910
FXUS02 KWBC 010705
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
202 AM EST MON JAN 01 2024
VALID 12Z THU JAN 04 2024 - 12Z MON JAN 08 2024
...HEAVY PRECIPITATION TO IMPACT MUCH OF THE EASTERN U.S. NEXT
WEEKEND...
..OVERVIEW
THE MEDIUM RANGE PERIOD FEATURES A RATHER PROGRESSIVE FLOW PATTERN
AS A PARADE OF STORM SYSTEMS TRAVERSES THE COUNTRY FROM WEST TO
EAST. ONE WILL BE EXITING THE EAST COAST AS ANOTHER MOVES THROUGH
THE SOUTHWEST ON THURSDAY, WITH POTENTIAL FOR ANOTHER ROUND OF
HEAVY RAIN ACROSS THE LOWER MISSISSIPPI VALLEY/SOUTHEAST BY
FRIDAY. AS THIS SYSTEM LIFTS UP THE EAST COAST NEXT WEEKEND, IT
HAS POTENTIAL TO BRING HEAVY PRECIPITATION (RAIN TO THE SOUTH,
SNOW TO THE NORTH) TO MUCH OF THE EAST. OUT WEST, THE NEXT SYSTEM
LOOKS TO MOVE IN NEXT WEEKEND AS WELL WITH ANOTHER ROUND OF VALLEY
RAIN AND MOUNTAIN SNOWS PROGRESSING FROM CALIFORNIA INTO THE FOUR
CORNERS REGION.
..GUIDANCE/PREDICTABILITY ASSESSMENT
THE LATEST GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE
OVERALL SYNOPTIC PATTERN DURING THE THURSDAY-MONDAY MEDIUM RANGE
PERIOD. THERE ARE SOME MORE SENSITIVE DIFFERENCES IN THE DETAILS
AND TIMING OF INDIVIDUAL SYSTEMS. THE BIGGEST UNCERTAINTY IS WITH
DEVELOPING LOW PRESSURE ACROSS THE GULF COAST WHICH MODELS ARE
INCREASINGLY SUGGESTING MAY STRENGTHEN AS IT LIFTS ALONG THE EAST
COAST NEXT WEEKEND. THERE REMAINS CONSIDERABLE SPREAD IN THE EXACT
TRACK AND TIMING OF THIS SYSTEM, WHICH HAS HUGE IMPLICATIONS FOR
PRECIPITATION TYPE ACROSS SOME OF THE MAJOR CITIES OF THE
MID-ATLANTIC/NORTHEAST. ELSEWHERE, SOME DIFFERENCES WITH NORTHERN
STREAM SHORTWAVES THROUGH THE GREAT LAKES AND ALSO WITH THE SECOND
TROUGH ENTERING THE WEST/SOUTHWEST NEXT WEEKEND AND POTENTIAL LOW
PRESSURE DEVELOPMENT ACROSS THE SOUTH-CENTRAL PLAINS NEXT MONDAY.
THE WPC FORECAST FOR TONIGHT USED A BLEND OF THE DETERMINISTIC
GUIDANCE EARLY IN THE PERIOD, INCREASING CONTRIBUTIONS FROM THE
ENSEMBLE MEANS BEGINNING ON DAY 5 TO HELP SMOOTH OUT SOME OF THE
DIFFERENCES WITH THE EAST COAST SYSTEM. THIS ALSO HELPED TO
MAINTAIN FAIRLY GOOD CONTINUITY WITH THE PREVIOUS WPC FORECAST FOR
THIS STORM AS WELL. LEANED MORE ON THE ECMWF AND ENSEMBLE MEANS
LATE PERIOD ACROSS THE WEST.
..WEATHER/HAZARDS HIGHLIGHTS
PRECIPITATION ACROSS THE FOUR CORNERS/SOUTHERN-CENTRAL PLAINS TO
START ON THURSDAY SHOULD BECOME MORE WIDESPREAD IN NATURE AS THE
FIRST OF A SERIES OF UPPER LOWS TAPS GULF OF MEXICO MOISTURE TO
FUEL ANOTHER ROUND OF MODERATE TO LOCALLY HEAVY RAINFALL ACROSS
THE LOWER MISSISSIPPI VALLEY/CENTRAL GULF COAST STATES ON FRIDAY.
THERE IS ENOUGH INSTABILITY AND MOISTURE TO SUPPORT A MARGINAL
RISK ACROSS THIS REGION ON THE DAY 5 EXCESSIVE RAINFALL OUTLOOK,
ESPECIALLY CONSIDERING THE POTENTIAL FOR MODEST RAINFALL ACROSS
PARTS OF THIS REGION DURING THE SHORT RANGE AS WELL. HEAVY
PRECIPITATION WILL SPREAD ACROSS THE
SOUTHEAST/MID-ATLANTIC/NORTHEAST NEXT WEEKEND, WITH INCREASING
POTENTIAL FOR SNOW TO THE NORTH AND WEST OF THE LOW. EXACT AMOUNTS
AND PRECIPITATION TYPE FOR SOME OF THE MAJOR EAST COAST CITIES
REMAINS HIGHLY UNCERTAIN AT THIS POINT, BUT DOES NEED TO BE
WATCHED AS THERE IS POTENTIAL FOR SOME MODEST SNOWS ACROSS AT
LEAST INTERIOR PORTIONS OF THIS REGION, AS HIGHLIGHTED BY THE WPC
WINTER WEATHER OUTLOOK, WHICH COULD AFFECT THE DC-NYC CORRIDOR
DEPENDING ON THE TRACK OF THE LOW.
THE NEXT SYSTEM MOVES INTO THE WESTERN STATES NEXT WEEKEND
SPREADING MODERATE TO LOCALLY HEAVY PRECIPITATION ACROSS THE WEST
COAST/CALIFORNIA AND INTO THE INTERIOR WEST NEXT MONDAY. SOME
SIGNAL FOR DECENT MOUNTAIN SNOWS ACROSS PARTS OF THE CASCADES,
SIERRAS, AND INTERIOR MOUNTAIN RANGES/SOUTHERN ROCKIES. SURFACE
CYCLOGENESIS ACROSS THE SOUTH-CENTRAL PLAINS EARLY NEXT WEEK
SHOULD ALLOW PRECIPITATION TO MOVE INTO THE CENTRAL U.S., WITH
POTENTIAL FOR SNOW TO THE NORTH OF THE LOW TRACK.
ABOVE NORMAL TEMPERATURES SHOULD BE MOSTLY CONFINED TO THE FAR
NORTHERN TIER WITH ANOMALOUS GENERALLY +5-15F. SOME MODERATELY
ABOVE NORMAL TEMPERATURES MAY RETURN TO THE SOUTHERN PLAINS/LOWER
MISSISSIPPI VALLEY EARLY NEXT WEEK. NEAR TO BELOW NORMAL
TEMPERATURES SHOULD SPREAD ACROSS THE EAST INTO THE WEEKEND, WITH
TEMPERATURES ALSO TRENDING MUCH COOLER ACROSS THE WEST AS UPPER
TROUGHING MOVES INTO THE REGION LATE IN THE PERIOD.
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY
MESSAGES 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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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