626
FXUS02 KWBC 260659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
259 AM EDT SUN MAR 26 2023
VALID 12Z WED MAR 29 2023 - 12Z SUN APR 2 2023
..SYNOPTIC OVERVIEW
THE WEATHER PATTERN MID NEXT WEEK WILL BE FEATURED WITH STRONG LOW
PRESSURE SYSTEM OVER CALIFORNIA THAT MOVES INLAND ACROSS THE
INTERMOUNTAIN WEST THURSDAY, AND THEN EMERGES OVER THE PLAINS AND
MIDWEST BY FRIDAY AND INTO NEXT WEEKEND. THIS WILL LIKELY RESULT
IN AN INCREASE OF SHOWERS AND THUNDERSTORMS ACROSS MUCH OF THE
PLAINS AND MIDWEST STATES. THIS TROUGH OVER THE WESTERN U.S. WILL
SERVE TO AMPLIFY THE DOWNSTREAM UPPER RIDGE OVER THE SOUTH-CENTRAL
U.S. AND THE GULF COAST REGION FOR THE END OF THE WEEK. BY
SATURDAY, A SECOND TROUGH WILL BECOME ESTABLISHED OVER THE PACIFIC
NORTHWEST AS A SHORTWAVE DROPS SOUTH FROM THE GULF OF ALASKA. THE
CLOSED UPPER LOW OVER THE HUDSON BAY REGION WILL REMAINED NEARLY
ANCHORED IN PLACE, AND THERE WILL BE SOME SHORTWAVES PIVOTING
AROUND THE SOUTHERN PERIPHERY OF THIS LOW ACROSS THE NORTH-CENTRAL
U.S. THROUGH THE END OF THE WEEK.
..MODEL GUIDANCE/PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE IS IN DECENT SYNOPTIC SCALE AGREEMENT
THROUGH THURSDAY NIGHT, AND A GENERAL MODEL BLEND SUFFICES FOR
THIS TIME PERIOD. THERE HAS BEEN A TREND FOR A MORE OFFSHORE AND
WEAKER SOLUTION WITH THE DEVELOPING LOW OFF THE EAST COAST
WEDNESDAY COMPARED TO THE 12Z GUIDANCE, AND THIS WOULD KEEP NEARLY
ALL OF ITS PRECIPITATION AWAY FROM NEW ENGLAND. LOOKING AHEAD TO
THE END OF THE WEEK, THE 00Z GFS DEVELOPS A CLOSED LOW BY FRIDAY
NIGHT ACROSS THE CENTRAL PLAINS AND A LITTLE FASTER THAN THE
ECMWF/CMC, BUT NOT QUITE AS FAST AS THE GEFS MEAN, WHICH HAS
CONSISTENTLY BEEN MORE PROGRESSIVE OVER THE PAST FEW DAYS WITH
THIS TROUGH. BY NEXT SUNDAY, THE GFS IS STRONGER WITH THE NEXT
TROUGH DEVELOPING OVER THE PACIFIC NORTHWEST. TAKING THESE
FACTORS INTO ACCOUNT, THE FORECAST FOR FRIDAY-SUNDAY WAS PRIMARILY
DERIVED FROM A CMC/ECMWF/GFS BLEND WHILE GRADUALLY INCREASING USE
OF THE ECENS AND SOME OF THE GEFS MEAN.
..WEATHER/HAZARDS HIGHLIGHTS
THE STORM SYSTEM AFFECTING CALIFORNIA EARLY NEXT WEEK WILL LIKELY
BE ABATING IN INTENSITY BY WEDNESDAY WITH LINGERING MODERATE TO
LOCALLY HEAVY RAINFALL, WITH PERHAPS HALF AN INCH TO ONE INCH OF
ADDITIONAL RAINFALL THROUGH WEDNESDAY EVENING BEFORE THINGS BEGIN
TO DRY OUT. MODERATE TO HEAVY SNOW IS ALSO LIKELY FOR THE HIGHER
TERRAIN OF THE SIERRA AND SOUTHERN CALIFORNIA MOUNTAINS, WHERE 6
TO 12 INCHES OF ACCUMULATION IS LIKELY ON WEDNESDAY. SINCE MOST
OF THE SIGNIFICANT RAINFALL SHOULD OCCUR PRIOR TO 12Z WEDNESDAY,
THERE ARE NO AREAS ON THE DAY 4 EXCESSIVE RAINFALL OUTLOOK,
ALTHOUGH THIS COULD CHANGE GOING INTO THE SHORT RANGE PERIOD IF
THIS STORM SYSTEM SLOWS DOWN IN FUTURE MODEL RUNS.
ON WEDNESDAY, A SURFACE LOW IS LIKELY TO DEVELOP OVER THE OFFSHORE
WATERS OF THE WESTERN ATLANTIC, AND WITH THIS FORECAST CYCLE, IT
APPEARS MOST OF THE PRECIPITATION SHOULD REMAIN OFFSHORE AND NOT
AFFECT THE NORTHEAST STATES, SO A MORE OPTIMISTIC FORECAST FOR
THIS REGION. BY THE END OF THE WEEK, SHOWERS AND STORMS ARE
EXPECTED TO INCREASE AHEAD OF A DEVELOPING STORM SYSTEM ACROSS THE
PLAINS AND MIDWEST. SOME OF THESE STORMS COULD BE SEVERE ON
THURSDAY ACROSS PORTIONS OF THE SOUTHERN PLAINS, AND WINDY
CONDITIONS ARE LIKELY TO DEVELOP ACROSS MUCH OF THE PLAINS IN
GENERAL.
TEMPERATURES ARE EXPECTED TO BE WELL BELOW LATE MARCH AVERAGES
ACROSS MUCH OF THE NORTHERN INTERMOUNTAIN WEST, THE ROCKIES, AND
THE DAKOTAS FOR THE WEDNESDAY TO FRIDAY TIME PERIOD, WITH HIGHS
RUNNING 10 TO 20+ DEGREES BELOW AVERAGE IN MANY CASES. THE
COLDEST CONDITIONS WILL RESIDE ACROSS NORTH DAKOTA WHERE SOME
MORNING LOWS NEAR OR EVEN SLIGHTLY BELOW ZERO WILL BE POSSIBLE
EARLY ON WEDNESDAY. MEANWHILE, THE PRESENCE OF THE GULF COAST
UPPER RIDGE WILL TEND TO FAVOR TEMPERATURES RUNNING UP TO 15
DEGREES ABOVE AVERAGE FROM TEXAS TO THE SOUTHEAST U.S. AND FLORIDA
FOR THE END OF THE WEEK, WITH THE GREATEST ANOMALIES FOR OVERNIGHT
LOWS WITH INCREASED CLOUDS AND WINDS.
HAMRICK
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, EXPERIMENTAL EXCESSIVE RAINFALL
OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES AND HEAT INDICES 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
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