Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 280340
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
840 PM PDT WED APR 27 2016

.SYNOPSIS...INSTABILITY SHOWERS OVER THE MOUNTAINS WILL END THIS
EVENING. HIGH PRESSURE WILL BUILD OVER THE REGION THURSDAY WITH
MOSTLY SUNNY AND SLIGHTLY WARMER WEATHER. AN UPPER TROUGH WILL
GENERATE SHOWERS ACROSS WESTERN WASHINGTON LATER THURSDAY NIGHT AND
FRIDAY. A STRONG UPPER RIDGE WILL BRING DRY WEATHER AND A WARMING
TREND SATURDAY THROUGH MONDAY. ONSHORE FLOW MAY RESUME TUESDAY WITH
A CHANCE OF SHOWERS AS A FRONTAL SYSTEM APPROACHES WESTERN
WASHINGTON.

&&

.SHORT TERM...A WEAK UPPER LEVEL RIDGE WILL BRING MAINLY DRY WEATHER
TO WESTERN WA TONIGHT AND THURSDAY. THERE IS JUST A SLIGHT CHANCE OF
SHOWERS OVER THE CASCADES. THE LOW LEVEL FLOW WILL REMAIN ONSHORE
AND TEMPERATURES WILL BE CLOSE TO NORMAL. WE WILL SEE SOME MID LEVEL
CLOUDS THROUGH THE DAY FOR PARTLY TO MOSTLY SUNNY SKIES.

A WEAK COLD FRONT WILL BRING A LITTLE RAIN AS IT MOVES INLAND ON
FRIDAY. A PUGET SOUND CONVERGENCE ZONE MAY FORM OVER THE
SNOHOMISH/KING LINE FOR SHOWERS. EXPECT ISOLATED TO SCATTERED
SHOWERS THROUGH FRIDAY EVENING AS THE UPPER LEVEL TROUGH MOVES
OVERHEAD.

SATURDAY IS LOOKING DRY ACROSS THE REGION AS ANOTHER UPPER LEVEL
RIDGE NUDGES INLAND. NORTHERLY FLOW WILL KEEP SKIES MOSTLY
SUNNY...WITH HIGHS IN THE LOW TO MID 60S. 33

.LONG TERM...PREVIOUS DISCUSSION...MODELS SHOW THE UPPER RIDGE
NARROWING AND SHIFTING NE OVER B.C. AND THE PAC NW SUNDAY. THE RIDGE
WILL BROADEN BUT BEGIN TO SHIFT EWD ON MONDAY AS A LOW OVER THE GULF
OF AK STARTS TO DIG SWD. THE FLOW WILL BE OFFSHORE AND DRIER AIR AND
SUNNY SKIES. HIGHS SHOULD EASILY REACH THE 70S WITH THE WARMEST
TEMPERATURES AROUND PUGET SOUND ON MONDAY WITH LOW 80S POSSIBLE.

MOST MODELS INDICATE THE NEXT APPROACHING TROUGH WILL INDUCE A FULL
OR PARTIAL MARINE PUSH MONDAY NIGHT OR TUESDAY. HIGHS SHOULD DROP
OFF SIGNIFICANTLY BUT THE TIMING AND STRENGTH OF THE TROUGH IS
HIGHLY UNCERTAIN. THERE IS A LOT OF UNCERTAINTY GOING INTO MID WEEK
BUT THE TREND APPEARS TO BE MOVING TOWARD A WEST COAST LONG WAVE
TROUGH. THE FORECAST TRENDS COOLER WITH A CHANCE OF SHOWERS TUESDAY
AND WEDNESDAY BUT STILL ABOVE AVERAGE. MERCER

&&

.AVIATION...CLOUDS OVER WRN WA WILL CONTINUE TO THIN AND BREAK UP
THIS EVENING...SCATTERING OUT BY LATE EVENING. PATCHES OF LOW CLOUDS
OR FOG COULD SET UP IN THE MOST FOG PRONE SPOTS LATE TONIGHT...SUCH
AS OLM.

KSEA...THE CLOUDS WILL SLOWLY THIN AND BREAK UP THIS EVENING.
PRES GRADIENTS ARE LIGHT RESULTING IN WINDS GENERALLY 6 KT OR LESS
THIS EVENING AND OVERNIGHT. SMR

&&

.MARINE...ONSHORE FLOW WILL CONTINUE WITH HIGH PRESSURE OVER
THE COASTAL WATERS AND LOWER PRES INLAND. THIS WILL ALLOW FOR SMALL
CRAFT ADVISORY WINDS IN THE CENTRAL AND EASTERN STRAIT AND ADMIRALTY
INLET TO CONTINUE THIS EVENING INTO TONIGHT BEFORE DIMINISHING LATE
TONIGHT. ANOTHER WEAK FRONT IS EXPECTED TO BREAK UP AS IT PASSES
OVER WRN WA ON FRIDAY. SMR

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORIES ARE IN EFFECT FOR THE CENTRAL/EASTERN
     STRAIT OF JUAN DE FUCA AND THE ADMIRALTY INLET TONIGHT.

&&

$$

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