321
FXUS66 KPQR 131027
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
300 AM PDT TUE AUG 13 2013
.SYNOPSIS...DRIER WEATHER WITH SEASONABLY WARM TEMPERATURES WILL
RETURN TODAY AND WEDNESDAY AS A WEAK UPPER RIDGE NOSES INTO THE
PACIFIC NORTHWEST FROM THE SOUTHEAST. ANOTHER UPPER LOW OFF THE
COAST SLOWLY EDGES INTO THE PACIFIC NORTHWEST DURING THE LATTER PART
OF THE WEEK WITH MORE CLOUDS...COOLING TEMPERATURES...AND EVEN A
CHANCE OF SOME LIGHT PRECIPITATION ESPECIALLY NEAR THE COAST.
&&
.SHORT TERM....TUESDAY THROUGH THURSDAY...SURFACE HIGH PRESSURE IS IN
PLACE ACROSS THE COASTAL WATERS AND COAST. WE ARE SEEING SOME VERY
SHALLOW FOG/LOW CLOUDS UNDERNEATH THE CALM SKIES LIGHT WIND REGIME AT
OUR COASTAL SITES. MEANWHILE THERE ARE SOME REMNANT CLOUDS
GENERALLY IN THE 4-5K FT RANGE INLAND...SCATTERED IN SPOTS...OVERCAST
IN OTHERS..AND NON-EXISTENT ELSEWHERE...ALONG WITH PASSING HIGH
CLOUDS FROM A SYSTEM WELL OFFSHORE.
HIGH PRESSURE IN THE GREAT BASIN WILL STRENGTHEN TODAY...AND THIS
WILL INCREASE 500 MB HEIGHTS FROM THE SOUTHEAST. THE LOWER CLOUDS
WILL BURN OFF EARLIER AND WE SHOULD SEE TEMPS PUSH UP TOWARD 85 FOR
THE INTERIOR LOWLANDS.
ATTENTION THEN SHIFTS TO THE NEXT LOW DROPPING OUT OF THE GULF OF
ALASKA...AND CURRENTLY PUSHING INSIDE OF 140W EARLY THIS MORNING. WE
WILL BE UNDER CONTINUED LIGHT SOUTHWEST FLOW ALOFT OVER THE
AREA...WITH CONDITIONS ON WEDNESDAY NOT THAT MUCH DIFFERENT FROM
THOSE ON TUESDAY. WE ARE NOT EXPECTING ANY LOW CLOUDS INLAND DUE TO
A VERY SHALLOW MARINE LAYER. THIS LOW WILL SPREAD AS SOME HIGH
CLOUDS INTO THE AREA A BIT MORE EACH DAY. THE MODELS ARE SHOWING AN
ASSOCIATED FRONTAL BOUNDARY GETTING CLOSE TO THE NORTH COAST AROUND
ASTORIA LATER WEDNESDAY. THEN WEAKLY MOVING ONSHORE WEDNESDAY NIGHT.
HAVE SPED UP THE ARRIVAL OF A FEW SHOWERS ALONG THE COAST EVEN
FURTHER INLAND WITH THIS MODEL SUITE..
A STRONG HIGH PRESSURE RIDGE IN THE INTERMOUNTAIN WEST EXTENDS WELL
NORTH INTO CANADA WEDNESDAY NIGHT INTO THE LATTER HALF OF THE WEEK.
THEREFORE THE LOW REMAINS BLOCKED OFFSHORE OFF THE SOUTHERN B.C.
COAST ON THURSDAY WITH SOUTHWEST FLOW ALOFT ACROSS THE PACIFIC
NORTHWEST. THERE WILL BE PLENTY OF LOW CLOUDS ALONG THE COAST AND
INLAND ESPECIALLY IN THE NORTH. AND WHILE THE SYSTEM IS GETTING
SHOVED NORTH...CONTINUED MOIST SW FLOW STILL LOOKS TO BRING SOME
DRIZZLE/LIGHT RAIN OR SHOWERS ALONG THE COAST ESPECIALLY IN THE
NORTH...POSSIBLY SPREADING INTO THE NORTH INTERIOR AND SOUTH
WASHINGTON CASCADES BY AFTERNOON. SOUNDINGS ARE NOT THAT IMPRESSIVE
FOR MUCH ACCUMULATION...THOUGH PRECIPITABLE WATER VALUES WILL BE
UNUSUALLY HIGH FOR THIS TIME OF YEAR TO SUPPORT SOME LIGHT RAIN.
THURSDAY SHOULD BE THE START OF ANOTHER COOLING TREND INLAND FOR A
FEW DAYS. KMD
.LONG TERM...DISCUSSION UNCHANGED...THURSDAY NIGHT THROUGH
MONDAY...THE MODELS SHOW THAT THE LOW OFF THE B.C. AND WASHINGTON
COASTS WILL CONTINUE INTO THE EARLY PART OF THE LONG TERM
PERIOD...LIFTING OUT TO THE NORTHEAST LATE FRIDAY AND SATURDAY.
STILL LOOKS LIKE A FEW SHOWERS OR SOME DRIZZLE ARE POSSIBLE NEAR THE
COAST AND LOCALLY INTO THE NORTH INTERIOR ZONES. EXPECT PLENTY OF
CLOUDS AND COOLER TEMPS AS WELL...ESPECIALLY INLAND. THIS SYSTEM IS
FORECAST TO MOVE INLAND BY SUNDAY. THERE WILL STILL BE SOME ONSHORE
FLOW REMAINING SUNDAY MORNING BUT DECREASING BY MONDAY. THERE ARE
SOME MODEL VARIATIONS ON HOW THINGS WILL PROGRESS EARLY NEXT WEEK SO
FOR NOW WILL KEEP THINGS NOT TOO FAR FROM NORMAL. TOLLESON
&&
.AVIATION...COASTAL CONDITIONS LARGELY VFR AS OF 09Z THOUGH IFR
LAYER CIGS FORMING IN SITU. EXPECT IFR CIGS/FG TO FORM KAST AND
KONP BY 12Z. FEW TO SCATTERED LAYER AROUND 4500 FT OVER THE NORTH
WILLAMETTE VALLEY. MODEL SOUNDINGS HINTING AT A LOWER LAYER AROUND
2000 FT FORMING INLAND BUT DO NOT EXPECT WIDESPREAD COVERAGE OF
THIS LOWER LAYER. EXPECT STRATUS INLAND AND COAST TO BURN OFF BY
17Z TUESDAY AM.
KPDX AND APPROACHES...VFR CONTINUES THROUGH TONIGHT. TUES
MORNING...MVFR CIGS 2000 FT RETURN AFTER 12Z TUESDAY...BUT WILL
LAST NO LONGER THAN 17Z.
&&
.MARINE...BENIGN CONDITIONS CONTINUE THIS WEEK. N TO NW WINDS
GENERALLY REMAINING IN THE 10 TO 15 KT RANGE...AND WESTERLY SWELL
AROUND 3 FT. NORTHERLY WINDS WILL PICK UP A BIT ON TUESDAY... WITH
MODELS HINTING AT A FEW GUSTS NEAR 20 KT POSSIBLE OVER THE
CENTRAL COASTAL WATERS. OTHERWISE...EXPECT LITTLE CHANGE THROUGH
NEXT WEEKEND.
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.
&&
$$
MORE WEATHER INFORMATION ONLINE AT...
HTTP://WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
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.