Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
000
FXUS66 KSEW 242154
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT FRI OCT 24 2014

.SYNOPSIS...RAIN WILL SPREAD FROM SOUTH TO NORTH TONIGHT. A FILLING
LOW PRESSURE CENTER WILL MOVE ACROSS THE AREA SATURDAY NIGHT...
BRINGING RAIN AND LOCALLY WINDY CONDITIONS. SUNDAY AND MONDAY WILL
BE SHOWERY. WET AND BREEZY WEATHER ARE LIKELY AT TIMES NEXT WEEK.

&&

.SHORT TERM...A DEEP LOW CENTER WELL OFF THE NORTHERN CALIFORNIA
COAST WILL MOVE NORTHEAST TONIGHT AND WEAKEN AS IT MOVES ONTO THE
WASHINGTON COAST SATURDAY AFTERNOON. THE LOW WILL MOVE ACROSS
WESTERN WASHINGTON SATURDAY NIGHT AND BE OUT OF THE AREA SUNDAY.

THE FIRST FEATURE ASSOCIATED WITH THIS SYSTEM IS A WEAK WARM FRONT
THAT WILL MOVE FROM SOUTH TO NORTH ACROSS WASHINGTON TONIGHT. THIS
WILL SPREAD RAIN OVER THE AREA. AMOUNTS EAST OF PUGET SOUND ARE
LIKELY TO BE LIGHT AS STRONG EASTERLY WINDS BEGIN IN RESPONSE TO
EASTERLY GRADIENTS. MODELS DO SHOW A FAIR AMOUNT OF RAIN OVER THE
OLYMPICS AND COAST...SPREADING INTO THE FAR NORTHERN INTERIOR
SATURDAY MORNING. A WIND ADVISORY IS IN EFFECT TONIGHT FOR THE EAST
PUGET SOUND LOWLANDS AND THE BELLEVUE AREA.

THE SECOND FEATURE IS THE STRONG ONSHORE GRADIENTS THAT FOLLOW THE
PASSAGE OF THE LOW CENTER SATURDAY NIGHT. THESE ARE LIKELY TO BRING
BREEZY TO WINDY CONDITIONS TO MOST AREAS. AT THIS TIME THERE DOES
NOT APPEAR TO BE A THREAT OF HIGH WIND.

THE FINAL FEATURE IS THE 18 HOURS OR SO OF HEAVY RAIN OVER THE
OLYMPICS...FROM 06Z TONIGHT TO 00Z SUNDAY. THE RAINIER PARTS WILL
GET 2-3 INCHES...WITH MOST OF THE OLYMPIC PENINSULA GETTING AN INCH
OR MORE. RAIN WILL DIMINISH CONSIDERABLY SATURDAY NIGHT...FIRST IN
THE OLYMPICS AND THEN IN THE CASCADES.

THE WEATHER WILL BE MORE SHOWERY SUNDAY AND MONDAY WITH LIKELY POPS
ON THE COAST AND IN THE MOUNTAINS...CHANCE POPS OVER THE INTERIOR
LOWLANDS. HIGHS WILL NOT VARY MUCH...55-60 ON SATURDAY FALLING TO
AROUND 55 ON MONDAY. LOWS WILL BE IN THE MID 40S TO LOW 50S. BURKE

.LONG TERM...MODELS AGREE THE NEXT SYSTEM WILL BE NEARING THE COAST
MONDAY NIGHT. THERE IS A DEEP LOW ASSOCIATED WITH THIS SYSTEM THAT
IS FORECAST TO CROSS NORTHERN VANCOUVER ISLAND TUESDAY. SOUTHEAST
GRADIENTS WILL BE STRONG ACROSS WESTERN WASHINGTON BUT WITH THIS
PATTERN THERE IS USUALLY NO HIGH WIND. AFTER RAIN TUESDAY...SHOWERS
FOLLOW ON WEDNESDAY AND THURSDAY. ANOTHER SYSTEM MAY ARRIVE AROUND
NEXT FRIDAY. TEMPERATURES NEXT WEEK WILL BE NEAR SEASONAL NORMS WITH
HIGHS IN THE 50S AND LOWS IN THE 40S. BURKE

&&

.HYDROLOGY...THE SKOKOMISH RIVER WILL RISE AGAIN IN RESPONSE TO
HEAVY RAIN TONIGHT AND SATURDAY. SINCE IT IS STILL RUNNING HIGH FROM
THE PREVIOUS EVENT...IT IS POSSIBLE THE RIVER WILL GET CLOSE TO
FLOOD STAGE ON SATURDAY. FOR NOW THE FORECAST TAKES THE STAGE AT
POTLATCH TO BETWEEN 15.5 AND 16 FEET. FLOOD STAGE IS 16.5 FEET. ON
OTHER RIVERS FLOODING IS UNLIKELY OVER THE NEXT 7 DAYS.

&&

.AVIATION...SOUTHWEST FLOW ALOFT WILL CONTINUE OVER WESTERN
WASHINGTON THROUGH SATURDAY AS A PACIFIC FRONTAL SYSTEM MOVES INTO
THE REGION. THE AIR MASS WILL BECOME MOIST ALL LEVELS THIS EVENING
AS A WARM FRONT MOVES INTO THE AREA FROM THE SOUTH. THE SURFACE LOW
AND TRAILING COLD FRONT WILL MOVE INTO THE FORECAST AREA LATE
SATURDAY.

MAINLY VFR CONDITIONS PREVAIL ACROSS THE AREA THIS AFTERNOON AS HIGH
CLOUDS SPREAD ACROSS WESTERN WASHINGTON AHEAD OF THE APPROACHING
SYSTEM. RAIN BEGAN IN PORTLAND JUST BEFORE 2 PM. IT WILL REACH THE
SOUTH PART OF THE FORECAST AREA IN THE NEXT COUPLE HOURS...SEATTLE
AROUND 9 PM AND BELLINGHAM AROUND MIDNIGHT. CONDITIONS WILL
DETERIORATE OVERNIGHT...WITH WIDESPREAD LOW-END MVFR AND LOCAL IFR
FROM ROUGHLY 6 AM TO NOON SATURDAY. MARGINAL IMPROVEMENT IS LIKELY
SATURDAY.

KSEA...LIGHT WIND BECOMING NORTHEAST 5-12 KT..AND OCCASIONAL
EASTERLY GUSTS TO 20 KT ARE POSSIBLE TONIGHT. THE WIND WILL SHIFT TO
SOUTHERLY 8-16 KT SAT AFTERNOON. CONDITIONS WILL LIKELY DETERIORATE
TO LOW-END MVFR AND PERHAPS OCCASIONAL IFR IN RAIN AND FOG SATURDAY
MORNING.   MCDONNAL

&&

.MARINE...A WARM FRONT WILL MOVE NORTH ACROSS THE AREA TONIGHT. A
995 MB LOW ASSOCIATED WITH THE FRONT WILL MOVE NORTHEAST ACROSS THE
PACIFIC NORTHWEST COASTAL WATERS SATURDAY AND ACROSS WESTERN
WASHINGTON SATURDAY NIGHT. THIS FEATURE WILL LIKELY PRODUCE SMALL
CRAFT ADVISORY WINDS ALL WATERS AT SOME POINT LATE TONIGHT THROUGH
SATURDAY NIGHT...BEGINNING WITH THE COASTAL WATERS AND SPREADING
INLAND. IN ADDITION THERE IS A GOOD CHANCE OF SOUTHERLY GALES ALONG
THE INNER COASTAL WATERS SATURDAY MORNING AS THE LOW ARRIVES. THE
TRACK OF THE LOW IS STILL UNCERTAIN...AND CONFIDENCE IN THE DETAILS
OF THE FORECAST IS ACCORDINGLY LOW.

HIGH PRESSURE WILL BUILD OVER THE REGION SUNDAY AND BEGIN TO MOVE
EAST OF THE AREA MONDAY. ANOTHER VIGOROUS FRONTAL SYSTEM WILL AFFECT
THE AREA MONDAY NIGHT AND TUESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...

WA...WIND ADVISORY FOR THE EAST PUGET SOUND LOWLANDS TONIGHT THROUGH
     SATURDAY MORNING.
     WIND ADVISORY FOR BELLEVUE AND VICINITY TONIGHT.
PZ...GALE WARNING FOR INNER COASTAL WATERS ZONES PZZ153 AND PZZ156.
     SMALL CRAFT ADVISORY REMAINING COASTAL WATERS ZONES AND WEST
     ENTRANCE STRAIT OF JUAN DE FUCA.

&&

$$

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





USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.