Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 132238
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
338 PM PDT SUN JUL 13 2014

.SYNOPSIS...A LOW PRESSURE SYSTEM OFF THE OREGON COAST WILL MOVE
ACROSS THE AREA OVERNIGHT. EXPECT THIS SYSTEM TO BE OVER EASTERN
WASHINGTON MONDAY AFTERNOON...WITH HIGH PRESSURE ALOFT BUILDING IN
ITS WAKE. HIGH PRESSURE ALOFT WILL THEN PREVAIL OVER THE REGION
THROUGH MIDWEEK. TEMPERATURES WILL CONTINUE TO RUN ABOVE NORMAL
ACROSS MUCH OF THE AREA.

&&

.SHORT TERM...
SHOWERS AND TSTMS WERE MOVING INTO THE FAR SOUTHERN PART OF THE
CWA AT THIS TIME. LOOK FOR THIS ACTIVITY TO CONTINUE MOVING
NORTH THROUGH THIS EVENING.

INCREASED CLOUD COVER AHEAD OF THE UPPER LOW OFF THE OREGON COAST
SERVED TO PREVENT TEMPS FROM REACHING THEIR POTENTIAL ACROSS THE
SOUTHERN PART OF THE CWA. IN FACT...MOST PLACES WERE COOLER THAN
WHAT THEY WERE YESTERDAY. THUS THE HEAT ADVISORY WAS CANCELLED.

LOOK FOR THE UPPER LOW OFF THE OREGON COAST TO MOVE ACROSS THE
AREA OVERNIGHT AND THEN EAST OF THE CASCADES BY MIDDAY MON. EXPECT
THE SHOWER AND TSTM THREAT TO DIMINISH LATE TONIGHT ACROSS MUCH OF
THE CWA. BY MON MORNING...THE RISK OF TSTMS WILL BECOME CONFINED
TO THE CASCADES. ONSHORE FLOW WILL PREVAIL ON MON. IT IS POSSIBLE
THAT THE FORECAST TEMPS MIGHT BE A LITTLE ON THE WARM SIDE.

AN UPPER RIDGE WILL REBUILD OVER THE REGION MON AFTERNOON AND
REMAIN OVER THE PACIFIC NORTHWEST THROUGH WED...ALTHOUGH IT WILL
GRADUALLY WEAKEN WITH TIME. LOW LEVEL ONSHORE FLOW WILL ALSO
PERSIST. EXPECT DAYTIME TEMPS TO REBOUND ON TUE AND THEN COOL
SLIGHTLY ON WED. OVERALL...TEMPS WILL REMAIN NORMAL DURING THIS
PERIOD.

.LONG TERM...
THE MEDIUM RANGE SOLUTIONS CONTINUED TO ADVERTISE AN UPPER TROF
DEVELOPING OVER THE PACIFIC NORTHWEST DURING THIS PERIOD. THE
MAIN DIFFERENCES WERE IN THE DETAILS. HAVE CONTINUED WITH THE
IDEA OF TEMPS APPROACHING NEAR NORMAL DURING THIS PERIOD. THERE
IS A CHANCE THAT THE FORECAST TEMPS FOR DAY 7 MIGHT BE TOO WARM.

&&

.AVIATION...SLY FLOW WILL BECOME NW ON MONDAY AS A WEATHER
DISTURBANCE MOVES THROUGH THE AREA. THE AIR IS UNSTABLE AND A PATCH
OF MOISTURE OVER NW OREGON WILL MOVE NORTH THROUGH WRN WA TONIGHT
FOR A CHANCE OF THUNDERSTORMS OVER WRN WA. MARINE LAYER FOG AND LOW
CLOUDS ALONG THE COAST WILL ALSO PUSH INLAND OVERNIGHT...BUT MAINLY
IN THE STRAIT AND CHEHALIS GAP.


KSEA...NW SURFACE WINDS WILL SWITCH TO SW THIS EVENING. MID AND HIGH
CLOUDS WILL INCREASE FROM THE SCATTERED THUNDERSTORMS THAT HAVE BEEN
OVER NW OREGON TODAY. THERE IS A CHANCE THAT A THUNDERSTORM MAY PASS
OVER SEATTLE THIS EVENING.

&&

.MARINE...HIGH PRESSURE OFFSHORE AND LOWER PRESSURE INLAND WILL
CONTINUE TO PRODUCE SMALL CRAFT ADVISORY LEVEL WINDS EACH EVENING IN
THE STRAIT OF JUAN DE FUCA. THE STRATUS LAYER ON THE COAST WILL
BRING FOG AND LOW CLOUDS DOWN THE STRAIT AGAIN TONIGHT. THERE IS A
WEATHER DISTURBANCE THAT HAS BEEN TRIGGERING THUNDERSTORMS OVER NW
OREGON TODAY...THAT WILL MOVE NORTH THRU WRN WA THIS EVENING.

&&

.FIRE WEATHER... HUNDERSTORMS ASSOCIATED WITH THE UPPER LEVEL LOW
MOVING INLAND THIS EVENING CAUSES A BIT OF A FORECAST PROBLEM. FOR
MOST LOCATIONS IN WESTERN WASHINGTON...THE ELEMENT OF CONCERN HAVE
A HARD TIME LINING UP. NOT MUCH TO WORRY ABOUT ON THE OLYMPIC
PENINSULA AND ALONG THE COAST...AS FUELS REMAIN TOO MOIST TO MEET
RED FLAG CRITERIA. MOVING INLAND TOWARD THE PUGET SOUND LOWLANDS...
HERE FUELS ARE READY...BUT THUNDERSTORM COVERAGE IS EXPECTED TO BE
MAINLY ISOLATED. IN THE CASCADES...FUELS ARE BORDERLINE...BUT ON
THE MOIST SIDE...AND COVERAGE IS EXPECTED TO BE SCATTERED. WHILE
CERTAINLY CANNOT RULE OUT THAT SOME AREAS ON THE WEST SLOPES OF
THE CASCADES MAY HAVE FUELS DRY ENOUGH TO IGNITE SHOULD THEY BE
STRUCK BY LIGHTNING...AT THIS TIME DO NOT EXPECT THAT DRYNESS TO
BE WIDESPREAD...SO HAVE OPTED TO NOT POST ANY ADDITIONAL FIRE
WEATHER PRODUCTS FOR THOSE ZONES AT THIS TIME. THE ONLY PLACE THE
ELEMENTS LINE UP...DRY FUELS THAT MEET RED FLAG ERC CRITERIA AND
SCATTERED LIGHTNING THREAT...IS IN FIRE WEATHER ZONE
662...INCLUDING THE EASTERN PART OF NORTH CASCADES NATIONAL PARK
AND THE LAKE CHELAN NATIONAL RECREATIONAL AREA. THE THUNDERSTORM
THREAT IS EXPECTED TO OCCUR MAINLY IN THE EVENING AND THROUGH THE
OVERNIGHT HOURS...BUT ZONE 662 MAY SEE SOME ACTIVITY IN THE
MORNING AS THE LOW CONTINUES TO MOVE EASTWARD.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...RED FLAG WARNING IN EFFECT UNTIL 8 AM MONDAY FOR THE EAST
     PORTION OF THE NORTH CASCADES NATIONAL PARK/LAKE CHELAN
     NATIONAL RECREATIONAL AREA.

PZ...SMALL CRAFT ADVISORY IN EFFECT UNTIL 7 AM MONDAY FOR THE
     CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA.

&&

$$

WWW.WEATHER.GOV/SEATTLE

FOR THE GRAPHICAL AFD...VISIT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML




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