Gale Warning 28, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 AM PST SAT MAR 5 2011

.SYNOPSIS...WESTERN WASHINGTON WILL HAVE QUIET AND MOSTLY DRY
WEATHER FOR THE NEXT THREE DAYS. SCATTERED LIGHT SHOWERS WILL
CONTINUE TODAY...AND THE REMNANTS OF AN OLD DISSIPATING FRONT COULD
BRING SOME LIGHT SHOWERS ON MONDAY. THERE WILL BE SOME SUNSHINE
DURING THE DAYS...AND TEMPERATURES WILL RUN A FEW DEGREES BELOW
NORMAL. A WETTER WEATHER PATTERN WILL RESUME NEXT WEEK.

&&

.SHORT TERM...FAIRLY WEAK SOUTHWEST FLOW PREVAILS OVER WESTERN
WASHINGTON BEHIND THE FRONT THAT MOVED THROUGH THE AREA FRIDAY
EVENING. SCATTERED SHOWERS CONTINUE OVER THE AREA WITH TEMPERATURES
RANGING FROM 35 TO 45. THE SNOW LEVEL OVER WESTERN WASHINGTON IS
2500 TO 3000 FT. ROUGHLY 6 TO 11 INCHES OF SNOW FELL IN THE
MOUNTAINS WITH AND BEHIND THE FRONT...BUT THERE HAS BEEN LITTLE
ADDITIONAL ACCUMULATION IN THE LAST COUPLE HOURS. '

IN THE BIGGER PICTURE AN UPPER RIDGE IS BUILDING ALONG 130W WEST OF
CALIFORNIA...AHEAD OF A MOIST SOUTHWESTERLY JET. THAT IS CAUSING
HEIGHTS OVER WESTERN WASHINGTON TO CLIMB SLIGHTLY. A DEEP UPPER LOW
REMAINS CENTERED IN THE GULF OF ALASKA NEAR 51N/148W.

WEAK WESTERLY FLOW WILL CONTINUE TODAY OVER WESTERN WASHINGTON...
WHILE A FRONTAL SYSTEM AT THE LEADING EDGE OF THE SOUTHWESTERLY JET
GETS READY TO MOVE INTO NORTHERN CALIFORNIA AND OREGON. THE AIR MASS
OVER WESTERN WASHINGTON WILL REMAIN SOMEWHAT MOIST WITH MARGINAL
INSTABILITY BELOW 8000 FT OR SO. JUST ABOUT ALL THE MODELS SHOW A
VERY WEAK PUGET SOUND CONVERGENCE ZONE. A FORECAST FOR PARTLY SUNNY
SKIES AND SCATTERED SHOWERS LOOKS GOOD FOR TODAY...WITH THE HIGHEST
POPS IN THE CONVERGENCE ZONE AREA. I WILL END THE WINTER WEATHER
ADVISORY FOR THE CASCADES WITH THE MORNING FORECAST PACKAGE.

THE SYSTEM TO OUR SOUTH WILL MOVE INLAND TONIGHT AND SUNDAY...
LEAVING OUR FORECAST AREA IN WEAK WESTERLY FLOW. THIS WILL BE A
GENERALLY DRY PERIOD FOR ALL OF WESTERN WASHINGTON...WITH THE
POSSIBLE EXCEPTION OF A LIGHT SHOWER OR TWO IN THE MOUNTAINS.

AN UPPER TROUGH WILL FOLLOW THE FRONTAL SYSTEM INTO OREGON AND
NORTHERN CALIFORNIA SUNDAY NIGHT...LEAVING WESTERN WASHINGTON IN
WEAK DRY NORTHWEST FLOW ALOFT AHEAD OF AN UPPER RIDGE OFFSHORE. THE
REMNANTS OF AN OLD FRONT WILL BE OFFSHORE SUNDAY NIGHT. THIS FEATURE
COULD BRING SOME LIGHT SHOWERS TO WESTERN WASHINGTON MONDAY AS IT
DISSIPATES AND MOVES INLAND...BUT THE EMPHASIS IS ON COULD AND LIGHT.

IN SUMMARY...THE NEXT THREE DAYS WILL BE A PERIOD OF QUIET FAIR
WEATHER. MOST PEOPLE IN WESTERN WASHINGTON WILL HAVE LITTLE OR NO
PRECIPITATION...THERE WILL BE SOME SUNSHINE DURING THE DAY...AND
TEMPERATURES WILL RUN A FEW DEGREES BELOW NORMAL.  MCDONNAL

.LONG TERM...THE UPPER RIDGE OFFSHORE WILL PROGRESS INLAND MONDAY
NIGHT...AND THE WARM FRONT OF A SYSTEM JUST UPSTREAM OF THE RIDGE
AXIS WILL MOVE THROUGH WESTERN WASHINGTON TUESDAY OR TUESDAY NIGHT.
MOIST SOUTHWEST FLOW WILL FOLLOW THE WARM FRONT WITH THE COLD FRONT
EVENTUALLY MOVING THROUGH THE AREA ON THURSDAY.

WHILE VARIOUS MODELS DIFFER ON THE DETAILS OF THIS SYSTEM...THEY ALL
AGREE ON THAT GENERAL SCENARIO. IF ANYTHING...OUR CURRENT POPS
MOSTLY IN THE CHANCE RANGE FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT
MIGHT BE ON THE LOW SIDE. OUR FORECAST SNOW LEVELS NEAR 1500 FT
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT MAY BE ON THE LOW SIDE AS
WELL. THE LATEST MODEL RUNS SUGGEST SNOW LEVELS MIGHT BE IN THE 2500
TO 4000 FT RANGE BEHIND THE WARM FRONT TUESDAY NIGHT AND UNTIL THE
COLD FRONT SWINGS THROUGH. THE PATTERN LOOKS PROGRESSIVE BEYOND
THURSDAY...WITH ANOTHER FRONTAL SYSTEM PROBABLY NEARING THE REGION
FROM OFFSHORE ON FRIDAY.  MCDONNAL

&&

.HYDROLOGY...NO FLOODING IS EXPECTED ON RIVERS IN THE FORECAST AREA
DURING THE NEXT TEN DAYS...INCLUDING THE GREEN RIVER. SNOW LEVELS
WILL REMAIN LOW AND HYDROLOGICALLY SIGNIFICANT PRECIPITATION IS NOT
EXPECTED.  MCDONNAL

&&

.AVIATION...MODERATE WESTERLY FLOW ALOFT WILL CONTINUE INTO SUNDAY.
MOIST STABLE AIR MASS WILL BEGIN TO DRY IN THE UPPER LEVELS BUT
PLENTY OF LOW LEVEL MOISTURE REMAINS. SCATTERED SHOWERS THIS MORNING
WILL TAPER IN THE AFTERNOON.

CEILINGS GENERALLY 2-3K FT WITH A FEW IFR SPOTS. CONDITIONS IMPROVE
TOWARD THE COAST. SOME CLEARING INLAND AFTER 21Z WITH VFR CONDITIONS
AFTER 00Z.

KSEA...DISCUSSION ABOVE APPLIES. SW WIND 10-15 KT...EASING LATER
THIS MORNING...AND SWITCHING TO NW 4-8 LATE IN THE AFTERNOON. CHB

&&

.MARINE...ONLY ANOTHER HOUR OR SO OF SMALL CRAFT ADVISORY WINDS OVER
THE INLAND WATERS...WESTERLIES DOWN THE STRAIT AND SOUTHERLIES
INLAND...AND THEN WINDS SHOULD BE LESS THAN 20 KT ALL AREAS THIS
WEEKEND. SWELL ON THE COAST WILL REMAIN IN THE 10 FT RANGE AND A
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS REMAINS IN EFFECT AT LEAST
THROUGH TONIGHT.

THE NEXT SYSTEM IS DUE ABOUT TUESDAY. THIS IS FORECAST TO BRING
SMALL CRAFT ADVISORY STRENGTH WINDS TO MOST WATERS. CHB

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 4 AM CENTRAL AND EAST STRAIT...
     NORTHERN INLAND WATERS...ADMIRALTY INLET...PUGET SOUND.

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