Heavy Snow in Washington, January 8 to 9, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
830 AM PST WED JAN 8 2014

.SYNOPSIS...SEVERAL WEATHER SYSTEMS WILL MOVE THROUGH WESTERN
WASHINGTON THROUGH THE END OF THE WEEK. IT WILL BE RAINY AND BREEZY
AT TIMES. THE STRONGEST WEATHER SYSTEM WILL MOVE THROUGH WESTERN
WASHINGTON FRIDAY NIGHT AND SATURDAY WITH WET WINDY WEATHER.

&&

.SHORT TERM...THE PATTERN THROUGH THE END OF THE WEEK WILL BE ZONAL
FLOW WITH FRONTAL SYSTEMS ASSOCIATED WITH PROGRESSIVE SHORT WAVE
TROUGHS. THE FIRST FRONT IS JUST OFF THE COAST THIS MORNING AND WILL
MOVE ACROSS THE AREA THROUGH THIS EVENING. EXPECT RAIN AND LOCALLY
WINDY CONDITIONS TO INCREASE THIS AFTERNOON AND CONTINUE THIS
EVENING IN THE LOWLANDS. THE SNOW LEVEL HAS NOT BEEN VERY LOW FOR
THE MIDDLE OF WINTER BUT THE PASSES SHOULD STILL PICK UP PRETTY GOOD
SNOW AMOUNTS FROM THIS SYSTEM AND AN ADVISORY IS IN EFFECT FROM NOON
TODAY TIL NOON THURS ABOVE 3000 FEET IN THE CASCADES. A SECOND
FRONTAL SYSTEM WILL REACH WESTERN WA THURSDAY EVENING FOR MORE RAIN
AND BREEZY WEATHER FOR WESTERN WA.

.LONG TERM...A STRONG FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT
THROUGH MIDDAY SATURDAY. THIS MOISTURE WILL BRIEFLY TAP IN TO
TROPICAL MOISTURE LIFTING NORTHWARD FROM AN UPPER LOW JUST TO THE
EAST OF THE HAWAIIAN ISLANDS. MODELS CONTINUE TO SHOW 850 MB
TEMPERATURES RISING TO 4C AND THE WRFGFS 4KM SOLUTION HAS BEEN
SHOWING AROUND 5 INCHES OF RAIN FOR THE 24 HOUR PRECIP TOTAL ENDING
18Z SATURDAY. THE 12Z MODELS THIS MORNING SHOW 2-4 INCHES OF RAIN IN
THE MOUNTAINS WITH THAT SYSTEM. IT WILL BE WINDY SATURDAY WITH A
PDX-BLI GRADIENT AROUND +15MB...SO THIS SYSTEM SEEMS A LOT LIKE A
NOVEMBER MILD WINDY STORM. DIRTY RIDGING OCCURS THROUGH EARLY NEXT
WEEK WITH WEAK SYSTEMS BRUSHING THE AREA.

&&

.HYDROLOGY...A HIGH SNOW LEVEL FRIDAY NIGHT IN A STRONG WET FRONTAL
SYSTEM SHOULD SEND SEVERAL RIVERS UP NEAR FLOOD STAGE SATURDAY AND
THE SKOKOMISH RIVER IN MASON COUNTY CERTAINLY COMES TO MIND AS IT IS
THE EASIEST RIVER TO REACH FLOOD STAGE. BUT ALL THE RIVERS OUGHT TO
BE RUNNING PRETTY HIGH THIS WEEKEND FROM A SYSTEM THAT LOOKS A LOT
LIKE A NOVEMBER STORM. THE SYSTEM MOVES FAIRLY QUICKLY THROUGH THE
AREA WITH THE WARM WET PLUME OVER WRN WA MAINLY FRI NITE. THE LATEST
24HR PRECIP TOTALS ENDING 10AM SATURDAY FROM THE GFS AND NAM ARE IN
THE RANGE OF 2-4" IN THE MOUNTAINS...OTHER MODEL RUNS HAVE BEEN
WETTER THAN THAT. THE PROGRESSIVE NATURE OF THE WEATHER PATTERN
THROUGH THE END OF THIS WEEK SUGGESTS THE SYSTEM WILL MOVE THROUGH
QUICK ENOUGH TO MAKE THIS A FAIRLY MINOR EVENT.

&&

.AVIATION...INCREASING SOUTHWEST FLOW ALOFT OVER WESTERN WASHINGTON
TODAY WITH AN OCCLUDED FRONT MOVING THROUGH THE FORECAST AREA LATE
THIS AFTERNOON AND EVENING. THE FLOW ALOFT WILL VEER TO WESTERLY
BEHIND THE FRONT. AT THE SURFACE SOUTHERLY WINDS WILL INCREASE AHEAD
OF THE FRONT...THEN BECOME STRONGLY ONSHORE BEHIND THE FRONT. THE
AIR MASS WILL REMAIN MOIST AND BECOME WEAKLY UNSTABLE TONIGHT.

MVFR AND LOCAL IFR CONDITIONS PREVAIL THIS MORNING WITH SKY COVER
ROUGHLY SCT-BKN008 OVC015-025 WITH HIGHER OVERCAST LAYERS ABOVE.
THERE ARE ALSO LOCAL VISIBILITIES 3-5SM IN RAIN. CONDITIONS ARE
LIKELY TO DETERIORATE SOMEWHAT THROUGH THIS EVENING AS RAIN
INCREASES...WITH MARGINAL IMPROVEMENT BEHIND THE FRONT LATER TONIGHT.

KSEA...SOUTH WIND 6-10 KT RISING TO 10-16 KT GUSTING 25 KT AROUND
00Z-03Z. CONDITIONS WILL DETERIORATE AND BE MAINLY IFR THROUGH THIS
EVENING AS RAIN INCREASES.   MCDONNAL

&&

.MARINE...AN OCCLUDED FRONT WILL MOVE QUICKLY THROUGH THE COASTAL
WATERS THIS AFTERNOON AND THROUGH THE INLAND WATERS OF WESTERN
WASHINGTON EARLY THIS EVENING. SMALL CRAFT ADVISORY WINDS ARE LIKELY
OVER ALL WATERS...AND BRIEF MARGINAL GALES ARE A POSSIBILITY FOR THE
COASTAL WATERS COINCIDENT WITH THE FRONT. STRONG ONSHORE FLOW WILL
DEVELOP BEHIND THE FRONT TONIGHT...WITH GALE WESTERLIES LIKELY IN
THE CENTRAL AND EASTERN STRAIT OF JUAN DE FUCA. THE GALE WATCH THERE
WILL BE UPGRADED TO A WARNING WITH THE MORNING FORECAST.

A WEAKER FRONTAL SYSTEM WILL MOVE THROUGH THE FORECAST AREA
THURSDAY. A WARM FRONT WILL MOVE NORTHEAST ACROSS WESTERN WASHINGTON
FRIDAY AFTERNOON AND EVENING...FOLLOWED BY A VIGOROUS COLD FRONT ON
SATURDAY. THIS SYSTEM WILL PROBABLY PRODUCE WIDESPREAD SOLID GALES
AND COMBINED SEAS IN EXCESS OF 20 FT. ANOTHER WEAKER SYSTEM WILL
AFFECT THE AREA ON SUNDAY.   MCDONNAL

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WINTER WEATHER ADVISORY ABOVE 3000 FEET FOR THE NORTH AND
CENTRAL CASCADES FROM NOON TODAY TIL NOON THURSDAY.

PZ...SMALL CRAFT ADVISORY COASTAL WATERS...EAST AND WEST STRAIT OF
     JUAN DE FUCA...ADMIRALTY INLET...NORTHERN INLAND WATERS...PUGET
     SOUND AND HOOD CANAL.
    .GALE WARNING IN EFFECT FOR THE CENTRAL AND EAST STRAIT TONIGHT.

&&

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