182
FXUS02 KWBC 070711
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
211 AM EST MON NOV 07 2022
VALID 12Z THU NOV 10 2022 - 12Z MON NOV 14 2022
...POTENTIALLY SIGNIFICANT WINTER STORM LIKELY FOR THE NORTHERN
PLAINS ON THURSDAY...
...TROPICAL DISTURBANCE WILL LIKELY BRING HEAVY RAINFALL FROM
FLORIDA TO THE MID-ATLANTIC LATER THIS WEEK/WEEKEND...
..OVERVIEW
AN AMPLIFIED UPPER TROUGH OVER THE WEST TO START THE PERIOD
THURSDAY IS FORECAST TO DEVELOP INTO A CLOSED LOW OVER THE UPPER
MIDWEST/GREAT LAKES BY EARLY FRIDAY. CONFIDENCE CONTINUES TO
INCREASE FOR A POTENTIALLY SIGNIFICANT WINTER STORM TO DEVELOP
OVER PARTS OF THE NORTHERN PLAINS WITH LIKELY APPRECIABLE
ACCUMULATING SNOWFALL THURSDAY INTO FRIDAY, THOUGH STILL PLENTY OF
UNCERTAINTY ON THE SPECIFICS. MEANWHILE, UPPER LEVEL RIDGING WILL
CONTINUE THURSDAY INTO FRIDAY ACROSS PARTS OF THE EASTERN U.S.
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. THIS SYSTEM
LIKELY WILL BRING WIDESPREAD HEAVY RAINFALL TO PARTS OF FLORIDA
AND SPREADING UP THE EASTERN SEABOARD FRIDAY AND SATURDAY.
..GUIDANCE AND PREDICTABILITY ASSESSMENT
THE MAJORITY OF THE MODELS ARE NOW IN AGREEMENT ON AMPLIFIED
TROUGHING OVER THE WEST BECOMING A WELL DEVELOPED CLOSED UPPER LOW
BY EARLY FRIDAY OVER THE UPPER MIDWEST. THERE IS STILL PLENTY OF
LINGERING UNCERTAINTY THOUGH ON THE EXACT TRACK OF THE ASSOCIATED
SURFACE LOW AND THUS THE POSITIONING OF THE HEAVIEST WINTRY
PRECIPITATION IN THE COLD SECTOR ON THE BACKSIDE OF THE LOW.
COMPARED TO PREVIOUS SHIFT, WPC STAYED PRETTY CLOSE TO CONTINUITY
UNTIL BETTER TRENDS NORTH OR SOUTH BECOME MORE APPARENT. OVERALL
THOUGH, CONFIDENCE IS INCREASING FOR A HIGH IMPACT TO POTENTIALLY
SIGNFIICANT WINTER STORM, BUT THE DETAILS ON PLACEMENT AND TIMING
REMAIN MUCH MORE UNCERTAIN AND ARE LIKELY TO CONTINUE TO SHIFT
SLIGHTLY OVER THE NEXT COUPLE OF DAYS AS THIS EVENT MOVES INTO THE
SHORT RANGE PERIOD. WPC GENERALLY LEANED MORE TOWARDS THE BETTER
CLUSTERED GFS, ECMWF, AND UKMET, AS THE CMC WAS A LITTLE MORE
EAST/QUICKER WITH THE SYSTEM THAN CONSENSUS.
FARTHER SOUTH, THE NHC CONTINUES TO SHOW HIGH LIKELYHOOD ON THE
FORMATION OF A TROPICAL OR SUBTROPICAL STORM REACHING THE EAST
COAST OF FLORIDA BY EARLY THURSDAY. THE GUIDANCE IN THE MEDIUM
RANGE PERIOD GENERALLY TRACK THIS SYSTEM ACROSS CENTRAL/NORTHERN
FLORIDA BEFORE IT EVENTUALLY GETS PICKED UP BY THE MIDLATITUDE
TROUGH AND ACCELERATES UP THE EASTERN SEABOARD. WHILE THERE IS
GOOD AGREEMENT ON THIS OVERALL TRACK, THE TIMING CONTINUES TO BE
HIGHLY UNCERTAIN WITH SOME MODELS SHOWING A QUICKER PHASING AND
TRANSITION UP THE COAST, AND SOME WANTING TO BRING IT MORE INTO
FLORIDA AND POSSIBLY THE EASTERN GULF BEFORE MOVING NORTHWARD. A
MIDDLE GROUND SOLUTION IS PREFERRED AT THIS POINT, MOST CLOSE TO
THE DETERMINISTIC ECMWF.
FINALLY, OUT WEST, RIDGING SHOULD BUILD IN BEHIND THE TROUGH BY
FRIDAY, BUT A LOT OF UNCERTAINTY THEREAFTER ON THE NEXT SYSTEM
INTO THE NORTHWEST WITH SOME GUIDANCE SUGGESTING A CLOSED LOW
OVER/NEAR THE PACIFIC NORTHWEST COAST EARLY NEXT WEEK. THE WPC
FORECAST TRENDED QUICKLY TOWARDS THE ENSEMBLE MEANS LATE PERIOD TO
ACCOUNT FOR THE UNCERTAINTIES.
..WEATHER/HAZARD HIGHLIGHTS
A WELL DEFINED SURFACE LOW LOOKS TO EMERGE OUT OF THE CENTRAL HIGH
PLAINS ON THURSDAY 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 4 CONTINUE TO INCREASE, WITH WIDESPREAD GREATER THAN 70%
PROBABILITIES FROM NORTHERN SOUTH DAKOTA INTO FAR NORTHERN
MINNESOTA. DEPENDING ON STRENGTH OF THE LOW, GUSTY WINDS COULD
ACCOMPANY SNOWFALL AND LEAD TO POSSIBLE BLIZZARD CONDITIONS AND
DANGEROUS TRAVEL. 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 AXIS 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 AND INTO THE GREAT
LAKES, WITH A CHANCE FOR STRONG THUNDERSTORMS AS WELL.
ADDITIONALLY, THERE COULD BE AN AXIS OF FREEZING RAIN AND/OR SLEET
BETWEEN THE SNOW AND RAIN THOUGH PLACEMENT IS STILL VERY UNCERTAIN.
COASTAL AND MARITIME IMPACTS, INCLUDING COASTAL FLOODING,
TROPICAL-STORM-FORCE WINDS, HEAVY RAINFALL, ROUGH SURF, AND BEACH
EROSION ARE POSSIBLE ASSOCIATED WITH THE TROPICAL DISTURBANCE
NEAR/OVER FLORIDA AND THE SOUTHEAST. SLIGHT RISKS ARE ON BOTH THE
DAY 4 AND 5 EXPERIMENTAL EXCESSIVE RAINFALL OUTLOOKS FROM
FLORIDA/THE SOUTHEAST COAST (DAY 4) AND INTO THE EASTERN CAROLINAS
(DAY 5) TO SHOW THE POTENTIAL FOR FLASH FLOODING FROM TROPICAL
RAINS. THE AREA MAY HAVE TO SHIFT OR BE UPGRADED IN FUTURE
FORECASTS DEPENDING ON RAINFALL AMOUNTS AND THE TRACK OF THE
TROPICAL SYSTEM. MOISTURE FROM THIS SYSTEM SHOULD MOVE UP MUCH OF
THE EAST COAST INTO THE WEEKEND THOUGH WITH MORE UNCERTAINTY IN
THE AMOUNTS AND COVERAGE.
TEMPERATURES OVER THE ROCKIES AND GREAT BASIN SHOULD FINALLY BEGIN
TO MODERATE SOME BY FRIDAY, BUT STILL REMAINING BELOW NORMAL. THE
COLDEST AIR WILL LIKELY BE ACROSS THE NORTHERN HIGH PLAINS AND
PLAINS AS THE PERIOD STARTS WITH RECENT FORECASTS SHOWING HIGHS IN
THAT AREA UP TO 20-30F BELOW NORMAL THROUGH THE UPCOMING WEEKEND.
IN CONTRAST, WELL ABOVE NORMAL TEMPERATURES WILL PROGRESS FROM THE
MIDWEST TO THE EAST COAST THURSDAY-FRIDAY WITH WIDESPREAD DAILY
RECORDS FOR WARM LOWS POSSIBLE AND A HANDFUL OF RECORD HIGHS AS
READINGS SOAR 15 TO 25 DEGREES ABOVE NORMAL. A STRONG COLD FRONT
THROUGH THIS REGION LATE THIS WEEK WILL USHER IN A MUCH COLDER
AIRMASS, WITH HIGH TEMPERATURES BY THE WEEKEND IN THE MIDWEST AS
MUCH AS 10 TO 20 DEGREES BELOW NORMAL. THE COOLER TEMPERATURES
WILL ALSO REACH THE EAST THIS WEEKEND, AND SUNDAY TO MONDAY LOOKS
TO BE NEAR OR BELOW NORMAL FOR ALMOST THE ENTIRE CONUS.
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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