283
FXUS02 KWBC 172011
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
311 PM EST MON NOV 17 2025
VALID 12Z THU NOV 20 2025 - 12Z MON NOV 24 2025
..SOUTH-CENTRAL U.S. HEAVY RAIN AND FLOODING THREAT INTO THURSDAY
..OVERVIEW
AN UPPER LOW WILL LIFT THROUGH THE SOUTH-CENTRAL U.S., BRINGING
HEAVY RAIN AND FLOODING POTENTIAL THERE, WITH WARMER THAN AVERAGE
TO RECORD WARM TEMPERATURES AHEAD OF IT IN THE SOUTHEAST.
MEANWHILE, ANOTHER UPPER LOW IS NOW FORECAST TO DROP SOUTH ACROSS
THE WEST COAST AND THEN MOVE EAST THROUGH THE SOUTHWEST OVER THE
WEEKEND. THIS COULD CAUSE ISOLATED HEAVY RAIN FOR SOUTHERN
CALIFORNIA AND THEN SPREADING EAST ACROSS THE SOUTHWEST AND
SOUTHERN PLAINS ONCE AGAIN OVER THE WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
RECENT MODEL GUIDANCE REMAINS CONSISTENT REGARDING THE FIRST UPPER
LOW PIVOTING THROUGH THE SOUTHWEST THURSDAY INTO THE SOUTH-CENTRAL
PLAINS FRIDAY, ALONG WITH A SURFACE LOW PRESSURE SYSTEM, THOUGH
OVER THE WEEKEND A LITTLE MORE SPREAD DEVELOPS REGARDING THE TIMING
OF WEAKENING OF THE SHORTWAVE AS IT PUSHES EAST. A GFS/ECMWF/UKMET
COMPROMISE SEEMED REASONABLE FOR THIS FEATURE.
UPSTREAM, MODELS HAVE BEEN MUCH LESS CONSISTENT WITH THE NEXT
UPPER TROUGH LIKELY FORMING AN UPPER LOW NEAR CALIFORNIA. COMPARED
TO A DAY AGO, DYNAMICAL AND AI MODELS ARE MOSTLY CONSISTENT WITH A
SOUTHERN STREAM UPPER LOW MAINTAINING AN OFFSHORE POSITION THROUGH
FRIDAY-SATURDAY BEFORE MOVING EAST, SLOWER THAN SOME OLDER
SOLUTIONS. CMC RUNS REMAIN MORE LIKE OLDER MODELS IN MAINTAINING A
FASTER PHASED TROUGH. BUT THE CONSISTENCY OF THE GFS/ECMWF, THEIR
MEANS, AND THE PRIMARY AI MODELS SEEMED TO BE THE WAY TO LEAN. THUS
THE WPC FORECAST WAS BASED ON A NON-CMC BLEND, FAVORING THE 00Z
GFS (AS THE 06Z RUN WAS EVEN A LITTLE SLOWER THAN CONSENSUS), 00Z
ECMWF, AND 00Z UKMET INITIALLY, AND THEN INCREASING PROPORTIONS OF
ENSEMBLE MEANS TO JUST OVER HALF BY DAY 7. THIS TRENDED THE QPF
TOWARD A SLOWER EMERGENCE OF INCREASING RAIN CHANCES IN THE SOUTH-
CENTRAL U.S. OVER THE WEEKEND COMPARED TO CONTINUITY.
..WEATHER/HAZARDS HIGHLIGHTS
AMPLIFIED UPPER TROUGH ENERGY WITHIN WELL SEPARATED SOUTHERN
STREAM FLOW WILL EJECT FROM THE SOUTHWEST TO THE SOUTH-CENTRAL U.S.
THURSDAY/FRIDAY. HEIGHT FALLS AND LEAD MOISTURE AND INSTABILITY
RETURN FLOW INTO WAVY FRONTAL SYSTEM AND MESOSCALE FEATURES FAVORS
EMERGENCE OF A GROWING AREA OF HEAVY RAINS AND POSSIBLY STRONG
THUNDERSTORMS OVER THE SOUTH-CENTRAL U.S., SHIFTING WITH REDUCED
IMPACT WITH EASTWARD PROGRESSION INTO THE WEEKEND. ACCORDINGLY, THE
DAY 4/THURSDAY EXCESSIVE RAINFALL OUTLOOK SHOWS A SLIGHT RISK
THROUGH PORTIONS OF TEXAS AND OKLAHOMA, WHERE HIGHER INSTABILITY
MAY LEAD TO HIGHER RAIN RATES, AND FARTHER NORTH INTO SOUTHERN
KANSAS AND THE LOWER/MIDDLE MISSISSIPPI VALLEY WHERE A WEST-EAST
ORIENTED FRONT COULD CAUSE REPEATING ROUNDS OF RAIN. BY DAY
5/FRIDAY THE LOW PRESSURE SYSTEM SHOULD PROGRESS FASTER AND THUS
LEAD TO LOWER RAIN TOTALS, BUT A MARGINAL RISK IS IN PLACE FOR
ISOLATED FLOODING ACROSS THE LOWER OHIO/TENNESSEE VALLEYS TO
SOUTHEAST FOR SIMILAR REASONS. PRECIPITATION SHOULD CONTINUE TO
DECREASE INTO THE MID-ATLANTIC SATURDAY
MEANWHILE UPSTREAM, A DIGGING EAST PACIFIC SYSTEM WILL CLOSE OFF
AND OFFER SOME ENHANCED PRECIPITATION CHANCES TO THE WEST COAST
THURSDAY/FRIDAY. GIVEN THE SENSITIVITY OF SOUTHERN CALIFORNIA AFTER
A FEW PREVIOUS RAIN EVENTS RECENTLY AND THE SLOWER MOTION OF THE
UPPER LOW/RESULTING SURFACE LOW PRESSURE SYSTEM, HAVE INTRODUCED
MARGINAL RISKS FOR THE DAY 4-5 EROS THERE. MODEST PRECIPITATION
SHOULD SPREAD ACROSS THE SOUTHWEST SATURDAY AND BACK INTO THE
SOUTH-CENTRAL U.S. PARTICULARLY INTO SUNDAY.
PRE-FRONTAL TEMPERATURES WILL LINGER MUCH WARMER THAN AVERAGE FOR
PORTIONS OF THE SOUTHERN U.S. INTO LATE WEEK WILL INCLUDE SOME
RECORD TEMPERATURES, WITH WARMING SHIFTING TO THE EAST LATE
WEEK/WEEKEND. THE NORTH-CENTRAL U.S. ALSO CAN EXPECT ABOVE AVERAGE
TEMPERATURES ESPECIALLY OVER THE WEEKEND INTO MONDAY. MEANWHILE,
ROUNDS OF TROUGHING IN CALIFORNIA TO THE WEST/SOUTHWEST WILL LEAD
TO BELOW AVERAGE HIGHS ABOUT 5-10+ DEGREES BELOW CLIMATOLOGY.
TATE/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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