450
FXUS02 KWBC 020653
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
153 AM EST SUN MAR 2 2025
VALID 12Z WED MAR 5 2025 - 12Z SUN MAR 9 2025
...HEAVY RAIN AND STRONG WINDS EXPECTED FOR THE EASTERN SEABOARD
WEDNESDAY INTO EARLY THURSDAY...
..GENERAL OVERVIEW
THE WEATHER PATTERN ACROSS THE CONTINENTAL U.S. WILL BE QUITE
ACTIVE MID-WEEK INTO THE WEEKEND WITH TWO STORM SYSTEMS OF
INTEREST. THE FIRST AND STRONGEST LOW PRESSURE SYSTEM WILL BE
GATHERING STRENGTH ACROSS THE MIDWEST AND GREAT LAKES ON WEDNESDAY
IN RESPONSE TO AN AMPLIFYING UPPER LEVEL SHORTWAVE CROSSING THE
MIDWEST. HEAVY RAINFALL, STRONG TO SEVERE THUNDERSTORMS, AND
STRONG WINDS WILL BE MAKING WEATHER HEADLINES FROM THE SOUTHEAST
U.S. TO THE MID-ATLANTIC AND NORTHEAST, AND THE STORM SYSTEM
EXITS THE EAST COAST BY THURSDAY MORNING. A SECOND AND WEAKER
STORM SYSTEM DEVELOPS OVER THE ROCKIES ON THURSDAY AND LIKELY
REACHES THE CENTRAL PLAINS ON FRIDAY, WITH ADDITIONAL SHOWERS AND
THUNDERSTORMS EXPECTED. THERE MAY BE ADDITIONAL LOW PRESSURE
DEVELOPMENT OVER SOUTHERN TEXAS NEXT WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
AT THE TIME OF FRONTS/PRESSURES PREPARATION, THERE WAS GOOD OVERALL
MODEL AGREEMENT WITH THE BIG STORM SYSTEM CROSSING THE GREAT LAKES
AND INTO THE NORTHEAST STATES THROUGH THURSDAY AFTERNOON, AND
THEREFORE A GENERAL MODEL COMPROMISE WORKS AS A STARTING POINT IN
THE FORECAST PROCESS. THINGS ARE LESS CERTAIN WITH THE SECOND STORM
SYSTEM THAT FOLLOWS BEHIND IT ON FRIDAY ACROSS THE CENTRAL PLAINS.
THE GUIDANCE DIVERGED QUITE A BIT GOING INTO FRIDAY NIGHT AND NEXT
WEEKEND, WITH THE GFS/GEFS INDICATING A MUCH MORE PROGRESSIVE
SOLUTION WITH A LEAD SURFACE LOW THAT IS GENERALLY WEAKER, IN
CONTRAST TO THE MUCH SLOWER CMC, WITH THE ECMWF FALLING IN BETWEEN.
THE GFS DEPICTS A SEPARATE AND STRONGER LOW DEVELOPING OVER
SOUTHERN TEXAS BY SATURDAY NIGHT AHEAD OF A AMPLIFYING TROUGH.
IN REGARDS TO THE BUILDING SOUTHERN STREAM TROUGH OVER THE
SOUTHWESTERN U.S. NEXT WEEKEND, THE SUITE OF ML GUIDANCE, ALONG
WITH THE AIFS, SUPPORTED A SOLUTION MORE IN LINE WITH THE GFS/GEFS
OVER THE SOUTHERN ROCKIES, INSTEAD OF THE CMC/ECMWF THAT ARE
DISPLACED TO THE EAST ACROSS THE CENTRAL PLAINS. THEREFORE, THE
MODEL BLEND WAS WEIGHTED A LITTLE MORE TO THE GEFS/GFS FOR THE
SECOND HALF OF THE FORECAST PERIOD, WITH THE ENSEMBLE MEANS
ACCOUNTING FOR ABOUT 70% OF THE BLEND BY NEXT SUNDAY OWING TO
GREATER THAN AVERAGE UNCERTAINTY.
..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 A
TRIPLE POINT LOW FORMING NEAR EASTERN MAINE BY FRIDAY MORNING. 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.
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page