193
FXUS02 KWBC 100725
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
325 AM EDT SAT OCT 10 2026
VALID 12Z TUE OCT 13 2026 - 12Z SAT OCT 17 2026
...HEAVY RAINFALL THREAT CONTINUES INTO THE INTERMOUNTAIN WEST
EARLY NEXT WEEK...
..RECORD HEAT FOR THE SOUTHERN PLAINS, MID-SOUTH, AND SOUTHEAST
..OVERVIEW
UPPER TROUGHING OVER THE WEST EARLY NEXT WEEK WILL BE A
COMBINATION OF NORTHERN STREAM ENERGY THAT DROPS DOWN THE WEST
COAST AND REMNANT ENERGY AND MOISTURE OF WHAT IS CURRENTLY TROPICAL
STORM RACHEL AS IT MOVES INTO THE SOUTHWEST U.S. THIS WEEKEND.
ANOMALOUS MOISTURE WITH THIS SYSTEM WILL CONTINUE TO BRING A FLASH
FLOODING THREAT ACROSS PORTIONS OF THE INTERMOUNTAIN WEST INTO THE
START OF THE MEDIUM RANGE PERIOD ON TUESDAY. MEANWHILE, MOISTURE
FROM EX- SIMON WILL STREAM NORTHWARD, WITH AN EXPANDING AREA OF
RAIN OVER THE CENTRAL U.S. AS THE WESTERN TROUGH DRIFTS SLOWLY
EASTWARD. ANOTHER SHORTWAVE OUT OF CANADA SHOULD DROP DOWN AND
LIKELY PULL AT LEAST SOME OF THIS WESTERN U.S. ENERGY EASTWARD WITH
TROUGHING BECOMING ESTABLISHED OVER THE EAST BY LATE PERIOD.
STRONG UPPER RIDGING OVER THE SOUTH-CENTRAL TO SOUTHEAST EARLY IN
THE PERIOD SHOULD ALLOW FOR MUCH ABOVE NORMAL TO RECORD-SETTING
WARM TEMPERATURES EARLY TO MID WEEK, SLOWLY MODERATING WITH TIME.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW REASONABLY GOOD AGREEMENT EARLY
IN THE FORECAST PERIOD WITH A POSITIVELY TILTED TROUGH/UPPER LOW
LOCATED OVER SOUTHERN NEVADA BY EARLY TUESDAY, SLOWLY DRIFTING
EAST-NORTHEASTWARD INTO WEDNESDAY. AFTER THIS, THE EVOLUTION
BECOMES INCREASINGLY UNCERTAIN AS ADDITIONAL SHORTWAVE ENERGY FROM
SOUTHWEST CANADA BEGINS TO INTERACT WITH THIS FEATURE. THE GFS AND
EC-AIFS (AND YESTERDAYS 12Z CMC) SHOW THE WESTERN LOW GETTING
PICKED UP BY THIS ENERGY RACING IT EASTWARD AND AMPLIFYING
TROUGHING OVER THE EAST BY NEXT WEEKEND. THE ECMWF, UKMET, AND NOW
THE NEW 00Z CMC SHOW LESS PHASING WITH THESE SYSTEMS ALLOWING THE
UPPER LOW TO MEANDER LONGER OVER THE WEST AND WEAKENING BEFORE
POSSIBLY GETTING ABSORBED INTO THE NEXT TROUGH INTO THE NORTHWEST
NEXT SATURDAY. THIS ALSO RESULTS IN A MUCH FASTER AND LESS
AMPLIFIED TROUGH OVER THE EAST LATE PERIOD. RECENT AI-GFS RUNS
CONTINUE TO BE INCREDIBLY STRONG WITH DIVING THE SOUTHWEST CANADA
NORTHERN STREAM ENERGY FARTHER SOUTH INTO THE WEST, WHICH STILL
SEEMS LIKE AN OUTLIER.
WITH THE NEW 00Z GUIDANCE TONIGHT, THERE MAY BE SOME SLIGHT TREND
TOWARDS WANTING TO HOLD BACK ENERGY FOR LONGER OVER THE WEST, AS
SUGGESTED PRIMARILY BY THE ECMWF, UKMET, AND 00Z CMC. DESPITE THIS,
THE WPC FORECAST TRENDED MORE TOWARDS THE ENSEMBLE MEANS LATE
PERIOD, AMIDST SIGNIFICANT UNCERTAINTY. THIS SHOWS A BIT FASTER
PROGRESSION OF THE LOW, CLOSER TO THE GFS, BUT IT IS ALSO
CONSISTENT WITH PREVIOUS WPC CONTINUITY WHICH SEEMS SAFER UNTIL A
MORE CONSISTENT SLOWER TREND EMERGES.
..WEATHER/HAZARDS HIGHLIGHTS
ACROSS THE WEST, THE REMNANTS OF RACHEL COMBINED WITH THE INCOMING
UPPER TROUGH WILL YIELD ADDITIONAL WIDESPREAD MODEST TO LOCALLY
HEAVY RAINFALL AND LOCALIZED FLASH FLOODING INTO THE GREAT BASIN ON
TUESDAY. SEE THE EXCESSIVE RAINFALL OUTLOOK FOR MORE INFORMATION.
COLD AIR SURGING BEHIND THE COLD FRONT WILL LOWER SNOW LEVELS,
LEADING TO ACCUMULATING SNOW OVER HIGHER ELEVATIONS OF THE WEST.
THIS COULD BE THE FIRST APPRECIABLE SNOW FOR THE UTAH RANGES. SNOW
IS POSSIBLE IN PORTIONS OF THE NORTHERN/CENTRAL ROCKIES AS WELL
TUESDAY-WEDNESDAY AND PERHAPS LINGERING INTO THURSDAY.
AS THE LOW PRESSURE SYSTEM LIFTS INTO THE NORTHERN PLAINS,
MOISTURE FROM WHAT IS LEFTOVER FROM SIMON MAY STREAM NORTHWARD AND
AID IN PRODUCING A WIDESPREAD AREA OF RAIN IN THE CENTRAL U.S.
TUESDAY-WEDNESDAY. THUNDERSTORMS, INCLUDING POTENTIAL SEVERE
WEATHER, ARE LIKELY IN THE SOUTHERN/CENTRAL PLAINS TO LOWER/MIDDLE
MISSISSIPPI VALLEY AHEAD OF THE ASSOCIATED COLD FRONT, WHICH COULD
LINGER INTO THURSDAY. FARTHER NORTH, RAIN IS LIKELY TO BE MORE
PROGRESSIVE, SPREADING ACROSS THE NORTHERN PLAINS TO UPPER MIDWEST
ON WEDNESDAY AND THE GREAT LAKES/OHIO VALLEY/NORTHEAST BY THURSDAY
AND FRIDAY. THE SURFACE LOW STRENGTHENING IN THE MIDWEST/GREAT
LAKES WHILE A COLD SURFACE HIGH DROPS INTO THE ROCKIES COULD LEAD
TO HIGH WINDS IN THE DAKOTAS AND VICINITY BY THURSDAY AND
ESPECIALLY FRIDAY.
ELSEWHERE, A ROUND OF RAIN IS POSSIBLE IN THE GREAT LAKES TO
NORTHEAST ON TUESDAY WITH A SHORTWAVE ALOFT AND A COLD FRONT.
AHEAD OF THE FRONT, TEMPERATURES IN THE SOUTHERN PLAINS TO THE
SOUTHEAST WILL BE WELL ABOVE NORMAL AND LIKELY SET NEW DAILY HIGH
TEMPERATURE RECORDS (UPPER 80S TO THE MID 90S). LOW TEMPERATURES
MAY ONLY FALL INTO THE 70S FOR SEVERAL NIGHTS, WITH THE COMBINATION
YIELDING WIDESPREAD MODERATE HEATRISK AND PERHAPS REACHING MAJOR
OVER SOUTH TEXAS. THE WARMER TEMPERATURES IN THE 90S WILL GRADUALLY
COOL BACK INTO THE 80S AS FRONTS APPROACH. MEANWHILE THE UPPER
TROUGHING IN THE WEST WILL BRING BROADLY BELOW AVERAGE TEMPERATURES
THERE THROUGH TUESDAY, ALONG WITH FROST/FREEZE THREATS. ADDITIONAL
CHILLY AIR MAY COME INTO THE NORTHERN ROCKIES AND VICINITY LATE
WEEK, WITH NORTHWEST FLOW ALOFT AND SURFACE HIGH PRESSURE. UPPER
RIDGING FRIDAY INTO SATURDAY OVER THE NORTHWEST SHOULD HELP
MODERATE TEMPERATURES BACK TOWARDS OR SLIGHTLY ABOVE NORMAL.
SANTORELLI/TATE
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, EXCESSIVE RAINFALL OUTLOOK,
WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES
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
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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