406
FXUS02 KWBC 281204
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
804 AM EDT FRI MAR 28 2025
VALID 12Z MON MAR 31 2025 - 12Z FRI APR 04 2025
..OVERVIEW
A PARADE OF SYSTEMS SHOULD BRING PERIODS OF ACTIVE WEATHER TO MUCH
OF THE U.S. NEXT WEEK. A COLD FRONT INTO THE EAST NEXT MONDAY
SHOULD BRING WIDESPREAD RAIN AND THUNDERSTORM CHANCES, WITH SOME
LOCALLY HEAVY RAIN ACROSS THE SOUTH. ANOTHER SYSTEM INTO THE WEST
SHOULD ULTIMATELY LEAD TO A SURFACE LOW EMERGING INTO THE PLAINS
AROUND MIDWEEK AND TRACKING TOWARDS THE GREAT LAKES. WIDESPREAD
MODERATE TO HEAVY RAIN MAY ACCOMPANY THIS SECOND COLD FRONT. THE
WEST SHOULD STAY RELATIVELY COOL UNDERNEATH OF ALMOST PERSISTENT
TROUGHING, WHILE THE CENTRAL TO EASTERN U.S. EXPERIENCES PERIODS OF
NORMAL TO ABOVE NORMAL TEMPERATURES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
A SHORTWAVE INTO THE EAST/NORTHEAST MONDAY-TUESDAY SHOW RELATIVELY
GOOD AGREEMENT BOTH ON AMPLITUDE AND TIMING. THE GUIDANCE AGREES
AN UPPER LOW OFF THE NORTHWEST COAST WILL SEND ENERGY INTO THE WEST
AROUND TUESDAY, BUT THERE REMAINS SOME SIGNIFICANT DIFFERENCES IN
THE EVOLUTION OF THIS ENERGY DOWNSTREAM. THE GFS CONTINUES TO BE AN
OUTLIER IN SHOWING A FASTER AND MORE COMPACT ENERGY INTO THE
PLAINS ON WEDNESDAY WITH A MORE EASTWARD TRACK INTO THE NORTHEAST
ON THURSDAY. THE ECMWF AND CMC (WITH AGREEMENT FROM THE ENSEMBLE
MEANS AND AI MODELS) SUGGESTS A MORE NORTHERLY TRACK OF THE
SHORTWAVE INTO THE GREAT LAKES, A RESULT OF MUCH STRONGER UPPER
RIDGING OVER THE WESTERN ATLANTIC AND EAST COAST AS COMPARED TO THE
GFS. ANOTHER SYSTEM ENTERS THE WEST LATE WEEK BUT THE GFS EXHIBITS
ISSUES OFFSHORE WITH AN UPPER LOW/OVERALL LESS BLOCKY PACIFIC
PATTERN COMPARED TO CONSENSUS. BY FRIDAY, THERE IS SOME AGREEMENT
THE FLOW PATTERN COULD TURN MORE AMPLIFIED AND ACTIVE WITH A DEEP
WESTERN RIDGE AND EASTERN U.S. RIDGING.
GOOD ENOUGH AGREEMENT THE FIRST FEW DAYS OF THE PERIOD ALLOWED FOR
A GENERAL MODEL COMPROMISE. ADDED IN ENSEMBLE MEAN GUIDANCE IN
PLACE OF THE GFS MIDWEEK AND BEYOND GIVEN THE GENERAL OUT OF SYNC
PATTERN SHOWN IN THE GFS. BY DAY 7, USED A 60/40 BLEND OF THE
ENSEMBLE MEANS WITH THE DETERMINISTIC ECMWF AND CMC. THIS HELPED
MAINTAIN GOOD AGREEMENT WITH YESTERDAY'S WPC FORECAST AS WELL.
..WEATHER/HAZARDS HIGHLIGHTS
A COLD FRONT INTO THE EAST SHOULD ALLOW FOR INCREASED RAIN AND
CONVECTION ACROSS MUCH OF THE EASTERN SEABOARD. THE BEST CHANCE FOR
LOCALLY HEAVY TO EXCESSIVE RAINFALL SHOULD BE MOSTLY CONFINED TO
PARTS OF THE SOUTHEAST WHERE A MARGINAL RISK IS IN PLACE FOR THE
DAY 4/MONDAY EXCESSIVE RAINFALL OUTLOOK. THE STORM PREDICTION
CENTER ALSO SUGGESTS STRONG TO SEVERE WEATHER IS POSSIBLE FROM THE
SOUTHEAST INTO THE MID-ATLANTIC AS WELL ON MONDAY.
EXPECT MULTIPLE SYSTEMS TO BRING RAIN AND HIGHER ELEVATION SNOW TO
THE WEST DURING THE PERIOD, WITH RAPIDLY INCREASING UNCERTAINTY IN
THE DETAILS AFTER EARLY NEXT WEEK. THE BEST PRECIPITATION FOCUS
LOOKS TO BE ACROSS NORTHERN CALIFORNIA ON MONDAY, SO A MARGINAL
RISK WAS CONTINUED FOR TONIGHTS NEW DAY 4 ERO. TRENDS IN THE
GUIDANCE SHOW ANOTHER POSSIBLY SIGNIFICANT SYSTEM INTO THE WEST
MID-WEEK ACCOMPANIED BY AT LEAST MODERATE PRECIPITATION. LEADING
DYNAMICS FROM THE WEST SHOULD EVENTUALLY SUPPORT A CENTRAL-EASTERN
U.S. SYSTEM BY WEDNESDAY-THURSDAY, GENERATING ANOTHER EPISODE OF
MEANINGFUL PRECIPITATION OVER THE EASTERN HALF OF THE COUNTRY. SOME
SNOW WILL BE POSSIBLE FROM THE NORTHERN PLAINS INTO NEW ENGLAND.
THE WARM SECTOR AHEAD OF THE FRONT CROSSING THE EASTERN HALF OF
THE COUNTRY INTO MONDAY WILL FEATURE WELL ABOVE NORMAL
TEMPERATURES. EXPECT PLUS 10-20F ANOMALIES FOR HIGHS AND UP TO PLUS
20-25F ANOMALIES FOR MORNING LOWS. NEAR TO BELOW NORMAL READINGS
WILL PROGRESS EASTWARD BEHIND THE EASTERN U.S. FRONT, WITH
PRECIPITATION KEEPING SOME NORTHERN PLAINS TO GREAT LAKES LOCATIONS
5-10F OR SO BELOW NORMAL FOR HIGHS INTO TUESDAY. TEMPERATURES MAY
REBOUND BACK ABOVE NORMAL OVER THE SOUTHERN HALF OF THE PLAINS ON
WEDNESDAY WITH THE WARMING TREND SPREADING BACK INTO THE EAST
THEREAFTER. PERIODS OF UNSETTLED WEATHER WILL KEEP THE DIURNAL
SPREAD OVER THE WEST COAST STATES MORE NARROW THAN USUAL, WITH COOL
HIGHS AND NEAR OR SLIGHTLY ABOVE NORMAL LOWS.
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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