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AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SEATTLE WA
330 PM PDT SUN MAY 3 2015

.SYNOPSIS...HIGH PRESSURE OVER THE PACIFIC NORTHWEST WILL PRODUCE 
DRY WEATHER TONIGHT. A FRONT WILL APPROACH THE REGION MONDAY WITH 
INCREASING CLOUDS. LOW PRESSURE WILL BRING SHOWERS AND COOLER 
TEMPERATURES MONDAY NIGHT THROUGH WEDNESDAY. MOUNTAIN SHOWERS WILL 
LINGER THROUGH FRIDAY BUT IT WILL BE MOSTLY DRY ACROSS THE LOWLANDS.

&&

.SHORT TERM...A WEAK UPPER LEVEL RIDGE WILL MAINTAIN DRY AND MILD 
WEATHER ACROSS WESTERN WA TONIGHT. STRATUS CLOUDS WILL FORM ALONG 
THE COAST WHICH MAY PUSH INTO THE LOWER CHEHALIS VALLEY AND 
SOUTHWEST INTERIOR. LOWS WILL DIP INTO THE UPPER 30S TO MID 40S.

THE UPPER LEVEL RIDGE WILL SHIFT INLAND ON MONDAY WHILE AN UPPER 
LEVEL LOW FORMS OVER THE NE PAC. LOW LEVEL ONSHORE FLOW WILL 
INCREASE FOR COOLER AND CLOUDIER WEATHER. TEMPS WILL BE AROUND 5-10 
DEGREES COOLER IN THE INTERIOR COMPARED TO TODAY...ALTHOUGH TEMPS 
WILL BE NEAR NORMAL. STRATUS CLOUDS WILL LIKELY COVER THE COAST FOR 
CLOUDY SKIES WITH HIGHS IN THE 50S. A COLD FRONT WILL BRING A CHANCE 
OF SHOWERS TO THE COAST DURING THE LATE AFTERNOON. SHOWERS WILL 
SPREAD TO THE INTERIOR BY MIDNIGHT AS THE FRONT MOVES INLAND. 

SHOWERS WILL CONTINUE ON TUESDAY AS THE UPPER LEVEL LOW SPINS 
OVERHEAD. THE AIR MASS WILL BE COOL AND UNSTABLE WITH ISOLATED 
THUNDERSTORMS POSSIBLE. SNOW LEVELS WILL BE AROUND 3500 FT WITH A 
FEW INCHES OF SNOW IN THE MOUNTAINS. 

ISOLATED TO SCATTERED SHOWERS WILL CONTINUE ON WEDNESDAY AS THE 
UPPER LEVEL LOW MOVES INTO EASTERN WA. THE AIR MASS WILL REMAIN COOL 
WITH TEMPS STILL A FEW DEGREES BELOW NORMAL. 33

.LONG TERM...AN UPPER LEVEL RIDGE WILL BUILD OFFSHORE ON THURSDAY 
WITH FLOW ALOFT OVER WESTERN WA BECOMING NORTHERLY. THE UPPER LEVEL 
LOW WILL SHIFT SOUTH INTO OREGON BUT THERE REMAINS ENOUGH LIFT AND 
MOISTURE FOR A FEW SHOWERS IN WESTERN WA...MAINLY IN THE CASCADES. 
THERE ARE 20 POPS FOR THE INTERIOR FOR ISOLATED SHOWERS. 

WEAK LOW PRESSURE IN EASTERN WA MAY TRIGGER A FEW MORE SHOWERS IN 
THE CASCADES FRIDAY AND SATURDAY...OTHERWISE THE LOWLANDS ARE 
LOOKING DRY. A WEAK FRONT MAY CROSS THE AREA SUNDAY OR SUNDAY NIGHT 
HOWEVER THE TIMING IS OFF IN THE MODELS. THUS NO MAJOR CHANGES JUST 
YET. 33

&&

.AVIATION...AN UPPER LOW OFFSHORE WILL CONT TO MOVE E. THE FLOW 
ALOFT WILL BECOME SW AND STRENGTHEN. WEAK LOW LEVEL ONSHORE FLOW 
WILL STRENGTHEN ON MON IN THE WAKE OF A COLD FRONT.

AREAS OF CIGS IN THE 1500 TO 2500 FOOT RANGE ARE ANTICIPATED TO
DEVELOP OVER THE COAST AFTER 0900 UTC. THE CLOUDS WILL LIKELY
EXPAND OVER THE COAST AND THEN SPREAD INLAND TO SOME EXTENT MON
MORNING. THE QUESTION WAS HOW FAR INLAND THE STRATUS WILL
PENETRATE. 

KSEA...VFR CONDITIONS WILL PREVAIL OVERNIGHT. THERE MIGHT BE SOME
STRATUS MON MORNING BUT NOT SURE THERE WILL BE A CEILING. NLY
WINDS THIS AFTERNOON WILL BECOME LIGHT THIS EVENING. 

&&

.MARINE...
WEAKENING HIGH PRES OFF THE WASHINGTON COAST AND LOWER PRES
INLAND WILL RESULT IN LIGHT ONSHORE FLOW TONIGHT. A COLD FRONT
WILL MOVE ACROSS THE AREA ON MON...RESULTING IN STRENGTHENING
ONSHORE FLOW. SMALL CRAFT ADVISORY CRITERION WIND SPEEDS ARE
ANTICIPATED OVER MUCH OF THE AREA ON MON. A TROUGH WILL FOLLOW
ON TUE...THEREBY KEEPING THE FLOW ONSHORE.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...NONE.

&&

$$

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