Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

000
FXUS66 KSEW 272219
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
319 PM PDT MON OCT 27 2014

.SYNOPSIS...A MOIST LOW PRESSURE SYSTEM OFFSHORE WILL CONTINUE
MOVING EAST. LOOK FOR THE ASSOCIATED WARM FRONT TO MOVE ACROSS
THE NORTHERN PART OF THE AREA OVERNIGHT. THE COLD FRONT WILL SWEEP
ACROSS THE REGION DURING THE DAY TUESDAY. HIGH PRESSURE ALOFT WILL
MOVE OVER THE REGION TUESDAY NIGHT FOR IMPROVING CONDITIONS.
ANOTHER MOIST PACIFIC STORM WILL IMPACT THE REGION ON THURSDAY.

&&

.SHORT TERM...
RAIN WAS OVERSPREADING THE COAST AT THIS TIME AHEAD OF A WARM
FRONT. LOOK FOR THE PRECIP TO REACH THE CASCADES EARLY THIS
EVENING. THE TAIL END OF THE WARM FRONT IS EXPECTED TO MOVE NORTH
ACROSS THE NORTHERN PART OF THE CWA LATE TONIGHT OR EARLY TUE.
EXPECT SLY WINDS TO INCREASE AHEAD OF AND WITH THIS FRONT...WITH
THE STRONGEST WINDS ANTICIPATED OVER THE COAST AND NORTHWEST
INTERIOR.

THE SYSTEM HEADING OUR WAY HAS TAPPED INTO MOISTURE FROM FORMER
HURRICANE ANA. CURIOUSLY...PREDICTED RAINFALL AMOUNTS IN THE
MODELS WERE NOT THAT IMPRESSIVE. HAVE CHOSEN TO NUDGE RAINFALL
AMOUNTS ABOVE THE MAJORITY OF THE MODEL SOLUTIONS. STRONG
OROGRAPHIC ENHANCEMENT TONIGHT ALONG WITH A RISING SNOW LEVEL
WILL LIKELY RESULT IN SIGNIFICANT RAINFALL ON THE SOUTHWEST FACING
SLOPES OF OLYMPIC RANGE.

EXPECT A COLD FRONT TO SWEEP ACROSS THE CWA DURING THE DAY TUE.
LOCALLY HEAVY RAINFALL IS ANTICIPATED TUE MORNING BEFORE THE
PRECIP TAPERS OFF AND BECOMES SHOWERY BEHIND THE COLD FRONT.

CONDITIONS WILL GRADUALLY IMPROVE TUE NIGHT AND ESPECIALLY ON WED
IN RESPONSE TO AN UPPER RIDGE AMPLIFYING OVER THE PACIFIC
NORTHWEST. THERE IS A CHANCE THAT WED AFTERNOON COULD BE DRY OVER
THE ENTIRE CWA. BASED ON MODEL TRENDS...WED EVENING SHOULD BE DRY.

WED NIGHT...EXPECT AN OLD BAROCLINIC BAND OFF THE OREGON COAST TO
BECOME RE-ENERGIZED AND CONSOLIDATED WITH AN OCCLUDED FRONT
EMANATING OUT OF THE GULF OF AK. THE OCCLUDED FRONT WILL SLOWLY
MOVE ACROSS THE CWA DURING THE DAY THU. THIS SYSTEM WILL ALSO BE
QUITE MOIST...THUS HEAVY RAIN IS POSSIBLE ON THE SOUTHWEST FACING
SLOPES OF THE OLYMPICS AND CASCADES.

.LONG TERM...
A PROGRESSIVE PATTERN WILL PREVAIL OVER THE PACIFIC NORTHWEST
DURING THIS PERIOD...THUS ANTICIPATE A SERIES OF FRONTAL SYSTEMS TO
MOVE ACROSS THE REGION ABOUT EVERY 1-2 DAYS. THERE WERE SOME
DIFFERENCES IN THE DETAILS...ESPECIALLY CONCERNING THE SYSTEM ON
SUNDAY. FOR NOW...WENT WITH CATEGORICAL POPS FOR SUNDAY.

&&

.HYDROLOGY...
A MOIST PACIFIC STORM IS EXPECTED TO DUMP 2-3 INCHES OF RAIN ON
THE SOUTHWEST FACING SLOPES OF THE OLYMPICS DURING THE 24-HOUR
PERIOD ENDING AT 5 PM PDT TUE. THIS SHOULD BE ENOUGH TO DRIVE THE
SKOKOMISH RIVER NEAR OR SLIGHTLY ABOVE FLOOD STAGE ON TUE. THUS
THE FLOOD WATCH WILL REMAIN POSTED.

ELSEWHERE...RIVER FLOODING IS NOT EXPECTED THE NEXT 7 DAYS.

&&

.AVIATION...A WARM FRONT WILL SPREAD RAIN INTO WESTERN WA TONIGHT
WITH INCREASING S/SE WINDS ALONG THE COAST AND AND NORTH INTERIOR.
THE COLD FRONT WILL MOVE INLAND TUE MORNING FOR ADDITIONAL SHOWERS.
THE FLOW ALOFT IS WESTERLY. CIGS ARE VFR ALTHOUGH MAY SEE MVFR CIGS
WITH PASSING SHOWERS TUE MORNING. THE TRAILING UPPER LEVEL TROUGH
WILL MAINTAIN SHOWERS ACROSS THE REGION TUE AFTERNOON AND EVENING. 33

KSEA...VFR CONDITIONS EXPECTED TONIGHT WITH S/SE WINDS AT THE
SURFACE. LIGHT RAIN WILL SPREAD INLAND BY 03-06Z TONIGHT. SHOWERS
WILL CONTINUE THROUGH TUE MORNING AND AFTERNOON AS A COLD FRONT
MOVES INLAND. MAY SEE MVFR CIGS IN -SHRA. 33

&&

.MARINE...SOUTH TO SOUTHEAST FLOW WILL INCREASE ACROSS WESTERN WA
TONIGHT AS A STRONG PACIFIC FRONTAL SYSTEM APPROACHES THE REGION.
MODELS SHOW A 987 MB LOW TRACKING NE TOWARD HAIDA GWAII BY 06Z
TONIGHT...THEN WEAKENING AS IT SLOWLY MOVES INLAND ON TUE. THIS
SYSTEM WILL PRODUCE S/SE GALES OVER THE COASTAL WATERS...STRAIT OF
JUAN DE FUCA...ADMIRALTY INLET AND NORTHERN INLAND WATERS TONIGHT.
PUGET SOUND AND HOOD CANAL WILL SEE SMALL CRAFT ADVISORY WINDS
DEVELOPING THIS EVENING AS WELL. WINDS WILL EASE TUE MORNING BUT
WILL STILL LIKELY SEE WIND SPEEDS WITHIN SMALL CRAFT ADVISORY RANGE
THROUGH THE AFTERNOON. WEAK HIGH PRES WILL SHIFT INLAND ON WED FOR A
PERIOD OF LIGHTER WINDS ACROSS WESTERN WA. ANOTHER FRONT WILL REACH
THE AREA ON THU. 33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...WIND ADVISORY IN EFFECT FROM 11 PM TONIGHT TIL 8 AM TUESDAY
     FOR THE COAST AND NORTHWEST INTERIOR.

     FLOOD WATCH IN EFFECT FROM LATE TONIGHT THROUGH LATE TUESDAY
     NIGHT FOR MASON COUNTY.

PZ...GALE WARNINGS ARE IN EFFECT FOR ALL WATERS EXCEPT THE PUGET
     SOUND/HOOD CANAL.

     SMALL CRAFT ADVISORY IN EFFECT TIL 6 PM TUESDAY FOR THE PUGET
     SOUND AND HOOD CANAL.

     SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH BAR FROM 5 AM TIL
     6 PM TUESDAY FOR THE GRAYS HARBOR BAR.

&&

$$

WWW.WEATHER.GOV/SEATTLE

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




USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.