLY WINDY PATTERN FOR PARTS OF THE WEST AS WELL.
MUCH OF THE INTERMOUNTAIN WEST AND ADJACENT HIGH PLAINS WILL HAVE COOLER
THAN AVERAGE TEMPERATURES WITH THE UPPER TROUGH POSITIONED ACROSS
THE SOUTHERN ROCKIES. TEMPERATURES WILL BEGIN TO MODERATE FOR THE
NORTH-CENTRAL U.S., WITH DAYTIME HIGHS POTENTIALLY 10-20+ DEGREES
ABOVE EARLY MARCH AVERAGES, WITH HIGHS POTENTIALLY REACHING WELL
INTO THE 60S FROM THE DAKOTAS INTO IOWA.
CAMPBELL/SANTORELLI
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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