857
FXUS02 KWBC 111935
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
335 PM EDT SUN OCT 11 2026
VALID 12Z WED OCT 14 2026 - 12Z SUN OCT 18 2026
...HEAVY RAINFALL THREAT FOR THE SOUTH-CENTRAL U.S. WEDNESDAY AND
THURSDAY...
..RECORD HEAT FOR THE MID-SOUTH AND SOUTHEAST THROUGH THURSDAY
..OVERVIEW
AN UPPER LOW LINGERING OVER THE INTERMOUNTAIN WEST AS THE MEDIUM
RANGE PERIOD BEGINS MIDWEEK WILL ALLOW FOR MOISTURE FROM EX-SIMON
TO STREAM NORTHWARD, BRINGING AN EXPANSIVE AREA OF RAIN AND
THUNDERSTORMS ACROSS THE CENTRAL U.S. WEDNESDAY AND LINGERING IN
THE SOUTH-CENTRAL U.S. THURSDAY. THE ENERGY FROM THIS TROUGH WILL
COMBINE WITH STRONG NORTHERN STREAM ENERGY TO ESTABLISH DEEP
TROUGHING IN THE EASTERN HALF OF THE U.S. LATE WEEK AND GRADUALLY
SHIFTING EASTWARD NEXT WEEKEND. BEFORE THEN, STRONG UPPER RIDGING
OVER THE SOUTH-CENTRAL TO SOUTHEASTERN U.S. EARLY IN THE PERIOD
SHOULD ALLOW FOR MUCH ABOVE NORMAL TO RECORD-SETTING WARM
TEMPERATURES BROADLY ON WEDNESDAY AND GRADUALLY LESSENING THURSDAY-
FRIDAY.
..GUIDANCE/PREDICTABILITY ASSESSMENT
MODEL GUIDANCE BEGINS IN FAIRLY GOOD AGREEMENT WITH AN UPPER LOW
OVER THE FOUR CORNERS ON WEDNESDAY, WITH UPPER RIDGING IN PLACE
OVER THE SOUTHEAST, AND A FEW WEAK SHORTWAVES SLIDING THROUGH THE
NORTHERN TIER. THEN AFTER SOME MODEL WAFFLING OVER THE PAST COUPLE
DAYS, IT SEEMS GUIDANCE HAS STABILIZED IN SHOWING ENERGY FROM THE
FOUR CORNERS UPPER LOW LIFTING TO JOIN NORTHERN STREAM ENERGY
DIVING SOUTHEAST FROM WESTERN CANADA. THEN THIS TROUGH WILL DEEPEN
ACROSS THE GREAT LAKES. THERE ARE SOME TYPICAL MODEL DIFFERENCES
WITH THE TIMING AND DEPTH OF THE TROUGH. 00/06Z GFS RUNS WERE ON
THE SLOW SIDE, ALONG WITH MANY GEFS MEMBERS, BUT HAVE TRACKED
FASTER AT 12Z. AIFS AND CMC HAVE SEEMED TO BE A GOOD MIDDLE GROUND
WHILE ECMWF RUNS ARE ON THE FAST SIDE. MEANWHILE THERE SHOULD BE
SOME ENERGY LINGERING BEHIND IN THE SOUTHWEST/NORTHWESTERN MEXICO
FOR A WEAK UPPER LOW THERE FROM DAY TO DAY, SPLITTING BROAD EASTERN
PACIFIC RIDGING THAT EXTENDS NORTH THROUGH THE INTERMOUNTAIN WEST
ATOP THAT UPPER LOW. THE WPC FORECAST WAS BASED ON A MULTI-MODEL
BLEND, FAVORING A MIDDLE GROUND SOLUTION WITH INCREASING ENSEMBLE
MEANS THROUGH THE PERIOD TO ABOUT HALF MEANS BY DAY 6-7.
..WEATHER/HAZARDS HIGHLIGHTS
THE LOW ALOFT OVER THE WEST WILL CONTINUE TO BRING SNOW TO THE
CENTRAL ROCKIES WEDNESDAY AND PERHAPS INTO THURSDAY. AHEAD OF THIS
UPPER LOW, A PLAINS LEE LOW PRESSURE SYSTEM PLUS MOISTURE FROM WHAT
IS LEFTOVER FROM SIMON STREAMING NORTHWARD WILL AID IN PRODUCING A
WIDESPREAD AREA OF RAIN IN THE CENTRAL U.S. WEDNESDAY AND
THURSDAY. THUNDERSTORMS AND HEAVY RAIN/FLOODING POTENTIAL ARE
LIKELY IN THE SOUTHERN/CENTRAL PLAINS TO LOWER/MIDDLE MISSISSIPPI
VALLEY AHEAD OF A COLD FRONT, AND WPC SLIGHT RISK AREAS ARE IN
PLACE FOR THE WEDNESDAY AND THURSDAY EXCESSIVE RAINFALL OUTLOOKS.
FARTHER NORTH, AREAS OF RAIN ARE FORECAST TO STRETCH FROM THE
NORTH-CENTRAL U.S. WEDNESDAY-THURSDAY AND INTO THE NORTHEAST
FRIDAY. THE PATTERN WILL BE FAVORABLE FOR LAKE EFFECT/ENHANCED RAIN
AND POSSIBLY SNOW ACROSS THE GREAT LAKES TO INTERIOR NORTHEAST
THROUGH FRIDAY-SATURDAY. GUSTY WINDS ARE POSSIBLE ESPECIALLY BEHIND
THE SURFACE LOW TRACK THROUGH THE NORTH-CENTRAL U.S. AND GREAT
LAKES. SHOWERS AND STORMS COULD ACCOMPANY THE FRONT AS IT PUSHES
THROUGH FLORIDA LATE WEEK AS WELL.
AHEAD OF THE FRONT, TEMPERATURES IN THE LOWER MISSISSIPPI VALLEY,
MID-SOUTH, AND 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 WEDNESDAY MORNING, WITH
THE COMBINATION YIELDING WIDESPREAD MODERATE HEATRISK AND PERHAPS
REACHING MAJOR OVER SOUTH TEXAS WEDNESDAY. THE SCOPE OF RECORD
TEMPERATURES WILL GRADUALLY LESSEN INTO THURSDAY AND CONTINUE TO
MODERATE LATE WEEK. MEANWHILE, THE UPPER TROUGH IN THE WEST WILL
BRING BROADLY BELOW AVERAGE TEMPERATURES THERE FOR MIDWEEK.
CANADIAN HIGH PRESSURE IS FORECAST TO GRADUALLY TRACK ACROSS THE
COUNTRY BEHIND THE COLD FRONT LATE WEEK INTO THE WEEKEND, COOLING
TEMPERATURES AND PROVIDING POTENTIALLY FAIRLY BROAD FROST/FREEZE
THREATS. MEANWHILE, THE WEST COAST COULD SEE ABOVE NORMAL
TEMPERATURES, INCLUDING SOME HIGHS IN THE 90S FOR PARTS OF COASTAL
CALIFORNIA AGAIN BY LATE WEEK.
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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