428
FXUS02 KWBC 010708
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
208 AM EST SUN JAN 01 2023
VALID 12Z WED JAN 04 2023 - 12Z SUN JAN 08 2023
...SIGNIFICANT MULTI-DAY HEAVY PRECIPITATION EVENT THIS WEEK INTO
THE WEST WITH PRIMARY FOCUS ACROSS CALIFORNIA...
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS AND ENSEMBLES ARE GRADUALLY CONVERGING ON A BETTER
CLUSTERED PATTERN AND SYSTEM FORECAST AT MEDIUM RANGE TIME SCALES.
WHILE DIFFERENCES INCLUDING LOCAL WEATHER FOCUS REMAIN, AN OVERALL
GFS/ECMWF/UKMET/CANADIAN MODEL COMPOSITE ALONG WITH THE NATIONAL
BLEND OF MODELS AND WPC CONTINUITY SEEMS TO OFFER A REASONABLE
FORECAST STARTING POINT MID-LATER THIS WEEK AND INCREASED
INCORPORATION OF THE COMPATIBLE GEFS/ECMWF ENSEMBLE MEANS SEEMS TO
OFFER A GOOD FORECAST CONTINUATION INTO NEXT WEEKEND AMID
GRADUALLY GROWING FORECAST SPREAD IN ACTIVE FLOW.
..WEATHER/HAZARD HIGHLIGHTS
THERE IS SOME CHANCE FOR SNOW IN MARGINALLY COOLED AIR FROM THE
LOWER GREAT LAKES THROUGH THE NORTHERN NORTHEAST THROUGH MIDWEEK
WITH SYSTEM PASSAGE. MEANWHILE TO THE SOUTH, A WAVY FRONTAL SYSTEM
WILL DEVELOP AND SPREAD SOME MODERATE RAIN UP THE EASTERN SEABOARD
MIDWEEK, WITH UNCERTAIN ADDITIONAL/MODEST FRONTAL WAVE FORMATION
OFFSHORE POSSIBLY LINGERING SOME LIGHT QPF INTO THE
MID-ATLANTIC/COASTAL NORTHEAST INTO LATER NEXT WEEK. PRIOR TO
THIS, MUCH MILDER THAN AVERAGE TEMPERATURES WILL LINGER ACROSS
MUCH OF THE EASTERN SEABOARD INTO MIDWEEK. LOWS OF AROUND 15-30F
ABOVE AVERAGE WILL BE COMMON. DAILY RECORDS WILL LIKELY BE
WIDESPREAD ACROSS THE BROAD REGION.
IT REMAINS THE EXPECTATION THAT ADDITIONAL ROUNDS OF PRECIPITATION
ARE ALSO EXPECTED TO WORK ACROSS THE WEST COAST THIS WEEK IN A
VERY WET PATTERN TO START 2023, BUT STILL PRIMARILY WITH A FOCUS
ON CALIFORNIA. AMOUNTS LOOK TO TREND UPWARD AGAIN IN EARNEST BY
WEDNESDAY-THURSDAY ACROSS CALIFORNIA AS A SYSTEM APPROACHES FROM
THE PACIFIC WITH ANOTHER POTENTIAL ATMOSPHERIC RIVER EVENT TO
SHIFT STEADILY SOUTHWARD ACROSS THE STATE OVER TIME. MANY AREAS
ARE LIKELY TO BE SENSITIVE TO ADDITIONAL RAINFALL BY THEN GIVEN
THE AMPLE RECENT RAINFALL AND ADDITIONAL RAIN DURING THE SHORT
RANGE PERIOD AND THEN WILL BE AN ADDITIONAL CHANCE FOR AN UPTICK
IN PRECIPITATION WITH ADDITIONAL SYSTEM APPROACH LATTER WEEK. WPC
EXPERIMENTAL MEDIUM RANGE EXCESSIVE RAINFALL OUTLOOK (ERO)
"SLIGHT" RISK AREAS HAVE BEEN ISSUED FOR THE WEDNESDAY-THURSDAY
EPISODE. THERE IS ALSO A MULTI-DAY THREAT FOR HEAVY SNOW THAT WILL
FOCUS OVER THE SIERRA THIS WEEK, BUT ALSO SPREAD NORTHWARD THROUGH
THE CASCADES AND WITH SOME GUSTO INLAND ACROSS THE INTERMOUNTAIN
WEST TOWARD THE ROCKIES OVER TIME WITH SYSTEM TRANSLATION. THIS
THREAT IS ADDRESSED IN THE WPC WINTER WEATHER OUTLOOK (WWO) AND
OTHER PRODUCTS. SYSTEM/ENERGY TRANSLATION AND ASSOCIATED/MODEST
SURFACE SYSTEM GENESIS IS THEN EXPECTED TO WORK DOWNSTREAM ACROSS
THE CENTRAL TO EAST CENTRAL U.S. HEADING INTO NEXT WEEKEND, BUT
WITH LIMITED QPF POTENTIAL.
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, 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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