440
FXUS02 KWBC 101859
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
158 PM EST THU NOV 10 2022
VALID 12Z SUN NOV 13 2022 - 12Z THU NOV 17 2022
..OVERVIEW
AN AMPLIFIED UPPER TROUGH OVER THE EAST ON SUNDAY SHOULD LIFT OUT
BY MONDAY WITH SOME WEAK RIDGING RETURNING EARLY NEXT WEEK OVER
THE FAR SOUTHEAST/BAHAMAS. MEANWHILE, A STRONG AND BLOCKY RIDGE
OVER THE EASTERN PACIFIC WILL FAVOR CYCLONIC MEAN FLOW ALOFT
ACROSS MOST OF THE LOWER 48 DURING THE PERIOD, WITH EMBEDDED
SHORTWAVES/UPPER LOWS DROPPING INTO THE CONUS. THIS PATTERN
SHOULD LEAD TO BELOW NORMAL TEMPERATURES OVER MUCH OF THE COUNTRY
THROUGH NEXT THURSDAY AND LIKELY BEYOND. CONFIDENCE IN EMBEDDED
DETAILS IS STILL ON THE LOWER SIDE, WITH PARTICULAR FOCUS ON AN
UPPER SHORTWAVE/SURFACE SYSTEM THAT COULD SPREAD PRECIPITATION OF
VARYING TYPES OVER PARTS OF THE CENTRAL/EASTERN U.S. IN THE
EARLY-MID WEEK TIME FRAME. OTHER AREAS OF PRECIPITATION WILL ALSO
BE POSSIBLE OVER PARTS OF THE NORTHERN TIER, ROCKIES, AND LATE IN
THE PERIOD OVER THE SOUTHERN TIER.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THERE CONTINUES TO BE FAIRLY HIGH CONFIDENCE/PREDICTABILITY FOR
THE LARGE SCALE PATTERN, BUT WITH LOWER CONFIDENCE IN THE EMBEDDED
SMALLER SCALE FEATURES THAT HAVE LOWER PREDICTABILITY. OVER
RECENT DAYS GUIDANCE HAS VARIED FOR HOW MUCH INTERACTION MAY OCCUR
BETWEEN A TROUGH/UPPER LOW REACHING THE NORTHERN TIER BY SUNDAY
AND THE UPPER LOW FORECAST TO TRACK FROM THE GREAT BASIN THROUGH
SOUTHERN ROCKIES/HIGH PLAINS SUNDAY-MONDAY. SPORADIC GFS/ECMWF
RUNS HAVE BEEN PHASING THE TWO, LEADING TO A MORE INLAND SURFACE
EVOLUTION OVER THE EAST BY TUESDAY-WEDNESDAY. ON THE OTHER HAND
THE CMC, REMAINING GFS/ECMWF RUNS, AND THE ENSEMBLE MEANS HAVE
BEEN KEEPING THE TWO FEATURES SEPARATE. THAT MAJORITY SCENARIO
YIELDS LOW PRESSURE ALONG THE EAST COAST BY WEDNESDAY (BUT STILL
THE POSSIBILITY OF A WEAK SURFACE REFLECTION OVER THE GREAT LAKES
IN RESPONSE TO THE NORTHERN STREAM DYNAMICS). LATEST GFS RUNS
HAVE ACTUALLY SWITCHED TO THE MOST SUPPRESSED SIDE OF THE ENVELOPE
FOR THE EAST COAST SURFACE PATTERN. PREFERENCE SIDED WITH THE
MAJORITY CLUSTER, ESSENTIALLY A SLIGHTLY WEAKER VERSION OF THE 00Z
ECMWF, AS SOLUTIONS DIVERGE AFTER EARLY TUESDAY. THIS MAINTAINS
GOOD CONTINUITY.
THE NEXT FEATURE OF INTEREST IS A TROUGH/POSSIBLE EMBEDDED LOW
DROPPING SOUTHWARD THROUGH THE WEST DURING EARLY-MID WEEK. A FAIR
AMOUNT OF DETAIL SPREAD DEVELOPS ALREADY BY MONDAY WITH
DIFFERENCES CONTINUING ONWARD WITH TIME. THE 00Z ECMWF OFFERED
THE MOST NOTABLE DIFFERENCE FROM MOST OTHER GUIDANCE, SHOWING LESS
SOUTHWESTWARD AMPLITUDE VERSUS OTHER MODELS AND ENSEMBLE MEANS
(INCLUDING THE ECENS), DUE TO THE MODEL PULLING OFF AN UPPER LOW
THAT STAYS JUST OFF THE WEST COAST FOR MULTIPLE DAYS. BY DAY 7
THURSDAY THIS DIFFERENCE LEADS THE 00Z ECMWF TO BE MUCH DRIER
ACROSS THE SOUTHERN TIER THAN MOST OTHER MODELS AND MEANS. THE
NEW 12Z ECMWF HAS TRENDED SOMEWHAT CLOSER TO CONSENSUS. ALSO BY
NEXT THURSDAY THE MODELS/MEANS SUGGEST ANOTHER EAST-WEST ORIENTED
SHORTWAVE MAY REACH DOWN CLOSE TO THE WESTERN U.S.-CANADIAN
BORDER. A MODEL-MEAN BLEND IS REASONABLE TO DEPICT THIS FEATURE
WHILE ACCOUNTING FOR DETAIL UNCERTAINTY.
THIS CYCLE'S CONSIDERATION OF 00Z/06Z GUIDANCE LED TO STARTING THE
UPDATED FORECAST WITH A 00Z/06Z MODEL COMPOSITE (06Z GFS FAVORED
OVER THE 00Z RUN) EARLY IN THE FORECAST AND THEN TRANSITIONING TO
A COMBINATION OF OPERATIONAL MODELS AND MEANS (06Z GEFS/00Z ECENS
AND CMCENS). 00Z ECMWF QUESTION MARKS OVER THE WEST AFTER EARLY
DAY 3 LED TO LOWER WEIGHT OF ITS SOLUTION THAN WOULD SOMETIMES BE
THE CASE. IN ADDITION TO THE EASTERN U.S. PATTERN NEXT WEEK, THE
PREFERRED SOLUTION ALSO PROVIDED GOOD CONTINUITY WITH MOST OTHER
ASPECTS OF THE FORECAST.
..WEATHER/HAZARD HIGHLIGHTS
AN UPPER TROUGH CROSSING THE EAST ALONG WITH COOL LOW LEVEL
CYCLONIC FLOW WILL SUPPORT SOME LAKE EFFECT SNOW WITHIN THE
TYPICAL SNOW BELTS OVER THE UPPER AND LOWER GREAT LAKES EARLY IN
THE WEEK. THE UPPER LOW TRACKING FROM THE GREAT BASIN INTO THE
SOUTHERN ROCKIES SUNDAY-EARLY MONDAY MAY PRODUCE SCATTERED LIGHT
PRECIPITATION. THIS FEATURE SHOULD THEN OPEN UP BUT ITS CONTINUED
PROGRESSION MAY PROMOTE SOME SURFACE WAVINESS FROM THE GULF COAST
TO EAST COAST, WITH AN AREA OF PRECIPITATION EXTENDING FROM THE
SOUTHERN HALF OF THE PLAINS THROUGH PORTIONS OF THE EAST. RAIN
COULD BE LOCALLY HEAVY ALONG THE WEST-CENTRAL/CENTRAL GULF COAST
AND IT WILL BE POSSIBLE FOR SOME WINTRY PRECIPITATION TO FALL IN
THE NORTHERN FRINGE OF THE MOISTURE SHIELD. CONFIDENCE REMAINS
BELOW AVERAGE FOR THE SPECIFICS OF PRECIPITATION COVERAGE,
INTENSITY, AND TYPE. TRAILING ENERGY DROPPING THROUGH THE WEST
MAY PUSH ONE OR MORE AREAS OF MOSTLY LIGHT SNOW SOUTHWARD OVER THE
ROCKIES/HIGH PLAINS. TOWARD NEXT THURSDAY ENOUGH OF THIS ENERGY
MAY EMERGE FROM THE WEST TO SUPPORT INCREASING PRECIPITATION OVER
THE SOUTHEAST QUADRANT OF THE LOWER 48. NORTHERN TIER DYNAMICS
MAY ALSO GENERATE AREAS OF LIGHT SNOW BETWEEN THE PLAINS AND GREAT
LAKES.
BROAD UPPER TROUGHING IN RESPONSE TO THE STRONG RIDGE OFFSHORE THE
WEST COAST SHOULD KEEP A COLD PATTERN IN PLACE SUNDAY-THURSDAY,
AND LIKELY BEYOND PER THE CLIMATE PREDICTION CENTER 8-14 DAY
FORECAST. THE COLDEST AIR RELATIVE TO NORMAL SHOULD BE OVER PARTS
OF THE GREAT BASIN AND PLAINS WHERE MULTIPLE DAYS WITH HIGHS
15-25F BELOW NORMAL ARE LIKELY. OVER THE PLAINS, NORTHERN
LOCATIONS WILL BE MOST CONSISTENTLY COLD FROM THE START OF THE
PERIOD WHILE CENTRAL/SOUTHERN AREAS WILL SEE THE COLDEST ANOMALIES
SETTLE IN MONDAY ONWARD. MAINE, FLORIDA, AND THE PACIFIC
NORTHWEST COAST HAVE THE BEST CHANCE TO BE THE EXCEPTIONS WITH
NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES.
RAUSCH/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, 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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