090
FXUS66 KSEW 281735
AFDSEW
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
935 AM PST MON NOV 28 2022
UPDATE
WHILE SOME SHOWERS REMAIN IN THE AREA THIS MORNING,
CONDITIONS ARE DRYING OUT. THE WINTER STORM WARNING FOR THE
CASCADES AND THE WINTER WEATHER ADVISORY FOR THE NORTH OLYMPIC
PENINSULA WILL EXPIRE AT 10AM. LOOKING AHEAD THERE REMAINS A LOT
OF UNCERTAINTY WITH THE FORECAST FOR TUESDAY-WEDNESDAY. LOWLAND
SNOW IS EXPECTED, HOW MUCH IS THE QUESTION. WITH SOUTHERLY LOW
LEVEL WINDS TEMPERATURES ARE EXPECTED TO BE WARM ENOUGH TO KEEP
MOST OF PRECIPITATION IN THE FORM OF RAIN; PARTICULARLY FOR SOUTH
OF PUGET SOUND AND ALONG THE COAST. FOR ALL OTHER AREAS,
PRECIPITATION TYPE IS GOING TO BE VERY DEPENDENT ON PRECIPITATION
RATES AS WELL AS HOW MUCH COLD AIR MOVES INTO THE AREA TODAY AND
EARLY TOMORROW. CONDITIONS ARE GOING TO VARY THROUGHOUT THE
REGION OVER THE COURSE OF THIS WEEK. MAKE SURE TO CHECK THE LATEST
FORECAST BEFORE HEADING OUT.
THE PREVIOUS FORECAST DISCUSSION WITH UPDATED AVIATION AND MARINE
SECTION IS BELOW.
PREV DISCUSSION
/ISSUED 455 AM PST MON NOV 28 2022/
SYNOPSIS
ACTIVE WEATHER WILL CONTINUE ACROSS THE REGION
THROUGH MUCH OF THE WEEK AHEAD. EXPECT CONTINUED SHOWERS TO
MAINTAIN MOUNTAIN SNOW AND LOWLAND RAIN OR RAIN AND SNOW THIS
MORNING. DRY BUT COOLER CONDITIONS DEVELOP LATE MONDAY THROUGH
EARLY TUESDAY, BUT THE NEXT WEATHER SYSTEM QUICKLY APPROACHES.
COOL AND UNSETTLED WEATHER CONTINUES LATE IN THE WEEK WITH
ADDITIONAL CHANCES FOR LOWLAND SNOW AT TIMES AS ADDITIONAL
DISTURBANCES CROSS THE REGION.
SHORT TERM /TODAY THROUGH WEDNESDAY/
PLENTY OF SHOWERS
REMAINING IN THE CASCADES AND ACROSS THE NORTHERN PORTIONS OF
PUGET SOUND THIS MORNING. THE WINTER STORM WARNING FOR THE
CASCADES (FROM SNOHOMISH THROUGH LEWIS COUNTIES) CONTINUES WITH A
FEW MORE INCHES OF SNOW EXPECTED TODAY. MEANWHILE, SOME SHOWERS
ACROSS WHIDBEY ISLAND AND EAST THROUGH THE I-5 CORRIDOR FROM
WHATCOM THROUGH SNOHOMISH COUNTIES MAY OCCASIONALLY CONTAIN SOME
LIGHT SNOW OR A RAIN/SNOW MIX OVER THE LOWLANDS, BUT GIVEN THE
RELATIVELY WEAK PRECIPITATION RATES AND TEMPERATURES HOLDING A FEW
DEGREES ABOVE MODEL GUIDANCE, HAVE ELECTED TO CANCEL THE ADVISORY
FOR WHATCOM/SKAGIT/SNOHOMISH COUNTIES. CONFIDENCE REMAINS LOWER
ALONG THE EASTERN STRAIT OF JUAN DE FUCA, ESPECIALLY THROUGH THE
SEQUIM TO PORT ANGELES CORRIDOR. WHILE THE EXPECTED FRASER OUTFLOW
HAS BEEN SLOW TO MATERIALIZE, THIS IS EXPECTED TO STILL DEVELOP
WITH THE POTENTIAL FOR SOME UPSLOPE ENHANCEMENT ACROSS THE
NORTHERN OLYMPIC PENINSULA. OTHERWISE, WE'LL SEE SHOWERS DIMINISH
FROM NORTH TO SOUTH THROUGH THE DAY, AND A DRY AFTERNOON FOR MOST.
THE NEXT WEATHER SYSTEM WILL THEN QUICKLY APPROACH THE AREA ON
TUESDAY, WITH THE LEADING PRECIPITATION EXPECTED TO REACH THE
OLYMPIC PENINSULA BY EARLY AFTERNOON. WITH COOLER AIR IN PLACE,
ESPECIALLY IF THE CURRENT TIMING HOLDS TRUE, EXPECT TO SEE SOME
LIGHT SNOW TO FALL AT ONSET WITH THE MOISTURE RUNNING AHEAD OF THE
APPROACHING WARM FRONT. SOUTHERLY LOW-LEVEL WINDS SHOULD BRING A
SLIGHT BUMP IN SNOW LEVELS AND PRECLUDE MUCH IN THE WAY OF SNOW
ACCUMULATIONS SOUTH OF AROUND TACOMA. MEANWHILE, CONFIDENCE IS
LOWER FOR AROUND SEATTLE, WHERE THE TIMING OF THE WARM SOUTHERLY
FLOW ARRIVING AND THE MOISTURE LEADS TO A SOMEWHAT TRICKY
FORECAST WHERE A FEW DEGREES IN THE TEMPERATURE PROFILE IS ALL THE
DIFFERENCE BETWEEN A FEW INCHES OF ACCUMULATING SNOW AND A COLD 35
DEGREE RAIN. THE MOST LIKELY SCENARIO FOR ACCUMULATING LOWLAND
SNOW DURING THIS TIME WOULD BE DURING PERIODS OF HEAVIER
PRECIPITATION, WHERE ENOUGH COLD AIR IS DRAGGED DOWN TO THE
SURFACE. SNOW LEVELS ARE THEN EXPECTED TO DROP BACK DOWN BELOW
1000 FEET BY WEDNESDAY AFTERNOON. WITH COLDER AIR FILTERING IN
WEDNESDAY THE THREAT OF ACCUMULATING LOWLAND SNOW INCREASES AND
WILL REMAIN.
ONE ADDITIONAL NOTE WITH WINDS INCREASING AHEAD OF THE COLD FRONT
LATE TUESDAY NIGHT INTO EARLY WEDNESDAY. WHILE NO HEADLINES HAVE
BEEN ISSUED YET, GUIDANCE CONTINUES TO TREND UPWARD WITH RESPECT
TO WINDS INCREASING. GUSTS UP TO 55 MPH ARE POSSIBLE THROUGH THE
SAN JUANS AND ADMIRALTY INLET AREAS, WHILE THE WINDY SPOTS IN
WHATCOM AND SKAGIT COUNTIES MAY SEE GUSTS TO NEAR 45 MPH.
MEANWHILE, CONFIDENCE IS HIGHER THAT ANOTHER ROUND OF
HEAVY SNOW WILL COME TO THE OLYMPICS AND CASCADES LATE TUESDAY
THROUGH WEDNESDAY OR PERHAPS EVEN THROUGH THURSDAY.
LONG TERM /THURSDAY THROUGH SUNDAY/
EXPECT AN UNSETTLED
WEATHER PATTERN TO REMAIN FOR MUCH OF THE SECOND HALF OF THE WEEK
WITH BELOW NORMAL TEMPERATURES RETURNING. WITH ADDITIONAL ROUNDS
OF MOISTURE ROTATING THROUGH, THERE WILL LIKELY BE ADDITIONAL
SHOWERS THAT BRING THE POTENTIAL FOR SNOW FLURRIES DOWN IN THE
LOWLANDS. THIS NEXT ONE WEDNESDAY NIGHT INTO THURSDAY LOOKS TO BE
MERELY LIGHT SNOW SHOWERS, BUT AGAIN PLENTY OF DETAILS YET TO BE
WORKED OUT SO FOR NOW THE KEY MESSAGE IS TO REMAIN AWARE OF THE
POSSIBILITY. THE OTHER MAIN POINT HERE IS THAT TEMPERATURES LOOK
TO REMAIN QUITE COLD THROUGH THE WEEK AHEAD WITH LOWS IN THE 20S
AND HIGHS ONLY TOPPING IN THE MID TO 30S ON THURSDAY ACROSS THE
INTERIOR. BELOW NORMAL TEMPERATURES THEN LIKELY TO CONTINUE LATE
IN THE WEEK, AND WITH SNOW LEVELS REMAINING LOW, WILL NEED TO
CLOSELY MONITOR THE POTENTIAL FOR SNOW TO AGAIN FALL IN THE
LOWLANDS AT SOME POINT.
AVIATION
UPPER TROUGHING IS MOVING ACROSS THE PACIFIC NORTHWEST
THIS MORNING WITH NORTHWESTERLY FLOW. ANY LINGERING MVFR
DECKS WILL IMPROVE TO VFR THROUGH THE REST OF THE MORNING WITH
CLEARING. SHOWERS WILL TAPER OFF LATE MORNING FOR MOST AREAS.
INCREASING FRASER RIVER OUTFLOW WINDS AT KBLI TODAY WITH MAINLY
NORTHERLY WINDS.
KSEA...ANY CHANCE FOR MVFR CEILINGS IS DECREASING THROUGH THE REST
OF THE MORNING. BY NOON, HIGH CONFIDENCE IN VFR CRITERIA AS CLOUDS
SCATTER. NORTHERLY WINDS FOR THE REMAINDER OF THE DAY BEFORE
SHIFTING TOWARDS THE SOUTH LATER TONIGHT INTO TUESDAY MORNING.
MCMILLIAN
MARINE
THE FLOW WILL TRANSITION OFFSHORE AND STRENGTHEN THROUGH
THE DAY. GUSTY FRASER OUTFLOW WINDS TODAY FOR THE NORTHERN INLAND
WATERS WITH A GALE WARNING IN PLACE. SMALL CRAFT ADVISORY WINDS ARE
IN EFFECT FOR ALL WATERS THROUGH THIS MORNING FOR THE INCREASING
NORTH/EAST OFFSHORE WINDS. OFFSHORE WINDS WILL TAPER
OFF THIS EVENING AND INTO TONIGHT. A RATHER BRIEF PERIOD OF LIGHT
WINDS IS EXPECTED TUESDAY MORNING. A STRONG WEATHER SYSTEM WILL MOVE
THROUGH TUESDAY EVENING AND WEDNESDAY FOR INCREASING
SOUTH/SOUTHEASTERLY WINDS ACROSS THE AREA. GALES ARE LIKELY FOR THE
COASTAL WATERS DURING THIS TIME PERIOD, AS WELL AS THE NORTHERN
INLAND WATERS, PUGET SOUND, EASTERN STRAIT OF JUAN DE FUCA, AND
ADMIRALTY INLET. IN ADDITION, THERE IS A CHANCE FOR STORM FORCE
WINDS GUSTS ACROSS THE EASTERN STRAIT OF JUAN DE FUCA TUESDAY NIGHT
INTO WEDNESDAY MORNING. WINDS WILL TAPER A BIT WEDNESDAY AFTERNOON
FOR ADDITIONAL SMALL CRAFT ADVISORY WINDS. OFFSHORE WINDS INCREASE
WEDNESDAY NIGHT AND INTO THURSDAY.
SEAS OF 10 TO 13 FT WILL SUBSIDE TONIGHT INTO TUESDAY MORNING TO 7
TO 9 FEET. SEAS WILL BUILD WEDNESDAY TO 13 TO 17 FT SUBSIDING
THURSDAY INTO THURSDAY NIGHT. JD
HYDROLOGY
NO RIVER FLOODING IS EXPECTED THROUGH THE NEXT SEVEN
DAYS.
SEW WATCHES/WARNINGS/ADVISORIES
WA...WIND ADVISORY UNTIL 10 PM PST THIS EVENING FOR SAN JUAN COUNTY-
WESTERN WHATCOM COUNTY.
WINTER WEATHER ADVISORY UNTIL 10 AM PST THIS MORNING FOR
ADMIRALTY INLET AREA-EASTERN STRAIT OF JUAN DE FUCA.
WINTER STORM WARNING UNTIL 10 AM PST THIS MORNING FOR WEST
SLOPES NORTH CENTRAL CASCADES AND PASSES-WEST SLOPES SOUTH
CENTRAL CASCADES AND PASSES.
PZ...SMALL CRAFT ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR GRAYS
HARBOR BAR.
SMALL CRAFT ADVISORY UNTIL 10 AM PST THIS MORNING FOR WEST
ENTRANCE U.S. WATERS STRAIT OF JUAN DE FUCA.
SMALL CRAFT ADVISORY UNTIL 10 PM PST THIS EVENING FOR ADMIRALTY
INLET-CENTRAL U.S. WATERS STRAIT OF JUAN DE FUCA-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-EAST ENTRANCE U.S. WATERS
STRAIT OF JUAN DE FUCA-PUGET SOUND AND HOOD CANAL.
GALE WARNING UNTIL 10 PM PST THIS EVENING FOR NORTHERN INLAND
WATERS INCLUDING THE SAN JUAN ISLANDS.
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