Winter Weather in Washington, June 10, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
930 PM PDT MON JUN 9 2008

.SYNOPSIS...SHOWERS AND WINDY CONDITIONS WILL GRADUALLY EASE
OVERNIGHT...BUT SNOW WILL CONTINUE IN THE MOUNTAINS TONIGHT WITH
LOCALLY HEAVY ACCUMULATIONS ABOVE 3500 FEET. EXPECT IMPROVING
WEATHER DURING THE DAY TUESDAY AS THE STRONG UPPER LOW MOVES INTO
IDAHO. HIGH PRESSURE ALOFT WILL PROVIDE MUCH OF THE AREA WITH DRY
AND WARMER WEATHER ON WEDNESDAY AND THURSDAY.

&&

.SHORT TERM...OUR VIGOROUS JUNE FRONT MOVED THROUGH THE WESTERN
WASHINGTON INTERIOR EARLY THIS EVENING AND INTO THE CASCADES. A 538
MB UPPER LOW -- REMARKABLY DEEP FOR JUNE -- IS OVER THE SOUTH END OF
VANCOUVER ISLAND. WE HAVE HAD GALES OR NEAR GALES OVER MANY OF THE
INLAND MARINE WATERS...WITH 20 TO 30 MPH SUSTAINED WINDS OVER MUCH
OF THE LAND AREA AND SPOTTERS HAVE REPORTED GUSTS INTO THE LOW 40
MPH RANGE. ISOLATED THUNDERSTORMS ALSO DEVELOPED OVER WESTERN
SNOHOMISH COUNTY AND THE NORTHWEST INTERIOR...AND ISSUED AN UPDATE
TO THE ZONE FORECAST FOR THAT AROUND 8 PM.

THE UPPER LOW WILL MOVE EAST ACROSS THE CASCADES TONIGHT...PROBABLY
CROSSING SOMEWHERE NEAR OR JUST NORTH OF STEVENS PASS. STRONG
SOUTHERLY ONSHORE GRADIENTS PEAKED WITH THE CROSSING OF THE COLD
FRONT...AND THEY SHOULD CONTINUE TO DECREASE OVERNIGHT. AND
LIGHTNING DETECTION SYSTEM AND SPOTTERS INDICATE THAT WE HAVE NOT
HAD ANY MORE THUNDERSTORMS IN THE LAST HOUR. SO ALL IN ALL THE
CURRENT FORECAST FOR THE REST OF TONIGHT LOOKS GOOD -- DECREASING
SHOWERS AND DECREASING WIND.

THE FORECAST AND WARNING FOR SNOW IN THE MOUNTAINS LOOKS GOOD TOO.
THE FREEZING LEVEL MEASURED AT QUILLAYUTE LATE THIS AFTERNOON WAS
4300 FT. RAIN CHANGED TO SNOW AT STAMPEDE PASS JUST BEFORE 8 PM AND
JUST BEFORE SUNSET THE STEVENS PASS WEBCAM SHOWED SNOW FALLING AND
STARTING TO STICK ON THE ROADWAY.

THE UPPER LOW WILL MOVE ACROSS EASTERN WASHINGTON TUESDAY...WHILE
WESTERN WASHINGTON SITS UNDER NORTHERLY FLOW ALOFT AHEAD OF THE
UPPER RIDGE OFFSHORE JUST OUTSIDE 140W. THE LOW LEVEL FLOW WILL
REMAIN ONSHORE AND THE AIR MASS WILL BE WEAKLY UNSTABLE. WE WILL
START TUESDAY CLOUDY WITH RESIDUAL SHOWERS...BUT THERE SHOULD BE
GRADUAL LIFTING OF THE CLOUDS WITH SOME SUN BREAKS IN THE AFTERNOON.

THE UPPER RIDGE WILL SLOWLY PROGRESS EASTWARD OVER THE NEXT COUPLE
DAYS...FINALLY MOVING INSIDE 130W ON THURSDAY. LOW LEVEL FLOW WILL
REMAIN ONSHORE. BY TUESDAY NIGHT AND WEDNESDAY MORNING SHOWERS WILL
BECOME MOSTLY LIMITED TO THE WEST SLOPES OF THE MOUNTAINS...WITH A
GENERALLY DRY FORECAST WEDNESDAY AFTERNOON THROUGH THURSDAY. WE
SHOULD SEE A BIT MORE CLEARING OF THE MORNING MARINE CLOUDS EACH
DAY...WITH TEMPERATURES FINALLY CLIMBING BACK TO NORMAL ON THURSDAY.
MCDONNAL

.LONG TERM...HERE IS THE LONG TERM SECTION FROM THE AFTERNOON
ISSUANCE OF THE FORECAST DISCUSSION -- CONFIDENCE IN THIS PERIOD WAS
NOT OVERLY HIGH DUE TO INCONSISTENCIES OR LACK OF CONTINUITY IN THE
MEDIUM RANGE MODELS. HAVE WENT CLOSE TO CLIMO FOR MUCH OF THE
PERIOD. BY THE END OF THE PERIOD...THE MEDIUM RANGE SOLUTIONS WERE
HINTING OF ANOTHER COOL...UPPER LOW DROPPING OVER THE AREA FROM THE
GULF OF AK. THE TIMING OF THIS SYSTEM WAS NOT CERTAIN...SO WENT WITH
THE IDEA OF INCREASED ONSHORE FLOW AND A MUCH DEEPER MARINE LAYER
WITH TIME. THUS HAVE LOWERED TEMPS A FEW DEGREES BELOW NORMAL BY THE
END OF THE PERIOD AND INCLUDED A CHANCE OF LIGHT RAIN OR DRIZZLE.

&&

.AVIATION...A COLD UPPER LEVEL LOW WILL MOVE EAST THRU WA TONIGHT.
THE WINDS ALOFT WILL GO FROM SW TO NW AS THE LOW PROGRESSES EAST.
THE AIR MASS WILL BE UNSTABLE WITH THE CASCADES OBSCURED IN SNOW
SHOWERS DOWN TO 3000FT. THE LOW CENTER IS OVER EASTERN WA WITH
STRONG ONSHORE FLOW INTO WRN WA FOR STRONG SFC PRES GRADIENTS.
WEATHERWISE...SHOWERS AND A CHANCE OF THUNDERSTORMS TONIGHT IN THE
UNSTABLE AIR MASS BEHIND THE COLD FRONT. THE BEST AREAS FOR HEAVIER
SHOWERS WILL BE IN THE SAN JUANS AND THE NORTH INTERIOR WHERE NW
WINDS DOWN THE STRAIT OF GEORGIA MEET THE WESTERLIES THROUGH THE
STRAIT OF JUAN DE FUCA...AND OVER THE PUGET SOUND CONVERGENCE ZONE
WHICH SHOULD STAY NEAR A LINE FROM THE HOOD CANAL BRIDGE NE THRU
SNOHOMISH COUNTY AND MAINLY AFFECT KPAE. THERE WERE A FEW LIGHTNING
STRIKES THIS EVENING HEADING TOWARD KBLI SO THAT IS THE TAF WITH
VCTS FOR NOW...BUT KPAE IS NEXT. 19

KSEA...WINDS WILL LIKELY STAY SW AND RATHER BLUSTERY WITH GUSTS ARND
30KTS TIL MIDNIGHT THEN DECREASE. THE PSCZ SHOULD STAY NORTH NEAR
KPAE...BUT RADAR AT 845PM DID SHOW SHOWERS COMING AROUND THE SOUTH
SIDE OF THE OLYMPICS AND HEADING NE TO KSEA. THERE IS A CHANCE OF A
THUNDERSTORM TIL ABOUT MIDNIGHT...AND THEN THE RISK WILL DECREASE AS
THE COLDEST AIR ALOFT WITH THIS UPPER LOW MOVES EAST. 19

&&

.MARINE...NO SGFNT UPDATES TO THE ALREADY VERY BLUSTERY FORECAST
TONIGHT...THE GALES WILL STAY UP TIL THE EARLY MORNING UPDATE. THE
HIGH SURF ADVISORY FOR THE COAST LOOKS GOOD...15 FOOT SEAS IS
NOTHING UNUSUAL FOR WINTER BUT IN JUNE IT IS IMPRESSIVE. 19

&&

.AVALANCHE...IT LOOKS LIKE A NEW MONTH IS BEING INVENTED CALLED
JUNEUARY. ANOTHER ROUND OF SIGNIFICANT SNOW IS EXPECTED MONDAY NIGHT
AND TUESDAY MORNING AT HIGHER ELEVATIONS. WARMER AFTERNOON
TEMPERATURES, SOLAR EFFECTS AND POSSIBLE SUN BREAKS SHOULD HELP MAKE
WET SNOW AVALANCHES PROBABLE AGAIN ON STEEP SLOPES AT HIGHER
ELEVATIONS TUESDAY AND POSSIBLY WEDNESDAY. THE NORTHWEST WEATHER AND
AVALANCHE CENTER HAS ISSUED A SPECIAL STATEMENT FOR TUESDAY. THE
STATEMENT WILL BE UPDATED AS WARRANTED. PLEASE SEE WWW.NWAC.US FOR
DETAILS. FERBER

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...HEAVY SNOW WARNING IN EFFECT FOR THE OLYMPICS AND CASCADES
     TONIGHT THRU EARLY TUESDAY.

     HIGH SURF ADVISORY IN EFFECT FOR THE COAST FOR LATE TONIGHT
     THRU TUESDAY.

PZ...GALE WARNING IN EFFECT FOR THE COASTAL WATERS AND CENTRAL/
     EASTERN STRAIT OF JUAN DE FUCA.

     SMALL CRAFT ADVISORY IN EFFECT FOR THE REMAINING WATERS.

     SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH GRAYS HARBOR BAR
     CONDITIONS.

WEATHER.GOV/SEATTLE