076
FXUS02 KWBC 021859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EST SUN MAR 2 2025
VALID 12Z WED MAR 05 2025 - 12Z SUN MAR 09 2025
...DEEP LOW PRESSURE SYSTEM COULD BRING BLIZZARD CONDITIONS ACROSS
THE UPPER MIDWEST WEDNESDAY MORNING AS WELL AS HEAVY RAIN, STRONG
THUNDERSTORMS, AND STRONG WINDS FOR THE EAST COAST INTO EARLY
THURSDAY...
..GENERAL OVERVIEW
A DEEP CYCLONE NEAR PEAK INTENSITY WILL LIKELY TRACK ACROSS THE
GREAT LAKES ON WEDNESDAY WITH A POTENT COLD FRONT SWEEPING THROUGH
THE EASTERN U.S. BEFORE THE CYCLONE WEAKENS AND MOVES AWAY INTO
THE CANADIAN MARITIMES THURSDAY INTO FRIDAY. UNSETTLED WEATHER
ASSOCIATED WITH A COUPLE OF UPPER TROUGHS WILL ATTEMPT TO MERGE
OVER THE SOUTHWESTERN PORTION OF THE COUNTRY THROUGH MIDWEEK
FOLLOWED BY UNCERTAIN TIMING, TRACK AND INTENSITY ON THE EJECTION
OF THE MERGED UPPER TROUGH INTO THE MID-SECTION OF THE COUNTRY LATE
IN THE WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
ENSEMBLE MEANS FROM GLOBAL DYNAMIC MODELS CONTINUE TO SHOW GOOD
AGREEMENT ON THE ABOVE-MENTIONED PATTERN EVOLUTION ACROSS MAINLAND
U.S. THROUGH THE MEDIUM RANGE PERIOD. THERE CONTINUES TO BE SOME
RESIDUAL TENDENCY FOR THE DEEP CYCLONE TO TRACK FARTHER NORTH
ACROSS THE GREAT LAKES WHILE THE POTENT COLD FRONT TRAILING SOUTH
FROM THE CYCLONE TO ADVANCE FASTER ACROSS THE EAST COAST ON
WEDNESDAY.
MEANWHILE, UNCERTAINTY REMAINS ABOUND ON BOTH THE DETERMINISTIC
AND ENSEMBLE MEAN GUIDANCE FOR THE NEXT SYSTEM OVER THE SOUTHWEST
WHICH IS FORECAST TO EJECT EASTWARD INTO THE MID-SECTION OF THE
COUNTRY LATE THIS WEEK. THERE HAS BEEN A GENERAL MODEL CONSENSUS TO
EJECT THIS SYSTEM FARTHER NORTH INTO THE CENTRAL PLAINS ON FRIDAY
WHERE A DEEPER LOW PRESSURE SYSTEM WOULD TEND TO FORM AND THEN
TRACK TOWARD THE EAST-NORTHEAST. THE GFS/GEFS SOLUTIONS HAVE BEEN
ON THE FASTEST SIDE; THE CMC/CMC MEAN SOLUTIONS HAVE BEEN THE
SLOWEST, WITH THE ECMWF/EC MEAN IN BETWEEN THESE EXTREMES. THE
MODEL SPREAD DIVERGES FURTHER BY THE WEEKEND AS THE SYSTEM TRACKS
TOWARD THE EAST COAST.
THE WPC MEDIUM-RANGE FORECAST PACKAGE BEGINS WITH A CONSENSUS OF
THE DETERMINISTIC AND ENSEMBLE MEAN GUIDANCE BUT THEN TRANSITIONS
TO 55% BASED ON THE 06Z GFS/GEFS, 35% FROM THE 00Z EC/EC MEAN, AND
10% FROM THE 00Z CMC FOR THIS WEEKEND, WHICH IS CONSISTENT WITH THE
PREVIOUS WPC BLEND. HOWEVER, THE LATEST FROM EC-AIFS AND THE 12Z
ECMWF APPEAR TO FAVOR MORE OF THE SOUTHERN STREAM WAVE DEVELOPMENT
THAN THE NORTHERN STREAM. THIS SCENARIO WILL BE MONITORED IN
FUTURE WPC FORECAST UPDATES.
..WEATHER/HAZARDS HIGHLIGHTS
AN AMPLIFIED UPPER LEVEL TROUGH/CLOSED LOW REACHES THE MIDWEST BY
WEDNESDAY MORNING, ALONG WITH A VERY STRONG SURFACE LOW THAT WILL
TRACK EASTWARD ACROSS THE GREAT LAKES AND INTO QUEBEC, WITH THE
POSSIBILITY OF BLIZZARD CONDITIONS WEDNESDAY MORNING ON THE BASC-
SIDE OF THE CYCLONE ACROSS THE UPPER MIDWEST. MEANWHILE, A STRONG
LOW LEVEL JET WILL ADVECT COPIOUS MOISTURE NORTHWARD ACROSS THE
EAST COAST REGION WEDNESDAY INTO THURSDAY MORNING, PRODUCING
WIDESPREAD MODERATE TO HEAVY RAINFALL FROM THE EASTERN CAROLINAS TO
NEW ENGLAND. THE HEAVIEST RAIN IS LIKELY TO BE FROM EASTERN
PENNSYLVANIA TO SOUTHERN MAINE, WHERE A MARGINAL RISK REMAINS FOR
THE NEW DAY 4 OUTLOOK. PARTS OF THIS REGION STILL HAVE SOME SNOW ON
THE GROUND, SO THIS WILL CONTRIBUTE TO RUN-OFF ISSUES.
A SECOND STORM SYSTEM IS EXPECTED TO FOLLOW BEHIND THIS, AND BRING
ADDITIONAL ROUNDS OF SHOWERS AND THUNDERSTORMS TO MANY OF THESE
SAME AREAS, BUT THE CURRENT THINKING IS THAT IT WILL NOT BE AS
INTENSE AS THE MIDWEEK STORM SYSTEM. SOME STRONG THUNDERSTORMS
WILL ALSO BE POSSIBLE WITH THIS EVENT LATE IN THE WEEK INTO
SATURDAY ACROSS THE SOUTHERN U.S., DEPENDING ON HOW LOW LEVEL
BOUNDARIES EVOLVE. BEFORE THIS SYSTEM REACHES THE PLAINS, IT WILL
AFFECT CENTRAL AND SOUTHERN CALIFORNIA WITH MODERATE SHOWERS AND
HEAVY SIERRA SNOWFALL ON WEDNESDAY. GIVEN RECENT BURN SCAR
SENSITIVITIES ACROSS PORTIONS OF SOUTHERN CALIFORNIA, A MARGINAL
RISK OF EXCESSIVE RAINFALL IS PLANNED FOR BOTH DAYS 4 AND 5, MAINLY
ACROSS THE TERRAIN.
TEMPERATURES ARE EXPECTED TO BE MILD ACROSS THE EASTERN THIRD OF
THE U.S. ON WEDNESDAY AHEAD OF THE BIG STORM SYSTEM, FOLLOWED BY A
RETURN TO MORE SEASONAL CONDITIONS TO CLOSE OUT THE WORK WEEK.
COOLER THAN AVERAGE READINGS ARE LIKELY FROM THE INTERMOUNTAIN WEST
TO THE WESTERN HIGH PLAINS IN CONJUNCTION WITH THE UPPER TROUGH
SITUATED ACROSS THE SOUTHERN ROCKIES. LOOKING AHEAD TO NEXT SUNDAY,
THERE MAY BE WARM-UP ACROSS THE NORTH-CENTRAL U.S., BUT THIS IS
LESS CERTAIN AT THIS POINT IN TIME.
KONG/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 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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