Funnel Cloud in Washington, April 28, 2011

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PDT THU APR 28 2011

.SYNOPSIS...SHOWERS AND SCATTERED THUNDERSTORMS WILL TAPER TONIGHT
AS A DEEP UPPER LOW MOVES AWAY TO THE EAST. A FEW SHOWERS WILL
LINGER INTO FRIDAY. WARMER AND DRIER WEATHER IS EXPECTED THIS
WEEKEND... ESPECIALLY ON SUNDAY. ANOTHER WEATHER SYSTEM IS DUE
MONDAY. THE MIDDLE OF NEXT WEEK ALSO LOOKS WARM AND DRY.

&&

.SHORT TERM...ONLY A FEW LIGHTNING STRIKES SO FAR TODAY BUT CELLS
KEEP POPPING UP AND WILL KEEP THEM IN THE FORECAST FOR THIS EVENING.
SHOWERS SHOULD TAPER OVERNIGHT AS THE DEEP AND COLD UPPER LOW MOVES
AWAY TO THE EAST. A PUGET SOUND CONVERGENCE ZONE IS POSSIBLE TONIGHT
AND HAVE DRAWN A ZONE OF SOMEWHAT HIGHER POPS OVER SNOHOMISH COUNTY.

FRIDAY WILL HAVE RESIDUAL SHOWERS AND TEMPERATURES SHOULD BE A FEW
DEGREES HIGHER THAN TODAY. HEIGHTS WILL BE SIGNIFICANTLY HIGHER.
MODELS CONTINUE TO SHOW LIGHT PCPN OF SOME KIND ON SATURDAY EVEN AS
HEIGHTS CONTINUE TO RISE. THIS COULD BE DRIZZLE IN A DEEP MARINE
LAYER AS ONSHORE SURFACE FLOW IS FAIRLY STRONG. THEN AGAIN IT COULD
BE SOME ARTIFACT. FOR NOW HAVE KEPT A MAINLY DRY FORECAST FOR
SATURDAY WITH A FURTHER WARMING OF A COUPLE OF MORE DEGREES.

SUNDAY CONTINUES TO LOOK LIKE THE BEST DAY. SURFACE FLOW IS LIGHT
AND THE UPPER RIDGE AXIS IS RIGHT OVER WESTERN WASHINGTON. HEIGHTS
RISE WELL INTO THE 560S AND HIGH TEMPERATURES WILL FOLLOW BY RISING
INTO THE 60S. THE GRIDS HAVE A FEW POINTS AROUND 70 IN THE SOUTH. BY
LATE IN THE DAY SOME HIGH CLOUDS FROM THE NEXT SYSTEM COULD START
DRIFTING OVER THE AREA. BURKE

.LONG TERM...A SYSTEM ARRIVES MONDAY. THE TREND IN THE MODELS HAS
BEEN TO WEAKEN THIS SYSTEM BUT IT STILL BRINGS A FEW TENTHS OF AN
INCH OF RAIN TO MOST AREAS WITH A BIT MORE ON THE COAST AND IN THE
MOUNTAINS. HAVE KEPT LIKELY POPS INLAND WITH CATEGORICAL ON THE
COAST. ONE IMPORTANT FACT ABOUT THIS SYSTEM IS IT WILL NOT BE NEAR
AS COLD AS THE CURRENT ONE.

AFTER SHOWERS TUESDAY ANOTHER RIDGE BUILDS...GIVING A DRY AND MOSTLY
SUNNY DAY WEDNESDAY. THE NEXT SYSTEM WILL BEGIN TO AFFECT THE AREA
THURSDAY. KEPT MOST AREAS DRY AND PARTLY SUNNY BUT STUCK A CHANCE OF
RAIN ON THE COAST. IT IS STARTING TO SEEM POSSIBLE THAT SPRING IS ON
THE WAY. AT LEAST THE PERCENTAGE OF DRY AND WARM DAYS WILL BE
ROUGHLY COMPARABLE TO THE PERCENTAGE COOL WET DAYS. BURKE

&&

.AVIATION...COLD UPPER LEVEL TROUGH OVER WESTERN WASHINGTON. WLY
FLOW ALF BECMG NLY FRI. AIR MASS MOIST AND UNSTABLE. CHANCE FOR
THUNDERSTORMS THRU THE EVENING WITH SMALL HAIL OR GRAUPEL...ALTHOUGH
SO FAR AS OF 230PM THEY'VE BEEN PRETTY FEW AND FAR BETWEEN. LOW
LEVEL ONSHORE FLOW. CIGS WILL SPREAD BACK OUT AND LOWER OVERNIGHT
AFTER THE CU COLLAPSE...PROBABLY MVFR STRATUS IN THE MORNING THEN
SCT-BKN CU BY FRI AFTERNOON. MTNS REMAINING MOSTLY OBSCURED IN
SCATTERED SNOW SHOWERS. 19

KSEA...SO FAR TODAY THE SEATTLE AREA HAS AVOIDED SHOWERS PRETTY
WELL...BUT AT 230PM THERE WERE SHOWERS FROM SNOHOMISH COUNTY WWD TO
THE NE OLYMPIC PENINSULA. THERE MIGHT BE ENOUGH OF A NW PUSH DOWN
ADMIRALTY INLET TO DRIVE SOME OF THAT SOUTH A NOTCH THIS EVENING BUT
KPAE IS MUCH MORE LIKELY TO SEE THE SHOWERS.

&&

.MARINE...ONSHORE FLOW HAS BEEN ON THE WEAK SIDE...CLOSER TO 15KT
THAN ENOUGH FOR THE SMALL CRAFT ADVISORIES. WITH THE CHANCE OF SOME
GUSTY WINDS NEAR SHOWERS THIS EVENING WILL KEEP THE ADVISORIES UP
FOR A FEW HOURS OF 15-25KT WINDS. THE FLOW SHOULD BE STRONGER FRIDAY
AS HIGH PRES BUILDS IN...AND THE WLY PUSH IN THE STRAIT FRI EVENING
HAS A GOOD SHOT OF BEING A GOOD 20-30KT AND A NW WINDS OVER THE
COASTAL WATERS OUGHT TO INCREASE AS WELL FRIDAY. HIGH PRES BUILDS IN
OVER THE WEEKEND. 19

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COASTAL WATERS AND STRAIT...AND PUGET
SOUND AND HOOD CANAL.