Small Craft Advisory 22, NWS Seattle, WA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
900 PM PST TUE FEB 3 2015

.SYNOPSIS...A WEAK WARM FRONT WILL MOVE NORTH ACROSS THE AREA ON
WEDNESDAY BRINGING LIGHT RAIN. A MUCH STRONGER WARM FRONT WILL BRING
HEAVY RAIN AND WINDY CONDITIONS ON THURSDAY. MOIST SOUTHWEST FLOW
ALOFT WILL BRING A SERIES OF WET FRONTAL SYSTEMS ACROSS THE AREA
FRIDAY THROUGH MONDAY.

&&

.SHORT TERM...THE UPPER RIDGE OVER THE REGION REMAINS CENTERED JUST
OFF THE PACIFIC NORTHWEST COAST THIS EVENING. THE RIDGE IS
AMPLIFYING SOMEWHAT AHEAD OF A DEVELOPING WAVE ABOUT 900 NM WEST OF
NORTHERN CALIFORNIA. OVER WESTERN WASHINGTON...SKIES REMAIN MAINLY
CLOUDY THIS EVENING WITH PATCH FOG AND SPOTTY LIGHT SHOWERS ALONG
THE WEST SLOPES OF THE CASCADES.

THE UPPER RIDGE WILL CONTINUE TO AMPLIFY SLIGHTLY AS IT MOVES SLOWLY
EAST TOWARD THE PACIFIC NORTHWEST COAST TONIGHT AND WEDNESDAY. A
WEAK WARM FRONT DRAPED ACROSS THE RIDGE WILL LIFT NORTH FROM OREGON
ACROSS WASHINGTON...AND IT SHOULD BRING AREAS OF LIGHT RAIN TO THE
FORECAST AREA. THE SNOW LEVEL WILL BE 4000 TO 4500 FT...BUT
PRECIPITATION -- EVEN IN THE MOUNTAINS -- WILL GENERALLY AMOUNT TO
0.10 INCH OR LESS.

THE FRONTAL WAVE THAT IS WELL WEST OF CALIFORNIA WILL TRACK
NORTHEAST...AND ITS WARM FRONT SHOULD BRING MORE SIGNIFICANT
PRECIPITATION TO WESTERN WASHINGTON LATER WEDNESDAY NIGHT AND
THURSDAY. ANOTHER FRONTAL WAVE RIGHT ON ITS HEELS WILL BRING MORE
PRECIPITATION THURSDAY NIGHT AND FRIDAY. UP TO 2 INCHES OF RAIN
COULD FALL IN PARTS OF THE WESTERN WASHINGTON LOWLANDS...MAINLY AT
THE COAST...DURING THE 48-HOUR PERIOD BETWEEN LATE WEDNESDAY AND
LATE FRIDAY. THE 48-HOUR PRECIPITATION TOTALS IN THE MOUNTAINS WILL
PROBABLY BE 3 TO 6 INCHES...WITH THE SNOW LEVEL RISING TO AROUND
6000 FT ON THURSDAY AND 7000 FT ON FRIDAY.   MCDONNAL

.LONG TERM...HERE IS THE LONG TERM SECTION FROM THE AFTERNOON
FORECAST DISCUSSION -- ANOTHER IMPULSE ARRIVES SATURDAY AND ANOTHER
ONE COMES SUNDAY NIGHT. THE GFS AND EURO ARE IN BROAD AGREEMENT
ABOUT THIS. THE SUNDAY NIGHT SYSTEM...WHICH WILL CONTINUE INTO
MONDAY...LOOKS LIKE THE LAST IN THE SERIES. MONDAY AFTERNOON AND
EVENING LOOKS MORE SHOWERY AND TUESDAY LOOKS PRETTY DRY AS AN UPPER
RIDGE BUILDS IN BOTH MODELS. TEMPERATURES WILL BE WELL ABOVE AVERAGE
EACH DAY. THERE WILL CONTINUE TO BE BREEZY OR WINDY CONDITIONS AT
TIMES. BURKE

&&

.HYDROLOGY...THE MAIN PROBLEM THIS WEEK WILL BE HEAVY RAIN. THE
FIRST TWO STRONGER WAVES...MAINLY THURSDAY AND THURSDAY NIGHT...
COULD BRING ENOUGH RAIN TO THE OLYMPICS TO CAUSE MINOR FLOODING ON
THE SKOKOMISH RIVER IN MASON COUNTY. A FLOOD WATCH FOR THAT RIVER IS
IN EFFECT FROM THURSDAY MORNING THROUGH FRIDAY AFTERNOON.

THE RAIN KEEPS COMING IN A SERIES OF WAVES...WHICH ALSO IMPLIES
THERE ARE BREAKS IN THE HEAVY RAIN. THAT MAY BE THE SAVING GRACE OF
WHAT WILL CERTAINLY BE A WET WEEK. THE 120-HOUR TOTAL...5 DAYS OF
RAIN...SHOWS 10-13 INCH BULLSEYES OF HEAVY RAIN IN THE MOUNTAINS AND
1-4 INCHES IN THE LOWLANDS. THE SNOW LEVEL WILL BE ABOVE 5000 FEET
THE ENTIRE TIME WITH OCCASIONAL EXCURSIONS TO 7000 FEET OR HIGHER.

IF THAT AMOUNT OF RAIN FELL IN 48 HOURS OR LESS THERE WOULD ALMOST
CERTAINLY BE WIDESPREAD MAJOR FLOODING ON MANY RIVERS. SINCE THE
RAIN IS SPREAD OUT OVER FIVE DAYS RIVERS WILL RISE...POSSIBLY TO
FLOOD STAGE...BUT MAJOR FLOODING SEEMS UNLIKELY. WILL ISSUE A
HYDROLOGIC OUTLOOK COVERING MOST OF THE AREA. A MIDDLE GROUND AT
THIS POINT IS THAT THERE WILL BE MINOR FLOODING ON SOME RIVERS...BUT
BOTH NO FLOODING OR MAJOR FLOODING ARE POSSIBLE AS WELL. BURKE

&&

.AVIATION...THE AIR MASS IS MOIST AND STABLE WITH WESTERLY FLOW
ALOFT. SURFACE PRESSURE GRADIENTS ARE WEAK WITH LIGHT SURFACE WINDS.
IT WILL RAIN ON WED AS A WARM FRONT LIFTS NORTH THROUGH THE REGION.

KSEA...THE AIR IS MOIST AND STABLE SO THERE MAY BE SOME FOG AND LOW
CLOUDS DEVELOPING OVERNIGHT...OTHERWISE INCREASING MID AND HIGH
CLOUDS. IT WILL RAIN AGAIN WEDNESDAY WITH A WARM FRONT.

&&

.MARINE...WEAK HIGH PRESSURE IS OVER THE REGION TONIGHT WITH
GENERALLY LIGHT WINDS OVER THE WATERS. A WARM FRONT WILL LIFT NORTH
THROUGH WESTERN WA ON WED. A STRONGER FRONT WILL THEN MOVE ASHORE
THU. GALES ARE POSSIBLE THU WITH SEAS POSSIBLY BUILDING TO 15 TO 20
FEET OFF THE COAST. ADDITIONAL STRONG FRONTAL SYSTEMS WILL IMPACT
THE REGION FRI THROUGH THE WEEKEND.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...FLOOD WATCH MASON COUNTY.
PZ...NONE.

&&

YOU CAN SEE AN ILLUSTRATED VERSION OF THIS FORECAST DISCUSSION AT
WWW.WEATHER.GOV/SEATTLE/GAFD/LATEST_WEBAFD.HTML