Heavy Rain in Washington, August 22, 2004

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
240 AM PDT SUN AUG 22 2004

.SYNOPSIS...AN UPPER LEVEL DISTURBANCE WILL MOVE ACROSS THE REGION
TODAY GENERATING SHOWERS AND A FEW THUNDERSTORMS. THE BULK OF TODAYS
ACTIVITY WILL OCCUR UP THROUGH THE MIDDLE PART OF THE DAY. ANOTHER
SYSTEM WILL MOVE TOWARD THE COAST MONDAY...SPREADING SHOWERS OVER
THE AREA. THERE WILL BE A SHORT BREAK IN THE RAIN MONDAY NIGHT AND
TUESDAY BEFORE ANOTHER STORM APPROACHES THE COAST. THIS SYSTEM IS
EXPECTED TO GENERATE RAIN ACROSS WESTERN WASHINGTON TUESDAY NIGHT
INTO EARLY WEDNESDAY...WITH SCATTERED SHOWERS LINGERING INTO
THURSDAY.

&&

.DISCUSSION...UPPER TROUGH APPROACHING THE COAST WITH A NICE AREA OF
MODERATE TO HEAVY SHOWERS OVER WESTERN WASHINGTON AT THIS TIME.
EARLIER IN THE EVENING WAS CONTEMPLATING INCLUDING A CHANCE OF
THUNDERSTORMS IN TODAYS FORECAST...THEN MOTHER NATURE BEGAN
PROVIDING A LIGHT SHOW BEGINNING AROUND MIDNIGHT...WHICH CLINCHED
THE IDEA. WITH COLD UPPER TROUGH MOVING ACROSS THE AREA...AIR MASS
WILL CONTINUE TO DESTABILIZE WITH LI/S APPROACHING -2 AND CAPE
VALUES PUSHING NEAR 700 J/KG. CURRENTLY TOPS ARE PUSHING 35000 FEET
WHICH IS THE LEVEL OF THE TROP. MAIN LINE OF CONVECTION WILL MOVE
ACROSS THE AREA DURING THE MORNING HOURS WITH THE UPPER LEVEL
FORCING...BUT WITH UNSTABLE AIR MASS REMAINING OVER THE AREA...WONT
TAKE MUCH OF A TRIGGER TO KICK OFF THE CONVECTION LATER IN THE DAY
AS WELL. A COUPLE OF DEGREES DUE TO A PEEK OF SUN WOULD DO IT AND
THERE IS ALSO THE POTENTIAL FOR A CONVERGENCE ZONE LATER IN THE
DAY...SO WILL LEAVE CHANCE OF A THUNDERSTORM THROUGH THE ENTIRE DAY
INLAND AREAS.

TONIGHT...SHOWER THREAT WILL TAPER OFF IN THE EVENING...HOWEVER
ANOTHER SYSTEM WILL BE APPROACHING THE COAST AT THAT TIME. MAIN
THRUST OF THIS FEATURE SHOULD BE TO OUR SOUTH BUT THE SOUTHERN HALF
TO TWO THIRDS OF THE FA WILL BE UNDER THE THREAT FOR RAIN. ADJUSTED
POPS ACCORDINGLY.

WILL HAVE A BIT OF A BREAK IN THE PRECIPITATION THREAT MONDAY NIGHT
INTO TUESDAY BEFORE WE HAVE TO GEAR UP FOR THE NEXT IN THE PARADE OF
WEATHER SYSTEMS. THIS NEXT STORM SYSTEM HAS BEEN HANDLED RATHER
CONSISTENTLY BETWEEN THE VARIOUS MODELS AND ACROSS SEVERAL RUNS SO
RATHER CONFIDENT IN ANOTHER SHOT OF WETNESS TUESDAY NIGHT INTO
WEDNESDAY. RAISED POPS INTO THE LIKELY RANGE ALONG WITH OUR PARTNERS
TO THE SOUTH. THIS STORM HAS THE POTENTIAL OF BEING A MODERATE TO
HEAVY RAIN PRODUCER AS WELL SO WATERING THE GARDEN WILL NOT BE AN
ISSUE THIS WEEK. THERE IS ALSO A DECENT MID/UPPER LEVEL COLD POOL
ASSOCIATED WITH THIS SYSTEM FOR ANOTHER POTENTIAL ROUND OF
THUNDERSTORMS...BUT WILL NOT ADD THAT TO THE FORECAST AT THIS TIME.

SCATTERED SHOWER ACTIVITY WILL FOLLOW THIS STORM WEDNESDAY NIGHT AND
THURSDAY...MAINLY OVER THE MOUNTAINS. LOOKS AS THO BY
THURSDAY...FIRE ACTIVITY OUGHT TO BE SIGNIFICANTLY REDUCED IF NOT
ELIMINATED OVER WASHINGTON FROM THE NEAR THE CREST OF THE CASCADES
WESTWARD.

BEYOND THURSDAY...FORECAST IS DRY WITH COOL TO SEASONAL TEMPS.
MODELS ALL OVER THE RANCH AS FAR AS SOLUTIONS GO...BOTH FROM ONE
MODEL TO THE NEXT AND BETWEEN RUNS SO CONFIDENCE IS LOW FROM
THURSDAY NIGHT ONWARD. AFTER COORDINATION WITH SURROUNDING OFFICES
WE ALL OPTED TO LEAVE EXTENDED PERIOD ALONE FOR NOW.

CERNIGLIA
&&

.SEW...SMALL CRAFT ADVISORY CENTRAL AND EASTERN STRAIT.

.KATX..VCP21/CSR21 OPERATIONAL.
&&