000
FXUS66 KPQR 160946
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
246 AM PDT SUN JUN 16 2013

.SYNOPSIS...AN UPPER LEVEL LOW WILL REMAIN OFF THE COAST THROUGH
SUNDAY AND INTO MONDAY...WITH A FEW SHOWERS AT TIMES OR POSSIBLY EVEN
A THUNDERSTORM MAINLY OVER THE HIGHER CASCADES. THE LOW WILL MOVE
CLOSER TO THE COAST ON MONDAY...THEN MAKE A SIGNIFICANT MOVE INTO
SOUTHWEST WASHINGTON AND NORTHWEST OREGON MONDAY NIGHT AND TUESDAY
FOR AN INCREASE IN SHOWERS. THE MAIN LOW CENTER AND COLD POOL ALOFT
MOVE ONSHORE LATE TUESDAY AND TUESDAY NIGHT...AND IS STILL OVER THE
AREA ON WEDNESDAY FOR CONTINUED SHOWERS AND POSSIBLY A THUNDERSTORM.
THE MAIN ENERGY WITH THE LOW WILL MOVE EAST DURING THE LATTER PART OF
THE WEEK...BUT WEAKER...BROADER LOW PRESSURE ALOFT WILL MAINTAIN
ONSHORE FLOW AND NIGHT AND MORNING CLOUDS AROUND...WITH A DECREASING
CHANCE OF SHOWERS.
&&

.SHORT TERM...LOW CLOUDS REMAIN BANKED ALONG THE COAST AND THROUGH
THE COASTAL GAPS EARLY THIS MORNING AS A COMPLEX UPPER LOW CONTINUES
TO ROTATE AROUND ITSELF NEAR 45N/140W AS SEEN IN BOTH INFRARED AND
FOG SATELLITE IMAGERY. MODELS ARE NOT SHOWING MUCH CHANGE IN THE
LOCATION OF THIS LOW TODAY...SO STILL EXPECTING A REPEAT OF SATURDAYS
CONDITIONS FOR TODAY WITH A SLIGHT CHANCE FOR THUNDERSTORMS RIGHT
ALONG THE CREST OF THE CASCADES THIS AFTERNOON AND EVENING. INLAND
LOCATIONS CAN EXPECT ANOTHER MILD DAY...WITH SEASONAL HIGHS AND
PARTLY CLOUDY SKIES.

THE UPPER LEVEL LOW BEGINS TO SWIFTLY MOVE TOWARDS THE REGION LATE
TONIGHT INTO EARLY MONDAY MORNING...INCREASING ONSHORE FLOW AND
ALLOWING MORE LOW STRATUS TO PUSH FURTHER INLAND THROUGH THE COASTAL
GAPS MONDAY MORNING. SHOWERS SPREAD INLAND MONDAY AS A STRONGER
SHORTWAVE WRAPS AROUND THE PARENT LOW.

THE BEST THREAT FOR ANY CONVECTION FOR THE REGION DOES NOT ARRIVE
UNTIL TUESDAY. MODELS ARE IN GOOD AGREEMENT BRINGING THE CENTER OF
THE LOW INTO CENTRAL OREGON BY TUESDAY...BRINGING THE MAIN COLD POOL
ONSHORE. THIS SHOULD INITIATE A DECENT THREAT FOR THUNDERSTORMS
ACROSS THE CASCADES. UPPER LEVEL FLOW TURNS MORE S-SE LATE TUESDAY...
ALLOWING ANY THUNDERSTORMS OVER THE CASCADES TO DRIFT ACROSS THE
VALLEY. LIFTED INDICES NEAR -1/-2 ARE POSSIBLE AGAIN FOR WEDNESDAY
AFTERNOON AND EVENING AS THE CENTER OF THE LOW STATIONS ITSELF RIGHT
OVER THE FORECAST AREA. /27

.LONG TERM...THE UPPER LOW SLOWLY PUSHES ACROSS THE FORECAST AREA
WEDNESDAY NIGHT...GRADUALLY SHIFTING EAST OF THE REGION BY THURSDAY.
POPS WILL ALSO GRADUALLY DISSIPATE INTO THURSDAY...WITH SOME WRAP
AROUND ENERGY KEEPING A SLIGHT CHANCE FOR SHOWERS ACROSS THE REGION
INTO THURSDAY NIGHT. THE POTENTIAL FOR DRIER WEATHER IMPROVES LATE IN
THE WEEK AS THE LOW MOVES E AND WEAK RIDGING FOLLOWS. EXPECT COOLER
THAN NORMAL TEMPS TO ACCOMPANY THE UPPER LOW...SIMILAR TO THIS PAST
WEEK...THEN TEMPS WARMING AGAIN AT THE END OF THE WEEK.
&&

.AVIATION...MARINE STRATUS IS A SLOW TO MOVE INLAND THIS MORNING...
BUT PATCHES ARE SPREADING NEAR KLS AND ALSO EUG. WILL PROBABLY SLOW
PUSH INLAND DOWN BY A COUPLE OF HOURS BASED ON CURRENT MOVEMENT.
MODELS HANDLE THIS PUSH QUITE DIFFERENTLY WITH GFS MUCH WEAKER ON
PUSH THAN NAM.RIGHT NOW WILL LEAN TOWARD NAM BUT BACK OFF ON
TIMING. EXPECT CLEARING TO OCCUR INLAND BEFORE NOON BASED ON WEAKNESS
OF PUSH...BUT LOW CLOUDS SHOULD LINGER ALONG THE COAST INTO THE EARLY
AFTERNOON.  LOOK FOR SOME CONVECTION TO DEVELOP ALONG THE CASCADE
CREST LATER THIS AFTERNOON AND EVENING.

KPDX AND APPROACHES...VFR CONDITIONS EXPECTED TO GIVE WAY TO SOME
PATCHY MVFR CIGS BETWEEN 14Z AND 17Z THIS MORNING. VFR CONDITIONS
WILL RETURN LATER THIS MORNING AND PERSIST THROUGH THE AFTERNOON AND
EVENING. LOOK FOR SOME CONVECTION TO DEVELOP OVER THE CASCADES LATER
THIS AFTERNOON.  TODD

&&

.MARINE...AN APPROACHING LOW PRESSURE SYSTEM WILL GRADUALLY SHIFT
THE WINDS OVER THE WATERS TO SOUTHERLY OVER THE NEXT 24 HOURS.
HOWEVER...THESE WINDS SHOULD GENERALLY REMAIN UNDER 15 KTS THROUGH
MONDAY. SEAS LOOK TO HOVER AROUND 2 AND 3 FT DURING THIS TIME. A
DIFFUSE FRONT MAY TIGHTEN PRESSURE GRADIENTS ENOUGH LATE MONDAY
NIGHT INTO TUESDAY MORNING TO REQUIRE A SMALL CRAFT ADVISORY FOR
WIND GUSTS OF AROUND 25 KTS. A SURFACE LOW PRESSURE WILL THEN
MEANDER OVER THE WATERS DURING THE MIDDLE OF THE WEEK...GIVING WAY TO
SURFACE HIGH PRESSURE AND CONTINUED BENIGN WEATHER LATE NEXT WEEK.
SEAS MAY BRIEFLY CLIMB INTO THE 4 TO 6 FT RANGE TUESDAY OR
WEDNESDAY...BUT OTHERWISE LOOK TO REMAIN IN THE 2 TO 4 FT RANGE ALL
WEEK. /TODD

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND

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.