High Wind and Strong Wind in Washington, November 5, 2009

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1005 AM PST THU NOV 5 2009

SKOKOMISH RIVER INFO UPDATED IN SHORT TERM SECTION.

.SYNOPSIS...A STRONG FRONTAL SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON THIS EVENING. RAIN ASSOCIATED WITH THE FRONT WILL
CONTINUE TO SPREAD INLAND TODAY. RAIN WILL BE HEAVY AT TIMES IN
THE MOUNTAINS WITH WINDY CONDITIONS ALONG THE COAST AND OVER THE
NORTHWEST INTERIOR. THE SNOW LEVELS WILL FALL TO PASS LEVEL BY
FRIDAY AND REMAIN LOW THROUGH THE WEEKEND. UNSETTLED WEATHER WILL
CONTINUE UNTIL SUNDAY AS WEATHER SYSTEMS SPIN OUT OF THE UPPER LEVEL
TROUGH OFFSHORE. THE TROUGH WILL MOVE THROUGH WESTERN WASHINGTON ON
SUNDAY. ANOTHER WET FRONTAL SYSTEM WILL ARRIVE MONDAY. THE UNSETTLED
WEATHER WILL CONTINUE THROUGH THE MIDDLE OF NEXT WEEK.

&&

.SHORT TERM...FIRST WAVE OF MOISTURE IS STARTING TO IMPACT THE
OLYMPIC PENINSULA AND NORTHERN INTERIOR THIS MORNING. A CUTOFF LOW
IS DEVELOPING OVER THE CALIFORNIA COAST AS NORTHERN BRANCH OF THE
ENERGY PRIMARILY HEADS INTO VANCOUVER ISLAND. MUCH STRONGER
CONSOLIDATED FRONTAL BOUNDARY WILL PASS THROUGH THIS
EVENING...ASSOCIATED WITH THE MONSTER 947 MB LOW IN THE GULF OF
ALASKA AND DRIVEN BY A 155 KT JET AT 250 MB. FRONTAL PASSAGE IS
PROGGED FOR 03Z FOR THE COAST AND 06Z FOR THE INTERIOR. THE BROAD
UPPER LEVEL TROUGH WILL IMPACT THE AREA THROUGH SAT NIGHT.

RAINFALL HAS RANGED FROM 0.30-0.60 ON THE COAST AND OLYMPIC
PENINSULA SO THIS MORNING. ARO PROFILER AT WESTPORT ALREADY SHOWS
UPSLOPE WINDS 210 DEGREES AT 50 KNOTS. PRECIP WILL PICK UP THIS
AFTERNOON AND WE ARE STILL ON TRACK FOR 3-5 INCHES FOR OLYMPICS AND
2-4 N. CASCADES WITH LESSER AMOUNTS FOR THE CENTRAL
CASCADES...EXCLUDING THE VOLCANOES. WESTPORT PROFILER SHOWS SNOW
LEVELS CURRENTLY 6700 FEET...AND THIS WILL DROP TO AROUND 3000 FEET
BY 12Z FRIDAY. A FLOOD WARNING WILL LIKELY BE ISSUED FOR THE
SKOKOMISH LATER THIS AFTERNOON. ABOUT 0.75-1.25 INCHES IN EXPECTED
IN 24 HOURS BY FRIDAY MORNING IN THE INTERIOR LOWLANDS SOUTH OF
SEATTLE...WITH LESSER AMOUNTS NORTH TOWARD THE CANADIAN BORDER.

NEW HYDRO FORECAST FOR THE SKOKOMISH SHOWS THE RIVER JUST TOUCHING
FLOOD STAGE FRIDAY AT 12Z. THE FLOOD WATCH WILL BE CONTINUED AT THIS
POINT.

WINDS WILL BE STRONG ON THE COAST...NORTH INTERIOR AND MOUNTAINS
TODAY AS SOUTHERLY WINDS INCREASE IN ADVANCE OF THE FRONT. A WIND
ADVISORY HAS BEEN HOISTED FOR THE N. INTERIOR AND KBLI HAS ALREADY
EXPERIENCED GUSTS IN EXCESS OF 50 MPH. BREEZY SOUTHWEST WINDS WILL
FOLLOW THE FRONT LATE THIS EVENING EASING OVERNIGHT.

ANOTHER SHORTWAVE WILL IMPACT THE AREA FRIDAY NIGHT AND
SATURDAY...FOLLOWED BY THE TROUGH AXIS SWINGING THROUGH SATURDAY
EVENING. AS A RESULT SHOWERS WILL REMAIN IN THE FORECAST THROUGH THE
WEEKEND WITH COOL LOWLAND HIGH TEMPERATURES ONLY REACHING INTO THE
UPPER 40S TO AROUND 50. COLD POOL OF NEAR -30C AT 500 MB WILL MOVE
WITH THE UPPER TROUGH OVER THE AREA BEGINNING FRIDAY...KEEPING THE
RISK FOR THUNDERSTORMS DURING THE DAY FRIDAY AND SATURDAY.

SNOW LEVELS WILL STICK AROUND 3000 FEET THROUGH THE WEEKEND...AND
SNOWFALL TOTALS WILL BE COPIOUS FOCUSING ON THE THE N.CASCADES AND
MOUNT RAINIER AT FIRST BUT EVENTUALLY AFFECTING THE LOWER PASSES AS
WELL. A WINTER STORM WARNING WILL LIKELY BE ISSUED FOR FRIDAY
THROUGH SATURDAY. DAMICO

.LONG TERM...FROM PREV DISCUSSION...EXTENDED MODELS IN GOOD
AGREEMENT THIS MORNING. UPPER LEVEL TROUGH MOVING THROUGH WESTERN
WASHINGTON SATURDAY NIGHT. TEMPORARY UPPER LEVEL RIDGE TRIES TO
BUILD OVER WESTERN WASHINGTON ON SUNDAY BUT A WARM FRONT OUT AHEAD
OF THE NEXT COLD FRONT ALSO DEVELOPING AT THE SAME TIME. BOTH THE
GFS AND THE ECMWF HAVE PRECIPITATION OVER THE AREA SUNDAY WITH A
BRIEF DRY SPELL SUNDAY NIGHT BEFORE THE PRECIPITATION OUT AHEAD OF
THE COLD FRONT REACHES WESTERN WASHINGTON. COLD FRONT MOVING THROUGH
ON MONDAY. THIS SYSTEM HAS THE POTENTIAL TO PRODUCE SOME MORE
SIGNIFICANT PRECIPITATION ESPECIALLY IN THE OLYMPICS BUT BECAUSE THE
UPPER PATTERN IS MORE PROGRESSIVE EXPECT THE FRONT TO MOVE THROUGH
WESTERN WASHINGTON DURING THE DAY ON MONDAY. ANOTHER COOL UPPER
LEVEL TROUGH MOVING THROUGH THE AREA ON TUESDAY FOLLOWED BY ANOTHER
COLD FRONT ON WEDNESDAY. BOTH THE GFS AND THE ECMWF HAVE A VERY WET
SYSTEM MOVING INLAND TO THE NORTH OF WESTERN WASHINGTON LATE IN THE
WEEK WITH A WEAK RIDGE OF HIGH PRESSURE OVER THE AREA. FELTON

&&

.HYDROLOGY...FROM PREV DISCUSSION...WHILE THE TIMING OF THE ONSET OF
THE PRECIPITATION OUT AHEAD OF THE APPROACHING COLD FRONT IS A
COUPLE HOURS BEHIND SCHEDULE THE IDEA OF HEAVY PRECIPITATION OVER
THE OLYMPICS AND NORTH CASCADES REMAINS INTACT. ARO PROFILER AT
WESTPORT ALREADY SHOWING 50 KT SOUTHWEST WINDS AT 850 MB SO IT IS
JUST A MATTER OF TIME BEFORE THE HEAVY PRECIPITATION STARTS ALONG
THE SOUTH SLOPES OF THE OLYMPICS. MODEL SOLUTIONS HAVE BEEN
CONSISTENT KEEP A 3-5 INCH PRECIPITATION TOTAL BULLSEYE OVER THE
SOUTH SLOPES OF THE OLYMPICS AND A 2-4 INCH BULLSEYE OVER THE NORTH
CASCADES. FRONTAL PASSAGE OVER THE OLYMPICS IS EXPECTED AROUND 03Z
FRI AND A COUPLE OF HOURS LATER OVER THE NORTH CASCADES. SNOW LEVELS
WILL REMAIN HIGH...AROUND 6500 FEET...SO MOST OF THE PRECIPITATION
WILL BE IN THE FORM OF RAIN. WITH THESE PRECIPITATION AMOUNTS THE
FLOOD WATCH FOR WHATCOM AND MASON COUNTY WILL REMAIN IN EFFECT THIS
MORNING. PRECIPITATION AMOUNTS ACROSS THE REST OF THE AREA WILL BE
LESS AND THE FLOOD THREAT REMAINS LOW FOR THE REMAINDER OF THE AREA
INCLUDING THE GREEN RIVER. PRECIPITATION RATES DROPPING OFF QUICKLY
BEHIND THE FRONT. THIS ALONG WITH THE AIR MASS COOLING DOWN WILL
BRING AN END TO THE FLOOD THREAT LATER FRIDAY.

SNOW LEVELS WILL REMAIN LOW THROUGH THE WEEKEND...SO EVEN WITH THE
ENHANCED PRECIPITATION ASSOCIATED WITH THE FEATURE FRIDAY NIGHT INTO
SATURDAY MORNING THE FLOOD THREAT WILL REMAIN LOW.

A STRONGER PACIFIC FRONTAL SYSTEM ARRIVES ON MONDAY. GFS SHOWS 2-3
INCHES OF PRECIPITATION OVER THE OLYMPICS AND ABOUT 2 INCHES OVER
THE NORTH CASCADES...BUT AGAIN SNOW LEVELS WILL STAY RELATIVELY LOW
NEAR 4000 FEET FOR MOST OF THE EVENT. IN ADDITION THE UPPER LEVEL
PATTERN LOOKS MORE PROGRESSIVE SO THE CHANCES OF THE SYSTEM
STALLING OVER WESTERN WASHINGTON ARE LOW. SHOWERS FOLLOW ON TUESDAY
WITH ANOTHER SYSTEM ON WEDNESDAY. BOTH THE ECMWF AND THE GFS HAVE A
VERY WET SYSTEM MOVING INLAND TO THE NORTH OF THE AREA BY THE
WEEKEND AFTER NEXT. EARLY ON MODEL SOLUTIONS HAVE VARIED WIDELY WITH
THIS FEATURE. FUTURE SHIFTS WILL BE KEEPING CLOSE TABS ON HOW THE
MODELS HANDLE THIS IN THE UPCOMING DAYS.

FROM THIS WEEKEND THROUGH THE MIDDLE OF NEXT WEEK THE FLOOD THREAT
IS LOW ACROSS WESTERN WASHINGTON INCLUDING THE GREEN RIVER. FELTON

&&

.AVIATION...A MESSY AND WINDY DAY IS IN STORE FOR AVIATION AS A
STRONG COLD FRONT APPROACHES AND THEN CROSSES WRN WA DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS. RAIN HAS ALREADY DEVELOPED OVER
MUCH OF WRN WA AND SPREAD ACROSS THE REMAINDER OF THE AREA BY LATE
MORNING WITH RAIN HEAVY ENOUGH TO REDUCE VSBYS. WINDS ALOFT ARE ALSO
STRONG WITH THE WESTPORT ARO PROFILER SHOWING SSW WIND OF 55 KT AT
ONLY 2K FT. WINDS ALOFT OF THIS MAGNITUDE WILL NOT BE UNCOMMON
ELSEWHERE.

KSEA...RAIN IS ON THE DOORSTEP NOW. EXPECTED REDUCED VSBYS AND
LOWERING CIGS AS RAIN PERSISTS. THERE IS A CHANCE OF A BRIEF LULL IN
THE RAIN AND REDUCED VSBYS ARND 00Z...BUT THEN CONDITIONS WILL
DETERIORATE AGAIN IN THE 03Z-06Z TIME FRAME WITH THE MAIN FROPA.
WINDS ALOFT ARE A CONCERN TODAY. 2000 FT WINDS WILL FLIRT WITH 50
KT...4500 FT WINDS OF 50-60 KT...AND 18000 FT WINDS NEAR 70 KT ARE
EXPECTED FROM NOW UNTIL FROPA. PROBABLY BEST TO ASSUME THAT WILL BE
ARND 05-06Z.        HANER

&&

.MARINE...AFTER SEEING THE 16Z OB FROM DESTRUCTION ISLAND WITH
SUSTAINED 47 KT...DECIDED TO UPGRADE THE NEARSHORE COASTAL ZONES TO
A STORM WARNING. SHOULD BE MARGINAL...BUT BETTER SAFE THAN SORRY.
WAS ALSO CONCERNED BY GUSTS TO 48 KT AT EASTPOINT...AND A RECENT
GUST TO 47 KT AT KBLI...BUT HAVE KEPT THE NORTH INTERIOR AS A GALE
WARNING FOR NOW. OTHERWISE...GALES ARE UP FOR ALL THE USUAL SUSPECT
ZONES IN SOUTH-SOUTHEAST WIND SITUATIONS. COLD FRONT WILL CROSS THE
WATERS LATE AFTERNOON AND EVENING. SOUTH-SOUTHEAST WINDS WILL
DECREASE AT THAT TIME...THOUGH POST-FRONTAL IS WHEN PUGET SOUND
TYPICALLY GETS ITS STRONGER WIND. HOWEVER...PRESSURE GRADIENTS STILL
MAINTAIN A SLIGHT EASTERLY COMPONENT FOR PUGET SOUNDS...SO EXPECTING
HIGH-END SMALL CRAFT AT THIS TIME BUT PROBABLY NOT A GALE.

OTHERWISE...BIG NEWS IS THE GIANT SWELL TRAIN BEING GENERATED BY THE
947 MB LOW CENTER IN THE SOUTHERN GULF OF ALASKA. SWELL OF 25 TO 30
FEET SHOULD REACH THE COASTAL WATERS ON FRI MORNING. WILL LIKELY
ISSUE A HIGH SURF WARNING FOR THE COAST WITH THE AFTERNOON PACKAGE.
HANER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCH MASON AND WHATCOM COUNTIES THIS AFTERNOON
     THROUGH LATE FRI NIGHT. WIND ADVISORY NORTH INTERIOR AND
     ADMIRALTY INLET AREA THRU TONIGHT.
PZ...STORM WARNING FOR THE NEARSHORE COASTAL WATERS. GALE
     WARNING OUTER COASTAL WATERS...ENTRANCES TO THE STRAIT
     OF JUAN DE FUCA...ADMIRALTY INLET AND NORTH INLAND
     WATERS.
     SMALL CRAFT ADVISORY CENTRAL STRAIT AND PUGET SOUND.      SMALL
CRAFT ADVISORY FOR ROUGH BAR CONDITIONS GRAYS HARBOR BAR.

WWW.WEATHER.GOV/SEATTLE

FOR AN ILLUSTRATED VERSION OF THE FORECAST DISCUSSION...PLEASE SEE
WWW.WEATHER.GOV/SEATTLE/GAFD/LATESTWEBAFD.HTML.