207
FXUS02 KWBC 151919
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
218 PM EST TUE NOV 15 2022
VALID 12Z FRI NOV 18 2022 - 12Z TUE NOV 22 2022
***PERSISTENT LAKE EFFECT SNOW TO IMPACT THE SHORELINES AND
FAVORED DOWNWIND LOCATIONS, ESPECIALLY FOR LAKES ERIE AND ONTARIO
WHERE SIGNIFICANT SNOWFALL WILL BE PARTICULARLY HAZARDOUS***
***VERY COLD TEMPERATURE TO CONTINUE ACROSS MUCH OF THE NATION
THIS WEEKEND WITH WIDESPREAD SUBFREEZING MAXIMUM TEMPERATURES
EXPECTED ACROSS THE NORTH-CENTRAL STATES***
..SYNOPTIC OVERVIEW
A HIGHLY AMPLIFIED UPPER LEVEL FLOW PATTERN WILL BE IN PLACE
ACROSS THE COUNTRY FOR THE END OF THE WORK WEEK WITH A DEEP TROUGH
EXTENDING FROM HUDSON BAY TO THE MIDWEST STATES. AN ARCTIC FRONT
IS PROGGED TO REINFORCE THE ALREADY VERY COLD AIRMASS THAT WILL BE
IN PLACE ACROSS THE NORTH-CENTRAL U.S. THAT IS FORECAST TO REACH
THE EAST COAST IN TIME FOR THE WEEKEND. THIS TROUGH AND
ACCOMPANYING JANUARY-LIKE TEMPERATURES WILL LIKELY HAVE SOME
STAYING POWER UNTIL EARLY NEXT WEEK, WHEN THERE ARE SIGNS OF A
PATTERN CHANGE EMERGING. THE DEEP TROUGH WILL LIKELY BEGIN
LIFTING OUT AS A MORE ZONAL FLOW PATTERN COMMENCES ACROSS MUCH OF
THE COUNTRY. OUT WEST, A PACIFIC STORM SYSTEM WILL LIKELY MOVE
INLAND AS THE UPPER RIDGE AXIS DECAYS BY SUNDAY AND INTO MONDAY.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE GLOBAL GUIDANCE AND THEIR ENSEMBLE MEANS ARE IN VERY GOOD
AGREEMENT WITH THE BROAD UPPER-LEVEL TROUGH THAT WILL BE TRACKING
THROUGH THE CENTRAL AND EASTERN STATES WILL ABOVE AVERAGE
CONFIDENCE THROUGH MUCH OF THE EXTENDED PERIOD. MULTIPLE SURGES OF
COLD AIR WILL REINFORCE THE BELOW SEASONAL AVERAGE TEMPERATURES
AND KEEP LAKE ENHANCED PRECIPITATION TO THE GREAT LAKES REGION AND
SURROUNDING LOCATIONS. THE MODELS ALSO AGREE WELL ON SAID TROUGH
LIFTING OUT STARTING MONDAY AND HERALDING A PATTERN CHANGE. THE
GREATEST MODEL DIFFERENCES ARE APPARENT ACROSS THE WESTERN U.S.
GOING INTO EARLY NEXT WEEK AS A PACIFIC SHORTWAVE APPROACHES THE
CENTRAL-NORTHERN WEST COAST REGION. THE CMC IS CONSIDERABLY
WEAKER THAN THE GFS/ECMWF FOR THE SYSTEM REACHING THE COAST
MONDAY, ALTHOUGH THE CMC SHOWS A STRONGER SHORTWAVE FOLLOWING
BEHIND IT THAT IS NOT REFLECTED MUCH IN THE OTHER GUIDANCE.
THE WPC FORECAST WAS PRIMARILY BASED ON A MULTI-DETERMINISTIC
MODEL BLEND THROUGH THE WEEKEND, WITH A GRADUAL INCREASE IN USE OF
THE EC AND GEFS MEANS GOING INTO THE FIRST PART OF THE WEEK. FOR
THE QPF FORECAST, PARTICULARLY IN THE VICINITY OF THE GREAT LAKES,
THE NBM 4.0 SOLUTION WAS TOO LIGHT GIVEN THE SETUP FOR THE LAKE
ENHANCED PRECIPITATION, SO TRENDED MORE TOWARD THE CMC REGIONAL
AND ECWMF TO INCREASE VALUES.
..WEATHER/HAZARD HIGHLIGHTS
CHILLY AIR WILL BE IN PLACE FOR A LARGE PORTION OF NATION THROUGH
THE WEEKEND AND INTO THE UPCOMING WEEK. SOME OF THE COLDEST AIR
WILL BE CENTERED OVER THE NORTH-CENTRAL U.S. WHERE THE DAILY
MAXIMUMS WILL STRUGGLE TO REACH THE 10S AND OVERNIGHT LOWS -/+ 5
DEGREES FROM ZERO. SOME RECORD LOW TEMPERATURES ARE ALSO POSSIBLE
ACROSS PORTIONS OF THE NORTHERN PLAINS AND MIDWEST, AND SOME
RECORD LOW MAXIMUMS ARE ALSO POSSIBLE ACROSS PORTIONS OF THE
CENTRAL PLAINS TO THE UPPER MIDWEST BEHIND THE NEXT SURGE OF
ARCTIC AIR. CHILLY TEMPERATURES WILL ALSO REACH THE GULF COAST
AND EVEN MUCH OF THE FLORIDA PENINSULA FOR AT LEAST THE FIRST HALF
OF THE FORECAST PERIOD, WITH HIGHS GENERALLY RUNNING 5 TO 15
DEGREES BELOW MID-NOVEMBER AVERAGES. TEMPERATURES WILL TREND LESS
COLD AS THE DEEP UPPER TROUGH BEGINS LIFTING OUT WITH A MORE
ZONAL FLOW EVOLVING.
IN TERMS OF PRECIPITATION, MUCH OF THE NATION SHOULD BE RELATIVELY
DRY AS A SPRAWLING SURFACE HIGH GOVERNS THE OVERALL WEATHER
PATTERN. LAKE EFFECT SNOW IS LIKELY TO BE PERSISTENT DOWNWIND OF
THE GREAT LAKES THROUGH SUNDAY OWING TO STRONG COLD AIR ADVECTION
OVER THE WARMER WATERS, WITH THE HEAVIEST SNOW EXPECTED EAST OF
LAKE ERIE AND LAKE ONTARIO WHERE OVER A FOOT OF ACCUMULATION IS
POSSIBLE. THIS EARLY SEASON, HEAVY AND WET SNOW MAY LED TO VERY
HAZARDOUS TRAVELING CONDITIONS AND POTENTIALLY HAVE SIGNIFICANT
IMPACTS TO STRUCTURES, TREES AND POWER LINES. SHOWERS AND MOUNTAIN
SNOW ARE LIKELY TO MAKE A RETURN TO THE WEST COAST STATES EARLY
NEXT WEEK AS THE PACIFIC STORM SYSTEM MOVES INLAND.
CAMPBELL/HAMRICK
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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