915
FXUS02 KWBC 070654
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
253 AM EDT FRI OCT 7 2022
VALID 12Z MON OCT 10 2022 - 12Z FRI OCT 14 2022
..GENERAL PATTERN OVERVIEW
AN ANOMALOUS MID-UPPER RIDGE AXIS ACROSS THE EASTERN PACIFIC AND
GULF OF ALASKA IS EXPECTED TO BE NEARLY ANCHORED IN PLACE FOR MUCH
OF NEXT WEEK, AND THIS WILL TEND TO RESULT IN AN AMPLIFYING
DOWNSTREAM TROUGH OVER CENTRAL CANADA AND INTO THE NORTH-CENTRAL
U.S. GOING INTO THE MIDDLE OF THE WEEK. THIS WILL HELP REINFORCE
THE AUTUMNAL AIRMASS ACROSS MUCH OF THE EASTERN U.S., WHILE STILL
REMAINING MILD TO WARM ACROSS THE NORTHWESTERN U.S. AND THE
SOUTHERN TIER STATES.
..MODEL AND PREDICTABILITY ASSESSMENT
IN TERMS OF THE BUILDING NORTHERN STREAM UPPER TROUGH FOR THE
MIDDLE OF NEXT WEEK, THERE HAS BEEN A DEFINITIVE TREND OVER THE
PAST 36 HOURS FOR LESS OF A CUT-OFF LOW DEVELOPING OVER THE
INTERMOUNTAIN WEST AND THE MAIN TROUGH AXIS DEVELOPING OVER THE
NORTH-CENTRAL U.S. WITH A POSITIVELY TILTED TROUGH EXTENDING
SOUTHWEST FROM IT. THE ECMWF AND GFS, ALONG WITH THE JMA, HAVE
TRENDED IN THIS DIRECTION, WHEREAS BOTH THE 12Z/00Z CMC CONTINUES
TO SHOW THE UPPER LOW BREAKING AWAY ACROSS THE INTERMOUNTAIN WEST
WITH NOT MUCH IN THE WAY OF SUPPORT FROM THE ENSEMBLE MEANS. THE
ECMWF IS FASTER IN TAKING THE COLD FRONT TOWARDS THE EAST COAST BY
THE END OF THE WEEK, COMPARED TO THE GFS. TELECONNECTIONS WITH
THE POSITIVE HEIGHT ANOMALY OVER THE GULF OF ALASKA AND THE
NEGATIVE HEIGHT ANOMALY NORTH OF HAWAII SUGGEST A NON-CMC
SOLUTION, AND THIS WOULD NOT SUPPORT A WELL-DEFINED UPPER LOW
BREAKING OFF FROM THE MAIN TROUGH.
THE FORECAST WAS PRIMARILY DERIVED FROM A UKMET/GFS/ECMWF/WPC
CONTINUITY COMPOSITE THROUGH TUESDAY, AND THEN SOME OF THE
GFS/ECMWF AND INCREASED USE OF THE ENSEMBLE MEANS FOR THE
WEDNESDAY THROUGH FRIDAY TIME PERIOD WITH GENERALLY BELOW AVERAGE
FORECAST CONFIDENCE AT THIS JUNCTURE OWING TO THE MODEL
VARIABILITY NOTED ABOVE.
..SENSIBLE WEATHER AND POTENTIAL HAZARDS
AN AMPLIFYING UPPER TROUGH AND A STRONG COLD FRONT REACHING THE
NORTHERN PLAINS AND UPPER MIDWEST BY WEDNESDAY WILL LIKELY PRODUCE
SHOWERS AND SOME THUNDERSTORMS FROM THE CENTRAL PLAINS TO THE
GREAT LAKES, ALTHOUGH RAINFALL TOTALS SHOULD BE LIGHT TO MODERATE.
THERE MAY BE AN UPTICK IN RAINFALL COVERAGE AS THE FRONT
APPROACHES THE NORTHEAST U.S. TOWARDS THE END OF THE WEEK, AND
ALSO FOR THE GULF COAST REGION AS THE FRONT TAPS INTO DEEPER
MOISTURE. ELSEWHERE, THE CONVECTION ACROSS THE SOUTHERN ROCKIES
AND ARIZONA IS FINALLY EXPECTED TO SUBSIDE GOING INTO THE MIDDLE
OF THE WEEK AS THE UPPER LOW/TROUGH WEAKENS. SOME HIGH ELEVATION
SNOW SHOWERS ARE ALSO POSSIBLE FOR THE HIGHEST TERRAIN OF THE
CENTRAL AND NORTHERN ROCKIES ON TUESDAY AND WEDNESDAY.
MUCH OF THE NORTHWESTERN U.S. SHOULD HAVE ABOVE NORMAL
TEMPERATURES NEXT WEEK WITH THE UPPER RIDGE JUST OFF THE COAST,
AND THINGS HAVE TRENDED MILDER COMPARED TO EARLIER FORECASTS.
FARTHER EAST, TEMPERATURES SHOULD BE MODERATING GOING INTO EARLY
IN THE WEEK AFTER A RELATIVELY CHILLY WEEKEND FOR MOST LOCATIONS.
READINGS SHOULD STILL BE WARM ACROSS MOST OF THE PLAINS AND
MIDWEST STATES THROUGH WEDNESDAY BEFORE THE FRONT PASSES THROUGH
THE REGION, FOLLOWED BY HIGHS ABOUT 5-15 DEGREES BELOW AVERAGE TO
CLOSE OUT THE WORK WEEK FOR THE OHIO VALLEY AND GREAT LAKES, AND
POTENTIAL FOR FROST AT NIGHT.
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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