875
FXUS02 KWBC 121918
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 PM EDT MON OCT 12 2026
VALID 12Z THU OCT 15 2026 - 12Z MON OCT 19 2026
..HEAVY RAINFALL THREAT FOR THE SOUTH-CENTRAL U.S. INTO THURSDAY
..RECORD HEAT FOR THE MID-SOUTH AND SOUTHEAST THROUGH THURSDAY
...BROAD FROST/FREEZE THREATS ACROSS THE NORTHERN/CENTRAL U.S.
LATE WEEK INTO EARLY NEXT WEEK...
..OVERVIEW
AN UPPER LOW LINGERING OVER THE INTERMOUNTAIN WEST WILL ALLOW FOR
MOISTURE FROM SIMON TO STREAM NORTHWARD, CONTINUING TO BRING AN
EXPANSIVE AREA OF RAIN AND THUNDERSTORMS ACROSS THE CENTRAL U.S.
INTO THURSDAY. A DOWNSTREAM RIDGE OVER THE SOUTH-CENTRAL TO
SOUTHEASTERN U.S. EARLY IN THE PERIOD SHOULD ALLOW FOR MUCH ABOVE
NORMAL TO RECORD-SETTING WARM TEMPERATURES BROADLY INTO THURSDAY.
THE ENERGY FROM THE INTERMOUNTAIN WEST TROUGH WILL SPLIT AFTER
THURSDAY, WITH PART OF IT MOVING INTO THE SOUTHWEST U.S. AND THE
REST COMBINING WITH STRONG NORTHERN STREAM ENERGY FROM CANADA. THIS
RESULTS IN A DEEP TROUGH INTO THE EASTERN HALF OF THE U.S. LATE
WEEK, SHIFTING OFFSHORE NEXT WEEKEND. A STRONG COLD FRONT AND
CHILLY SURFACE HIGH PRESSURE BEHIND IT WILL BRING FROST/FREEZE
CONCERNS TO BROAD AREAS PRESSING EAST ACROSS THE PLAINS, MIDWEST,
AND EAST THROUGH THE PERIOD.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE CONTINUES TO SHOW GOOD AGREEMENT ON THE EVOLUTION
OF THE UPPER LOW OVER THE WEST AFTER THURSDAY, WITH SOME ENERGY
COMBINING WITH A STRONG SHORTWAVE MOVING SOUTHEAST INTO THE NORTH-
CENTRAL U.S. TO DEVELOP AN AMPLIFIED TROUGH OVER THE GREAT LAKES
LATE WEEK, AND SOME ENERGY HELD BACK ACROSS THE SOUTHWEST AS A WEAK
UPPER LOW. THE NORTHERN TROUGH WILL SUPPORT A STRENGTHENING
SURFACE LOW AHEAD OF IT, WHICH SHOWS GOOD 12Z MODEL AGREEMENT ATOP
THE LOWER GREAT LAKES EARLY FRIDAY AND OVER ATLANTIC CANADA
SATURDAY. THE TROUGH SHOULD TRACK THROUGH THE NORTHEAST OVER THE
WEEKEND, WITH ONLY MINOR TIMING DIFFERENCES.
MODELS CONTINUE THEIR REASONABLY GOOD AGREEMENT AS RIDGING
STRETCHES ACROSS THE GREAT BASIN NORTH OF THE UPPER LOW AND ACROSS
THE SOUTHERN PLAINS LATE WEEK INTO THE WEEKEND. SHALLOW TROUGHING
LOOKS TO MOVE THROUGH THE NORTHERN TIER/SOUTHERN CANADA OVER THE
WEEKEND WITH JUST MINOR TIMING AND DEPTH SPREAD IN THE GUIDANCE.
THEN A TROUGH IS FORECAST TO DEEPEN IN THE EASTERN PACIFIC AND MOVE
TOWARD OR INTO THE WEST COAST BY THE END OF THE PERIOD MONDAY.
THIS ONCE AGAIN SHOWS A LITTLE MODEL SPREAD, BUT NOTHING OUT OF THE
ORDINARY FOR THE LATE MEDIUM RANGE PERIOD.
GOOD MODEL AGREEMENT WITH THE LARGE SCALE PATTERN ALLOWED THE WPC
FORECAST TO USE A MULTI-MODEL DETERMINISTIC/AIFS BLEND FOR MUCH OF
THE PERIOD, WITH SOME MINIMAL ENSEMBLE MEAN INCLUSION. OVERALL,
THIS APPROACH IS CONSISTENT WITH WPC CONTINUITY AND THE NATIONAL
BLEND OF MODELS.
..WEATHER/HAZARDS HIGHLIGHTS
ASSOCIATED WITH THE UPPER LOW OVER THE WEST, A PLAINS LEE LOW
PRESSURE SYSTEM PLUS MOISTURE FROM SIMON STREAMING NORTHWARD WILL
CONTINUE TO BRING RAIN IN THE SOUTH-CENTRAL U.S. INTO THURSDAY.
THUNDERSTORMS AND HEAVY RAIN/FLOODING POTENTIAL ARE LIKELY IN THE
SOUTHERN/CENTRAL PLAINS TO MID-MISSISSIPPI VALLEY AHEAD OF A COLD
FRONT, AND A WPC SLIGHT RISK AREA IS IN PLACE FOR THE THURSDAY
EXCESSIVE RAINFALL OUTLOOK. SOME HEAVY RAIN MAY LINGER FRIDAY IN
THE SOUTHERN HIGH PLAINS. FARTHER NORTH, AREAS OF RAIN ARE FORECAST
TO STRETCH FROM THE NORTH-CENTRAL U.S. INTO THE NORTHEAST THURSDAY
AND FRIDAY WITH A SURFACE LOW. THE PATTERN WILL BE FAVORABLE FOR
LAKE EFFECT/ENHANCED RAIN AND EVEN SNOW ACROSS THE GREAT LAKES
REGION TO INTERIOR NORTHEAST THROUGH FRIDAY-SATURDAY, ALONG WITH
UPSLOPE PRECIPITATION IN THE APPALACHIANS. HIGH WINDS ARE POSSIBLE
BEHIND THE SURFACE LOW/COLD FRONT TRACK IN THE PLAINS THURSDAY,
SHIFTING EAST ACROSS THE GREAT LAKES FRIDAY, INTO THE HIGHER
ELEVATIONS OF THE NORTHEAST SATURDAY, AND ALSO BEHIND THE TAIL END
OF THE FRONT IN THE SOUTHWEST TO SOUTHERN HIGH PLAINS. SHOWERS AND
STORMS ARE POSSIBLE IN FLORIDA, WITH AMOUNTS POTENTIALLY INCREASING
BY THE WEEKEND WITH THE FRONT PASSING THROUGH. ELSEWHERE, THE
PACIFIC NORTHWEST SHOULD SEE INCREASING PRECIPITATION CHANCES INTO
SUNDAY AHEAD OF AN UPPER TROUGH. BUT OVERALL A DRIER PATTERN IS IN
STORE BY THE WEEKEND INTO EARLY NEXT WEEK, COMPARED TO THE BUSY
PERIOD LATELY.
AHEAD OF THE FRONT, TEMPERATURES IN THE LOWER MISSISSIPPI VALLEY,
MID-SOUTH, AND THE SOUTHEAST WILL BE WELL ABOVE NORMAL AND LIKELY
CONTINUE TO SET NEW DAILY HIGH TEMPERATURE RECORDS (UPPER 80S TO
THE MID 90S) INTO THURSDAY. THEN CANADIAN HIGH PRESSURE IS FORECAST
TO GRADUALLY TRACK ACROSS THE COUNTRY BEHIND THE COLD FRONT LATE
WEEK INTO THE WEEKEND, COOLING TEMPERATURES FOR THE CENTRAL AND
EASTERN U.S. AND PROVIDING FAIRLY BROAD FROST/FREEZE THREATS.
MEANWHILE, THE WEST COAST COULD SEE ABOVE NORMAL TEMPERATURES,
INCLUDING SOME HIGHS NEAR AND ABOVE 90 FOR PARTS OF COASTAL
CALIFORNIA AGAIN BY LATE WEEK. ABOVE AVERAGE TEMPERATURES ARE
LIKELY TO SPREAD INTO THE NORTH-CENTRAL U.S. OVER THE WEEKEND.
TATE/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, 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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