198 
FXUS66 KPQR 101000
AFDPQR

AREA FORECAST DISCUSSION 
NATIONAL WEATHER SERVICE PORTLAND OR 
300 AM PDT MON AUG 10 2015

.SYNOPSIS...A LOW PRESSURE SYSTEM CENTERED OFF THE WASHINGTON COAST
ALONG 130W EARLY THIS MORNING WILL CONTINUE MOVING SOUTHWARD OFF THE
COAST...REACHING WEST OF THE NORTHERN CALIFORNIA COAST TUESDAY...
THEN LIFTING OUT TO THE NORTHEAST AND THROUGH THE PACIFIC NORTHWEST
THURSDAY AND FRIDAY. LOOK FOR OCCASIONAL SHOWERS OR THUNDERSTORMS IN
THE AFTERNOONS AND EVENINGS DURING THE WEEK THAT MAY DRIFT OUT INTO
THE VALLEYS AND THE COAST RANGE AT TIMES IN THE EVENINGS AND
OVERNIGHT PERIODS. THE BEST CHANCE OF MORE WIDESPREAD SHOWERS OR
THUNDERSTORMS IS LATER THURSDAY INTO FRIDAY AS THE LOW MOVES ONSHORE
AND INLAND. WARMER AND DRY WEATHER IS EXPECTED TO RETURN NEXT
WEEKEND.
&&

.SHORT TERM...AS ADVERTISED...A CLOSED UPPER LOW WAS LOCATED OFF THE
WASHINGTON COAST EARLY THIS MORNING CENTERED ALONG 130W. THE LOW WILL
CONTINUE TO MOVE SOUTHWARD AND WILL BE CENTERED OFF THE OREGON COAST
THIS AFTERNOON. THIS WILL CAUSE THE FLOW ALOFT TO BACK TO MORE
SOUTHERLY TODAY...WARMING THE AIR MASS SOME. A BAROCLINIC OR FRONTAL
ZONE HAS DEVELOPED OVER THE COASTAL WATERS BUT WILL HAVE TROUBLE
MAKING MUCH INLAND PROGRESSION TODAY DUE TO THE SOUTHERLY FLOW ALOFT.
THE COAST MIGHT GET BRUSHED WITH A FEW SHOWERS THOUGH. TEMPS INLAND
TODAY WILL BE IN AT LEAST THE MID 80S AND POSSIBLY THE UPPER 80S. THE
MODELS ALSO INDICATE THAT CONVECTION WILL DEVELOP OVER THE CASCADES
AND FOOTHILLS THIS AFTERNOON AS A SHORT WAVE LIFTS NORTH ALONG THE
EASTERN PERIPHERY OF THE OFFSHORE LOW...AND POSSIBLY EVEN OVER THE
VALLEY OR INTO THE COAST RANGE LATER TODAY OR TONIGHT. THERE IS SOME
UPPER JET SUPPORT FOR THIS CONVECTION TODAY AND THIS EVENING...AND
SOME OF THE THUNDERSTORMS THAT DO DEVELOP COULD BE STRONGER THAN WHAT
WE NORMALLY SEE. AS THE LOW CONTINUES TO MOVE SOUTH TONIGHT INTO
TUESDAY...THE UPPER FLOW TURNS SOUTHEASTERLY AND WILL CAUSE ANY
RESIDUAL ACTIVITY TO DRIFT OUT OVER THE VALLEYS AND TOWARD THE COAST
RANGE TONIGHT.

THINGS SHOULD SETTLE DOWN BY TUESDAY MORNING AS THE LAST OF THE
MOISTURE DRIFTS OUT OVER THE COASTAL WATERS AND WEAKENS. THE LOW WILL
CONTINUE TO MOVE SOUTH AND BE CENTERED SOUTH OF 40N AND WEST OF 130W
OFF THE NORTHERN CALIFORNIA COAST BY LATER TUESDAY. THERE IS AGAIN A
CHANCE OF THUNDER OVER THE CASCADES TUESDAY AFTERNOON THAT COULD
DRIFT OUT OVER THE VALLEYS TUESDAY NIGHT UNDER PREVAILING SOUTHEAST
FLOW ALOFT. THE AIR MASS WILL CONTINUE TO BE QUITE WARM TO THE EAST
AND NORTHEAST OF THE LOW ON TUESDAY...AND INLAND TEMPS MAY APPROACH
90 ON TUESDAY.

THE LOW MEANDERS OFF THE NORTHERN CALIFORNIA COAST WEDNESDAY. THE
MODELS SUGGEST THAT AFTER THE RESIDUAL CONVECTIVE ACTIVITY FROM
TUESDAY NIGHT DRIFTS NORTHWEST AND AWAY FROM OUR AREA WEDNESDAY
MORNING...THAT ACTIVITY WILL BE LESS WEDNESDAY AFTERNOON AND EVENING.
HAVE KEPT A SLIGHT CHANCE OF AFTERNOON AND EVENING THUNDER OVER THE
CASCADES.

THE MODELS SHOW OUR CURRENT SOUTH WINDS ALONG THE COAST THIS MORNING
TURNING NORTHERLY IN THE WAKE OF THE LOW LATER TODAY AND TONIGHT. THE
WINDS THEN TURN BACK TO SOUTHERLY AGAIN WEDNESDAY AS A SOUTHERLY WIND
REVERSAL AND STRATUS SURGE MOVES UP THE COAST IN RESPONSE TO SHORT
WAVE MOVING NORTH ALONG THE COAST. THIS SHOULD BUILD THE MARINE LAYER
ALONG THE COAST AND IS THE FIRST STEP IN STARTING TO INCREASE THE
ONSHORE FLOW. WE MAY SEE SOME PATCHY DRIZZLE IN THIS STRENGTHENING
MARINE LAYER. THE SOUTHERLY WINDS THAT DEVELOP ALONG THE COAST
WEDNESDAY MAY BE A BIT BREEZY AS WELL. TOLLESON 

.LONG TERM...THE LOW THAT DROPPED SOUTH ALONG THE COAST DURING THE
EARLY PART OF THE FORECAST IS EXPECTED TO APPROACH THE OREGON COAST
THURSDAY AND MOVE NORTHEAST ACROSS SOUTHWEST WASHINGTON AND NORTHWEST
OREGON THURSDAY NIGHT AND EARLY FRIDAY. THIS WILL BRING AN INCREASED
CHANCE OF SHOWERS...WITH A FEW THUNDERSTORMS POSSIBLE DUE TO
INSTABILITY FROM THE COLD POOL ALOFT WITH THE UPPER LOW. THIS WILL
ALSO BRING A STRONG SOUTHWEST MARINE PUSH TO OUR FORECAST AREA WITH
WIDESPREAD CLOUDS AND COOLER TEMPS THROUGH FRIDAY. THE MODELS ARE
THEN GENERALLY DRY FOR THE WEEKEND BUT DIFFER ON HOW WARM IT WILL
BE...AND HAVE OPTED FOR A BLEND OF THE MODELS FOR NOW AS NORTHWEST
FLOW ALOFT PREVAILS. THE MODELS HINT AT ANOTHER TROUGH DROPPING DOWN
FROM THE NORTHWEST EARLY NEXT WEEK...BUT THE GFS IS STRONGER AND DIGS
IT MORE SOUTHWARD WHILE THE ECMWF KEEPS THE MAIN PART OF THE TROUGH
SLIDING BY TO OUR NORTH. HAVE OPTED TO STAY DRY FOR NOW BUT WITH SOME
ONSHORE FLOW CONTINUING/INCREASING. TOLLESON
&&

.AVIATION...VFR CONDITIONS WITH CIGS BETWEEN 10K-25K FT WILL
GENERALLY PERSIST NEXT 24 HRS FOR INLAND SITES. MVFR AND IFR CIGS
ALONG THE COAST WILL CONTINUE TONIGHT UNDER SOUTH-SOUTHWEST
FLOW...BUT CIGS APPEAR TO BE RISING PARTICULARLY ALONG THE N OR
COAST. EXPECT MOSTLY MVFR CIGS ON THE COAST THROUGH MORNING. FOR
MON...CHANCE OF TSRA FROM THE COAST RANGE EASTWARD IN THE LATE
AFTERNOON AND EVENING BUT WITH DISAGREEMENT AMONG MODELS...WILL LEAVE
OUT MENTION FOR NOW.

KPDX AND APPROACHES...VFR NEXT 24 HOURS. SLIGHT CHANCE SHRA OR TSRA
MAINLY AFTER 00Z. BOWEN
&&

.MARINE...NOT MUCH CHANGE TO THE FORECAST WITH WINDS BELOW ABOUT 15
KTS AND SEAS AROUND 4 FT THROUGH MUCH OF THE WEEK. WEAK SURFACE LOW
CURRENTLY SITS OFF THE WASHINGTON COAST OVER THE OFFSHORE WATERS BUT
BIGGEST IMPACT WILL BE VARIABLE WIND DIRECTION WITH A VARYING DEGREE
OF SOUTH OR WEST COMPONENT IN THE WIND AS THE LOW SLOWLY DRIFTS
THROUGH THE REGION OVER THE NEXT 48 HOURS. SURFACE HIGH PRESSURE
BUILDS OVER THE NE PACIFIC STARTING MIDWEEK AND ESPECIALLY INTO LATE
WEEK. THE NEXT THREAT FOR SMALL CRAFT ADVISORY STRENGTH WINDS LOOKS
TO BE AROUND FRIDAY AS THERMAL LOW PRESSURE DEEPENS ALONG THE N
CALIFORNIA/SW OREGON COAST. HOWEVER MODELS HAVE AT LEAST TEMPORARILY
BACKED OFF ON WINDS LATE WEEK.	BOWEN
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM NOON TODAY TO 11 PM PDT TUESDAY FOR 
     CENTRAL OREGON CASCADE FOOTHILLS-MT. HOOD NATIONAL FOREST 
     WEST OF CASCADE CREST-NORTH OREGON CASCADE FOOTHILLS-
     WILLAMETTE NATIONAL FOREST.

WA...FIRE WEATHER WATCH FROM 1 PM PDT THIS AFTERNOON THROUGH LATE 
     TONIGHT FOR EXTREME SOUTH WASHINGTON CASCADES AND FOOTHILLS.

PZ...NONE.
&&

$$

INTERACT WITH US VIA SOCIAL MEDIA		
WWW.FACEBOOK.COM/NWSPORTLAND		
WWW.TWITTER.COM/NWSPORTLAND

THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON 
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS 
COMMONLY REFERRED TO AS THE FORECAST AREA.