418
FXUS02 KWBC 060659
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT THU OCT 6 2022
VALID 12Z SUN OCT 9 2022 - 12Z THU OCT 13 2022
..SYNOPTIC OVERVIEW
A RATHER AMPLIFIED UPPER LEVEL FLOW PATTERN IS EXPECTED TO BE IN
PLACE FOR THE UPCOMING WEEKEND AND EXTENDING INTO THE MIDDLE
PORTION OF NEXT WEEK. FOR THE EASTERN U.S., A BIG CANADIAN
SURFACE HIGH SETTLING IN FROM THE PLAINS TO THE EAST COAST WILL
BRING A PRISTINE FALL-LIKE AIRMASS AFTER THE PASSAGE OF A STRONG
COLD FRONT. THE NEXT COLD FRONT ARRIVES ACROSS THE CENTRAL AND
NORTHERN PLAINS BY TUESDAY WITH SOME SHOWERS AND A FEW STORMS
AHEAD OF IT. FOR THE WESTERN U.S., THE PERSISTENT WEAK UPPER
LOW/TROUGH OVER NORTHWESTERN MEXICO IS EXPECTED TO EVOLVE INTO AN
OPEN TROUGH, ALTHOUGH SHOWER AND STORMS WILL LIKELY REMAIN. BY
TUESDAY, A MORE IMPRESSIVE UPPER TROUGH BEGINS BUILDING ACROSS THE
WESTERN U.S. WHICH WILL LIKELY BRING MUCH COOLER CONDITIONS FOR
MUCH OF THIS REGION BY THE MIDDLE OF NEXT WEEK.
..GUIDANCE EVALUATION/PREDICTABILITY ASSESSMENT
OVERALL, THE 00Z DETERMINISTIC GUIDANCE IS IN GOOD OVERALL
AGREEMENT ON MOST FEATURES FOR SUNDAY, WITH THE MAIN DIFFERENCE AT
THIS TIME BEING A SLOWER AND STRONGER SOLUTION WITH THE UKMET
ACROSS THE UPPER MIDWEST AND GREAT LAKES WITH THE TROUGH DROPPING
SOUTHWARD FROM CANADA. THE MODELS ALSO AGREE WELL ON THE UPPER
LOW THAT EVOLVES INTO A TROUGH NEAR THE DESERT SOUTHWEST THROUGH
THE WEEKEND. LOOKING AHEAD, THE DETERMINISTIC GUIDANCE STILL
SUGGESTS A CUT-OFF LOW WILL DEVELOP ACROSS THE INTERMOUNTAIN WEST
BY WEDNESDAY, ALBEIT WEAKER THAN THE 12Z GUIDANCE. THE CMC STILL
MAINTAINS A STRONGER SOLUTION REGARDING THAT LOW. THE MAIN TROUGH
AXIS IS FORECAST TO BE OVER THE NORTHERN TIER STATES, ACCOMPANIED
WITH ANOTHER STRONG COLD FRONT.
A MAINLY CMC/GFS/ECMWF MODEL BLEND SUFFICES EARLY IN THE PERIOD,
FOLLOWED BY INCREASING THE WEIGHTING OF THE ENSEMBLE MEANS FOR
TUESDAY-THURSDAY AND MAINTAINING SOME PREVIOUS WPC CONTINUITY.
FOR THE QPF, THE NBM COMBINED WITH SOME OF THE OPERATIONAL
GFS/ECMWF WAS USED AS A BASELINE THROUGH ABOUT TUESDAY, AND THEN
MAINLY WENT WITH NBM FOR WEDNESDAY.
..WEATHER/HAZARDS HIGHLIGHTS
THE COMBINATION OF PERSISTENT MONSOONAL MOISTURE AND AN UPPER LOW
OVER NORTHWEST MEXICO WILL CONTINUE TO FUEL DIURNAL SHOWERS AND
THUNDERSTORMS OVER PARTS OF THE DESERT SOUTHWEST/SOUTHERN ROCKIES
THROUGH SUNDAY, WITH THE GREATEST RAINFALL TOTALS EXPECTED FOR
CENTRAL AND SOUTHERN NEW MEXICO BASED ON LATEST MODEL GUIDANCE.
THE UPPER LOW SHOULD EVOLVE INTO AN OPEN TROUGH BY MONDAY, BUT
ISOLATED TO SCATTERED CONVECTION WILL LIKELY PERSIST ACROSS THE
INTERMOUNTAIN WEST AS THE NEXT DISTURBANCE ENTERS THE REGION. AN
AMPLIFYING UPPER TROUGH AND A STRONG COLD FRONT REACHING THE
NORTHWEST/NORTHERN ROCKIES BY NEXT TUESDAY WILL LIKELY PRODUCE
SHOWERS AND EVEN HIGH ELEVATION SNOW FOR PORTIONS OF THE NORTHERN
ROCKIES FOR THE TUESDAY AND WEDNESDAY TIME PERIOD. ELSEWHERE,
LIGHT TO LOCALLY MODERATE RAINFALL WILL LIKELY SPREAD NORTHWARD
OVER THE FLORIDA PENINSULA AS EASTERLY LOW LEVEL FLOW STRENGTHENS
BEHIND A FRONT, AND SCATTERED SHOWERS AND SOME STORMS ARE LIKELY
FROM THE CENTRAL PLAINS TO THE GREAT LAKES AHEAD OF THE NEXT FRONT.
MUCH OF THE NORTHWESTERN U.S. SHOULD HAVE ABOVE NORMAL
TEMPERATURES AT LEAST THROUGH MONDAY, FOLLOWED BY A NOTICEABLE
COOLING TREND COMMENCING BY TUESDAY AS THE STRONG COLD FRONT DROPS
SOUTHEASTWARD, AND THEN TEMPERATURES MORE TYPICAL OF NOVEMBER ARE
EXPECTED ACROSS THE ROCKIES AND INTERMOUNTAIN WEST BY NEXT
WEDNESDAY WITH HIGHS GENERALLY 5-15 DEGREES BELOW AVERAGE.
FARTHER EAST, TEMPERATURES SHOULD BE MODERATING GOING INTO EARLY
IN THE WEEK AFTER A RELATIVELY CHILLY WEEKEND FOR MOST LOCATIONS.
READINGS SHOULD STILL BE MILD ACROSS MOST OF THE PLAINS STATES
THROUGH WEDNESDAY BEFORE THE FRONT PASSES THROUGH THE REGION.
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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