859
FXUS02 KWBC 010704
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
203 AM EST WED FEB 01 2023
VALID 12Z SAT FEB 04 2023 - 12Z WED FEB 08 2023
...DANGEROUSLY COLD TEMPERATURES AND WIND CHILLS ARE FORECAST
ACROSS THE NORTHEAST ON SATURDAY...
..OVERVIEW
THE OVERALL UPPER-LEVEL PATTERN DURING THE MEDIUM RANGE PERIOD
WILL REMAIN FAIRLY WAVY AND PROGRESSIVE. AS THE PERIOD BEGINS
SATURDAY, TROUGHING WILL EXTEND FROM A DEEP UPPER LOW OVER THE
CANADIAN MARITIMES INTO THE NORTHEAST, LEADING TO SIGNIFICANTLY
COLD TEMPERATURES AND WIND CHILLS THERE. ANOTHER TROUGH IS
FORECAST TO PRESS ACROSS THE CENTRAL TO EASTERN U.S. THROUGH EARLY
NEXT WEEK, BUT WITH PRECIPITATION LIMITED TO THE GREAT LAKES
REGION AND PERHAPS THE EASTERN SEABOARD. YET ANOTHER TROUGH
APPROACHING THE WEST SHOULD LEAD TO A WETTER PATTERN THERE FOR THE
WEEKEND, WITH GENERALLY LIGHT TO MODERATE RAIN AND SNOW AMOUNTS.
THIS LATTER TROUGH IS FORECAST TO TRACK INTO THE CENTRAL U.S. IN
SOME FASHION BY TUESDAY-WEDNESDAY, LEADING TO A WETTER PATTERN
THERE.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE REMAINS IN GENERALLY GOOD AGREEMENT FOR THE EARLY
PART OF THE MEDIUM RANGE PERIOD THIS WEEKEND. NO REAL OUTLIERS
WERE NOTED, SO WPC WAS ABLE TO USE A BLEND OF THE DETERMINISTIC
12/18Z MODEL GUIDANCE THROUGH DAYS 3-4. GREATER MODEL DIFFERENCES
START TO ARISE BY DAY 5/MONDAY WITH THE TROUGH IN THE WEST AND
ESPECIALLY AS IT SHIFTS EASTWARD. MODELS HAVE BEEN WAFFLING IN
TERMS OF HOW MUCH STREAM SEPARATION TO CREATE WITH THIS ENERGY.
GFS RUNS HAVE BEEN FAIRLY PERSISTENT IN SHOWING A SOUTHERN STREAM
CLOSED LOW BREAKING OFF AND LINGERING IN THE SOUTHWEST
TUESDAY-WEDNESDAY. IN TERMS OF THE ENSEMBLES, MAINLY GEFS MEMBERS
ARE THE ONES THAT EXHIBIT THIS TYPE OF PATTERN AS WELL. MEANWHILE
ECMWF RUNS HAVE BEEN INDICATING A PHASED STEADILY PROGRESSIVE
TROUGH, AS HAVE THE CMC RUNS LATELY, BUT OLDER RUNS OF THE CMC HAD
SHOWN THE SOUTHERN STREAM CLOSED LOW. THERE ARE ALSO SOME
DIFFERENCES IN THE MODELS REGARDING WHETHER ADDITIONAL ENERGY
COMING FROM THE NORTHWEST INTERACTS WITH THE TROUGH, WHICH
COMPLICATES MATTERS ALL THE MORE. THUS THE WPC FORECAST
TRANSITIONED TO A BLEND FAVORING THE ENSEMBLE MEANS BY HALF DAY 6
AND OVER HALF ON DAY 7 GIVEN THE OPERATIONAL MODEL DIFFERENCES.
FORTUNATELY THE ENSEMBLE MEANS WERE ALIGNED FAIRLY WELL--THOUGH,
THE GEFS MEANS DO INDICATE MAINTAINING MORE SEPARATION THROUGH
MIDWEEK THAN THE EC MEAN AND ESPECIALLY THE CMC MEAN.
..WEATHER/HAZARD HIGHLIGHTS
VERY COLD CONDITIONS ARE LIKELY FOR THE NORTHEASTERN U.S. ON
SATURDAY UNDERNEATH COLD UPPER TROUGHING. MANY LOW TEMPERATURES ON
SATURDAY MORNING ARE FORECAST TO BREAK RECORDS, AND THE BITTER
COLD COMBINED WITH WIND WILL PRODUCE DANGEROUS WIND CHILLS. WELL
BELOW NORMAL HIGH TEMPERATURES COULD ALSO SET RECORDS, AS
TEMPERATURES COULD STAY BELOW ZERO ALL DAY IN PARTS OF MAINE AND
IN THE SINGLE DIGITS IN MUCH OF NORTHERN NEW ENGLAND. CHILLY
TEMPERATURES ARE FORECAST TO EXPAND ACROSS THE EASTERN SEABOARD
SATURDAY, WITH TEMPERATURES COMMONLY 10-20F BELOW NORMAL. BUT A
PRONOUNCED WARMING TREND IS EXPECTED TO OCCUR ACROSS MUCH OF THE
COUNTRY STARTING IN THE CENTRAL U.S. THIS WEEKEND AND EXPANDING
INTO THE EAST EARLY NEXT WEEK. THE WEST HOWEVER COULD STAY AROUND
5-10F BELOW AVERAGE ESPECIALLY IN TERMS OF HIGHS UNDERNEATH UPPER
TROUGHING.
A FRONTAL SYSTEM COULD SPREAD SOME LIGHT SNOW TO THE MIDWEST/GREAT
LAKES REGIONS AND NORTHEAST THIS WEEKEND, AND AMOUNTS COULD BE
ENHANCED DOWNWIND OF THE GREAT LAKES. LIGHT PRECIPITATION IS
POSSIBLE ALONG THE EASTERN SEABOARD WITH SOME MOISTURE RETURN BY
SUNDAY, BUT UNCERTAINTY REMAINS AS TO HOW MUCH FALLS ONSHORE.
TODAY'S FORECAST SHOWS LESS EAST COAST PRECIPITATION COMPARED TO
THE FORECAST FROM 24 HOURS AGO. MEANWHILE IN THE WEST, GENERALLY
LIGHT TO MODERATE PRECIPITATION IS EXPECTED THIS WEEKEND IN THE
FORM OF LOWER ELEVATION RAIN AND HIGHER ELEVATION SNOW, WITH
TYPICAL TERRAIN ENHANCEMENT ACROSS THE COASTAL RANGES AND THE
SIERRA NEVADA. SNOW IS FORECAST TO SPREAD INTO THE INTERMOUNTAIN
WEST AND ROCKIES EARLY NEXT WEEK, AND THEN PRECIPITATION COULD
OVERSPREAD THE CENTRAL U.S. BY MONDAY-TUESDAY ALONG AND AHEAD OF A
LOW PRESSURE/FRONTAL SYSTEM. GENERALLY THIS LOOKS TO BE IN THE
FORM OF RAIN OTHER THAN SOME POSSIBLE SNOW IN THE NORTHERN TIER
(MIDWEST-GREAT LAKES), BUT WILL CONTINUE TO MONITOR. THE PACIFIC
NORTHWEST TO NORTHERN ROCKIES ARE LIKELY TO SEE ADDITIONAL ROUNDS
OF PRECIPITATION INTO THE FIRST HALF OF NEXT WEEK.
TATE
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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page