334
FXUS02 KWBC 090651
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 AM EDT WED OCT 9 2024
VALID 12Z SAT OCT 12 2024 - 12Z WED OCT 16 2024
..DESERT SOUTHWEST RECORD HEAT MODERATES/LINGERS INTO SATURDAY
..OVERVIEW
A SHORTWAVE DIVING THROUGH THE NORTH-CENTRAL U.S. THIS WEEKEND
WILL AMPLIFY TROUGHING ACROSS THE EAST BY EARLY WEEK, WITH MULTIPLE
WAVES OF IMPULSES TO REINFORCE IT. MUCH BELOW NORMAL TEMPERATURES
AND FROST/FREEZE MAY BE A CONCERN FOR SOME. THIS SHOULD INITIALLY
SUPPRESS CENTRAL U.S. HEAT SOUTHWARD TOWARDS THE SOUTHERN PLAINS
RESULTING IN ANOTHER FEW DAYS OF MUCH ABOVE NORMAL TEMPERATURES
(NEARING DAILY RECORDS). A DEEP TROUGH INTO THE WEST COAST WILL
AMPLIFY UPPER RIDGING AGAIN ACROSS THE WEST-CENTRAL U.S. WHICH
ANOTHER ROUND OF ABOVE NORMAL TEMPERATURES.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODELS CONTINUE TO SHOW GOOD AGREEMENT ON THE OVERALL PATTERN
EVOLUTION ACROSS THE CONUS DURING THE PERIOD, BUT WITH SOME TYPICAL
DIFFERENCES ESPECIALLY INTO NEXT WEEK. THIS ALLOWED FOR AN EARLY
PERIOD BLEND OF THE DETERMINISTIC MODELS. THERE IS A LOT OF
UNCERTAINTY BY NEXT TUESDAY-WEDNESDAY WITH MULTIPLE SHORTWAVE
IMPULSES THAT ROUND/REINFORCE THE TROUGH OVER THE EAST, WITH SOME
MODELS INDICATING POTENTIAL FOR A CUT OFF LOW OVER/NEAR THE MID-
ATLANTIC NEXT WEEK. THE ENSEMBLE MEANS SHOW JUST AMPLIFIED
TROUGHING WHICH EXEMPLIFIES THE UNCERTAINTY IN THE EVOLUTION OF THE
EASTERN TROUGH. SEEMED PRUDENT THEN TO LEAN MORE HEAVILY TOWARDS
THE ENSEMBLE MEANS THE SECOND HALF OF THE PERIOD FOR THE WPC
FORECAST TONIGHT.
..WEATHER/HAZARDS HIGHLIGHTS
A LARGE PART OF THE LOWER 48 WILL SEE FAIRLY DRY WEATHER FOR A
MAJORITY OF THE PERIOD. A COMPACT EASTERN PACIFIC UPPER TROUGH/LOW
MAY BRING A BRIEF PERIOD OF MOSTLY LIGHT RAINFALL TO THE CENTRAL
WEST COAST AROUND INTO SATURDAY, WITH A LITTLE LIGHT PRECIPITATION
POSSIBLY REACHING FARTHER EASTWARD INTO THE WEST THEREAFTER. THEN A
FRONT APPROACHING THE PACIFIC NORTHWEST MAY BRING SOME MOISTURE
AND LIGHT TO MODERATE RAINFALL INTO THE REGION BY THE START OF NEXT
WEEK. THE AMPLIFYING UPPER TROUGH AND ACCOMPANYING SURFACE
EVOLUTION SHOULD BRING SOME AREAS OF LOCALLY ENHANCED RAINFALL TO
PARTS OF THE GREAT LAKES/NORTHEAST BY LATE WEEKEND INTO THE EARLY
PART OF NEXT WEEK.
A CENTRAL U.S. UPPER RIDGE WILL CONTINUE TO PROMOTE A PERIOD OF
WELL ABOVE NORMAL TEMPERATURES WITH NORTHERN STREAM TROUGHING AND A
COLD FRONT PUSHING THE GREATEST WARM ANOMALIES SOUTHEAST WITH TIME
FROM THE CENTRAL PLAINS AND MID/UPPER MISSISSIPPI VALLEY TO THE
SOUTHEAST. TEMPERATURES AROUND 10 DEGREES ABOVE NORMAL IN THE
SOUTHWEST TO SOUTHERN HIGH PLAINS COULD SET ADDITIONAL DAILY
RECORDS THOUGH THE TEMPERATURES HAVE MODERATED COMPARED TO RECENT
DAYS AND THE SHORT RANGE. THE NORTHERN ROCKIES/HIGH PLAINS MAY SEE
TEMPERATURES REACH UP TO 10-20F ABOVE NORMAL BY EARLY NEXT WEEK.
MEANWHILE, SOME NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES IN THE
EAST THIS WEEKEND SHOULD BE REPLACED BY TEMPERATURES GENERALLY 5-10
DEGREES BELOW NORMAL NEXT WEEK UNDERNEATH AMPLIFIED TROUGHING.
LATER PERIOD COLD FRONTAL PASSAGE IS ALSO EXPECTED TO PROVIDE A
SPREAD OF MUCH COOLER TEMPERATURES FROM THE NORTH-CENTRAL U.S.
THROUGH THE MIDWEST/GREAT LAKES AND NORTHEAST STARTING IN ABOUT A
WEEK WITH SOME FROST/FREEZE CONCERNS.
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 FORECAST (QPF), EXCESSIVE RAINFALL
OUTLOOK (ERO), WINTER WEATHER OUTLOOK (WWO) PROBABILITIES, HEAT
INDICES, AND KEY MESSAGES CAN BE ACCESSED FROM:
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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