867
FXUS02 KWBC 010630
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
130 AM EST SUN DEC 1 2024
VALID 12Z WED DEC 04 2024 - 12Z SUN DEC 08 2024
...ANOTHER BLAST OF ARCTIC COLD IN THE CENTRAL AND EASTERN U.S.
LATER THIS WEEK...
...SIGNIFICANT LAKE EFFECT SNOW TO CONTINUE FOR THE GREAT LAKES
THIS WEEK...
..OVERVIEW
MEAN UPPER LEVEL TROUGHING OVER MUCH OF THE CENTRAL AND EASTERN
U.S. WILL DOMINATE THE WEATHER PATTERN THROUGH THIS WEEK INTO NEXT
WEEKEND, AND WEATHER SYSTEMS WILL BE DRIVEN BY SHORTWAVE TROUGHS
ROTATING AROUND THE BROAD UPPER LEVEL TROUGH. A COUPLE COLD FRONTS
WILL PUSH SOUTH ACROSS THE EASTERN TWO-THIRDS OF THE NATION THIS
WEEK AND WILL BRING ANOTHER BLAST OF COLD ARCTIC AIR. THIS PATTERN
WILL ALSO FAVOR LONG-DURATION LAKE EFFECT SNOW IN THE GREAT LAKES,
AND SIGNIFICANT SNOW ACCUMULATIONS WILL BE POSSIBLE IN FAVORED
DOWNWIND LOCATIONS. ELSEWHERE, HIGH PRESSURE WILL PERSIST IN THE
WEST BEFORE A FRONTAL SYSTEM APPROACHES NEXT WEEKEND, AND MOIST
RETURN FLOW FROM THE GULF WILL SUPPORT DAILY RAIN CHANCES ALONG THE
GULF COAST.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE WEATHER
PATTERN THROUGH THE MEDIUM RANGE PERIOD. MODELS HAVE TRENDED FASTER
WITH THE PROGRESSION OF A STRONG COLD FRONT MID/LATE THIS WEEK,
WHICH WILL BRING COLD ARCTIC AIR INTO THE CENTRAL AND EASTERN U.S.
BY THURSDAY. THIS WILL ALSO RESULT IN RAINFALL SPREADING FURTHER
INTO THE SOUTH AHEAD OF THE FRONT ON WEDNESDAY. MODEL SPREAD
INCREASES AN EXPECTED AMOUNT FRIDAY INTO NEXT WEEKEND, WHICH MAY
HAVE AN AFFECT ON DETAILS AND TIMING OF FRONTAL SYSTEMS.
THE WPC FORECAST BLEND CONSISTED OF THE DETERMINISTIC
GFS/ECMWF/CMC/UKMET FOR WEDNESDAY AND THURSDAY, THEN THE
DETERMINISTIC CMC/UKMET WERE REDUCED AND THE ECENS/GEFS ENSEMBLE
MEANS WERE ADDED IN INCREASING AMOUNTS FOR FRIDAY THROUGH SUNDAY.
..WEATHER/HAZARDS HIGHLIGHTS
LAKE EFFECT SNOW IS FORECAST TO CONTINUE THIS WEEK AS A CLIPPER
LOW PRESSURE SYSTEM MOVES ACROSS THE REGION WEDNESDAY AND THURSDAY
FOLLOWED BY STRONG WEST-NORTHWESTERLY WINDS. SIGNIFICANT SNOW
ACCUMULATIONS WILL BE POSSIBLE IN FAVORED DOWNWIND LOCATIONS, AND
TRAVEL CONDITIONS WILL LIKELY BE HAZARDOUS. SNOW WILL ALSO BE
POSSIBLE ELSEWHERE IN THE NORTHEAST AS THE CLIPPER SYSTEM MOVES
THROUGH, ESPECIALLY IN THE HIGHER TERRAIN OF THE APPALACHIANS.
CONDITIONS SHOULD IMPROVE BRIEFLY LATE THIS WEEK, BUT ANOTHER LOW
PRESSURE SYSTEM WILL BRING ANOTHER CHANCE FOR WINTRY PRECIPITATION
TO THE REGION NEXT WEEKEND.
THE REST OF THE NATION WILL BE MAINLY DRY THIS WEEK WITH A COUPLE
EXCEPTIONS. MOIST RETURN FLOW FROM THE GULF WILL RESULT IN DAILY
RAIN CHANCES ALONG THE GULF COAST AND INTO PORTIONS OF THE SOUTH.
THERE WILL LIKELY BE ENOUGH INSTABILITY TO SUPPORT LOCALLY HEAVY
RAINFALL ON WEDNESDAY IN PORTIONS OF EASTERN TEXAS AND LOUISIANA,
AND THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THESE
AREAS. THE RISK OF HEAVY RAINFALL WILL DECREASE THURSDAY THROUGH
THE END OF THE WEEK AS INSTABILITY DECREASES AND PRECIPITATION
BECOMES MORE SPREAD OUT ACROSS THE GULF COAST REGION AS FRONTS MOVE
THROUGH. PRECIPITATION CHANCES WILL ALSO RETURN TO THE NORTHWEST
LATE THIS WEEK INTO NEXT WEEKEND AS A PACIFIC FRONTAL SYSTEM
APPROACHES AND PUSHES INLAND.
TEMPERATURES WILL DROP BELOW NORMAL FOR MUCH OF THE CENTRAL AND
EASTERN U.S. THIS WEEK AS A COLD FRONT USHERS IN ANOTHER BLAST OF
ARCTIC AIR. ELSEWHERE, TEMPERATURES WILL BE MILD FOR THIS TIME OF
YEAR, GENERALLY NEAR TO SLIGHTLY ABOVE AVERAGE.
DOLAN
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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