070
FXUS02 KWBC 061923
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
223 PM EST THU FEB 6 2025
VALID 12Z SUN FEB 09 2025 - 12Z THU FEB 13 2025
...HEAVY RAIN DEVELOPING IN THE SOUTHEASTERN QUADRANT OF THE LOWER
48 MONDAY-WEDNESDAY...
...ROUNDS OF SNOW AND ICE ARE POSSIBLE STRETCHING FROM THE
CENTRAL PLAINS TO MID-ATLANTIC/NORTHEAST NEXT WEEK...
..OVERVIEW
THE SYNOPTIC PATTERN SETTING UP NEXT WEEK WILL CONSIST OF A
DEVELOPING POSITIVELY TILTED TROUGH AXIS IN THE INTERIOR WEST
TOWARD HUDSON BAY, WITH GENERAL SOUTHWESTERLY UPPER FLOW OVER THE
EAST THAT ALLOWS FOR SHORTWAVES MOVING THROUGH. ONE SHORTWAVE AND
SURFACE LOW WILL PULL AWAY FROM THE NORTHEAST SUNDAY AFTER
SPREADING SOME HEAVY SNOW TO THE REGION. RAIN CHANCES WILL INCREASE
FROM THE ARK-LA-TEX INTO THE SOUTHEAST MONDAY AND BEYOND, WITH
HEAVY RAIN AND FLOODING POSSIBLE. MEANWHILE SNOW IS POSSIBLE ON THE
NORTHERN SIDE OF THE PRECIPITATION SHIELD, GENERALLY ACROSS THE
CENTRAL PLAINS/MIDDLE MISSISSIPPI VALLEY AND OHIO VALLEY TOWARD THE
MID-ATLANTIC AND NORTHEAST, WITH SOME PLACES SEEING MULTIPLE
ROUNDS OF WINTRY WEATHER. SLEET AND FREEZING RAIN ARE POSSIBLE AS
WELL. MEANWHILE, THE WEST WILL SEE DRIER CONDITIONS EARLY NEXT WEEK
BEFORE AN ATMOSPHERIC RIVER RETURNS AROUND MIDWEEK, THOUGH WITH
HIGH UNCERTAINTY IN THE COVERAGE AND EXTENT OF POTENTIAL
PRECIPITATION. TEMPERATURE- WISE, BELOW AVERAGE TEMPERATURES IN THE
NORTHERN TIER ARE FORECAST TO TREND COLDER AND SPREAD ACROSS THE
CENTRAL U.S. AS THE WEEK PROGRESSES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS SHOW GENERALLY GOOD AGREEMENT ON THE LARGE-SCALE PATTERN
DURING MOST OF THE PERIOD AS SOUTHWESTERLY FLOW PREVAILS OVER THE
CONUS WITH GENERAL TROUGHING TO THE WEST AND RIDGING OVER THE
SOUTHEAST/BAHAMAS. MODELS SHOW A WESTERN ATLANTIC SURFACE LOW
PRODUCING SNOW IN THE NORTHEAST AT THE START OF THE PERIOD SUNDAY
THAT QUICKLY PULLS AWAY TO THE NORTHEAST. THEREAFTER, MULTIPLE
SHORTWAVES IN THE FLOW WILL LEAD TO PERIODS OF PRECIPITATION FROM
THE SOUTHERN U.S. TO EAST COAST BUT WAVE TIMING AND SMALL FRONTAL
DIFFERENCES WILL HAVE AN IMPACT ON THE EXTENT AND COVERAGE OF THIS
PRECIPITATION.
IN THE WESTERN AND CENTRAL U.S., SEVERAL NORTHERN AND SOUTHERN
STREAM ENERGIES MOVING THROUGH THE TROUGH ARE MORE UNCERTAIN AS THE
PERIOD PROGRESSES. THE CMC WAS MOST PROGRESSIVE WITH A MORE
DOMINANT SHORTWAVE EJECTING FROM THE TROUGH IN THE TUESDAY-
THURSDAY TIMEFRAME AND TRAVERSING THE CONUS, WHILE THE ECMWF AND
PARTICULARLY THE GFS WERE SLOWER. THE ECMWF TENDED TO FAVOR
BROADER, MORE AMPLIFIED TROUGHING AND LOWER HEIGHTS BUILDING OVER
THE WEST WHILE THE CMC AND GFS REMAINED LESS AMPLIFIED AND MORE
PROGRESSIVE OVERALL. THE ECENS AND CMC MEAN SHOWED A BIT MORE FAVOR
TO THE BROADER UPPER-TROUGHING PATTERN IN THE ECMWF. MODEL
GUIDANCE SHOWS THE POTENTIAL FOR AN ATMOSPHERIC RIVER FOR THE WEST
COAST BY MID- NEXT WEEK BUT THE DETERMINISTIC GUIDANCE IN
PARTICULAR SHOWS SIGNIFICANT DISAGREEMENT IN QPF PLACEMENT AND
AMOUNTS.
THE UPDATED WPC FORECAST BEGAN WITH A COMPOSITE BLEND OF THE 00Z
ECMWF/CMC/UKMET AND 06Z GFS, WITH THE MOST WEIGHT ON THE ECMWF. A
CONTRIBUTION FROM THE ENSEMBLE MEANS WAS GRADUALLY ADDED THROUGH
THE MID- TO LATE PERIOD. ECENS MEAN DATA WAS UNAVAILABLE FOR THE
BLEND BUT THE CMC ENSEMBLE MEAN PROVIDED A GOOD COMPROMISE SOLUTION
GIVEN ITS SIMILARITY TO THE ECENS MEAN. PREFERENCE WAS PLACED ON
THE ECMWF AND MEAN GUIDANCE THAT HELD THE UPPER- TROUGHING/LOWER
HEIGHTS FURTHER BACK OVER THE WEST WITH RIDGING OVER THE
SOUTHEAST/BAHAMAS.
..WEATHER/HAZARDS HIGHLIGHTS
THE PATTERN LOOKS TO BECOME INCREASINGLY FAVORABLE FOR RAIN ACROSS
PARTS OF THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY TO
TENNESSEE VALLEY AND SOUTHEAST FOR EARLY TO MID-NEXT WEEK. LOCAL TO
WIDESPREAD HEAVY RAIN COULD BE A THREAT IN THESE AREAS. ON MONDAY,
MOISTURE AND INSTABILITY MAY POOL CENTERED IN ARKANSAS AND
TRAINING OF CONVECTION IS POSSIBLE GIVEN THE WEST-EAST ORIENTED
FRONTS. THUS A MARGINAL RISK SEEMS PRUDENT FOR THE DAY 5/MONDAY ERO
FROM THE ARKLATEX TO THE MID-SOUTH. ERO AREAS WILL LIKELY BE
NEEDED IN THE SOUTHEAST TUESDAY- WEDNESDAY ONCE THOSE HEAVY RAIN
AREAS PHASE INTO THE ERO TIMEFRAME.
ON THE NORTHERN SIDE OF THE PRECIPITATION SHIELD, ROUNDS OF
POTENTIALLY DISRUPTIVE WINTRY PRECIPITATION ARE POSSIBLE NEXT WEEK.
THE FAVORED AREA FOR WINTER WEATHER WILL BE GENERALLY FROM THE
CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY, OHIO VALLEY,
CENTRAL APPALACHIANS, AND MID-ATLANTIC/NORTHEAST WHERE MOISTURE
OVERRUNNING SOUTHERN TIER FRONTS WILL INTERACT WITH COLD AIR.
CURRENTLY THE HIGHEST PROBABILITIES (50-70 PERCENT) FOR A QUARTER
INCH OF LIQUID EQUIVALENT SNOW/SLEET ARE IN PLACE FROM THE CENTRAL
APPALACHIANS INTO PARTS OF THE MID-ATLANTIC FOR TUESDAY TO
WEDNESDAY MORNING, INCLUDING SOME OF THE LARGER I-95 METROPOLITAN
AREAS. MEANWHILE SLEET AND FREEZING RAIN ARE POSSIBLE IN BETWEEN
THE CHANCES FOR HEAVY RAIN TO THE SOUTH AND SNOW TO THE NORTH. STAY
TUNED FOR REFINEMENTS TO THE FORECAST AS THE PLACEMENT, AMOUNT,
AND TYPE OF PRECIPITATION REMAINS UNCERTAIN AT ANY INDIVIDUAL
LOCATION.
PRECIPITATION IS FINALLY FORECAST TO LESSEN IN SCOPE AND MAGNITUDE
IN THE WEST EARLY NEXT WEEK, WITH JUST SOME LIGHT AMOUNTS IN THE
PACIFIC NORTHWEST AND PARTS OF THE NORTHERN/CENTRAL ROCKIES. MODELS
VARY ON THE TIMING, STRENGTH, AND POSITIONING OF ANOTHER ROUND OF
PRECIPITATION ENTERING THE WEST NEXT WEEK WITH A POSSIBLE
ATMOSPHERIC RIVER. PRECIPITATION CHANCES GENERALLY LOOK TO INCREASE
TUESDAY AND ESPECIALLY WEDNESDAY FOR PARTS OF THE WEST COAST, BUT
STAY TUNED FOR POTENTIAL FORECAST CHANGES FOR THIS UNCERTAIN
SYSTEM.
COLDER THAN AVERAGE TEMPERATURES ARE FORECAST FOR NORTHWESTERN AND
NORTH-CENTRAL PARTS OF THE LOWER 48 THROUGH THE PERIOD. THE COLD
WILL BE ESPECIALLY PRONOUNCED ACROSS MONTANA AND NORTH DAKOTA INTO
MINNESOTA AS THE WORKWEEK BEGINS. BY MONDAY THROUGH MUCH OF THE
WEEK, LOWS ARE FORECAST TO BE IN THE -10S AND -20S, ALONG WITH SOME
BELOW ZERO HIGHS. COLDER THAN AVERAGE TEMPERATURES WILL SPREAD
SOUTH BEHIND A COLD FRONT NEXT WEEK, DISPLACING UNSEASONABLE WARMTH
THAT PERSISTS ACROSS THE SOUTHERN TIER INTO SUNDAY. WARMER THAN
AVERAGE TEMPERATURES SHOULD BE LIMITED TO FLORIDA AND THE ADJACENT
SOUTHEAST BY MIDWEEK.
PUTNAM/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 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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