National Weather Service National Headquarters

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KSEW 281041
AFDSEW

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
340 AM PDT MON JUL 28 2014

.SYNOPSIS...HIGH PRESSURE ALOFT WILL BRING DRY AND WARM WEATHER THIS
WEEK.

&&

.SHORT TERM...THE SHORT VERSION FOR BOTH THE SHORT AND LONG
TERM...UPPER LEVEL RIDGE...WEAK ONSHORE FLOW...HIGH TEMPERATURES A
FEW DEGREES ABOVE NORMAL. THANKS FOR STOPPING BY. DRIVE SAFELY.

SATELLITE IMAGERY SHOWS WESTERN WASHINGTON ON THE BACK SIDE OF AN
UPPER LEVEL RIDGE WITH SOUTHWESTERLY FLOW ALOFT OVER THE AREA. SOME
LOW CLOUDS ARE PRESENT ALONG THE NORTH COAST WITH A BIT OF STRATUS
MAKING ITS WAY DOWN THE STRAIT OF JUAN DE FUCA. CLEAR SKIES ACROSS
THE REMAINDER OF THE AREA. TEMPERATURES AT 3 AM RANGED FROM THE
LOWER 50S AT FRIDAY HARBOR TO THE MID 60S IN THE SEATTLE METRO AREA.

UPPER LEVEL RIDGE CENTERED OVER THE ROCKIES SHOWING NO SIGNS OF
WEAKENING OR MOVING TODAY. 500 MB HEIGHTS REMAIN IN THE MID TO UPPER
580 DMS. MODEL 850 MB TEMPERATURES WARM UP A DEGREE OR TWO C FROM
YESTERDAY TO PLUS 16 TO 19 C. AT THE SURFACE THE LIGHT ONSHORE FLOW
PATTERN REMAINS INTACT. WITH THE SLIGHT WARMING ALOFT EXPECT HIGH
TEMPERATURES OVER THE INTERIOR TO WARM A COUPLE OF DEGREES TODAY
VERSUS SUNDAYS HIGHS WITH 80S COMMON AND LOWER 90S IN THE WARMEST
LOCATIONS. ALONG THE COAST AND STRAIT WHERE THE LIGHT ONSHORE FLOW
WILL PROVIDE AN AFTERNOON SEABREEZE HIGHS WILL REMAIN IN THE 70S.

NO CHANGE IN THE PATTERN BOTH AT THE SURFACE AND ALOFT ON TUESDAY.
TEMPERATURES ALOFT SIMILAR TO MONDAYS READINGS. WILL GO WITH A
PERSISTENCE FORECAST ON TUESDAY.

A SMALL CHANGE IN THE OFFING FOR WEDNESDAY. UPPER LEVEL RIDGE
REMAINING OVER THE AREA WITH THE 500 MB HEIGHTS WEAKENING A TOUCH.
LOW LEVEL ONSHORE GRADIENTS ALSO PICK UP A TOUCH. BOTH THESE CHANGES
ARE MINOR AND IT CERTAINLY DOES NOT LOOK LIKE A FULL BLOWN MARINE
PUSH BUT WITH THE SMALL CHANGES EXPECT THE LOW CLOUDS AND FOG TO
SPREAD A LITTLE INLAND WEDNESDAY MORNING AND THE AFTERNOON HIGHS TO
BE A COUPLE OF DEGREES COOLER OVER THE INTERIOR WITH A LITTLE MORE
COOLING ALONG THE COAST.

.LONG TERM...EXTENDED MODELS IN GOOD AGREEMENT WITH LITTLE CHANGE IN
THE PATTERN...BOTH SURFACE AND ALOFT...THROUGH THE WEEKEND. MODEL
500 MB HEIGHTS REMAIN IN THE MID 580 DMS WITH LIGHT ONSHORE FLOW AT
THE SURFACE. FLOW ALOFT REMAINS SOUTHWESTERLY WHICH WILL PUSH ANY
CONVECTION THAT DEVELOPS OVER THE OREGON CASCADES EAST OF THE
NORTHERN AND CENTRAL WASHINGTON CASCADES. WITH THE PATTERN REMAINING
INTACT FOR OVER A WEEK IN A HALF WILL HAVE TO START THINKING ABOUT A
MARINE PUSH AT SOME POINT LATE IN THE PERIOD OR EARLY NEXT WEEK BUT
RIGHT NOW NEITHER THE GFS OR THE ECMWF INDICATE ANYTHING EXCEPT
SHALLOW MARINE PUSHES IN THE EARLY MORNING HOURS THROUGH THE
WEEKEND. END RESULT A CONTINUATION OF THE CURRENT WEATHER WITH HIGHS
A FEW DEGREES ABOVE NORMAL FOR MOST OF THE AREA AND PLENTY OF
SUNSHINE. FELTON

&&

.CLIMATE...SO FAR THIS MONTH SEATTLE HAS HAD 15 DAYS WITH HIGHS 80
DEGREES PLUS AND IS ON TRACK TO END UP THE MONTH WITH 19 DAYS OF 80
PLUS DAYS. THIS IS NOT A RECORD FOR THE MONTH BUT WILL BE THE THIRD
HIGHEST NUMBER OF 80 PLUS DAYS IN ANY MONTH IN SEATTLE INCLUDING THE
FEDERAL BUILDING RECORDS WHICH GO BACK TO 1891. THE OTHER TWO MONTHS
WITH MORE 80 PLUS DAYS ARE JULY 1985 AND AUGUST 1967. BOTH OF THOSE
MONTHS HAD 21 DAYS OF 80 PLUS HIGH TEMPERATURES.

THE AVERAGE HIGH TEMPERATURE SO FAR THIS MONTH IN SEATTLE IS 79.6
DEGREES. THERE IS A GOOD CHANCE THE AVERAGE HIGH TEMPERATURE FOR THE
MONTH WILL END UP ABOVE 80 DEGREES. THERE HAVE ONLY BEEN SEVEN OTHER
MONTHS SINCE 1891 WITH THE AVERAGE HIGH TEMPERATURE 80 DEGREES PLUS.
THE PREVIOUS SEVEN MONTHS WERE AUGUST 1961...1967...1986 AND JULY
1941...1958...1985 AND 2009 ( THE MONTH WITH THE ALL-TIME RECORD
HIGH TEMPERATURE FOR SEATTLE 103 ON THE 29TH ). FELTON

&&

.AVIATION...AN UPPER LEVEL RIDGE WILL CONTINUE TO BUILD DOWN STREAM
OVER THE NORTHERN INTERMOUNTAIN AREA THROUGH TUESDAY. THE FLOW ALOFT
WILL REMAIN SOUTHWESTERLY AND LIGHT AND THE AIR MASS WILL REMAIN DRY
AND STABLE. LOW LEVEL ONSHORE FLOW HAS BROUGHT LOW CLOUDS TO THE
NORTH COAST AND WEST ENTRANCE AS OF 09Z..EXPECT EXTENT WILL REMAIN
LIMITED TO THE NORTH COAST AND STRAIT...CLEARING BY LATE MORNING.
SKIES WILL REMAIN CLEAR AND VFR ALL OTHER AREAS.

KSEA...CLEAR SKIES AND VFR CONDITIONS WILL PERSIST THROUGH MONDAY
NIGHT. NORTHEASTERLY WINDS 6 TO 8 KTS WILL BECOME NORTHWESTERLY
AROUND MIDDAY.

&&

.MARINE...THE PERSISTENT PATTERN OF HIGH PRESSURE OVER THE COASTAL
WATERS AND LOWER PRESSURE INLAND WILL CONTINUE THROUGH MID
WEEK...SUPPORTING VARYING DEGREES ONSHORE FLOW. STRONGEST WINDS WILL
OCCUR THROUGH THE CENTRAL AND EAST STRAIT...LIKELY REACHING SMALL
CRAFT ADVISORY LEVELS DURING THE LATE AFTERNOON AND EVENING HOURS.
IN ADDITION...MODERATE NORTHWESTERLY WINDS OVER THE COASTAL WATERS
WILL PERSIST THROUGH MUCH OF THE WEEK...NEAR OR JUST ABOVE SCA
LEVELS AT TIMES DURING THE AFTERNOON AND EVENING HOURS. AREAS OF
MORNING FOG WILL DEVELOP OVER THE COASTAL WATERS AND STRAIT THROUGH
TUESDAY.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY COASTAL WATERS...AND STRAIT OF JUAN DE
FUCA.

&&

$$

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