197
FXUS02 KWBC 030701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT THU NOV 03 2022
VALID 12Z SUN NOV 06 2022 - 12Z THU NOV 10 2022
...CHILLY PATTERN OVER THE WEST WITH SIGNIFICANT RAIN/MOUNTAIN
SNOW OVER SOME AREAS...
..OVERVIEW
GUIDANCE TRENDS OVER THE PAST DAY HAVE YIELDED IMPROVED AGREEMENT
IN PRINCIPLE FOR THE SHAPE OF STRONG UPPER RIDGING FORECAST TO
BUILD INTO ALASKA AND NORTHWESTERN CANADA. AS A RESULT THE LATEST
MODELS/MEANS ARE NOW BETTER CLUSTERED FOR THE DOWNSTREAM EVOLUTION
FROM THE EASTERN PACIFIC THROUGH THE LOWER 48. CURRENT CONSENSUS
SHOWS A STRONGLY AMPLIFYING TROUGH NEAR THE WEST COAST
SUNDAY-TUESDAY, ANCHORED BY AN UPPER LOW DRIFTING SOUTHWARD JUST
WEST OF VANCOUVER ISLAND AND PACIFIC NORTHWEST COAST. THEN THE
TROUGH SHOULD PROGRESS INLAND DURING WEDNESDAY-THURSDAY. THE EARLY
WEEK DEEPENING OF THE TROUGH WILL SERVE TO REBUILD AN UPPER RIDGE
OVER THE EAST. MEANWHILE MOST SOLUTIONS SHOW AN UPPER LOW
INITIALLY NEAR THE EASTERN BAHAMAS TRACKING INTO FLORIDA OR
SOUTHEASTERN COAST, UNDERNEATH THE RIDGE THAT BUILDS FARTHER
NORTH. THE WESTERN TROUGH WILL BRING MULTIPLE DAYS OF WELL BELOW
NORMAL TEMPERATURES AND A BROAD AREA OF RAIN/MOUNTAIN SNOW, WITH
SIGNIFICANT TOTALS OVER SOME AREAS. EJECTING ENERGY/MOISTURE COULD
SPREAD SOME PRECIPITATION FARTHER EAST ACROSS THE NORTHERN TIER.
ON THE OTHER HAND MOST OF THE EASTERN HALF OF THE COUNTRY WILL SEE
UNSEASONABLY WARM TEMPERATURES AND THE BAHAMAS SYSTEM MAY
EVENTUALLY SPREAD RAINFALL INTO SOME AREAS NEAR THE EAST COAST.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THERE IS STILL A WINDOW FOR MORE CHANGES TO OCCUR, BUT WITH OTHER
GUIDANCE OVER THE PAST 24-36 HOURS GRAVITATING TO THE PRIOR
GFS/GEFS IDEA OF AN OPEN RIDGE BUILDING INTO ALASKA/NORTHWESTERN
CANADA LEADING TO STRONG WEST COAST TROUGH AMPLIFICATION,
CONFIDENCE IS FINALLY INCREASING THAT THIS IS THE MOST LIKELY
SCENARIO TO OCCUR. THIS EVOLUTION OVER THE WEST HAS LED TO
STRONGER TRENDS FOR RIDGING THAT BUILDS OVER THE EAST, AND IN TURN
POTENTIALLY A FARTHER SOUTH TRACK OF THE BAHAMAS SYSTEM COMPARED
TO SOME RUNS FROM PREVIOUS DAYS.
WITH RESPECT TO SPECIFICS, THERE IS NOW DECENT CLUSTERING WITH
MOST ASPECTS OF THE FORECAST INTO EARLY DAY 5 TUESDAY. THIS
FAVORED A 12Z/18Z OPERATIONAL MODEL COMPOSITE FOR THE PREPARATION
OF THE LATEST FORECAST. THE NEW 00Z GFS BRINGS THE CORE OF ITS
UPPER SYSTEM A LITTLE SOUTH OF OTHER SOLUTIONS BY TUESDAY BUT IS
STILL WITHIN THE REALM OF POSSIBILITY. FARTHER EAST, AN INITIAL
MIDWEST COLD FRONT TRAILING FROM A SOUTHERN CANADA SYSTEM MAKES
GREATER SOUTHWARD PROGRESS OVER THE EAST THAN PRIOR CONSENSUS BY
TUESDAY AND THE STRONGER TREND FOR EASTERN UPPER RIDGING SLOWS THE
RETROGRESSION OF THE BAHAMAS SYSTEM.
BY DAYS 6-7 WEDNESDAY-THURSDAY, SOME TYPICAL SPREAD DEVELOPS FOR
HOW LEADING ENERGY MAY EJECT FROM THE WESTERN TROUGH--LEADING TO
DIFFERENCES FOR NORTHERN TIER U.S./SOUTHERN CANADA LOW
PRESSURE--AND FOR DETAILS/TIMING OF THE WESTERN TROUGH ITSELF. THE
ULTIMATE PATH OF THE BAHAMAS SYSTEM WILL DEPEND ON HOW QUICKLY THE
CENTER OF THE EASTERN UPPER RIDGE SHIFTS INTO THE ATLANTIC. THE
GFS HAS BEEN MORE PERSISTENT WITH THE RIDGE, KEEPING THE SYSTEM
FARTHER SOUTH RELATIVE TO THE PAST COUPLE ECMWF RUNS THROUGH 12Z.
BOTH THE 00Z ECMWF AND CMC HAVE FLIPPED FROM THEIR 12Z RUNS, THE
NEW ECMWF SWITCHING TO THE GFS IDEA AND THE CMC SWITCHING FROM THE
GFS TYPE SOLUTION TO LOOKING MORE LIKE THE 12Z ECMWF. NEEDLESS TO
SAY, CONFIDENCE IS STILL BELOW AVERAGE FOR THIS ASPECT OF THE
FORECAST. A GENERAL MODEL/MEAN BLEND PROVIDED A GOOD INTERMEDIATE
DEPICTION FOR THE FEATURES OF INTEREST DURING DAYS 6-7.
..WEATHER/HAZARD HIGHLIGHTS
THE WEST WILL SEE A BROAD AREA OF RAIN AND HIGHER ELEVATION SNOW
DURING THE PERIOD AS THE UPPER TROUGH AMPLIFIES NEAR THE COAST AND
EVENTUALLY MOVES INLAND. STRONG LEADING DYNAMICS WILL INITIALLY
PROVIDE THE BEST RAIN/MOUNTAIN SNOW FOCUS OVER WESTERN OREGON AND
NORTHERN CALIFORNIA ON SUNDAY. BROAD SOUTHERLY FLOW EAST OF THE
OFFSHORE UPPER LOW COULD ALSO ENHANCE PRECIPITATION OVER PARTS OF
NORTHERN-NORTHWESTERN WASHINGTON. FROM MONDAY ONWARD THE HIGHEST
PRECIPITATION TOTALS SHOULD PUSH SOUTHEASTWARD, EXTENDING FROM THE
COASTAL RANGES AND SIERRA NEVADA IN CALIFORNIA THROUGH THE GREAT
BASIN AND NORTH-CENTRAL/CENTRAL ROCKIES. WESTERNMOST AREAS SHOULD
BEGIN TO SEE A DRIER TREND AROUND MIDWEEK. MOISTURE/ENERGY
EJECTING FROM THE WESTERN TROUGH MAY SPREAD ONE OR MORE AREAS OF
PRECIPITATION ACROSS THE NORTHERN TIER DURING THE FIRST HALF OF
NEXT WEEK. BEST SNOW POTENTIAL SHOULD BE OVER MONTANA WITH THE
COLD AIR IN PLACE OVER THE AREA. A WEAKENING AND
STALLING/RETREATING FRONT MAY PRODUCE SOME LIGHT RAINFALL OVER
PARTS OF THE EAST INTO THE SOUTHERN PLAINS EARLY IN THE PERIOD.
MOISTURE ASSOCIATED WITH THE BAHAMAS SYSTEM TRACKING TOWARD
FLORIDA/SOUTHEASTERN COAST MAY SPREAD INTO PARTS OF THE EAST
TUESDAY ONWARD. DETAILS OF COVERAGE AND TOTALS ARE STILL FAIRLY
UNCERTAIN AT THIS TIME, BUT SOME AREAS OF LOCALLY MODERATE TO
HEAVY RAINFALL MAY BE POSSIBLE.
THE WEST WILL SEE A BRIEF RECOVERY TO ONLY MODERATELY BELOW NORMAL
TEMPERATURES EXTEND INTO SUNDAY. THEN THE AMPLIFYING UPPER TROUGH
NEAR THE WEST COAST SHOULD SPREAD AN INCREASING AREA OF HIGHS
10-20F BELOW NORMAL ACROSS THE REGION DURING MONDAY-THURSDAY. THE
COLDEST AIR WILL LIKELY EXTEND FROM WESTERN CANADA INTO MONTANA
WITH RECENT FORECASTS CONSISTENTLY SHOWING HIGHS IN THAT STATE UP
TO 20-35F BELOW NORMAL MONDAY-THURSDAY. SOME LOCATIONS OVER THE
WEST MAY SEE DAILY RECORDS FOR COLD HIGHS MONDAY-WEDNESDAY. IN
CONTRAST, WELL ABOVE NORMAL TEMPERATURES WILL PREVAIL OVER MUCH OF
THE EAST AND AT TIMES OVER THE PLAINS. THE EAST WILL SEE
TEMPERATURES 10-25F ABOVE NORMAL ESPECIALLY DURING SUNDAY-MONDAY
WHEN DAILY RECORDS FOR HIGHS AND/OR WARM LOWS ARE POSSIBLE. HIGHS
WILL MODERATE NEAR THE EAST COAST THEREAFTER WITH INCREASING
CLOUDS/MOISTURE BUT LOWS WILL REMAIN UNSEASONABLY WARM.
TUESDAY-WEDNESDAY SHOULD BE THE WARMEST DAYS FOR THE
CENTRAL-SOUTHERN PLAINS WITH READINGS 10-20F OR SO ABOVE NORMAL.
RAUSCH
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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