789
FXUS02 KWBC 251854
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
154 PM EST TUE FEB 25 2025
VALID 12Z FRI FEB 28 2025 - 12Z TUE MAR 04 2025
..OVERVIEW
OVERALL IT GENERALLY REMAINS THE CASE THAT THE MEDIUM RANGE
CONTINUES TO FEATURE A RATHER PROGRESSIVE OVERALL FLOW PATTERN.
TROUGHING OVER THE EAST ON FRIDAY WILL BE REINFORCED AGAIN THIS
WEEKEND BY A SHORTWAVE THROUGH THE UPPER MIDWEST. MEANWHILE OUT
WEST, A CUTOFF UPPER LOW WILL SLIDE INTO SOUTHERN CALIFORNIA ON
FRIDAY, ACROSS THE SOUTHWEST THIS WEEKEND, AND WEAKEN AND GET
ABSORBED INTO THE LARGER SCALE FLOW EARLY NEXT WEEK OVER THE
SOUTHERN PLAINS AND GENERALLY EASTWARD AS PER TRENDS FROM 12 UTC
GUIDANCE. BEHIND THIS, ANOTHER DEEP TROUGH OR UPPER LOW WILL MOVE
INTO THE WEST COAST SUNDAY INTO MONDAY, WITH GENERAL INDICATIONS OF
A MORE AMPLIFIED PATTERN OVER THE WEST TO CENTRAL U.S. NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT GUIDANCE CYCLES CONTINUE TO SHOW GOOD AGREEMENT ON THE
OVERALL PATTERN PROGRESSION AND DOMINANT FEATURES OF THE MEDIUM
RANGE PERIOD, BUT WITH UNCERTAINTY IN THE DETAILS. TWO MAIN
SOURCES OF UNCERTAINTY LIE WITH THE PAIR OF UPPER LOWS THROUGH THE
WESTERN U.S. THIS WEEKEND AND AGAIN NEXT WEEK. THE FIRST, INTO
SOUTHERN CALIFORNIA ON FRIDAY, HAS SHOWN IMPROVED CONSISTENCY IN
THE TIMING, BUT THERE IS VARIABILITY IN THE TRACK. THE LAST FEW GFS
RUNS REMAINS NOTABLY DISPLACED NORTH OF THE UKMET, CMC, AND ECMWF.
THE EC-BASED AI MODELS WERE ALSO VARIED AND THUS SUGGESTING THAT
EITHER PLACEMENT WAS LESS LIKELY BUT PLAUSIBLE. FOR THE SECOND
TROUGH EARLY NEXT WEEK, THE GUIDANCE AGREES ON ITS EXISTENCE BUT
THERE'S CONSIDERABLE UNCERTAINTY IN THE TIMING AND EVOLUTION. THE
12 UTC ECMWF WAS ON THE FASTER SIDE, WITH THE TROUGH OVER THE
CENTRAL U.S. BY NEXT TUESDAY. THE NEWER 12 UTC ECMWF HAS SLOWED
DOWN SOME. RECENT GFS RUNS, HOWEVER, STILL HAVE THE MAIN TROUGH
OVER THE WEST BY THAT TIME. CMC RUNS OFFER AN IN BETWEEN SOLUTION,
SLIGHTLY FASTER THAN CONCENSUS. ENSEMBLE MEANS GENERALLY SIDED
WITH THEIR DETERMINISTIC COUNTERPARTS, BUT CLOSER TO CONSENSUS.
THE PREFERRED WPC BLEND USED A MULTI-MODEL BLEND THE FIRST FEW
DAYS OF THE PERIOD FOR FRIDAY/SATURDAY, TRANSITIONING SUNDAY TO AN
ENSEMBLE MEAN BLEND FOR NEXT MONDAY/TUESDAY. THIS ACTS TO MAINTAIN
REASONABLY GOOD WPC PRODUCT CONTINUITY AMID LINGERING UNCERTAINTY.
..WEATHER/HAZARDS HIGHLIGHTS
A CLIPPER SYSTEM SHOULD BRING A ROUND OF PRECIPITATION TO THE
GREAT LAKES AND NORTHEAST FRIDAY INTO SATURDAY, WITH MODERATE
SNOWFALL POSSIBLY ENHANCED BY THE LAKE WATERS ACROSS THE UPPER
GREAT LAKES, WITH MIXED PRECIPITATION JUST TO THE SOUTH. A PERIOD
OF STRONG AND GUSTY WINDS CAN ALSO BE EXPECTED ON FRIDAY ACROSS THE
NORTHERN PLAINS AND PERHAPS INTO SATURDAY NEAR THE GREAT LAKES ON
THE BACK-SIDE OF THE SYSTEM AS COLD AIR RUSHES IN BEHIND IT.
A BUILDING RIDGE SHOULD KEEP CONDITIONS QUIET AND DRY ACROSS THE
WEST INTO FRIDAY. THE SOUTHERN STREAM UPPER LOW MOVING ACROSS
SOUTHERN CALIFORNIA FRIDAY AND INLAND NEXT WEEKEND MAY LEAD TO
LIGHT SHOWERS OVER CALIFORNIA, THE SOUTHWEST, AND INTO THE SOUTH-
CENTRAL U.S., WITH INCREASING RAIN CHANCES IN THE SOUTHERN PLAINS
BY NEXT SUNDAY AS MOISTURE INCREASES. THERE APPEARS TO BE A BETTER
SIGNAL FOR THE PRECIPITATION TO SPREAD FARTHER EAST/NORTHEAST
ACROSS THE SOUTHERN PLAINS SUNDAY INTO MONDAY, AND WITH MUCH MORE
UNCERTAINTY INTO THE EAST-CENTRAL U.S. THROUGH EARLY NEXT WEEK TO
MONITOR GIVEN AMBIENT MOIST SOIL CONDITIONS. THE NORTHERN STREAM
TROUGH MOVING THROUGH THE EASTERN PACIFIC AND INTO THE WEST NEXT
WEEKEND WILL ALSO BRING PRECIPITATION CHANCES BACK FOR THE WEST
COAST, SPREADING ACROSS THE GREAT BASIN/ROCKIES EARLY NEXT WEEK.
MUCH ABOVE NORMAL TEMPERATURES WILL BE WELL ESTABLISHED BY
FRIDAY ACROSS THE WEST AND INTO THE NORTHERN/CENTRAL PLAINS. THE
GREATEST ANOMALIES WILL BE ACROSS THE NORTHERN PLAINS WITH DAYTIME
HIGHS 20 TO LOCALLY 30 DEGREES ABOVE NORMAL, WITH 60S FOR HIGHS AS
FAR NORTH AS NEBRASKA/SOUTH DAKOTA. THE ABOVE NORMAL TEMPERATURES
WILL SPREAD SOUTH AND EAST, WITH THE WEST TRENDING COOLER BY EARLY
NEXT WEEK. ACROSS THE EAST, TEMPERATURES WILL VARY BETWEEN NORMAL
AND ABOVE NORMAL INTO SATURDAY, BUT BE MOSTLY BELOW NORMAL SUNDAY
AND MONDAY IN POST-FRONTAL HIGH PRESSURE BEFORE AGAIN MODERATING.
SANTORELLI/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
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