High Wind Watch 1, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
920 AM PST THU JAN 9 2014

.SYNOPSIS...A WEATHER SYSTEM WILL MOVE THROUGH WESTERN WASHINGTON
THIS AFTERNOON AND TONIGHT. A STRONG FRONTAL SYSTEM WILL REACH THE
AREA FRIDAY NIGHT. A STRONG LOW PRESSURE TROUGH WILL MOVE THROUGH
WESTERN WASHINGTON SATURDAY. WEAK WEATHER SYSTEMS WILL BRUSH THE
AREA EARLY NEXT WEEK.

&&

.SHORT TERM...A WEATHER SYSTEM IS JUST OFF THE COAST OF B.C. AND WA
THIS MORNING. RAIN IS INCREASING ON THE COAST AND WILL SPREAD INLAND
THIS AFTERNOON. THE GREATEST PRESSURE FALLS ARE OFF NORTHERN
VANCOUVER ISLAND AND 988 MB LOW WILL REACH QUEEN CHARLOTTE SOUND
LATER THIS AFTERNOON. SNOW AMOUNTS SHOULD BE PRETTY DECENT TONIGHT
IN THE CASCADES ABOVE 3000 FT...THERE WILL BE STRONG ONSHORE FLOW
AND GOOD OROGRAPHICS. A STRONGER FRONTAL SYSTEM WILL REACH THE AREA
FRIDAY NIGHT AND THE DEEP LOW PRESSURE TROUGH ASSOCIATED WITH THIS
FRONTAL SYSTEM WILL REACH WESTERN WA SATURDAY. IT WILL BE WINDY
AREAS FRIDAY NIGHT AND SATURDAY...THEN NAM FOR EXAMPLE SHOWS A
AST-UIL GRADIENT OF +8MB DEVELOPING SATURDAY EVENING ON THE
COAST...AND THEN THE PDX-BLI GRADIENT RISES TO +15 MB AT 18Z
SATURDAY ON THE 12Z NAM FORECAST. THIS IS FASTER THEN THE GFS40 SLP
FORECAST WHICH SHOWS THE GRADIENT CLIMBING AND ALSO PEAKING AROUND
+15MB...BUT LATER SATURDAY AFTERNOON.
A
.LONG TERM...WEAKER FRONTAL SYSTEMS WILL BRUSH THE REGION SUN
THROUGH TUE WITH A BROAD FLAT DIRTY UPPER RIDGE NOSING BACK OVER THE
WEST COAST. HARD TO SAY WITHER THE RIDGE WILL AMPLIFY ENOUGH TO GIVE
DRY OFFSHORE FLOW AND POTENTIAL FOG...CLOUDY DRIPPY WEATHER WITH A
LOT OF STRATUS AND A CHANCE OF RAIN SEEMS LIKELY FOR A FEW DAYS
EARLY NEXT WEEK.

&&

.HYDROLOGY...THE 24 HOUR PRECIP TOTAL FORECAST FROM THE NAM ENDING
18Z SATURDAY SHOWS 2 OR 3 INCHES OF PRECIP IN THE NORTH AND CENTRAL
CASCADES...HALF OF WHICH SHOULD FALL AS RAIN FRIDAY NIGHT. IN THE
OLYMPICS THE NAM HAS 2 TO 4 INCHES OF PRECIP. A PLACE LIKE HURRICANE
RIDGE OUGHT TO GET SOME SNOW...THEN AN INCH OF RAIN...AND THEN SOME
ORE SNOW. IT WILL CERTAINLY BE WINDY FRIDAY NIGHT...HURRICANE RIDGE
WILL REALLY LIVE UP TO ITS NAME. LOWER ELEVATIONS WILL GET MOSTLY
RAIN. THE SKOKOMISH RIVER IN MASON COUNTY HAS A GOOD CHANCE TO REACH
FLOOD STAGE AND AN FLOOD POTENTIAL OUTLOOK WAS ISSUED YESTERDAY.
LOOKING AT THE GFS...THE 24 HOUR PRECIP TOTAL FROM THE GFS40 ENDING
18Z SATURDAY IS ABOUT AN INCH WETTER THAN THE NAM. THE SNOW LEVEL
SHOULD ONLY BE HIGH IN THE CASCADES FOR JUST ABOUT A 12HR
PERIOD...MAYBE 7PM FRI TO 7AM SAT...AND ALTHOUGH THE RIVERS FLOWING
OUT OF THE CASCADES OUT TO BE RISING THROUGH SATURDAY FLOODING DOES
NOT LOOK LIKE A BIG RISK...A RIVER OR TWO MIGHT FLIRT WITH FLOOD
STAGE BUT MAINLY THIS LOOKS LIKE A GOOD SNOW BASE BUILDING
FRONT...TYPICAL OF A GOOD NOVEMBER STORM.

&&

.AVIATION...NORTHWEST FLOW ALOFT OVER WESTERN WASHINGTON THIS
MORNING WILL CONTINUE THROUGH TONIGHT. AN OCCLUDED FRONT WILL REACH
THE AREA THIS AFTERNOON AND MOVE EAST OF THE CASCADES TONIGHT...
FOLLOWED BY STRONG ONSHORE FLOW. THE AIR MASS WILL REMAIN AND
GENERALLY STABLE.

MAINLY VFR CONDITIONS PREVAIL THIS MORNING. THE AREA OF WIDESPREAD
FRONTAL PRECIPITATION APPROACHING THE COAST WILL MOVE INLAND DURING
THE NEXT SEVERAL HOURS...AND CONDITIONS WILL DETERIORATE TO MOSTLY
LOW-END MVFR AND IFR. THERE WILL BE LITTLE IMPROVEMENT TONIGHT
BEHIND THE FRONT AS MOIST ONSHORE FLOW CONTINUES. IN ADDITION THE
FRONT WILL BRING LOCAL SURFACE WIND GUSTING TO OR ABOVE 25 KT.

KSEA...SOUTH WIND 8-12 KT RISING TO 12-18 KT GUSTING 25 KT THIS
EVENING. CONDITIONS WILL DETERIORATE THIS AFTERNOON AS STEADY RAIN
ARRIVES.   MCDONNAL

&&

.MARINE...WEAK HIGH PRESSURE OVER WESTERN WASHINGTON THIS MORNING
WILL MOVE EAST OF THE CASCADES...AND AN OCCLUDED FRONT WILL MOVE
THROUGH THE FORECAST AREA THIS AFTERNOON AND EVENING. IT SHOULD
PRODUCE WIDESPREAD SMALL CRAFT ADVISORY SOUTHERLIES. STRONG ONSHORE
FLOW WILL FOLLOW THE FRONT TONIGHT...AND GALE WESTERLIES ARE LIKELY
AGAIN IN THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA. A GALE
WARNING WILL BE ISSUED WITH THE MORNING FORECAST. ONSHORE FLOW WILL
EASE FRIDAY.

A STRONG WARM FRONT WILL MOVE NORTHEAST ACROSS WESTERN WASHINGTON
LATE FRIDAY AND FRIDAY EVENING...FOLLOWED BY A VIGOROUS COLD FRONT
ON SATURDAY AFTERNOON. THIS SYSTEM WILL PRODUCE WIDESPREAD HIGH-END
GALES ACROSS THE FORECAST.

SWELLS OF 10 TO 12 FT TODAY WILL GRADUALLY BUILD THROUGH SATURDAY
EVENING...EVENTUALLY REACHING 26 TO 32 FT WITH A DOMINANT PERIOD OF
AROUND 18 SECONDS. ASTRONOMICAL TIDES ARE NOT VERY HIGH...BUT THE
SIZE AND ENERGY OF THE WAVES WILL JUSTIFY THE ISSUANCE OF A COASTAL
FLOOD WATCH THIS AFTERNOON.

A WEAKER FRONTAL SYSTEM WILL MOVE THROUGH THE AREA SUNDAY...AND HIGH
PRESSURE WILL BUILD OVER THE PACIFIC NORTHWEST MONDAY AND TUESDAY.
MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.

PZ...GALE WARNING IN EFFECT FOR THE CENTRAL AND EASTERN STRAIT OF
     JUAN DE FUCA TONIGHT.
     SMALL CRAFT ADVISORY ALL OTHER WATERS.
     SMALL CRAFT ADVISORY GRAYS HARBOR FOR ROUGH BAR CONDITIONS.

&&

YOU CAN SEE AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML