Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000
FXUS66 KSEW 290335
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 PM PDT SAT MAR 28 2015

.SYNOPSIS...A STALLED FRONTAL BOUNDARY WILL BRING LIGHT RAIN TO THE
NORTH INTERIOR AND COAST AT TIMES THROUGH MONDAY. A COLD FRONT WILL
MOVE THROUGH WESTERN WASHINGTON MONDAY NIGHT...BRINGING RAIN INTO
THE REST OF THE INTERIOR. UPPER LEVEL LOW PRESSURE OVER THE REGION
NEXT WEEK WILL MAINTAIN A COOL AND SHOWERY WEATHER PATTERN.

&&

.SHORT TERM...RADAR RETURNS LOOK REMARKABLY LIKE MODEL PRECIPITATION
WITH LIGHT RAIN AT TIMES OVER THE NORTH COAST AND EXTREME NORTH
INTERIOR...EXTENDING SOUTH INTO THE CENTRAL CASCADES. THIS IS
FORECAST TO BE THE PATTERN THROUGH MONDAY AND NO CHANGES TO THE
ZONES OR GRIDS ARE ANTICIPATED. HIGH TEMPERATURES WILL BE IN THE
UPPER 50S TO MID 60S. THE SNOW LEVEL WILL RISE TO 6000 FEET.

ON MONDAY NIGHT A COLD FRONT WILL FINALLY MOVE THROUGH THE AREA...
SPREADING RAIN TO EVERYWHERE. SHOWERS WILL FOLLOW TUESDAY. HIGH
TEMPERATURES ON TUESDAY WILL BE IN THE LOW TO MID 50S AND THE SNOW
LEVEL WILL FALL TO 4000 FEET. BURKE

.LONG TERM...PREVIOUS DISCUSSION...MODELS HAVE NOT BEEN AT ALL
CONSISTENT IN THE EXTENDED RANGE. THE OVERALL PATTERN LOOKS
PROGRESSIVE AND SPLIT WITH A SERIES OF WEAK SHORT WAVES PASSING NEAR
WRN WA. TIMING THESE SYSTEMS IS DIFFICULT AND IT DOESN`T SEEM
PRUDENT TO TRY PICK OUT SHORT BLOCKS OF DRY WEATHER. WILL KEEP THE
CLIMO BROAD BRUSH CHANCE OF SHOWERS IN THE FORECAST.  MERCER

&&

.HYDROLOGY...FLOODING IS UNLIKELY OVER THE NEXT 7 DAYS.

&&

.AVIATION...WESTERLY FLOW ALOFT OVER WESTERN WASHINGTON THIS EVENING
WILL CONTINUE THROUGH SUNDAY AS A FLAT UPPER RIDGE REMAINS OVER THE
PACIFIC NORTHWEST. A WARM FRONT WILL REMAIN ALONG THE NORTHWEST SIDE
OF THE RIDGE...EXTENDING FROM SOUTHERN BRITISH COLUMBIA SOUTHWEST
INTO THE OFFSHORE WATERS. THE AIR MASS WILL REMAIN FAIRLY MOIST...
ESPECIALLY AT MIDDLE AND UPPER LEVELS.

SKY COVER ACROSS THE FORECAST AREA IS GENERALLY BKN-OVC BETWEEN
6000-8000 FT WITH HIGHER OVC LAYERS ABOVE. CONDITIONS WILL LOWER
SOMEWHAT TONIGHT BUT SHOULD REMAIN PREDOMINANTLY VFR. THERE WILL
PROBABLY BE SOME LIGHT PRECIPITATION IN THE NORTH PART OF THE
FORECAST AREA.

KSEA...SOUTH OR SOUTHWEST WIND 6-12 KT. BKN-OVC CEILING SHOULD LOWER
TO AROUND 5000 FT TONIGHT BUT REMAIN VFR THROUGH SUNDAY.   MCDONNAL

&&

.MARINE...A RIDGE WILL BE OVER WESTERN WASHINGTON THROUGH MONDAY
MORNING WHILE A FRONT EXTENDS FROM VANCOUVER ISLAND SOUTHWEST INTO
THE OFFSHORE WATERS. THE SOUTHERLY PRESSURE GRADIENT THAT RESULTS
SHOULD BE ENOUGH FOR SMALL CRAFT ADVISORY WINDS OVER THE COASTAL
WATERS AND WEST ENTRANCE STRAIT OF JUAN DE FUCA DURING THE PERIOD...
AND THEY SHOULD DEVELOP OVER THE INLAND WATERS LATER TONIGHT AND
SUNDAY MORNING.

A COLD FRONT WILL MOVE ACROSS THE COASTAL WATERS AND WESTERN
WASHINGTON LATE MONDAY AND MONDAY NIGHT...WITH SMALL CRAFT ADVISORY
WINDS MOST OR ALL WATERS. MODERATELY STRONG ONSHORE FLOW WILL FOLLOW
THE FRONT MONDAY NIGHT AND TUESDAY. SMALL CRAFT ADVISORY
WESTERLIES...AND POSSIBLY GALES...WILL DEVELOP IN THE CENTRAL AND
EASTERN STRAIT OF JUAN DE FUCA. A WEAK RIDGE WILL BUILD OVER THE
AREA WEDNESDAY.

THERE WILL ALSO BE A WESTERLY SWELL OF 10 TO 12 FT OVER THE COASTAL
WATERS LATER TONIGHT THROUGH TUESDAY...WITH ROUGH BAR CONDITIONS AS
WELL.   MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY ALL WATERS EXCEPT THE CENTRAL STRAIT.
     SMALL CRAFT ADVISORY GRAYS HARBOR FOR ROUGH BAR.

&&

$$

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




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