River Flood Warning 4, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
300 PM PST TUE JAN 6 2009

.SYNOPSIS...A WARM PLUME OF MOISTURE WILL BRING SIGNIFICANT RAINFALL
WITH HIGH SNOW LEVELS THROUGH THURSDAY MORNING. THE POTENTIAL FOR
RIVER AND SMALL STREAM FLOODING WILL INCREASE TONIGHT AND WEDNESDAY.
THE RAIN WILL TAPER LATE WEDNESDAY NIGHT INTO THURSDAY AS A LOW
PRESSURE SYSTEM PUSHES THE MOISTURE SOUTH OF THE AREA. THURSDAY WILL
BE SHOWERY. DRY WEATHER IS LIKELY ON FRIDAY.

&&

.SHORT TERM...FOCUS OF PRECIPITATION IS OVER THE NORTH CASCADES THIS
AFTERNOON. NEW MODEL RUNS HAVE A DEFINITE TREND TOWARD HAVING THE
HEAVIEST RAIN OVER THE NORTH CASCADES FOR THE FIRST 24 HOURS OF THE
EVENT. RADAR AND SURFACE OBS CONFIRM THIS TREND...AT LEAST IN THE
FIRST 6 HOURS OR SO THAT HAVE ALREADY OCCURRED. AMOUNTS APPEAR TO BE
IN THE 2 INCH RANGE AT THE NWS GAUGES IN THE NORTH CASCADES.

IF THE MODELS ARE CORRECT THE NEXT PLACE TO GET A LOT OF RAIN WILL
BE THE SOUTHWEST ON WEDNESDAY AND WEDNESDAY NIGHT. THE LIKELY UPSHOT
OF ALL THIS IS THAT NORTH CASCADE RIVERS WILL FLOOD SOONER AND
SOUTHWEST RIVERS WILL FLOOD LATER. SO FAR THE AMOUNTS IN THE
OLYMPICS HAVE BEEN UNIMPRESSIVE...GENERALLY LESS THAN AN INCH...SO
FLOODING COULD BE DELAYED THERE AS WELL.

REST OF SHORT TERM IS LARGELY ON TRACK...WITH COLD FRONT MOVING
THROUGH ON THURSDAY...CHANGING RAIN TO SHOWERS AND LOWERING SNOW
LEVELS...AND EVENTUALLY SHUTTING OFF THE RAIN ALTOGETHER. FRIDAY
LOOKS PRETTY DRY WITH BOTH THE GFS AND EURO BUILDING A SURFACE
RIDGE. BURKE

.LONG TERM...SATURDAY BEGINS DRY BUT A WEAK SYSTEM BRUSHES THE AREA
FROM THE NORTH. HAVE MOSTLY BROAD BRUSHED THE REST OF THE
EXTENDED...KEEPING CHANCE POPS AS EURO IS WETTER THAN GFS. BURKE

&&

.AVIATION...NO UPDATES FROM THE MORNING DISCUSSION...WARM FRONT WILL
MOVE SLOWLY THRU WRN WA THRU WED. STRONG WSW FLOW ALOFT. DEEP
MOISTURE IN STABLE AIR MASS. COLD FROPA IS AROUND 12Z THU. PDX-BLI
GRADIENT WILL BE AROUND +10MB FOR WINDY SOUTHERLIES FOR THE INLAND
TAFS AND MORE SWLY FOR THE COAST TAFS. FREEZING LEVEL WILL BE
HIGH...THE 0C ISOTHERM ON THE CROSS SECTION LIFTS UP TO NEARLY 700MB
THIS EVENING...NOT FALLING BACK TO 850MB TIL DAYBREAK ON THU. AT
LEAST +6C AT 850MB THIS AFTERNOON THRU MOST OF WED INDICATING VERY
WARM AIR MASS FOR THIS TIME OF YEAR WHICH...IF NOT FOR SOME
RAINSHADOWING BEHIND THE OLYMPICS...WILL GIVE MODERATE TO HEAVY
RAIN. KSEA KBFI AND KPAE WILL CATCH A BREAK FROM THE HEAVY RAIN BUT
VSBY AND CIGS HAVE A GOOD CHANCE OF COMING DOWN TO 1SM -RA OVC005 AT
TIMES TONIGHT...MAINLY NORTH AND SOUTH OF THE RAINSHADOW OVER PUGET
SOUND. 19

KSEA...WIND AND VSBY BOTH UP DUE TO THE DOWNSLOPE OFF THE OLYMPICS.
CIGS WILL PROBABLY STAY 010-015 HOWEVER. CONDITIONS SHOULD NOT
CHANGE MUCH...AS A FEW BANDS OF RAIN DOUSE THE PUGET SOUND BASIN THE
VSBY MAY DROP TO 2 OR 3 MILES AT TIMES BUT WILL MAINLY STICK CLOSE
TO WHAT IT WAS DOING THIS AFTERNOON. 19

&&

.MARINE...EXTENDED THE GALE WARNINGS INTO THE WEST ENTRANCE OF THE
STRAIT. THE MESO MODEL SHOWS SW GALES INTO THE CENTRAL STRAIT AS
WELL BUT WITH RACE ROCKS ESE16KT AT 2PM WILL WAIT AND WATCH...DO
HAVE A FORECAST OF SW20-30 FOR THE CENTRAL STRAIT. PUT THE GALE UP
FOR PUGET SOUND AND HOOD CANAL EARLIER AND THE WINDS THAT WE HAVE
HAD THIS AFTERNOON SHOULD CONTINUE THRU THE NIGHT...AND PROBABLY
UNTIL ARND 18Z WED. 19

&&

.AVALANCHE...FORECASTS ON TRACK WITH CURRENT HEAVY LOADING AND
RAPIDLY INCREASING STRESS ON A VARIETY OF BURIED WEAK LAYERS. THESE
WEAKNESSES EXIST BOTH WITHIN MORE RECENT SNOWFALL SINCE DEC 31 AND
IN THE VERY WEAK RECRYSTALLIZED SNOW OR FACETS FROM EARLY TO MID
DECEMBER THAT EXIST NEAR THE BASE OF THE OLDER SNOWPACK. OVERALL
IMPACT OF ANTICIPATED VERY HEAVY PRECIPITATION ...MOSTLY AS
RAIN...DURING NEXT 36 HOURS SHOULD BE SEVERE AND EXTREME AVALANCHE
DANGER LIKELY MANIFESTING OVER A SIGNIFICANT PORTION OF OUR NW
AVALANCHE TERRAIN. AS MUCH AS 6-10 INCHES OR MORE OR WATER
EQUIVALENT EXPECTED FROM NOW THROUGH WEDNESDAY NIGHT...WHICH IS
EQUIVALENT TO ADDING 5 TO 10 FEET OR MORE OF SNOW LOAD TO OUR STILL
FRAGILE SNOWPACK AT DEPTH...ALL IN THE SPACE OF TWO DAYS. BEST TO
AVOID AVALANCHE TERRAIN...PRACTICE BEACON SEARCHES...AND USE THIS
OPPORTUNITY TO GET YOUR GEAR READY FOR WHEN THE SNOWPACK ACTUALLY
DOES STABILIZE AND STRENGTHEN. MOORE

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...AVALANCHE WARNING IN EFFECT FOR THE OLYMPICS AND CASCADES
THROUGH WEDNESDAY.
FLOOD WATCH IN EFFECT FOR MUCH OF THE AREA FROM THIS EVENING THROUGH
FRIDAY AFTERNOON.
WIND ADVISORY IN EFFECT TONIGHT FOR THE SEATTLE METROPOLITAN AREA
INCLUDING THE EAST PUGET SOUND LOWLANDS AND THE HOOD CANAL AREA.

PZ...GALE WARNING IN EFFECT FOR THE COASTAL WATERS...WEST ENTRANCE
TO THE STRAIT OF JUAN DE FUCA...PUGET SOUND AND HOOD CANAL.
SMALL CRAFT ADVISORY IN EFFECT FOR THE REMAINING WATERS.
SMALL CRAFT ADVISORY IN EFFECT FOR SEVERE GRAYS HARBOR BAR.

WEATHER.GOV/SEATTLE

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SEATTLE WA
109 PM PST TUE JAN 06 2009

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0100 PM     NON-TSTM WND DMG 1 NNE NORTH BEND        47.51N 121.78W
01/06/2009                   KING               WA   TRAINED SPOTTER

            SPOTTER REPORTED FREQUENT GUSTS TO 35 MPH BEFORE HE LOST
            POWER.

0108 PM     NON-TSTM WND GST 1 NNE ISSAQUAH          47.55N 122.03W
01/06/2009  M51 MPH          KING               WA   TRAINED SPOTTER

            3 GUSTS OF 51 MPH SO FAR.

&&

GRUB