Winter Storm Warning 4, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
905 PM PST MON FEB 29 2016

.SYNOPSIS...IT WILL BE WET AND WINDY TUESDAY AS A VIGOROUS FRONTAL
SYSTEM MOVES THROUGH THE REGION. THERE WILL BE A BREAK IN THE
WEATHER DURING THE DAY WEDNESDAY BEFORE ANOTHER FRONT ARRIVES
WEDNESDAY NIGHT. THERE MAY BE A BREAK IN THE WEATHER ON THURSDAY
BEFORE ADDITIONAL SYSTEMS REACH THE AREA FRIDAY THROUGH SUNDAY.

&&

.SHORT TERM...MARCH COMES IN LIKE A LION. A STRONG SYSTEM WILL BRING
RAIN...MOUNTAIN SNOW AND WINDY CONDITIONS TO WESTERN WASHINGTON ON
TUESDAY.

A WARM FRONT WILL SPREAD RAIN INLAND TONIGHT...WITH RAIN PERSISTING
THROUGH TUESDAY MORNING AS THE FRONT LIFTS NORTH THROUGH THE REGION.
THE COLD FRONT WILL THEN PUSH INLAND TUESDAY AFTERNOON FOR SHOWERS
AND WINDY CONDITIONS. THE MOUNTAINS WILL SEE SEVERAL INCHES OF SNOW
WITH THIS SYSTEM AND A WINTER WEATHER ADVISORY IS IN EFFECT. SNOW
LEVELS WILL BE TRICKY AS THEY WILL START AROUND 3000-4000 FT...THEN
RISE TO AROUND 6000 FT WITH THE WARM FRONT...THEN FALL BACK DOWN TO
AROUND 2500 FT BEHIND THE COLD FRONT TUESDAY NIGHT. THE COAST AND
NORTH INTERIOR WILL SEE WINDY CONDITIONS WITH THE WARM FRONT TUESDAY
MORNING. WINDS WILL INCREASE IN THE INTERIOR DURING THE AFTERNOON
WITH THE COLD FRONT. EXPECT WINDS OF 20-30 MPH WITH GUSTS TO 45-50
MPH POSSIBLE. WINDS WILL GRADUALLY EASE TUESDAY NIGHT. HEAVY
RAINFALL IN THE OLYMPICS MAY FORCE THE SKOKOMISH RIVER INTO FLOOD
STAGE AND A FLOOD WATCH IS IN EFFECT FOR MASON COUNTY.

THERE WILL BE A BRIEF BREAK IN THE ACTION ON WEDNESDAY AS A WEAK
RIDGE MOVES OVERHEAD AND THE FLOW FLIPS BACK TO OFFSHORE. THEN MORE
RAIN WEDNESDAY NIGHT AS THE NEXT PACIFIC SYSTEM ROLLS IN. BUT
OVERALL THIS SECOND SYSTEM LOOKS WEAKER COMPARED TO THE TUESDAY
SYSTEM. MOIST SOUTHWEST FLOW WILL CONTINUE THROUGH WEDNESDAY NIGHT
FOR MORE SHOWERS. TEMPS WILL BE CLOSE TO NORMAL THROUGH THE PERIOD.
33

.LONG TERM...PREVIOUS DISCUSSION...THURSDAY AND THURSDAY NIGHT MAY
SEE A BREAK BETWEEN SIGNIFICANT WEATHER SYSTEMS. ADDITIONAL VIGOROUS
FRONTAL WAVES ARE LIKELY TO ARRIVE AT TIMES FRI THRU SUNDAY...AND IT
WILL CONTINUE TO BE BLUSTERY AT TIMES. THESE SYSTEMS DO NOT HAVE A
GREAT DEAL OF COLD AIR TO WORK WITH AND LOOK UNUSUALLY MILD AND WET
FOR EARLY MARCH.

&&

.HYDROLOGY...MODERATE TO HEAVY RAIN ALONG THE SOUTH SLOPES OF THE
OLYMPICS BEGINNING TONIGHT AND CONTINUING AT LEAST INTO TUESDAY
AFTERNOON MAY BE ENOUGH TO BRING MINOR FLOODING ON THE SKOKOMISH
RIVER STARTING TUESDAY...BASED ON THE CURRENT FLOOD STAGE OF 16.5
FEET FOR THE SKOKOMISH RIVER AT POTLATCH. FLOOD STAGE ON THE
SKOKOMISH AT POTLATCH WILL OFFICIALLY BE RAISED TO 17.0 FEET ON
MARCH 6.

ELSEWHERE...NO RIVER FLOODING IS EXPECTED FOR THE NEXT 7 DAYS.

&&

.AVIATION...AN ENERGETIC UPPER TROUGH WILL START APPROACHING WRN WA
TONIGHT...WITH SW FLOW ALOFT BECOMING STRONG. WARM FRONT ASSOCIATED
WITH THIS FEATURE STARTING TO MAKE ITS WAY ONSHORE INTO WESTERN
WASHINGTON...ACCOMPANIED BY GENERALLY LIGHT SCATTERED PRECIP.
EXPECTING PRECIP TO PICK UP AS THE NIGHT PROGRESSES...POTENTIALLY
RESULTING IN REDUCED VISIBILITIES LATE TONIGHT AND INTO TUESDAY
UNDER MORE MODERATE RAINFALL RATES. COLD FRONT ASSOCIATED WITH THIS
FEATURES WILL SWEEP IN RATHER QUICKLY BEHIND THE WARM FRONT ON
TUESDAY AFTERNOON. THIS WILL BRING WINDY CONDITIONS AND STRONG WINDS
ALOFT...WITH 2000-FOOT MSL WINDS OF 50-60 KT AT TIMES THROUGH THE
DAY. THE AIR MASS WILL BE MOIST AND STABLE UNTIL THE COLD
FRONT...THEN QUICKLY BECOME UNSTABLE BEHIND THE TUE AFTN COLD FRONT.

KSEA...TIMING CONTINUES TO LOOK GOOD FOR WARM FRONT BRINGING RAIN TO
TERMINAL AT OR AROUND 06Z TONIGHT...WITH RAINFALL PICKING UP
OVERNIGHT AND INTO EARLY TUESDAY MORNING. MAY SEE VIS REDUCED
BETWEEN 12Z-15Z. RAIN WILL EASE FOR A BIT AROUND MID-DAY...BUT THEN
PICK UP AGAIN AROUND THE TIME THAT A VIGOROUS COLD FRONT PASSES THE
TERMINAL ARND 23Z TUE. WINDS ALOFT SHOULD BE AN ISSUE ON TUE...WITH
S/SW WINDS AT 020 ARND 40-45 KT FOR MOST OF THE DAY...BUT PEAKING
NEAR 50 KT ARND THE TIME OF A COLD FRONTAL PASSAGE ARND 23Z TUE
AFTN.	 HANER/SMR

&&

.MARINE...EASTERLY GRADIENTS AND WINDS OVER THE COASTAL WATERS ARE
EXPECTED TO CONTINUE TO INCREASE IN ADVANCE OF A WARM FRONT. GALE
SPEEDS ARE EXPECTED BY LATE TONIGHT OVER THE COASTAL WATERS AND AT
THE WEST ENTRANCE. FOLLOWING THE WARM FRONT...GRADIENTS WILL BECOME
MORE SOUTHEASTERLY...WHICH WILL EXPAND GALES TO THE EAST ENTRANCE
AND NORTHERN INLAND WATERS. THEN A VIGOROUS COLD FRONT WILL CROSS
THE WATERS ON TUE AFTN...FOLLOWED BY GALES ALL WATERS EXCEPT THE
CENTRAL STRAIT. A 12-HOUR LULL IN WIND BETWEEN WEATHER SYSTEMS IS
THEN EXPECTED DURING THE DAY ON WED. MULTIPLE STRONG FRONTS DURING
THE SECOND HALF OF THE WEEK WILL BRING MORE OPPORTUNITIES FOR
GALES...ESPECIALLY IN AREAS PRONE TO WINDS FROM THE EAST THROUGH
SOUTH...AND ESPECIALLY THE COASTAL WATERS.		HANER/SMR

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCH SKOKOMISH RIVER IN MASON COUNTY.
     WIND ADVISORY NORTH AND CENTRAL WASHINGTON COAST 6 AM TO 9 PM
     TUESDAY.

     WIND ADVISORY INTERIOR LOWLANDS WESTERN WASHINGTON MAINLY
     TUESDAY AFTERNOON AND EVENING.

     WINTER WEATHER ADVISORY CASCADES 10 PM THIS EVENING TO 10 AM
     TUESDAY.

PZ...SMALL CRAFT ADVISORY FOR ROUGH BAR UNTIL 4 PM PST WEDNESDAY
     FOR GRAYS HARBOR BAR.

     GALE WARNING ALL WATERS EXCEPT FOR THE CENTRAL STRAIT.

     SMALL CRAFT ADVISORY FOR THE CENTRAL STRAIT OF JUAN DE FUCA.

&&

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