823
FXUS02 KWBC 260700
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
300 AM EDT SAT OCT 26 2024
VALID 12Z TUE OCT 29 2024 - 12Z SAT NOV 02 2024
...HEAVY SNOW AND WIND THREAT FOR THE NORTH-CENTRAL ROCKIES AND
NEARBY HIGH PLAINS TUESDAY-WEDNESDAY...
..HEAVY RAIN THREAT FOR THE PLAINS/MIDWEST MID-LATER NEXT WEEK
..GENERAL OVERVIEW
AN AMPLIFIED UPPER-LEVEL TROUGH SET TO DIG INTO THE WEST THIS
WEEKEND WILL SPREAD HIGHLY UNSETTLED WEATHER ACROSS MUCH OF THE
WESTERN U.S. EARLY NEXT WEEK TO INCLUDE HIGH-ELEVATION SNOW, GUSTY
WINDS AND COLDER TEMPERATURES. THIS TROUGH WILL THEN PUSH EASTWARD
AGAINST A WARM AND EXPANDING UPPER RIDGING OVER THE CENTRAL TO
EASTERN U.S., RESULTING IN A WAVY SHARP FRONT ACROSS THE MID-
SECTION OF THE COUNTRY WHERE A MODERATELY HEAVY RAIN EVENT APPEARS
TO EMERGE FROM THE PLAINS THROUGH THE MISSISSIPPI VALLEY AND
MIDWEST FOR THE LATTER HALF OF NEXT WEEK.
..GUIDANCE/PREDICTABILITY ASSESSMENT
FORECAST SPREAD SEEMS LOWER THAN NORMAL TUE/WED AND A GUIDANCE
BLEND SEEMS TO OFFER A SOLID FORECAST BASE. MODEL DIFFERENCES GROW
THU INTO FRI WITH 12/18 UTC GFS RUNS OUTLIERS WITH SLOWER BRINGING
OF PACIFIC SYSTEM ENERGY INLAND INTO THE WEST. ECMWF/GEFS/CANADIAN
ENSEMBLES SUPPORT A SOLUTION CLOSER TO BEST CLUSTERED GUIDANCE OF
THE MORE PREFERRED 12 UTC ECMWF/CANADIAN. HOWEVER, SUBSEQUENT
PACIFIC SYSTEM ENERGY INTO NEXT WEEKEND MAY DIG MORE ROBUSTLY INTO
THE WEST THAN THE ECMWF/CANADIAN GIVEN UPSTREAM UPPER RIDGE
AMPLITUDE. THIS SOLUTION IS CHAMPIONED BY THE MACHINE LEARNING 18
UTC AIFS AND GEFS MEAN THAT WERE MAINLY UTILIZED AT THIS LONG TIME
FRAME. LATEST 00 UTC MODEL RUNS HAVE OVERALL TRENDED FAVORABLY.
..WEATHER/HAZARDS HIGHLIGHTS
GUIDANCE HAS BEEN CONSISTENT THAT A COLD FRONT ASSOCIATED WITH A
DIGGING UPPER LEVEL TROUGH FROM THE PACIFIC WILL BE STEADILY
MOVING THROUGH THE WESTERN U.S. EARLY NEXT WEEK. PERIODS OF RAIN,
HIGH ELEVATION SNOW, WINDY AND COLDER CONDITIONS ARE EXPECTED TO
OVERSPREAD MUCH OF THE REGION WITH FRONTAL PASSAGE. LOCALLY HIGH
WINDS COULD IMPACT PORTIONS OF THE SOUTHERN ROCKIES AND SOUTHERN
HIGH PLAINS AS THE COLDER AIRMASS DIGS INTO THE REGION. THIS MAY
ALSO LEAD TO THE ONSET OF FROST/FREEZE FOR SOME OF THESE AREAS FOR
THE FIRST TIME THIS SEASON.
MODEST CYCLOGENESIS WILL ADVANCE A FRONT ACROSS THE NORTHERN
PLAINS AND UPPER MIDWEST THROUGH EARLY NEXT WEEK. THIS FRONT IS
FORECAST TO SHARPEN WITH TIME AS IT CONTINUES TO PUSH AGAINST AN
EXPANSIVE HIGH PRESSURE SYSTEM ACROSS THE EASTERN AND SOUTHERN
U.S. SNOW WILL LINGER OVER THE NORTHERN TO CENTRAL ROCKIES AND
INTO THE NORTHERN HIGH PLAINS BEHIND A LOW PRESSURE WAVE, ESPECIALLY
FOR THE HIGHER ELEVATIONS OF WYOMING TUESDAY INTO WEDNESDAY GIVEN
UPPER DIVERGENCE AND LOWER LEVEL UPSLOPE FLOW. ACCUMULATING SNOW
COULD SPILL INTO THE NEARBY HIGH PLAINS AND BLACK HILLS AS WELL.
AHEAD OF THE SHARPENING FRONT, A LONG FETCH OF RETURN FLOW FROM THE
GULF OF MEXICO APPEARS TO INITIATE AND SUPPORT A THREAT OF HEAVY
RAIN FROM THE CENTRAL/SOUTHERN PLAINS THROUGH THE MISSISSIPPI
VALLEY AND INTO THE MIDWEST WITH EMBEDDED THUNDERSTORMS EMERGING
MIDWEEK, WITH LINGERING FOCUS HOLDING BACK OVER THE SOUTHERN PLAINS
WHERE MODERATE TO HEAVY RAINFALL COULD LINGER INTO LATE NEXT WEEK.
THE WPC DAY5/WED EXCESSIVE RAINFALL OUTLOOK INTRODUCED A MARGINAL
RISK AREA GIVEN POTENTIAL FOR TRAINING AND FAVORABLE UPPER TROUGH
AND RIGHT ENTRANCE REGION JEY DYNAMICS. IN THE MEANTIME,
PRECIPITATION ASSOCIATED WITH THE NEXT PACIFIC SYSTEM AND LONG
FETCH MOISTURE IS FORECAST TO RE-FOCUS MODERATE PRECIPITATION INTO
THE PACIFIC NORTHWEST THROUGH LATTER NEXT WEEK, WITH HIGH-
ELEVATION SNOW REACHING INTO THE NORTHERN ROCKIES.
THE DIGGING TROUGH IN THE WEST WILL USHER IN AND SUSTAIN COLDER
THAN NORMAL TEMPERATURES FOR PRETTY MUCH THE ENTIRE WESTERN U.S.
THROUGH LATE NEXT WEEK. IN CONTRAST, HIGH TEMPERATURES REACHING
INTO THE UPPER 80S TO LOWER 90S WILL CHALLENGE SOME DAILY RECORDS
ACROSS THE SOUTHERN PLAINS TO THE MID-SOUTH EARLY NEXT WEEK. THE
EXPANDING UPPER RIDGE TOGETHER WITH A LONG FETCH OF STRONG AND
GUSTY SOUTHERLY WINDS AT THE SURFACE WILL SEND THE WARMTH WELL TO
THE NORTH AND EAST, REACHING INTO THE GREAT LAKES AND EVENTUALLY
NEW ENGLAND THROUGH THE MIDDLE AND LATE NEXT WEEK. HIGH
TEMPERATURES REACHING WELL UP INTO THE 70S TO NEAR 80 DEGREES
WILL BE ENOUGH TO SET SOME NEW DAILY RECORD HIGH TEMPERATURES FROM
THE GREAT LAKES TO NEW ENGLAND WEDNESDAY AND THURSDAY.
SCHICHTEL
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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