957
FXUS66 KSEW 170413 AAA
AFDSEW
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SEATTLE WA
813 PM PST THU JAN 16 2025
SYNOPSIS
A WEAK FRONTAL SYSTEM WILL EXIT THE REGION THIS
EVENING AS LINGERING SHOWER CHANCES GRADUALLY END. SURFACE HIGH
PRESSURE WILL REBUILD OFFSHORE TONIGHT AND REMAIN THE MAIN WEATHER
FACTOR INTO THE MIDDLE OF NEXT WEEK. THIS WILL RESULT IN DRIER
AND COLDER WEATHER.
SHORT TERM /TODAY THROUGH SUNDAY/
OVERALL A QUIET EVENING
ACROSS WESTERN WASHINGTON, WITH SOME LOW CLOUD BEGINNING TO FILL
IN OVER THE CENTRAL PUGET SOUND AREA. A FEW LIGHT SHOWERS PERSIST
OVER THE NORTHERN PUGET SOUND UP TOWARDS PORT TOWNSEND, BUT THESE
SHOWERS WILL CONTINUE TO DIMINISH LATER TONIGHT. OVERALL NO
CHANGES TO THE FORECAST. SEE BELOW FOR AN UPDATED AVIATION
SECTION. 62
FOR TONIGHT, CHILLY CONDITIONS ARE IN STORE WITH LOWS FORECAST TO
BOTTOM OUT IN THE 20S AND 30S. PATCHY FOG/LOW STRATUS IS LIKELY
AGAIN INTO FRIDAY MORNING AS WELL.
DRIER CONDITIONS ARE FAVORED INTO FRIDAY AS AN UPPER-RIDGE BUILDS
OFFSHORE. W WA IS ALONG THE LEADING EDGE OF THE RIDGE AS COOL
NORTH-NORTHWEST FLOW ALOFT USHERS IN. A SUBTLE 700MB VORT MAX IS
BEING HINTED AT BY GLOBAL MODELS SO CAN'T RULE OUT A STRAY SHOWER
OR TWO DURING THE DAY, PRIMARILY OVER THE MOUNTAINS BUT AGAIN
MOSTLY DRY CONDITIONS ARE EXPECTED. THIS PATTERN WILL REMAIN
LOCKED THROUGH THE WEEKEND AS RIDGING PARALLELS THE US WEST COAST
WITH BROAD TROUGHING OVER THE REST OF CONUS. ALTHOUGH CONDITIONS
ARE TO REMAIN BENIGN, COLD OVERNIGHT LOWS ARE EXPECTED.
CONFIDENCE IS INCREASING IN WIDESPREAD 20S FOR LOW TEMPERATURES
THROUGHOUT THE WEEKEND. COLD WEATHER MAY CAUSE IMPACTS TO
VULNERABLE POPULATIONS, INFRASTRUCTURE, ETC. HIGH TEMPERATURES ARE
TO TOP INTO THE 40S.
LONG TERM /MONDAY THROUGH FRIDAY/
MODELS HAVE RIDGING
REMAINING INTO EARLY NEXT WEEK. HOWEVER, A GENTLE SHIFT EASTWARD
WILL ALLOW THE PATTERN TO REOPEN BRIEFLY AS A WEAK FRONT BRINGS
THE RETURN OF SLIGHT POPS INTO THE FORECAST. SHORTLY AFTERWARD,
STUBBORN RIDGING WILL RETURN BY WEDNESDAY-THURSDAY AS THE MOSTLY
DRY TREND CONTINUES. MIN TEMPS WILL REMAIN IN THE 20S AND 30S WITH
DAILY HIGHS IN THE 40S.
AVIATION
NORTHWESTERLY FLOW WILL CONTINUE INTO FRIDAY WITH AN
UPPER RIDGE BUILDING OFFSHORE. A MIX OF VFR/MVFR CIGS THIS EVENING
WITH GENERALLY DRIER CONDITIONS OTHER THAN A FEW LINGERING SHOWERS
AROUND PUGET SOUND. CIGS WILL LOWER TONIGHT INTO FRIDAY MORNING TO
IFR/MVFR FOR MOST AREAS. LOCALIZED LIFR WILL BE POSSIBLE AS WELL,
MAINLY OLYMPIA SOUTHWARDS AND TOWARDS KHQM DUE TO LOW STRATUS AND
POTENTIAL FOG DEVELOPMENT. SLOW IMPROVEMENT TOWARDS MVFR FOR MOST
AREAS BY LATER FRIDAY MORNING, AND LOW-END VFR BY EARLY FRIDAY
AFTERNOON WITH FURTHER CLEARING LATER FRIDAY. LIGHT WINDS THROUGH
FRIDAY MORNING WILL SLIGHTLY INCREASE ON FRIDAY AFTERNOON WITH A
NORTHERLY-NORTHEASTERLY COMPONENT.
KSEA...MVFR CIGS THIS EVENING WILL CONTINUE TO SLOWLY FALL TO LOW-
END MVFR INTO TONIGHT. PERIODS OF IFR CIGS MAY OCCUR AS WELL, MAINLY
BETWEEN 10-17Z, WITH PROBABILITIES OF IFR CIGS AROUND 25 TO 30%.
CIGS WILL SLOWLY IMPROVE TO VFR EARLY FRIDAY AFTERNOON (AROUND 20-
21Z). LIGHT, VARIABLE WINDS FOR THE MAJORITY OF TONIGHT. NORTH WINDS
WILL INCREASE MIDDAY FRIDAY BETWEEN 5 TO 8 KTS. JD
MARINE
A WEAK COLD FRONT IS CURRENTLY LOCATED OVER THE EAST
STRAIT OF JUAN DE FUCA, WEST OF THE PUGET SOUND WATERS THIS
AFTERNOON. THE ONSHORE FLOW BEHIND THIS FRONT CONTINUES, BUT WILL
GRADUALLY WEAKEN GOING INTO TONIGHT AS HIGH PRESSURE FOLLOWS THE
FRONT ONTO LAND THROUGH THE WEEKEND. GUSTY WINDS THIS AFTERNOON WILL
CONTINUE TO DIMINISH IN THE STRAIT OF JUAN DE FUCA (AND LINGER INTO
FRIDAY MORNING IN THE COASTAL WATERS). GRADIENTS THIS WEEKEND WILL
BE NORTHERLY OR OFFSHORE. SEAS WILL DROP DOWN FROM 6 TO 8 FEET
TODAY/FRIDAY TO 4 TO 6 FEET THIS WEEKEND, WITH ANOTHER ROUND OF 6 TO
8 FOOT WAVES SUNDAY INTO MONDAY.
HPR
HYDROLOGY
NO RIVER FLOODING EXPECTED IN THE NEXT 7 DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING FOR COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL
WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT 10 NM-
COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER OUT
10 NM-WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 10 AM PST FRIDAY FOR COASTAL WATERS
FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER 10
TO 60 NM.
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