961
FXUS66 KPQR 040339
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
838 PM PDT FRI JUL 3 2009
SYNOPSIS
A STRONG UPPER LEVEL RIDGE OF HIGH PRESSURE WILL REMAIN
OVER THE PACIFIC NORTHWEST THROUGH THE HOLIDAY WEEKEND. EXPECT THE
4TH OF JULY TO BE AS HOT AS THE PREVIOUS TWO DAYS...WITH ONLY
SLIGHTLY COOLER TEMPS EXPECTED SUNDAY. AN UPPER LEVEL TROUGH WILL
APPROACH THE AREA SUNDAY NIGHT...USHERING IN A FAIRLY STRONG MARINE
PUSH AND A QUICK 15 TO 20 DEGREE COOL DOWN FOR MOST INLAND AREAS BY
MONDAY MORNING.
SHORT TERM
VIS SATELLITE IMAGERY SHOWS LOW TOPPED MARINE STRATUS
AND FOG REFORMING OVER THE COASTAL WATERS AND PUSHING BACK TOWARDS
THE COAST THIS EVENING. WHILE MARINE LAYER DOES NOT DEEPEN
TONIGHT...PRESSURE GRADIENTS REMAIN ONSHORE OVERNIGHT SO EXPECT
SIMILAR CLOUD COVER SAT MORNING AS OCCURRED THIS MORNING. THIS BEING
THAT SHALLOW MARINE STRATUS WILL PUSH ONTO THE BEACHES AND LOCALLY
INTO COASTAL RIVER VALLEYS...AS WELL AS DOWN THE COLUMBIA RIVER TO
KELSO AT THE FURTHEST.
DESPITE THE ONSHORE GRADIENTS TONIGHT...LITTLE RELIEF IS IN STORE FOR
THE INLAND AREAS FOR THE 4TH OF JULY. IN FACT...H85 TEMPS WILL WARM A
COUPLE OF DEGREES CELSIUS TOMORROW AFTERNOON SO LOOK FOR 4TH OF JULY
MAX TEMPS TO BE FAIRLY SIMILAR TO TODAY.
ON SUNDAY...MID LEVEL SLY FLOW IN ADVANCE OF AN APPROACHING TROUGH
FOR SUNDAY NIGHT WILL HOLD H85 TEMPS UP AROUND 18-20C. THIS WILL
SUPPORT INLAND HIGHS AROUND 90 ONCE AGAIN SUNDAY AFTERNOON. HOWEVER
THIS WILL BE THE LAST WARM DAY OF THE CURRENT HEAT WAVE. MODELS SHOW
SOUTHERLY WIND SURGE OCCURRING ALONG THE COAST SUNDAY AFTERNOON AND
EVENING...THE PRECURSOR TO A SOUTHWEST MARINE PUSH AND A SIGNIFICANT
COOL DOWN FOR THE AREA...AS MUCH AS 15-20 DEGREES FOR INLAND AREAS BY
MONDAY MORNING.
A SHORTWAVE TROUGH WILL SWING OVERHEAD SUNDAY NIGHT. PREVIOUS MODEL
RUNS WERE SHOWING A DECENT AMOUNT OF INSTABILITY OVER THE CASCADES
SUNDAY EVENING AND INTO THE EARLY MORNING HOURS ON MONDAY AS THIS
SHORTWAVE PASSES BY. PREVIOUS SHIFTS HAD SLIGHT CHANCES FOR
THUNDERSTORMS THROUGHOUT THE CASCADES FOR SUNDAY NIGHT/MONDAY
MORNING. FOR NOW THIS LOOKS FINE AS IT IS STILL THE DAY3
FORECAST...THOUGH MODELS HAVE BEEN TRENDING DOWNWARD WITH RESPECT TO
WEST SIDE TSTM POTENTIAL.
ON MONDAY THE ASSOCIATED UPPER LOW MOVES OVERHEAD FOR AN INCREASED
CHANCE OF PRECIPITATION...MAINLY ALONG THE COAST AND TO THE
CASCADES/COASTAL RANGE. DALTON
LONG TERM
AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL ESTABLISH
ITSELF OVER THE FORECAST AREA THE FIRST PART OF NEXT WEEK AND WILL
PERSIST THROUGH THE WEEK. THIS WILL BRING COOLER TEMPERATURES AND A
CHANCE OF SHOWERS.
AVIATION
IFR STRATUS ALONG THE COAST LINE TONIGHT. MARINE LAYER
IS SHALLOW SO STRATUS WILL MAKE LIMITED PROGRESS INLAND. STRATUS
LIKELY TO FILL IN THE VALLEYS ALONG THE COAST AND PERHAPS UP THE
LOWER COLUMBIA RIVER TO KKLS. STRATUS EXPECTED TO RETREAT BACK
TO THE BEACHES LATE SAT MORNING. CLEAR SKIES ARE EXPECTED ELSEWHERE
FOR THE NEXT 24 HOURS.
KPDX AND APPROACHES...NO SIGNIFICANT WEATHER IMPACTS EXPECTED.
MARINE
SEAS ARE NOT VERY HIGH BUT WITH SHORT PERIOD WIND WAVES
SEAS CONDITIONS WILL REMAIN A LITTLE CHOPPY. NO ADVISORIES EXPECTED
THROUGH THE WEEKEND. WINDS WILL SHIFT TO THE SOUTH TO SOUTHWEST ON
SUN AS A TROUGH SWINGS INLAND AND SURFACE HIGH PRES BUILDS IN FROM
THE SOUTHWEST.
PQR WATCHES/WARNINGS/ADVISORIES
OR/WA...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.
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