601
FXUS66 KSEW 190036
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
436 PM PST WED DEC 18 2024
SYNOPSIS
DRIER CONDITIONS TONIGHT AS UPPER-RIDGING BUILDS.
A SYSTEM WILL BRING LIGHTER PRECIPITATION THURSDAY INTO THURSDAY
NIGHT. ADDITIONAL WEAKER FRONTS WILL BRING PRECIPITATION CHANCES
LATE IN THE WEEK. A MORE ACTIVE PATTERN DEVELOPS LATER IN THE
WEEKEND THROUGH NEXT WEEK.
SHORT TERM /TONIGHT THROUGH SATURDAY/
A CONVERGENCE ZONE OVER
SNOHOMISH COUNTY HAS FIZZLED OUT THIS AFTERNOON. ONSHORE FLOW WILL
KEEP SHOWERS IN THE FORECAST, MAINLY FOR THE MOUNTAINS BUT SHOULD
END BY THE EVENING. DRIER WEATHER TONIGHT HOWEVER IT WON'T BE
LONG LASTING UNTIL THE NEXT DISTURBANCE ARRIVES. CLOUD COVERAGE
WILL BE ON THE INCREASE, KEEPING TEMPERATURES FROM BOTTOMING OUT
TOO MUCH. OVERNIGHT LOWS ARE FORECAST TO BE IN THE LOWER TO MID
40S WITH A FEW UPPER 30S.
A LOW CENTER IN THE GULF OF ALASKA WILL SWEEP A WARM FRONT INTO
THE AREA ON THURSDAY, REACHING THE COAST BY THE EARLY MORNING
HOURS BEFORE SPREADING INLAND TOWARDS DAYBREAK WITH LIGHT RAIN.
THE ASSOCIATED TRAILING AND DECAYING "COLD" FRONT WILL USHER
ANOTHER ROUND OF PRECIPITATION INTO THE AFTERNOON-EVENING. SNOW
LEVELS WILL BE WELL-ABOVE THE PASSES SO WINTRY PRECIPITATION IS
NOT EXPECTED. BRIEF RIDGING OVERNIGHT THURSDAY INTO FRIDAY BUT AN
ADDITIONAL FRONT WILL ENTER FRIDAY AFTERNOON WITH ANOTHER SHOT OF
LIGHT PRECIPITATION ALONG WITH A VERY SIMILAR STORY INTO SATURDAY.
NO MAJOR IMPACTS ARE EXPECTED FROM THIS NEXT SET OF SYSTEMS
CURRENTLY BUT NEVERTHELESS THE PATTERN LOOKS TO REMAIN ACTIVE.
TEMPERATURES ARE FORECAST TO BE ABOVE-AVERAGE WITH HIGHS IN THE
LOWER TO MID 50S AND OVERNIGHT LOWS IN THE 40S.
LONG TERM /SUNDAY THROUGH WEDNESDAY/
A STRONGER SYSTEM IS EXPECTED TO
APPROACH THE AREA ON SUNDAY WITH THE POTENTIAL FOR BREEZY WINDS.
ENSEMBLES SUGGEST THIS ACTIVE PATTERN CONTINUES THROUGH AT LEAST
THE MIDDLE OF NEXT WEEK, WITH SYSTEMS ACCOMPANIED BY LOWLAND RAIN,
MOUNTAIN SNOWFALL, AND GUSTY WINDS PARTICULARLY MONDAY INTO
TUESDAY. THIS IS HIGHLIGHTED WELL BY THE CPC WEEK 2 HAZARDS
OUTLOOK. TEMPERATURES WILL BE SLIGHTLY COOLER SATURDAY INTO NEXT
WEEK.
MCMILLIAN
AVIATION
NORTHWESTERLY FLOW ALOFT TURNING SOUTHWESTERLY INTO
THURSDAY MORNING AS ANOTHER WEAK UPPER TROUGH SWINGS TROUGH
WESTERN WA. A MIX OF MVFR/VFR CONDITIONS OUT THERE THIS AFTERNOON
AS SCATTERED SHOWER ACTIVITY BEGINS TO DISSIPATE ACROSS THE
REGION, WITH A FULL REBOUND TO VFR LIKELY BY THIS EVENING HEADING
INTO THURSDAY MORNING.
BREEZY SOUTHWESTERLY WINDS IN THE INTERIOR WITH GUSTS UP TO 20 KTS
WILL CONTINUE TO DECREASE INTO THE EVENING HOURS, WITH WINDS
TURNING SOUTHEASTERLY AND REMAINING AROUND 8 TO 12 KTS.
KSEA...VFR THIS AFTERNOON WITH CEILINGS RISING. SW WINDS 15 TO 20
KTS WITH POTENTIAL GUSTS UP TO 25 KTS DECREASING BY 00Z. WINDS
WILL TURN SOUTHEASTERLY LATE TONIGHT WITH SPEEDS AROUND 5 TO 10
KNOTS.
MAZURKIEWICZ
MARINE
A BREAK IN THE WEATHER AS THE PREVIOUS WEATHER
SYSTEM PUSHES EASTWARD AWAY FROM OUR AREA. THE NEXT FRONTAL SYSTEM
WILL BE APPROACHING RIGHT BEHIND, PUSHING THROUGH THE COASTAL
WATERS INTO THURSDAY AFTERNOON. SMALL CRAFT SOUTHERLIES CAN BE
EXPECTED ACROSS THE COASTAL WATER ZONES, WITH LATEST GUIDANCE
DECREASING THE INTENSITY OF THESE WINDS, ALTHOUGH CANNOT RULE OUT
A GUST UP TO GALE STRENGTH HERE AND THERE - BUT NOT WIDESPREAD.
ADDITIONAL WEATHER SYSTEMS WILL IMPACT THE WATERS THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK, WITH MORE CHANCES OF GUSTY WINDS
AND ELEVATED SEAS.
COASTAL SEAS THIS AFTERNOON AROUND 9 TO 12 FEET, WITH SEAS
REMAINING LARGELY ABOVE 10 FEET THROUGH FRIDAY. AS WE HEAD INTO
THE WEEKEND, SEAS WILL BEGIN TO BUILD UPWARDS TOWARDS 15 TO 20
FEET.
MAZURKIEWICZ
HYDROLOGY
HEAVY RAIN HAS ENDED ACROSS WESTERN WASHINGTON.
HOWEVER, WITH 4 TO 7 INCHES OF RAINFALL RECORDED OVER THE PAST 24
HOURS, SIGNIFICANT RISES ON AREA RIVERS OCCURRED. THE SKOKOMISH
RIVER AND SATSOP RIVERS HAVE CRESTED, BUT REMAIN IN FLOOD STAGE.
THE SKOKOMISH IS EXPECTED TO RECEDE SLOWLY, BUT WILL FLUCTUATE
NEAR FLOOD STAGE FOR THE NEXT FEW DAYS. THE CHEHALIS RIVER WILL
CONTINUE TO RISE THROUGH THURSDAY.
ADDITIONAL INCOMING PRECIPITATION FROM WET SYSTEMS LATER IN THE
WEEK AND INTO NEXT WEEK WILL MAINTAIN THE THREAT OF RIVER FLOODING
ACROSS WESTERN WASHINGTON, BUT MODELS CONTINUE TO SHOW LARGE
DISCREPANCIES AND THE FORECAST REMAINS UNCERTAIN AT THIS TIME. 14
SEW WATCHES/WARNINGS/ADVISORIES
WA...FLOOD WATCH FROM 10 PM PST THIS EVENING THROUGH THURSDAY
AFTERNOON FOR SOUTHWEST INTERIOR.
FLOOD WATCH FROM 10 PM PST THIS EVENING THROUGH LATE THURSDAY
NIGHT FOR CENTRAL COAST-LOWER CHEHALIS VALLEY AREA-OLYMPICS.
PZ...SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR GRAYS
HARBOR BAR.
SMALL CRAFT ADVISORY UNTIL 4 AM PST THURSDAY FOR COASTAL WATERS
FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL
WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM-COASTAL
WATERS FROM JAMES ISLAND TO POINT GRENVILLE 10 TO 60 NM-
COASTAL WATERS FROM JAMES ISLAND TO POINT GRENVILLE OUT 10
NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE SHOALWATER
10 TO 60 NM-COASTAL WATERS FROM POINT GRENVILLE TO CAPE
SHOALWATER OUT 10 NM-WEST ENTRANCE U.S. WATERS STRAIT OF
JUAN DE FUCA.
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