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FXUS21 KWNC 111904
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST NOVEMBER 11 2025
SYNOPSIS: DYNAMICAL MODELS CONTINUE TO FAVOR AN ACTIVE PATTERN HEADING INTO
NEXT WEEK. FORECAST MID-LEVEL LOW PRESSURE IS EXPECTED TO BRING AN INCREASED
RISK OF HEAVY PRECIPITATION, HIGH ELEVATION SNOW, AND PERIODS OF HIGH WINDS
ACROSS MANY PARTS OF THE INTERIOR WEST AND THE WEST COAST. SURFACE LOW
FORMATION IN THE LEE OF ROCKIES WITH AMPLE MOISTURE FROM THE GULF SUPPORTS
ELEVATED CHANCES FOR HEAVY PRECIPITATION OVER THE SOUTHCENTRAL AND SOUTHEASTERN
CONTIGUOUS U.S. EARLY IN WEEK-2. MID-LEVEL LOW PRESSURE CENTERED OVER THE
BERING STRAIT AND ASSOCIATED SURFACE LOW DEVELOPMENT MAY LEAD TO LOCALLY HEAVY
PRECIPITATION AND HIGH WINDS OVER PARTS OF THE ALASKA MAINLAND AND THE
SOUTHEAST.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHERN PLAINS,
MISSISSIPPI, TENNESSEE, AND OHIO VALLEYS, AND THE SOUTHEAST, WED-THU, NOV
19-20.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE GREAT PLAINS, MISSISSIPPI,
TENNESSEE AND OHIO VALLEYS, APPALACHIANS, AND SOUTHEAST, WED-THU, NOV 19-20,
SAT-SUN, NOV 22-23.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PARTS OF THE SOUTHWEST AND SOUTHERN
ROCKIES, WED-THU, NOV 19-20.
SLIGHT RISK OF HEAVY SNOW OVER MUCH OF THE ROCKIES AND GREAT BASIN, WED-SUN,
NOV 19-23.
SLIGHT RISK OF HIGH WINDS FOR MANY PARTS OF THE WESTERN AND CENTRAL CONUS,
WED-SUN, NOV 19-23.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE PACIFIC NORTHWEST, WED-SUN,
NOV 19-23.
SLIGHT RISK OF HIGH ELEVATION SNOW FOR THE CASCADE MOUNTAINS, WED-SUN, NOV
19-23.
SLIGHT RISK OF HIGH WINDS FOR PARTS OF THE ALEUTIANS, SOUTHERN AND WESTERN
MAINLAND, AND SOUTHEAST ALASKA, WED-FRI, NOV 19-21.
DETAILED SUMMARY
FOR FRIDAY NOVEMBER 14 - TUESDAY NOVEMBER 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY NOVEMBER 19 - TUESDAY NOVEMBER 25: EARLY IN WEEK2, BOTH THE GEFS
AND ECMWF ENSEMBLE MEAN 500-HPA HEIGHT FORECASTS CONTINUE TO FEATURE AMPLIFIED
TROUGHING OVER THE INTERIOR WEST AND EXTENDING INTO NORTHERN MEXICO, WITH
DOWNSTREAM RIDGING OVER THE EASTERN HALF OF THE CONUS. ALTHOUGH GOOD MODEL
AGREEMENT EXISTS IN THE HEIGHT PATTERN OVER EASTERN NORTH AMERICA, AND IN
REGARDS TO THE HIGHLY AMPLIFIED RIDGE CENTER FAVORED OVER BAFFIN BAY, THE GEFS
AND ECMWF REMAIN SPLIT IN HOW THE PATTERN BECOMES ESTABLISHED OVER THE EASTERN
PACIFIC AND WESTERN CONUS. THE GEFS CONTINUES TO FAVOR AN EXTENSION OF POSITIVE
HEIGHT DEPARTURES INTO BRITISH COLUMBIA AND THE PACIFIC NORTHWEST, WHEREAS THE
ECMWF FEATURES THE DEVELOPMENT AND PROPAGATION OF MORE SHORTWAVE ENERGY OVER
THE WESTERN CONUS, WITH A DEEPER AND TROUGH AXIS THAT TILTS MORE NEGATIVELY
ACROSS THE INTERIOR WEST BY THE OUTSET OF THE PERIOD. AS A RESULT OF THESE
DISCREPANCIES IN THE MID-LEVEL PATTERN, PRECIPITATION RESPONSES ARE MORE ROBUST
IN THE ECMWF, WHICH NAMELY CONSIST OF ENHANCED ONSHORE FLOW RETURNING TO THE
WEST COAST, AS WELL AS THE DEVELOPMENT OF A STRONGER SURFACE LOW IN THE LEE OF
THE SOUTHERN ROCKIES TO ELEVATE THE THREAT OF HEAVY PRECIPITATION OVER THE
SOUTHERN PLAINS AND MISSISSIPPI VALLEY NEXT WEEK. DUE TO 0Z CANADIAN ENSEMBLE
BETTER ALIGNING WITH THE ECMWF, AS WELL AS A TELECONNECTION ANALYSIS ON THE
AFOREMENTIONED BLOCKING RIDGE CENTER OVER NEAR GREENLAND WHICH FAVORS GENERALLY
WETTER THAN NORMAL CONDITIONS WEST OF THE MISSISSIPPI, THERE IS LESS RELIANCE
ON THE DRIER 0Z GEFS ENSEMBLE IN THE UPDATED OUTLOOK.
BASED ON THE UNCALIBRATED ECMWF AND CANADIAN ENSEMBLE GUIDANCE EARLY IN WEEK-2,
A MODERATE RISK OF HEAVY PRECIPITATION REMAINS POSTED FROM THE SOUTHERN PLAINS
EASTWARD TO THE TENNESSEE VALLEY AND THE SOUTHEAST FOR NOV 19-20. WITHIN THE
HIGHLIGHTED AREA, THE RAW ECMWF INDICATES 50% (20%) CHANCES FOR 3-DAY
PRECIPITATION AMOUNTS EXCEEDING ONE INCH ( TWO INCHES). A BROADER SLIGHT RISK
AREA FOR HEAVY PRECIPITATION REMAINS POSTED WHERE PROBABILITIES FOR
PRECIPITATION EXCEEDANCE ARE LESS THAN 40 PERCENT FOR NOV 19-20, WITH THE VALID
TIMES EXTENDED TO INCLUDE DAYS 11 AND 12 (NOV 22-23) WHERE THERE IS THE
POTENTIAL FOR ADDITIONAL SURFACE LOW DEVELOPMENT IN THE LEE OF THE ROCKIES AND
THE RETURN OF INCREASED PRECIPITATION LATER IN WEEK-2. THIS POTENTIAL IS
SUPPORTED IN BOTH THE GEFS AND ECMWF PROBABILISTIC EXTREMES TOOLS (PETS) WHICH
MAINTAIN AT LEAST 20% CHANCES FOR PRECIPITATION AMOUNTS EXCEEDING THE 85TH
PERCENTILE THROUGH THE MIDDLE OF WEEK-2. ON THE BACKSIDE OF THE MEAN SURFACE
LOW THAT IS FAVORED EARLY IN THE PERIOD , IT IS WORTH NOTING THAT ACCUMULATING
SNOWFALL IS POSSIBLE OVER THE LOWER ELEVATIONS OF THE SOUTHERN AND CENTRAL HIGH
PLAINS.
TIED TO THE AMPLIFIED TROUGHING FAVORED OVER THE INTERIOR WEST, A SLIGHT RISK
OF HEAVY PRECIPITATION REMAINS ISSUED OVER THE LOWER FOUR CORNERS REGION (NOV
19-20) WHERE PETS CONTINUE TO SHOW INCREASED CHANCES FOR AMOUNTS EXCEEDING THE
85TH PERCENTILE AND 0.5 INCHES. DUE TO THE POTENTIAL FOR ADDITIONAL SHORTWAVE
ENERGY TO REINFORCE THE ANOMALOUS TROUGHING ACROSS THE WEST DURING THE PERIOD,
A SLIGHT RISK OF HIGH ELEVATION HEAVY SNOW ALSO REMAINS POSTED FOR MUCH OF THE
INTERIOR WEST AND IS EXTENDED THROUGH THE MIDDLE OF WEEK-2 (NOV 23) WHICH IS
SUPPORTED IN THE RAW ECMWF PROBABILISTIC SNOWFALL GUIDANCE. SIMILARLY, A SLIGHT
RISK OF HIGH WINDS IS ALSO EXTENDED THROUGH NOV 23 NEAR THE BASE AND AHEAD OF
THE MEAN TROUGHING ALOFT.
OVER THE PACIFIC NORTHWEST, DIFFERENCES BETWEEN THE GEFS AND ECMWF ARE ALSO
EVIDENT IN THE INTEGRATED VAPOR TRANSPORT (IVT) ASSOCIATED WITH THE VARIED
MID-LEVEL PATTERN. SPECIFICALLY, THE ECMWF HEAVILY FAVORS THE RETURN ENHANCED
ONSHORE WITH 40-60% CHANCES FOR IVT VALUES TO EXCEED 250 KG/M/S THROUGH THE
MIDDLE OF WEEK-2, CONSISTENT WITH MODERATE ATMOSPHERIC RIVER (AR) ACTIVITY,
WHEREAS THE GEFS IS VIRTUALLY ABSENT OF THESE SIGNALS. IN SPITE OF THESE
DIFFERENCES, DEFERENCE IS GIVEN TO THE ECMWF AND CANADIAN ENSEMBLES, WHICH SHOW
ELEVATED CHANCES FOR 3-DAY AMOUNTS EXCEEDING 2 INCHES ACROSS THE PACIFIC
NORTHWEST TO SUPPORT THE ADDITION OF SLIGHT RISK OF HEAVY PRECIPITATION, VALID
FOR NOV 19-23. A CORRESPONDING SLIGHT RISK AREA FOR HIGH ELEVATION SNOWFALL IS
ALSO POSTED FOR THE CASCADES ALSO VALID FOR THE SAME PERIOD.
OVER ALASKA, AN AMPLIFYING 500-HPA TROUGH CENTERED OVER THE BERING STRAIT IS
EXPECTED TO LEAD TO ONE OR MORE SURFACE LOWS DEVELOPING AND POTENTIALLY BRING
PERIODS OF HIGH WINDS AND HEAVY PRECIPITATION TO MANY PARTS OF SOUTHERN ALASKA.
SINCE YESTERDAY, BOTH THE GEFS AND ECMWF HAVE BECOME QUICKER TO WEAKEN THIS
MID-LEVEL FEATURE AND DEVELOP MORE RIDGING BY THE MIDDLE OF THE PERIOD. WHILE
THERE IS STILL SOME UNCERTAINTY AS TO WHETHER REALIZED AMOUNTS EXCEED HAZARD
THRESHOLDS EARLY IN WEEK-2, THE MID-LEVEL AND SURFACE PATTERN SUPPORTS THE
CONTINUATION OF A SLIGHT RISK OF HIGH WINDS, BUT IS NOW VALID THROUGH NOV 21
BEFORE THE TROUGHING ALOFT IS FAVORED TO DEAMPLIFY.
FORECASTER: NICK NOVELLA
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