837
FXUS02 KWBC 110659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT TUE OCT 11 2022
VALID 12Z FRI OCT 14 2022 - 12Z TUE OCT 18 2022
..PATTERN OVERVIEW
A MORE ACTIVE FALL WEATHER PATTERN IS EXPECTED TO EVOLVE BY THE
END OF THIS WEEK AND CONTINUING INTO THE WEEKEND AS A COUPLE OF
COLD FRONTS ASSOCIATED WITH AN EASTERN U.S. AMPLIFYING UPPER LEVEL
TROUGH (AND EMBEDDED SHORTWAVES) MOVE ACROSS THE CENTRAL AND
EASTERN STATES. THE FIRST COLD FRONT WILL BE EXITING THE EAST
COAST BY EARLY FRIDAY WITH WIDESPREAD SHOWERS AND STORMS LIKELY
AHEAD OF IT ACROSS NEW ENGLAND, AND LAKE EFFECT PRECIPITATION
BEHIND IT. BY THIS WEEKEND, A SECOND COLD FRONT DROPPING
SOUTHWARD FROM CANADA IS EXPECTED TO REINFORCE THE COOL AIRMASS
ACROSS THE EASTERN HALF OF THE NATION AND LIKELY LASTING INTO
EARLY NEXT WEEK. THE OPPOSITE IS EXPECTED TO BE THE CASE ACROSS
THE WEST COAST REGION AS AN UPPER RIDGE BRINGS A PERIOD OF WELL
ABOVE NORMAL TEMPERATURES FROM CALIFORNIA TO THE PACIFIC NORTHWEST
AS SUMMER TRIES TO HANG ON A LITTLE LONGER
..MODEL AND PREDICTABILITY ASSESSMENT
THE 00Z MODEL GUIDANCE SUITE CONTINUES TO STRONGLY SUPPORT A DEEP
AND EXPANSIVE CLOSED LOW OVER SOUTHERN ONTARIO AND THE NORTHERN
GREAT LAKES FOR BASICALLY THE ENTIRE FORECAST PERIOD WITH MULTIPLE
SHORTWAVE PERTURBATIONS PIVOTING AROUND IT, WHICH WILL GOVERN
OVERALL FRONTAL PROGRESSION ACROSS THE CENTRAL/EASTERN STATES. AT
THE TIME OF THE FRONTS/PRESSURES COMPILATION, THE 12Z CMC WAS AN
OUTLIER SOLUTION FOR THE SUNDAY-TUESDAY TIME PERIOD BY HAVING THE
CORE OF THE UPPER LOW MUCH FARTHER SOUTH ACROSS THE OHIO VALLEY,
WHEREAS THE 00Z CMC HAS TRENDED CLOSER TO THE CONSENSUS, SO THE
12Z CMC WAS NOT USED. FOR THE CLOSED LOW OVER THE DESERT
SOUTHWEST/NORTHWESTERN MEXICO, MODEL AGREEMENT IS GOOD THROUGH
SUNDAY AS IT DRIFTS EASTWARD, ALTHOUGH THE GFS DOES TEND TO HAVE
THE LOW LINGER A LITTLE LONGER THAN THE ECMWF/CMC SOLUTIONS.
IN TERMS OF QPF, AMOUNTS WERE RAISED FROM THE NBM ACROSS THE GREAT
LAKES TO BETTER ACCOUNT FOR LAKE EFFECT PRECIP, AND A 75%
ECMWF/25% GFS BLEND WAS USED AS A STARTING POINT FOR THIS REGION,
AND ALSO ACROSS THE OHIO VALLEY TO BETTER ACCOUNT FOR LIGHTER
PRECIP NEAR THE FRONT. A SLIGHT INCREASE OF THE ENSEMBLE MEANS
WAS USED FOR THE LATTER HALF OF THE FORECAST PERIOD FOR
FRONTS/PRESSURES.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
THE FIRST STRONG COLD FRONT OF THIS SERIES AND THE ASSOCIATED
UPPER TROUGH WILL RESULT IN MODERATE TO LOCALLY HEAVY RAIN ACROSS
CENTRAL AND EASTERN NEW ENGLAND ON FRIDAY, WITH THE POTENTIAL FOR
SOME 2+ INCH TOTALS. THIS AREA WILL CONTINUE TO BE MONITORED FOR
POSSIBLE FLOOD POTENTIAL, BUT FOR NOW THE RISK APPEARS TO BE BELOW
SLIGHT RISK CRITERIA, IN PART OWING TO RECENT DRY CONDITIONS.
STRONG AND GUSTY WINDS ARE ALSO A CONCERN THERE AS THE TROUGH
BECOMES NEGATIVELY TILTED AND THE PRESSURE GRADIENT TIGHTENS.
ELSEWHERE, LAKE ENHANCED RAIN AND SNOW SHOWERS ARE LIKELY ACROSS
THE GREAT LAKES FOR THE FRIDAY THROUGH SATURDAY TIME PERIOD, AND
SHOWERS COULD BECOME MORE WIDESPREAD WITH ANOTHER FRONTAL SYSTEM
BY SUNDAY. OUT WEST, SHOWERS AND THUNDERSTORMS ARE FORECAST TO
INCREASE IN COVERAGE GOING INTO SUNDAY AND EVEN MORE SO BY MONDAY
AS MOISTURE IS ADVECTED NORTHWARD AHEAD OF THE SLOW MOVING UPPER
LOW ACROSS ARIZONA, NEW MEXICO, AND MUCH OF TEXAS.
MUCH OF THE NORTHWESTERN U.S. AND CALIFORNIA SHOULD HAVE ABOVE
NORMAL TEMPERATURES EACH DAY WITH THE UPPER RIDGE REMAINING NEARLY
ANCHORED IN PLACE NEAR THE COAST. THE OPPOSITE WILL HOLD TRUE
ACROSS THE NORTH-CENTRAL U.S. AND EXTENDING TO THE EAST COAST,
WITH HIGHS ABOUT 5-15+ DEGREES BELOW AVERAGE TO CLOSE OUT THE
WORKWEEK AND GOING INTO NEXT WEEKEND AND BEYOND, WITH HIGHS ONLY
IN THE 40S AND 50S FROM THE GREAT LAKES TO THE NORTHEAST ON MOST
DAYS.
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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