Tornado in Washington, June 16, 2006

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
1205 PM PDT FRI JUN 16 2006

.SYNOPSIS...THE TAIL END OF AN UPPER LEVEL TROUGH WILL CROSS THE
AREA TODAY...ENHANCING ONSHORE FLOW AND GENERATING SOME LIGHT RAIN
SHOWERS. A BRIEF PERIOD OF WEAK UPPER RIDGING ON SATURDAY SHOULD
SPELL A DRIER DAY WITH MORE SUN BREAKS. ANOTHER UPPER TROUGH WILL
PASS BY ON SUNDAY WITH ANOTHER ENHANCEMENT OF ONSHORE FLOW. MODERATE
ONSHORE FLOW AND FAIRLY DEEP MARINE AIR WILL PERSIST THROUGH MUCH OF
NEXT WEEK.

&&

.SHORT TERM...UPDATED AVIATION DISCUSSION AT NOON. A BROAD UPPER
TROUGH IS MOVING BY TODAY. A WEAK SURFACE REFLECTION IS CURRENTLY
HEADING INTO THE CASCADES...SO EXPECT ONSHORE PRESSURE GRADIENTS TO
INCREASE BEHIND THIS FEATURE DURING THE AFTERNOON. THE 12Z KUIL
SOUNDING SHOWED A MOIST LAYER EXTENDING FROM THE SURFACE TO OVER
7000 FEET WITH DRY AIR ABOVE THAT. THIS WILL SPELL MOSTLY CLOUDY
SKIES FOR TODAY...EXCEPT IN A SMALL HOLE DOWNWIND OF THE OLYMPICS.
WITH SUCH A DEEP MOIST LAYER AND INCREASING ONSHORE FLOW...LOOK FOR
LIGHT RAIN SHOWERS AND DRIZZLE TO CONTINUE...PARTICULARLY ALONG THE
WINDWARD SIDE OF THE OLYMPICS AND CASCADES. SOUTHWESTERLY ONSHORE
PRESSURE GRADIENTS WILL BECOME FAVORABLE FOR A PUGET SOUND
CONVERGENCE ZONE FROM LATE THIS AFTERNOON THROUGH
TONIGHT...ENHANCING SHOWER ACTIVITY IN TYPICAL LOCATIONS OVER
SNOHOMISH...SOUTHERN ISLAND...AND PERHAPS NORTHERN KING COUNTIES.

WEAK UPPER HEIGHT RISES WILL MOVE IN ON SATURDAY...PUTTING A SQUASH
ON ANY FURTHER SHOWER CHANCES BY LATE MORNING. SHOULD ALSO ALLOW FOR
MORE WIDESPREAD SUN BREAKS ON SATURDAY AFTERNOON.

THE TAIL END OF ANOTHER UPPER TROUGH WILL PASS ACROSS WRN WA ON
SUNDAY. THE PATTERN LOOKS SIMILAR TO TODAY...BUT MOS GUIDANCE IS
GOING WITH CONSIDERABLY LOWER POPS THAN THEY WERE POINTING TO FOR
TODAY. STILL...CAN AT LEAST EXPECT AN INCREASE IN ONSHORE FLOW AND
MARINE CLOUDS LATER SUNDAY.      HANER

.LONG TERM...FROM PREVIOUS DISCUSSION...GENERALLY WILL HAVE MODERATE
ZONAL FLOW THROUGH THE EXTENDED PERIOD WITH SYSTEMS PASSING BY JUST
TO THE NORTH SO THE PERIOD SHOULD BE DRY. HOWEVER WITH THIS
FLOW...WILL HAVE MODERATE ONSHORE FLOW WHICH WILL HOLD AFTERNOON
TEMPS BACK A BIT AND PROVIDE PLENTY OF LATE NIGHT AND MORNING CLOUDS
WITH SOME AFTERNOON SUNSHINE. BASICALLY A MARINE CLIMATE.
ENJOY....   CERNIGLIA

&&

.AVIATION...UPDATED AT NOON...PSCZ SETTING UP NOW OVER ADMIRALTY
INLET. SHOWERS AROUND PORT TOWNSEND AND AROUND EDMONDS-KPAE...SHOULD
ALL MERGE TOGETHER EARLY THIS AFTERNOON INTO A CLASSIC PSCZ.

ONSHORE FLOW AND A MOIST AIR MASS WILL GIVE MAINLY MVFR BKN STRATOCU
TODAY...PROBABLY GOING SCT-BKN030 THIS AFTERNOON AND EVENING. AT
NOON THE SUNSHINE IN SEQUIM HAS GIVEN WAY TO THE CONVERGENCE ZONE
SETTING UP. STRATUS SHOULD BECOME OVERCAST OVERNIGHT AND MOSTLY MVFR
AGAIN. SSW WIND 10 TO 15KTS SEA TAC TODAY. MM

&&

.SEW WATCHES/WARNINGS/ADVISORIES...SMALL CRAFT ADVISORY COAST AND
STRAIT.

WEATHER.GOV/SEATTLE