AFDSEW AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SEATTLE WA 940 AM PST TUE JAN 9 2024 .UPDATE...WE`RE IN A REGIME OF STRONG POST-FRONTAL ONSHORE FLOW ACROSS WESTERN WASHINGTON HERE THIS MORNING. WITHIN IT, WIDESPREAD CONVECTIVE SHOWERS ARE EVIDENT. LOW-LEVEL AND MID-LEVEL LAPSE RATES (7.5 C/KM) ARE BOTH STEEP, INDICATIVE OF THE PRESENT INSTABILITY AS A COOL UPPER-TROUGH IS OVERHEAD. THUNDERSTORMS HAVE BEEN OBSERVED WITH THE POTENTIAL CONTINUING INTO THE AFTERNOON. ALONG WITH THUNDERSTORMS, LOWLAND RAIN, HEAVY MOUNTAIN SNOW, AND GUSTY WINDS ARE TO CONTINUE. A STRONG WESTERLY SURGE THROUGH STRAIT OF JUAN DE FUCA IS EXPECTED TODAY WITH AREAS IN AND AROUND IT (WHIDBEY ISLAND, SAN JUANS, ADMIRALTY INLET, ETC.) WILL LIKELY SEE GUSTS UP TO 60 MPH AS THE DAY PROGRESSES. THE PREVIOUS DISCUSSION REMAINS BELOW ALONG WITH AN UPDATED MARINE/AVIATION SECTION. && .SYNOPSIS...A STRONG COLD FRONT HAS PASSED EAST OF THE REGION EARLY THIS MORNING AS STRONG SURFACE LOW PRESSURE MOVES TO OUR NORTH WITH CONTINUED WIDESPREAD SHOWERS AND MOUNTAIN SNOW TODAY IN ABUNDANCE ALONGSIDE STRONG WIND GUSTS. ANOTHER LOW WILL TRACK JUST TO OUR SOUTH ACROSS NORTHERN OREGON WEDNESDAY WITH THE POTENTIAL FOR LOWLAND SNOW ACROSS SOUTHERN WASHINGTON. ADDITIONAL DISTURBANCES INTO THIS WEEKEND MAY BRING ADDITIONAL CHANCES FOR LOWLAND SNOW ALONG WITH COLDER TEMPERATURES. && .SHORT TERM /TODAY THROUGH THURSDAY/...FORECAST, WHILE CONTINUING ON THE WILD SIDE EVEN FOR WESTERN WASHINGTON, CONTINUES LARGELY ON TRACK. WIND GUSTS LAST NIGHT WERE WELL WITHIN HIGH WIND WARNING CRITERIA ALONG THE COAST AND ADVISORY LEVEL BETWEEN 40 AND 50 MPH ACROSS THE INLAND AREAS WITH NUMEROUS AREAS OF POWER OUTAGES BEING REPORTED. THE COLD FRONT FROM LAST NIGHT HAS PUSHED EAST OF THE CASCADES WITH NEAR- TO BLIZZARD CONDITIONS COMMENCING AT THE PASSES WITH HEAVY AND BLOWING SNOW. WEBCAMS ARE NEAR WHITE- OUT AS OF 4 AM WITH SNOW- COVERED ROADWAYS AT SNOQUALMIE AND STEVENS PASSES. PLEASE HEED LOCAL TRAVEL RESTRICTIONS AND REQUIREMENTS IF TRAVELING CANNOT BE AVOIDED TODAY AND TONIGHT. THIS REMAINS HIGHLY DISCOURAGED, HOWEVER. MEANWHILE, WIDESPREAD SHOWERS OVER THE LOWLANDS WILL PIVOT FROM NORTHWEST TO SOUTHEAST ON THE BACKSIDE OF A DEEP 980 MB LOW THAT CONTINUES TO MOVE ACROSS SOUTH-CENTRAL BRITISH COLUMBIA. HIGHS TODAY WON`T CHANGE MUCH, REMAINING IN THE LOW TO MID 40S ACROSS THE LOWLANDS. SUMMARY OF ONGOING IMPACTS: * WIND: WEST-SOUTHWESTERLY WINDS WILL CONTINUE TO TO RACE ACROSS WESTERN WASHINGTON TODAY EVEN WELL BEHIND LAST NIGHT`S COLD FRONT MOVES WELL TO OUR EAST. HIGH WIND WARNINGS CONTINUE THROUGH 4 PM ALONG THE COAST, AND THROUGH 10 PM AT WHIDBEY ISLAND AND THE SAN JUAN ISLANDS. WINDS GUSTS COULD APPROACH 65 MPH AT TIMES ACROSS THESE LOCATIONS. WIND ADVISORIES CONTINUE ACROSS THE LOWLANDS ELSEWHERE THROUGH 10 PM THIS EVENING WITH GUSTS TO 55 MPH STILL POSSIBLE. * MOUNTAIN SNOW: HEAVY SNOW CONTINUES ACROSS THE MOUNTAINS WITH HEFTY STORM TOTALS STILL ON TRACK AS SNOW LEVELS HAVE DROPPED BACK BELOW PASS LEVEL TO AROUND 2000 FEET. LITTLE CHANGE TO THIS PORTION OF THE FORECAST WITH ADDITIONAL TOTALS OF 2-3 FEET BRINGING STORM TOTALS TO 3-5 FEET. FULL FLEDGED BLIZZARD CONDITIONS WILL CONTINUE WITH WIND GUSTS TO 65 MPH CREATING WHITE-OUT CONDITIONS AT TIMES ALONG WITH BLOWING AND DRIFTING SNOW. * COASTAL FLOOD: WITH ANOTHER KING TIDE CYCLE ARRIVING TODAY, THE CONCERN FOR COASTAL FLOODING HASN`T CHANGED FROM YESTERDAY. LOW BAROMETRIC PRESSURE DUE TO DEEP SURFACE LOW PRESSURE BELOW 990 MB OVER BRITISH COLUMBIA AND STRONG WESTERLY WINDS WILL ENHANCE TIDAL ANOMALIES, WHICH CAN BE SEEN IN THE LATEST TIDAL FORECAST THIS MORNING. UPGRADED THE COASTAL FLOOD ADVISORY TO A WARNING FOR SAN JUAN COUNTY AND ISSUED COASTAL FLOOD ADVISORIES FOR WESTERN WHATCOM AND SKAGIT COUNTIES WITH THE FORECAST INCREASING SLIGHTLY FOR CHERRY POINT THIS MORNING TO MINOR LEVELS. ADDITIONAL CHANCES FOR COASTAL FLOODING WILL CONTINUE THROUGH AT LEAST THURSDAY. * HIGH SURF: A COMBINATION OF LARGE WEST-NORTHWESTERLY SWELL AROUND 25 TO 28 FEET AND WIND WAVES WILL LIKELY LEAD TO THE DEVELOPMENT OF DANGEROUSLY LARGE BREAKING WAVES OF 15 TO 30 FEET IN THE SURF ZONE ALONG THE COAST TODAY AND TONIGHT. DETERMINISTIC AND ENSEMBLE GUIDANCE HAS AGREED ON A NEW WEAKER SURFACE LOW THAT WILL MOVE ACROSS NORTHERN OREGON TONIGHT INTO WEDNESDAY MORNING WITH LOWLAND SNOW POTENTIAL ACROSS THE SOUTHWEST INTERIOR, MOSTLY SOUTH OF SEATTLE WITH 20-30% CHANCES FOR AT LEAST AN INCH OF SNOW INTO WESTERN LEWIS AND SOUTHERN THURSTON. COLDER TEMPERATURES WITH HIGHS IN THE LOW 40S THROUGH MOST OF THE LOWLANDS WEDNESDAY WITH FRASER OUTFLOW STARTING THURSDAY NIGHT. LINGERING PRECIP MAY CONTINUE INTO THURSDAY, THOUGH THIS DAY LOOKS A BIT QUIETER COMPARED TO THE NEXT COUPLE OF DAYS. .LONG TERM /FRIDAY THROUGH MONDAY/...THE EXTEND FORECAST REMAINS ACTIVE, WITH SOME UNCERTAINTY AS A SERIES OF SHORTWAVES AND DISTURBANCES MOVE SOUTHEAST ACROSS THE AREA. LOWLAND SNOW CHANCES HAVE INCREASED WITH 40 TO 60% CHANCES FOR SNOWFALL TOTALS OF AT LEAST 2 INCHES ACROSS THE LOWLANDS 30 TO 40% CHANCES FOR SNOWFALL TOTALS OF AT LEAST 4 INCHES ACROSS MOST OF THE LOWLANDS. ENSEMBLES HAVE HONED IN ON HIGHEST TOTALS MOSTLY FROM SEATTLE AND EVERETT SOUTHWARD BASED ON LATEST TRACKS OF THESE DISTURBANCES BUT THERE ARE MANY FACTOR AT PLAY THAT COULD INFLUENCE THIS PLACEMENT. MAIN STORY IS CONFIDENCE IS INCREASING FOR LOWLAND SNOW IN THE FRIDAY- SATURDAY TIMEFRAME. THERE IS ALSO CHANCES FOR MIXED PRECIPITATION SHOULD SOME OF THE WARMER MORE NORTHERLY LOW TRACKING SOLUTIONS COME TO FRUITION. CURRENTLY THERE IS A 10 TO 20% CHANCE FOR FREEZING RAIN ACCUMULATIONS OF AT LEAST A TENTH OF AN INCH ACROSS THE SOUTHWEST INTERIOR AND SOUTHERN WASHINGTON COAST. DAVIS && .AVIATION...A COLD FRONT HAS PASSED THROUGH WESTERN WA EARLY THIS MORNING. THE UPPER LEVEL TROUGH WILL SHIFT FLOW FROM WESTERLY TO NORTHWESTERLY ALOFT. SHOWERS WITH A COUPLE THUNDERSTORMS CONTINUE ACROSS THE REGION THIS MORNING. THE LIGHTNING HAS BEEN CONFINED TO THE COAST, BUT A STRONGER BAND OF OF PRECIP (INCLUDING GRAUPEL AND POTENTIALLY SMALL HAIL) IS PUSHING EAST OFF THE STRAIT OF JUAN DE FUCA OVER PORT TOWNSEND, AND IS MOVING EAST TOWARDS THE VICINITY OF KPAE. FOR NOW, CONVECTION IS NOT EXPECTED TO IMPACT ANY OF THE TERMINALS (BUT REMAIN IN THE VICINITY). THIS ACTIVITY IS EXPECTED TO CONTINUE THROUGH AT LEAST 00Z (ALTHOUGH ADDITIONAL ACTIVITY IS POSSIBLE AROUND NEAH BAY AFTERWARDS). CEILINGS WILL BE A MIX BAG OF MVFR/VFR THIS MORNING, BUT WILL TREND TOWARDS MVFR LATE THIS MORNING AND INTO THE FORECAST PERIOD. STRONG CELLS WILL HAVE THE POTENTIAL TO DROP VISIBILITIES TO IFR DUE TO HEAVY RAIN. STRONG WINDS WILL ALSO CONTINUE OUT OF THE SOUTH, WITH GUSTS RANGING FROM 25 TO 40 KTS. EXPECT THE STRONGEST WINDS TO BE NEAR THE STRAIT OF JUAN DE FUCA, AND ALONG THE COAST. KSEA...MVFR CONDITIONS EXPECTED THROUGH THE PERIOD. CONVECTION IS ONGOING TO THE NORTHWEST OF THE TERMINAL WITH GRAUPEL OVER PORT LUDLOW (NO LIGHTNING STRIKES AS OF YET). THIS ACTIVITY IS EXPECTED TO REMAIN NORTH OF THE TERMINAL (BUT MAY IMPACT AIRCRAFT ON APPROACH INTO SEA). GUSTY WINDS OUT OF THE SOUTH WILL REMAIN SUSTAINED AT 15 TO 20 KT (WITH GUSTS TO 25 TO 40 KT POSSIBLE). HPR && .MARINE...A COLD FRONT HAS PUSHED THROUGH THE AREA WATERS EARLIER THIS MORNING, AND HAS BROUGHT STRONG GALE FORCE WEST-SOUTHWESTERLY WINDS ACROSS THE AREA WATERS. A STRONG WESTERLY PUSH THROUGH THE COASTAL WATERS NORTH OF JAMES ISLAND AND DOWN THE STRAIT OF JUAN DE FUCA HAS WARRANTED A STORM WARNING. AS OF 8AM, WINDS ARE CURRENTLY IN THE PROCESS OF RAMPING UP, WITH GUSTS 45-50 KT BEING REPORTED ALONG THE CANADIAN COAST OF THE STRAIT OF JUAN DE FUCA, AS WELL AS AT BUOY 87. WINDS WILL PEAK IN THE EARLY AFTERNOON, WITH THE FOCUS FOR THE HIGHEST WINDS IN THE EAST ENTRANCE TO THE STRAIT, REACHING 40 TO 50 KT WITH GUSTS REACHING 60 TO 65 KT. ALONG WITH STRONG W/SW WINDS, A DOMINANT AND PERSISTENT WESTERLY SWELL HAS DRIVEN SEAS OFFSHORE ALREADY AROUND 20 TO 25 KT AT 15 SECONDS. ADDITIONALLY, SOME ISOLATED STRONG SHOWERS AND A FEW RUMBLES OF THUNDER REMAIN POSSIBLE, WITH SOME REDUCED VISIBILITY AND SMALL HAIL POSSIBLE THROUGH THIS AFTERNOON AND EVENING. WINDS WILL EASE TONIGHT INTO TOMORROW FOR THE INTERIOR WATERS, BUT REMAIN GUSTY IN THE COASTAL WATERS INTO TOMORROW. THE AFOREMENTIONED PERSISTENT WESTERLY SWELL WILL ONLY CONTINUE TO TRAIN THROUGH THE AFTERNOON - PUSHING COASTAL SEAS INTO THE MID TO UPPER 20S BY THIS EVENING. HEADING INTO LATE TONIGHT, WINDS WILL START TO SLOWLY EASE OVER THE WATERS, BUT WILL LIKELY REMAIN ELEVATED - WHERE ADDITIONAL HEADLINES WILL BE EXPECTED TO CAPTURE THE DOWNWARD TREND. COASTAL SEAS WILL CONTINUE TO REMAIN ELEVATED IN THE MID TEENS ON THURSDAY, THEN SUBSIDE TO AROUND 8 TO 10 FEET BY FRIDAY. STRONG HIGH PRESSURE OVER SOUTHERN BRITISH COLUMBIA WILL HELP DEVELOP FRASER OUTFLOW WINDS THURSDAY INTO FRIDAY AS WE LOOK FORWARD TO THE LATTER HALF OF THE WEEK. MAZ/LH && .HYDROLOGY...ADDITIONAL RAINFALL TOTALS OF 1-2 INCHES IN THE OLYMPICS AND 2-3 INCHES IN THE CASCADES ASSOCIATED WITH A STRONG FRONTAL SYSTEM WILL LEAD TO SHARP RISES ON STREAMS AND RIVERS LATE THROUGH TODAY. THE SKOKOMISH RIVER AT POTLATCH CONTINUES TO RISE AND IS NEARING FLOOD STAGE THIS MORNING, WHICH SHOULD CREST IN MINOR FLOOD STAGE LATER THIS MORNING OR EARLY AFTERNOON. THOUGH CONTINUED SHOWERS WILL MOVE ACROSS THE AREA, THESE SHOULDN`T LEAD TO MAJOR RISES ON THE SKOKOMISH BEYOND THE RAINFALL FROM LAST NIGHT. THE ONLY OTHER MAIN AREA FOR CONCERN IS THE TOLT RIVER IN THE CENTRAL CASCADES WHICH HAS A LOW PROBABILITY OF REACHING MINOR FLOOD FLOW. THE RAINFALL AND ANY LOW TO MID ELEVATION SNOW MELT WILL INCREASE THE THREAT FOR LANDSLIDES TO A MARGINAL LEVEL. FOR WEDNESDAY AND BEYOND THE WEATHER TURNS MUCH COLDER AND SOMEWHAT DRIER SO THE FLOODING THREAT WILL BE DONE FOR A WHILE. JBB/DAVIS && .SEW WATCHES/WARNINGS/ADVISORIES... WA...COASTAL FLOOD WARNING UNTIL 4 PM PST THIS AFTERNOON FOR SAN JUAN COUNTY. HIGH WIND WARNING UNTIL 10 PM PST THIS EVENING FOR ADMIRALTY INLET AREA-SAN JUAN COUNTY. COASTAL FLOOD ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR ADMIRALTY INLET AREA-EASTERN STRAIT OF JUAN DE FUCA-WESTERN SKAGIT COUNTY-WESTERN STRAIT OF JUAN DE FUCA-WESTERN WHATCOM COUNTY. WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR BELLEVUE AND VICINITY-BREMERTON AND VICINITY-EAST PUGET SOUND LOWLANDS- EASTERN STRAIT OF JUAN DE FUCA-EVERETT AND VICINITY-HOOD CANAL AREA-LOWER CHEHALIS VALLEY AREA-SEATTLE AND VICINITY- SOUTHWEST INTERIOR-TACOMA AREA-WESTERN SKAGIT COUNTY- WESTERN STRAIT OF JUAN DE FUCA-WESTERN WHATCOM COUNTY. COASTAL FLOOD ADVISORY UNTIL 7 PM PST THIS EVENING FOR EVERETT AND VICINITY-SEATTLE AND VICINITY-TACOMA AREA. BLIZZARD WARNING UNTIL 10 AM PST WEDNESDAY FOR OLYMPICS-WEST SLOPES NORTH CASCADES AND PASSES-WEST SLOPES NORTH CENTRAL CASCADES AND PASSES-WEST SLOPES SOUTH CENTRAL CASCADES AND PASSES. COASTAL FLOOD WARNING UNTIL 2 PM PST THIS AFTERNOON FOR CENTRAL COAST-NORTH COAST. HIGH WIND WARNING UNTIL 4 PM PST THIS AFTERNOON FOR CENTRAL COAST-NORTH COAST. HIGH SURF WARNING UNTIL 10 AM PST WEDNESDAY FOR CENTRAL COAST- NORTH COAST. PZ...SMALL CRAFT ADVISORY UNTIL 2 PM PST WEDNESDAY FOR GRAYS HARBOR BAR. STORM WARNING UNTIL 7 PM PST THIS EVENING FOR CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-EAST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA-WEST ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA. GALE WARNING UNTIL 4 AM PST WEDNESDAY FOR ADMIRALTY INLET- 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-NORTHERN INLAND WATERS INCLUDING THE SAN JUAN ISLANDS. GALE WARNING UNTIL 7 PM PST THIS EVENING FOR PUGET SOUND AND HOOD CANAL. STORM WARNING UNTIL 4 PM PST THIS AFTERNOON FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM. GALE WARNING FROM 4 PM THIS AFTERNOON TO 4 AM PST WEDNESDAY FOR COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND 10 TO 60 NM-COASTAL WATERS FROM CAPE FLATTERY TO JAMES ISLAND OUT 10 NM. &&