340
FXUS02 KWBC 061913
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
212 PM EST SUN NOV 06 2022
VALID 12Z WED NOV 09 2022 - 12Z SUN NOV 13 2022
...HEAVY SNOW OVER THE WEST ON WEDNESDAY, WITH AN INCREASING
WINTER STORM THREAT IN THE NORTHERN PLAINS ON THURSDAY...
...TROPICAL DISTURBANCE COULD BRING HEAVY RAINFALL TO PARTS OF
FLORIDA AND THE SOUTHEAST MID TO LATE WEEK...
..OVERVIEW
AN AMPLIFIED UPPER TROUGH OVER THE WEST COAST TO START THE PERIOD
WEDNESDAY WILL TRANSLATE INLAND OVER THE ROCKIES BY THURSDAY AND
STRENGTHEN INTO A POSSIBLE CLOSED LOW OVER THE UPPER MIDWEST/GREAT
LAKES BY EARLY FRIDAY. THERE IS AN INCREASING THREAT FOR A WINTER
STORM TO DEVELOP OVER PARTS OF THE NORTHERN PLAINS WITH POSSIBLY
APPRECIABLE ACCUMULATING SNOWFALL THURSDAY INTO FRIDAY, THOUGH
STILL PLENTY OF UNCERTAINTY ON THE SPECIFICS. MEANWHILE, UPPER
LEVEL RIDGING WILL PREVAIL ACROSS THE EASTERN U.S. THROUGH ABOUT
THURSDAY BEFORE A TROPICAL DISTURBANCE (THAT REMAINS QUITE LIKELY
TO DEVELOP INTO A SUBTROPICAL OR TROPICAL STORM PER THE NATIONAL
HURRICANE CENTER) OVER THE BAHAMAS/FLORIDA IS LIKELY TO GET
WRAPPED UP INTO THE APPROACHING TROUGH FROM THE WEST. MODERATE TO
HEAVY RAINFALL IS EXPECTED FOR FLORIDA AND SHOULD SPREAD UP THE
EASTERN SEABOARD DURING THE LATTER HALF OF THE WEEK.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MODELS AGREE ON THE PRESENCE OF AMPLIFIED TROUGHING OVER THE WEST
BY THE MIDDLE OF NEXT WEEK AND THAT IT SHOULD HAVE A GENERAL TRACK
EASTWARD, WITH A TREND OVER THE PAST DAY OR SO TOWARD AN UPPER LOW
CLOSING OFF IN THE MIDWEST BY FRIDAY ESPECIALLY AMONG THE GFS AND
ECMWF RUNS. THE WPC FORECAST CONTINUED TO INDICATE THIS CLOSED
LOW. MORE UNCERTAIN IS THE EXACT TRACK OF THE ASSOCIATED SURFACE
LOW AND THUS THE POSITIONING OF THE HEAVIEST WINTRY PRECIPITATION
IN THE COLD AIR ON THE BACKSIDE OF THE LOW. THE 00/06Z
MODEL/ENSEMBLES SEEMED TO HAVE A BIT OF A TREND SOUTH COMPARED TO
THE PREVIOUS FORECAST AND THE WPC FRONTS/PRESSURES PLOTS REFLECTED
THIS, AS DID THE QPF (LESS PRECIPITATION FROM NORTH DAKOTA TO
NORTHERN MINNESOTA AND MORE PRECIPITATION FROM SOUTH DAKOTA TO
SOUTHERN MINNESOTA. THESE ARE SOMEWHAT MINOR CHANGES FOR THE
MEDIUM RANGE TIMEFRAME BUT COULD HAVE CONSIDERABLE IMPACTS.
OVERALL CONFIDENCE CONTINUES TO INCREASE FOR A WINTER STORM, BUT
THE PLACEMENT AND TIMING MAY CONTINUE TO SHIFT.
FARTHER SOUTH, MODELS ALSO CONTINUE TO TREND TOWARDS THE POTENTIAL
FOR A TROPICAL OR SUBTROPICAL STORM TO FORM LIKELY IN THE NEXT
COUPLE OF DAYS PER THE NATIONAL HURRICANE CENTER. MODELS GENERALLY
TRACK THIS FEATURE WESTWARD POTENTIALLY OVER THE NORTHERN BAHAMAS
AND INTO AT LEAST EASTERN FLORIDA. MODELS/ENSEMBLE MEMBERS DIVERGE
NOTABLY AFTER THAT. MOST SHOW THE TROPICAL SYSTEM ACCELERATING
NORTHEASTWARD NEAR THE EASTERN SEABOARD AS IT GETS PICKED UP BY
THE MIDLATITUDE TROUGH. BUT SOME (MAINLY GFS RUNS AND GEFS
MEMBERS) SHOW THE FEATURE LINGERING OVER FLORIDA FOR LONGER,
TRACKING IT WEST AND POTENTIALLY EVEN INTO THE EASTERN GULF. SO
ITS TRACK REMAINS UNCERTAIN AT THIS POINT WITH PHASING
DIFFERENCES. MONITOR THE LATEST OUTLOOKS AND FORECASTS FROM THE
NHC REGARDING POSSIBLE TROPICAL DEVELOPMENT OF THIS SYSTEM.
UPSTREAM, A BRIEF PERIOD OF RIDGING IS FORECAST FOR THE WEST
BEHIND THE MAIN TROUGH LATE THIS WORKWEEK, BUT THERE IS SOME
UNCERTAINTY WITH THE TIMING OF ANOTHER TROUGH/POSSIBLE ELONGATED
UPPER LOW APPROACHING THIS WEEKEND.
THE UPDATED WPC FORECAST UTILIZED A BLEND OF THE 00Z/06Z
DETERMINISTIC MODELS LED BY THE GFS AND ECMWF THROUGH DAY 5,
ATTEMPTING TO MAINTAIN SOME STRENGTH OF SYSTEMS LIKE THE
UPPER/SURFACE LOWS IN THE MIDWEST, AND GOING FOR MIDDLE GROUND
POSITIONS. INTRODUCED AND INCREASED THE PROPORTION OF THE GEFS AND
EC ENSEMBLE MEANS ON DAYS 6-7 GIVEN INCREASING LARGE SCALE
UNCERTAINTIES.
..WEATHER/HAZARD HIGHLIGHTS
HEAVY MOUNTAIN SNOW AND VALLEY RAIN WILL BE ONGOING ACROSS PARTS
THE WEST ON WEDNESDAY, WITH THE HEAVIEST TOTALS ACROSS THE HIGHER
TERRAIN OF THE GREAT BASIN. AS THE TROUGH MOVES INLAND AND
STRENGTHENS, A DEFINED SURFACE LOW LOOKS TO EMERGE OUT OF THE
CENTRAL HIGH PLAINS DEEPENING AS IT MOVES INTO THE UPPER
MISSISSIPPI VALLEY BY FRIDAY. WITH MODEL RUNS CONTINUING TO SHOW
THE POTENTIAL FOR ACCUMULATING AND POSSIBLY SIGNIFICANT SNOWFALL
ACROSS PARTS OF THE DAKOTAS AND FAR NORTHERN MINNESOTA THURSDAY
INTO FRIDAY, THE PROBABILITIES IN THE WINTER WEATHER OUTLOOK FOR
DAY 5 CONTINUE TO INCREASE, AND FOCUS A LITTLE FARTHER SOUTH GIVEN
THE RECENT MODEL TRENDS. DEPENDING ON STRENGTH OF THE LOW, GUSTY
WINDS COULD ACCOMPANY SNOWFALL AND LEAD TO POSSIBLE BLIZZARD
CONDITIONS. AGAIN, WHILE A MEANINGFUL WINTER STORM OVER PARTS OF
THE NORTHERN TIER CONTINUES TO BECOME MORE LIKELY, THE SPECIFICS
IN THE PLACEMENT OF THE HEAVIEST SNOW REMAIN IN QUESTION AND ARE
DEPENDENT ON THE LOW PLACEMENT AND STRENGTH. IN THE WARM SECTOR OF
THIS STORM, MODERATE TO HEAVY RAINFALL IS POSSIBLE ACROSS PARTS OF
THE UPPER MIDWEST/GREAT LAKES. ADDITIONALLY, THERE COULD BE AN
AXIS OF FREEZING RAIN AND/OR SLEET BETWEEN THE SNOW AND RAIN WHERE
TEMPERATURES AT THE SURFACE AND ALOFT SUPPORT IT, BUT THE
PLACEMENT REMAINS UNCERTAIN.
DESPITE PLENTY OF UNCERTAINTY IN THE DETAILS STILL, THE TROPICAL
DISTURBANCE MOVING TOWARDS FLORIDA LATER THIS WEEK CONTINUES TO
SHOW AN INCREASING THREAT FOR COASTAL AND MARITIME IMPACTS,
INCLUDING COASTAL FLOODING, TROPICAL-STORM-FORCE WINDS, HEAVY
RAINFALL, ROUGH SURF, AND BEACH EROSION. A SLIGHT RISK OF
EXCESSIVE RAINFALL WAS ADDED TO THE DAY 5 EXPERIMENTAL EXCESSIVE
RAINFALL OUTLOOK FOR THIS FORECAST TO SHOW THE POTENTIAL FOR FLASH
FLOODING WITH THE HEAVY RAIN. THE AREA MAY HAVE TO SHIFT IN FUTURE
FORECASTS DEPENDING ON THE TRACK OF THE TROPICAL SYSTEM. MOISTURE
FROM THIS SYSTEM SHOULD MOVE UP THE EAST COAST LATER THIS WEEK.
AMOUNTS AND COVERAGE REMAIN UNCERTAIN. BUT IN THIS FORECAST, THERE
HAPPENED TO BE GOOD MODEL AGREEMENT FOR HEAVIER RAIN TO COME
ONSHORE IN THE CAROLINAS, MID-ATLANTIC, AND NORTHEAST, SO THE
FORECAST REFLECTED HIGHER AMOUNTS ALONG THE EASTERN SEABOARD.
MUCH BELOW NORMAL TEMPERATURES ARE EXPECTED TO EXPAND ACROSS THE
WEST THROUGH THE LATTER PART OF THIS WEEK ASSOCIATED WITH THE
DEEPENING UPPER TROUGH. THE COLDEST AIR WILL LIKELY BE ACROSS THE
NORTHERN HIGH PLAINS AND PLAINS WITH RECENT FORECASTS SHOWING
HIGHS IN THAT AREA UP TO 20-30F BELOW NORMAL WEDNESDAY-FRIDAY.
MANY LOCATIONS OVER THE WEST COULD SEE DAILY RECORDS FOR COLD
HIGHS THROUGH WEDNESDAY. IN CONTRAST, WELL ABOVE NORMAL
TEMPERATURES WILL PROGRESS FROM THE CENTRAL PLAINS TO THE EAST
COAST WED-FRI WITH WIDESPREAD DAILY RECORDS FOR WARM LOWS
POSSIBLE. WEDNESDAY SHOULD BE THE WARMEST DAY FOR THE PLAINS AND
THURSDAY SHOULD BE FOR THE UPPER MIDWEST WITH READINGS 15-25F
ABOVE NORMAL. A STRONG COLD FRONT THROUGH THIS REGION BY THURSDAY
WILL USHER IN A MUCH COLDER AIRMASS, WITH HIGH TEMPERATURES BY
FRIDAY AND THE WEEKEND IN THE PLAINS AND MIDWEST AS MUCH AS 10 TO
20 DEGREES BELOW NORMAL. THE COOLER TEMPERATURES WILL REACH THE
EAST THIS WEEKEND, AND SUNDAY LOOKS TO BE NEAR OR BELOW NORMAL FOR
ALMOST THE ENTIRE CONUS.
TATE/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
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page