409
FXUS21 KWNC 061914
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST NOVEMBER 06 2023
SYNOPSIS: MID-LEVEL LOW PRESSURE IS FORECAST TO SHIFT INLAND TO THE WEST DURING
MID-NOVEMBER. THIS MID-LEVEL LOW PRESSURE AND ASSOCIATED ONSHORE FLOW INCREASES
THE CHANCE OF HEAVY PRECIPITATION ACROSS THE PACIFIC NORTHWEST AND CALIFORNIA
WITH THE POTENTIAL FOR HEAVY SNOW FOR THE SIERRA NEVADA MOUNTAINS ALONG WITH
PARTS OF UTAH AND COLORADO. LOW PRESSURE DEVELOPMENT IS EXPECTED ACROSS THE
CENTRAL U.S. ON NOVEMBER 16 OR 17, BUT PRECIPITATION AMOUNTS ARE UNCERTAIN.
STRONG MID-LEVEL LOW PRESSURE IS FORECAST OVER THE BERING SEA AND ALASKA WITH
AN INCREASED RISK FOR HIGH WINDS AND HEAVY PRECIPITATION.
HAZARDS
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE PACIFIC NORTHWEST AND CALIFORNIA,
TUE-FRI, NOV 14-17.
SLIGHT RISK OF HEAVY SNOW FOR THE SIERRA NEVADA MOUNTAINS, TUE-FRI, NOV 14-17.
SLIGHT RISK OF HEAVY SNOW FOR THE HIGHER ELEVATIONS OF UTAH AND SOUTHWESTERN
COLORADO, TUE-SAT, NOV 14-18.
SLIGHT RISK OF HIGH WINDS FOR THE WEST, TUE-SAT, NOV 14-18.
SLIGHT RISK OF HIGH WINDS FOR THE ALEUTIANS, ALASKA PENINSULA, KODIAK ISLAND,
AND COASTAL WESTERN ALASKA, TUE-THU, NOV 14-16.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE KENAI PENINSULA AND SOUTHEASTERN
ALASKA, TUE-FRI, NOV 14-17.
SLIGHT RISK OF HEAVY PRECIPITATION FOR EASTERN OKLAHOMA, EASTERN TEXAS, MIDDLE
TO LOWER MISSISSIPPI VALLEY, AND OHIO VALLEY, NOV 16-18, THU-SAT.
DETAILED SUMMARY
FOR THURSDAY NOVEMBER 09 - MONDAY NOVEMBER 13:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY NOVEMBER 14 - MONDAY NOVEMBER 20: THE GEFS AND ECMWF ENSEMBLE MEANS
ARE IN GOOD AGREEMENT AND DEPICT AN AMPLIFIED 500-HPA TROUGH PROGRESSING EAST
FROM THE NORTHEASTERN PACIFIC TO THE WESTERN CONTIGUOUS (CONUS) EARLY IN
WEEK-2. BASED ON THE GEFS AND ECMWF PROBABILISTIC EXTREMES TOOLS (PETS) AND THE
UNCALIBRATED ECMWF MODEL OUTPUT, A BROAD SLIGHT RISK OF HEAVY PRECIPITATION IS
POSTED FOR THE PACIFIC NORTHWEST AND CALIFORNIA FROM NOV 14 TO 17. IF MODEL
AGREEMENT IMPROVES ON HEAVIER PRECIPITATION AMOUNTS, A MODERATE RISK OF HEAVY
PRECIPITATION MAY BE WARRANTED FOR PARTS OF CALIFORNIA IN SUBSEQUENT OUTLOOKS.
AS THE AMPLIFIED MID-LEVEL TROUGH TRACKS INLAND AND 500-HPA HEIGHTS DECREASE,
SNOW LEVELS ARE LIKELY TO LOWER WHICH SUPPORTS A SLIGHT RISK OF HEAVY SNOW FOR
THE SIERRA NEVADA MOUNTAINS (NOV 14-17) ALONG WITH THE HIGHER ELEVATIONS OF
UTAH AND THE SAN JUAN MOUNTAINS OF SOUTHWESTERN COLORADO (NOV 14-18). THE
EVOLVING 500-HPA LONGWAVE PATTERN ALSO SUPPORTS A BROAD SLIGHT RISK OF HIGH
WINDS FROM THE WEST COAST TO THE CONTINENTAL DIVIDE FROM NOV 14-18. LATER IN
WEEK-2, THE ENSEMBLE MEAN SOLUTIONS FEATURE A WEAK MID-LEVEL RIDGE DEVELOPING
OFFSHORE OF THE WEST COAST WHICH WOULD BRING A DRYING TREND TO THE PACIFIC
NORTHWEST AND CALIFORNIA.
A HIGH AMPLITUDE TROUGH IS LIKELY TO LEAD TO A STRENGTHENING LOW PRESSURE
SYSTEM OVER THE BERING SEA BY THE BEGINNING OF WEEK-2. THE DETERMINISTIC 0Z
ECMWF MODEL HAS A 948-HPA LOW APPROACHING COASTAL WESTERN ALASKA ON NOV 14 AND
15 AND THERE IS SUPPORT FOR THIS INTENSITY AMONG SEVERAL OF THE 0Z ECMWF AND 6Z
GEFS ENSEMBLE MEMBERS. BASED ON THIS MODEL GUIDANCE, A SLIGHT RISK OF HIGH
WINDS IS POSTED FOR COASTAL WESTERN ALASKA, THE ALEUTIANS, ALASKA PENINSULA,
AND KODIAK ISLAND FROM NOV 14 TO 16. IF THE MODEL SOLUTIONS MAINTAIN GOOD
CONSISTENCY, A MODERATE RISK OF HIGH WINDS MAY BE NEEDED FOR PARTS OF ALASKA.
HEAVY PRECIPITATION IS MORE PROBABLE TO THE EAST ACROSS THE KENAI PENINSULA AND
SOUTHEASTERN ALASKA WHERE THE GEFS AND ECMWF PETS AND UNCALIBRATED MODEL
GUIDANCE SUPPORT A SLIGHT RISK OF HEAVY PRECIPITATION FROM NOV 14 TO 17.
MODEL GUIDANCE DIFFERS ON HOW MUCH PRECIPITATION OCCURS DURING WEEK-2 ACROSS
THE CENTRAL CONUS. THE ECMWF MODEL IS MUCH HEAVIER WITH PRECIPITATION AMOUNTS
WITH A MORE VIGOROUS SHORTWAVE TROUGH EJECTING FROM THE WEST, WHILE THE GEFS
DAMPENS THIS SHORTWAVE TROUGH. GIVEN THESE MODEL DIFFERENCES, ONLY A SLIGHT
RISK OF HEAVY PRECIPITATION IS POSTED FOR EASTERN OKLAHOMA AND TEXAS, MIDDLE TO
LOWER MISSISSIPPI VALLEY, AND OHIO VALLEY FROM NOV 16 TO 18.
FORECASTER: BRAD PUGH
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