Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 240508 CCA
AFDSEW

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE SEATTLE WA
1008 PM PDT MON MAR 23 2015

CORRECTED THE FIRST SENTENCE OF THE SHORT TERM SEGMENT.

.SYNOPSIS...A LOW PRESSURE SYSTEM WILL KEEP CONDITIONS UNSETTLED
OVERNIGHT. WEAK HIGH PRESSURE ALOFT WILL PREVAIL ON TUESDAY. A
WARM FRONT WILL BRING RAIN TO THE REGION TUESDAY NIGHT AND
WEDNESDAY. BUILDING HIGH PRESSURE ALOFT WILL CAUSE THE WARM FRONT
TO BE SHOVED NORTH INTO CANADA EARLY THURSDAY. DRY WEATHER ALONG
WITH WELL ABOVE NORMAL TEMPERATURES ARE LIKELY ON THURSDAY.

&&

.SHORT TERM...
A 1011 MB LOW WAS JUST OFF THE NORTHERN OREGON COAST AT THIS TIME
WHILE THE UPPER LOW WAS OFF THE NORTH WA COAST. THE SHOWERS OVER
THE CWA RAPIDLY DIMINISHED ABOUT SUNSET BUT...AT THE SAME TIME...
RAIN ASSOCIATED WITH THE FRONTAL SYSTEM OFF THE OREGON COAST SPREAD
NWD INTO THE SOUTHWEST PART OF THE CWA. THE RAIN SPREAD FARTHER
NORTH THAN PREVIOUSLY ANTICIPATED...THUS THE FORECAST WAS UPDATED
TO BRING THE RAIN AS FAR NORTH AS THE CENTRAL PUGET SOUND.

THE UPPER AND SURFACE LOWS WILL MOVE QUICKLY EAST OVERNIGHT...
THEREFORE LOOK FOR THE STEADY RAIN TO MOVE INTO THE CENTRAL
CASCADES BY SUNRISE. AN UPPER RIDGE WILL MOVE OVER THE REGION
DURING THE DAY TUE. HOWEVER THE AIR MASS WILL REMAIN COOL AND
UNSETTLED FOR SCATTERED SHOWERS...MORE NUMEROUS OVER THE MOUNTAINS.

LOOK FOR A WARM FRONT TO BRING STEADY RAIN BACK INTO THE CWA TUE
NIGHT. THE RAIN IS ANTICIPATED TO CONTINUE ON WED. THE UPPER RIDGE
WILL STRENGTHEN WED NIGHT AND THU...THEREBY SHUNTING THE WARM
FRONT NORTHWARD INTO CANADA BY WED MORNING. DRY CONDITIONS ALONG
WITH WELL ABOVE NORMAL TEMPS ARE LIKELY ON THU.

.LONG TERM FROM THE PREV DISCUSSION...
THE GFS NOW HAS A NEW SYSTEM ARRIVING OVER THE AREA FRIDAY AFTERNOON.
THIS IS A NEW IDEA AND IS NOT COMPLETELY ACCEPTED. THE EURO IS DRY
FRIDAY. FOR NOW HAVE LIMITED THE CHANCE OF RAIN TO THE COAST BUT
INCREASED CLOUDINESS. MODELS CONTINUE OUT OF PHASE INTO THE WEEKEND
SO FROM FRIDAY NIGHT ON HAVE JUST FORECAST CHANCE POPS THAT DO NOT
DIFFER MUCH FROM CLIMATOLOGY. HIGH AND LOW TEMPS WILL BOTH BE A
FEW DEGREES ABOVE AVERAGE. BURKE

&&

.HYDROLOGY...
FLOODING IS UNLIKELY THE NEXT 7 DAYS.

&&

.AVIATION...AN UPPER LEVEL TROUGH WILL MOVE INLAND TONIGHT FOR
SHOWERS ACROSS WESTERN WA. THE AIR MASS IS MOIST AND UNSTABLE. MVFR
CIGS ARE POSSIBLE IN MODERATE SHOWERS. A FRONTAL SYSTEM WILL MOVE
INTO OREGON OVERNIGHT WITH RAIN MAINLY OVER SOUTHWEST WA AND THE
AIR MASS BECOMING STABLE. MVFR CIGS WILL LIKELY PERSIST THROUGH
TUE MORNING.

KSEA...ISOLATED SHOWERS WILL CONTINUE IN THE VICINITY THIS
EVENING...THEN TAPER OFF OVERNIGHT. SURFACE WINDS WILL DIMINISH AND
BECOME VARIABLE OVERNIGHT. MVFR CONDITIONS EXPECTED. 33/13

&&

.MARINE...A SURFACE TROUGH WILL MOVE INLAND THIS EVENING. BRIEF
SMALL CRAFT ADVISORY WINDS HAVE DIMINISHED THIS EVENING. AND WITH
THE A 1011 MB LOW MOVING EAST ACROSS THE NORTHERN OREGON COASTAL
WATERS LATE TONIGHT, THE WINDS WILL BECOME LIGHT AND MAYBE EVEN
BECOME NORTHERLY AT TIMES. A WARM FRONT WILL ARRIVE TUE NIGHT WITH
S/SE WINDS RISING OVER THE COASTAL WATERS AND ENTRANCES TO THE
STRAIT - SMALL CRAFT ADVISORY WINDS ARE LIKELY. WINDS WILL EASE WED
NIGHT AND THU AS HIGH PRES BUILDS OVER WESTERN WA. 33/13

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...NONE.
PZ...SMALL CRAFT ADVISORY IN EFFECT FOR ROUGH GRAYS HARBOR BAR TIL
     11 AM TUESDAY.

&&

$$

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