434
FXUS02 KWBC 060701
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
200 AM 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 NEXT WEEK...
..OVERVIEW
AN AMPLIFIED UPPER TROUGH OVER THE WEST COAST TO START THE PERIOD
WEDNESDAY WILL TRANSLATE INLAND OVER THE ROCKIES BY THURSDAY AND
STRENGTHENING 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 (WITH AN
INCREASING CHANCE FOR DEVELOPMENT PER THE NATIONAL HURRICANE
CENTER) OVER THE BAHAMAS/FLORIDA MAY GET WRAPPED UP INTO THE
APPROACHING TROUGH FROM THE WEST. CONFIDENCE IS INCREASING IN AT
LEAST MODEST RAINFALL SPREADING FROM PARTS OF FLORIDA UP THE EAST
COAST.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
MODELS AGREE ON THE PRESENCE OF AMPLIFIED TROUGHING OVER THE WEST
BY THE MIDDLE OF NEXT WEEK, BUT CONTINUE TO DISPLAY PLENTY OF
UNCERTAINTY REGARDING SPEED AND EVOLUTION THEREAFTER. THE 18Z/NOV
5TH GFS AND 12Z/NOV 5TH ECMWF WERE AMONG THE FIRST DETERMINISTIC
SOLUTIONS TO SUGGEST A MUCH STRONGER EVOLUTION OF AN EVENTUAL
CLOSED LOW OVER THE UPPER MIDWEST BY DAY 5/FRIDAY WHILE THE
PREVIOUS RUNS OF THE CMC AND UKMET (INCLUDING THOSE AVAILABLE AT
FORECAST GENERATION TIME) WERE MUCH FASTER AND WEAKER SHOWING JUST
AN AMPLIFIED SHORTWAVE THROUGH THE REGION. HOWEVER, THE MOST
RECENT 00Z RUNS OF THE CMC AND UKMET HAVE TRENDED MORE TOWARDS THE
GFS AND ECMWF SOLUTIONS (BOTH OF WHICH HAD SUPPORT FROM THEIR
ENSEMBLE MEANS) INCREASING CONFIDENCE IN A DEVELOPED SURFACE LOW
TRACKING FROM ABOUT THE CENTRAL PLAINS INTO THE UPPER MISSISSIPPI
VALLEY THURSDAY INTO FRIDAY, WITH SUFFICIENT COLD AIR ON THE
BACKSIDE OF THE LOW TO SUPPORT A POTENTIAL WINTER STORM ACROSS
PORTIONS OF THE NORTHERN PLAINS. AGAIN, PLENTY OF UNCERTAINTY ON
THE DETAILS AND EXACTLY WHERE ANY POTENTIAL BAND OF HEAVY SNOW MAY
FALL, BUT WITH THE MOST RECENT 00Z MODEL RUNS, CONFIDENCE IS
BEGINNING TO INCREASE IN THE POSSIBILITY.
FARTHER SOUTH, MODELS ALSO CONTINUE TO TREND TOWARDS THE POTENTIAL
FOR A TROPICAL OR SUBTROPICAL DISTURBANCE TO AFFECT FLORIDA AND
PARTS OF THE EAST COAST MID TO LATER THIS WEEK. THE NATIONAL
HURRICANE CENTER HAS UPPED THE POTENTIAL FOR DEVELOPMENT THROUGH 5
DAYS TO 80 PERCENT. MODELS GENERALLY TRACK THIS FEATURE WESTWARD
NEAR/NORTH OF THE BAHAMAS AND TOWARDS OR OVER THE FLORIDA EAST
COAST BEFORE IT COULD GET SWEPT NORTHWARD BY THE TROUGH MOVING
FROM THE CENTRAL U.S. INTO THE EAST NEXT WEEKEND. MODELS CONTINUE
TO SHOW PLENTY OF VARIABILITY REGARDING THE PHASING OF THESE
FEATURES LATER IN THE PERIOD. MONITOR THE LATEST OUTLOOKS AND
FORECASTS FROM THE NHC REGARDING POSSIBLE TROPICAL DEVELOPMENT OF
THIS SYSTEM.
THE WPC FORECAST FOR TONIGHT USED A MOSTLY DETERMINISTIC MODEL
BLEND HEAVILY WEIGHTED TOWARDS THE GFS AND ECMWF THROUGH DAY 5,
ALTHOUGH ENSEMBLE MEANS WERE INTRODUCED INTO THE BLEND ON DAY 4 A
LITTLE EARLIER THAN USUAL JUST GIVEN THE EARLY PERIOD
UNCERTAINTIES. BY 6 AND 7, FAVORED A MOSTLY ENSEMBLE MEAN BLEND TO
HELP MITIGATE THE LATE PERIOD DIFFERENCES BOTH IN THE
CENTRAL/EASTERN U.S. AS WELL AS ANOTHER SHORTWAVE/CLOSED LOW INTO
THE PAC NORTHWEST.
..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. VERY RECENT MODEL RUNS HAVE SHOWN
INCREASING POTENTIAL FOR ACCUMULATING (POSSIBLY SIGNIFICANT)
SNOWFALL ACROSS PARTS OF THE DAKOTAS AND FAR NORTHERN MINNESOTA
THURSDAY INTO FRIDAY WITH A NOTICEABLE JUMP IN THE PROBABILITIES
ON THE DAY 5 WINTER WEATHER OUTLOOK. DEPENDING ON STRENGTH OF THE
LOW, GUSTY WINDS COULD ACCOMPANY SNOWFALL LEADING TO POSSIBLE
BLIZZARD CONDITIONS. IT SHOULD BE NOTED THOUGH THAT THE SPECIFICS
OF THIS POSSIBLE SYSTEM REMAINS HIGHLY UNCERTAIN AS MODELS STILL
SHOW SOME SIGNIFICANT DIFFERENCES IN LOW PLACEMENT AND STRENGTH
WHICH LEADS TO A LOT OF VARIABILITY ON HEAVY RAIN/SNOWFALL AXES.
DESPITE THIS, THE POTENTIAL FOR A MEANINGFUL WINTER STORM OVER
PARTS OF THE NORTHERN TIER IS THERE. IN THE WARM SECTOR OF THIS
STORM, MODERATE TO HEAVY RAINFALL IS POSSIBLE ACROSS PARTS OF THE
UPPER MIDWEST/GREAT LAKES.
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 HEAVY RAIN, COASTAL FLOODING, HIGH WAVES, AND RIP
CURRENTS. MOISTURE FROM THIS SYSTEM SHOULD MOVE UP THE EAST COAST
LATER IN THE WEEK, ALTHOUGH AMOUNTS AND COVERAGE REMAIN HIGHLY
UNCERTAIN STILL.
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 TO
THE UPPER MIDWEST WITH READINGS 10-20+ 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.
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