Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 220426
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
924 PM PDT THU AUG 21 2014

.SYNOPSIS...AN UPPER LEVEL LOW PRESSURE DROPPING SOUTHEAST
ACROSS THE REGION TONIGHT COULD RESULT IN A SOME LIGHT
PRECIPITATION THROUGH TOMORROW MORNING AND A SLIM THREAT OF
THUNDERSTORMS ACROSS THE SOUTH WASHINGTON CASCADES TOMORROW AFTERNOON
AND EVENING. NORTHWEST TO NORTH FLOW ALOFT CONTINUES OVER THE WEEKEND
MAINTAINING ONSHORE LOW-LEVEL FLOW AND NEAR HIGH TEMPERATURES. HIGH
PRESSURE STRENGTHENS JUST OFFSHORE EARLY NEXT WEEK...WHICH MAY
RESULT IN SOME LIGHT OFFSHORE LOW-LEVEL FLOW. EXPECT A WARM UP FOR
THE FIRST HALF OF NEXT WEEK.

&&

.SHORT TERM...TONIGHT THROUGH SATURDAY...AN UPPER LEVEL LOW PRESSURE
SYSTEM OUT OF THE NORTHWEST IS BEGINNING TO PUSH ONSHORE THIS
EVENING. VISIBLE SATELLITE IMAGERY FROM THE AFTERNOON AND EARLIER
THIS EVENING SHOWED A BAND OF CLOUDS ASSOCIATED WITH A WEAK FRONTAL
FEATURE OFFSHORE THAT WAS SLOWLY PUSHING TOWARD THE COAST. THE
LATEST DOPPLER RADAR IMAGERY IS ACTUALLY SHOWING SOME LIGHT ECHOES
ALONG THE SOUTH WASHINGTON COAST...BUT IT IS UNCLEAR IF ANY
PRECIPITATION IS ACTUALLY REACHING THE GROUND AT THIS TIME. THE
MODELS CONTINUE TO SHOW THE FRONT PUSHING TO THE SOUTHEAST
TONIGHT...WITH THE BEST MOISTURE AVAILABILITY OVER THE SOUTHERN
PORTIONS OF THE FCST AREA. WILL CONTINUE WITH THE CURRENT FCST
KEEPING DRIZZLE CHANCES FOR ALL OF THE COAST AND COAST RANGE
OVERNIGHT...THEN BRING CHANCES INTO THE SOUTHERN WILLAMETTE VALLEY
AND CASCADES TOMORROW MORNING.

DRIZZLE SHOULD TAPER OFF BY MIDDAY TOMORROW AS THE MAIN UPPER LEVEL
SHORTWAVE WILL BE THROUGH THE REGION. HOWEVER...IT APPEARS THAT THERE
WILL BE THUNDERSTORM CHANCES FOR PORTIONS OF OUR CASCADE ZONES. THE
BEST INSTABILITY STILL LOOKS LIKE IT WILL REMAIN OVER CENTRAL AND
EASTERN WASHINGTON...WITH THE BEST THUNDER CHANCES IN OUR AREA NEAR
THE MT ADAMS AREA. OTHERWISE...EXPECT ONLY A FEW SHOWERS OVER THE
SOUTH WASHINGTON AND NORTH OREGON CASCADES. PRECIP CHANCES DROP OFF
QUICKLY SATURDAY AS THE UPPER LOW MOVES OFF TO THE EAST. WITH WINDS
OUT OF THE NORTH AND MINIMAL AFTERNOON SKY COVER...TEMPS WILL WARM
THROUGH THE WEEKEND AS HIGH PRESSURE MOVES BACK INTO THE AREA.
PYLE/BOWEN

.LONG TERM...UPPER LEVEL RIDGING WILL MOVE ONSHORE ALLOWING
TEMPERATURES TO INCREASE SLIGHTLY ABOVE SEASONAL NORMS FOR THE
BEGINNING PART OF NEXT WEEK. AS THE RIDGE BEGINS TO BREAKDOWN AND
BECOME MORE ZONAL WE WILL SEE AN INCREASE IN LOW AND MID LEVEL
MOISTURE. THIS WILL PROVIDE FOR AN INCREASE IN CLOUD COVER FOR THE
LATTER PART OF NEXT WEEK. DO NOT EXPECT ANY PRECIPITATION IN THE
NEAR FUTURE. /64

&&

.AVIATION...WEAK FRONT IS SLOWLY APPROACHING THE COAST THIS
EVENING...AND WILL GRADUALLY DRAG SOUTH AND PUSH INTO THE CENTRAL
OR COAST OVERNIGHT. MARGINAL MVFR CIGS ARE POSSIBLE ALONG THE
COAST AS THE FRONT MOVES ONSHORE BETWEEN 09-12Z FRI. WIDESPREAD
VFR CONDITIONS WITH BROKEN CIGS AROUND 5000 FT SHOULD PREVAIL
THROUGH FRI MORNING...WITH THE EXCEPTION OF LOWER CIGS AND A
THREAT FOR DRIZZLE NEAR KONP WITH THE FRONTAL PASSAGE AFTER 09Z.

KPDX AND APPROACHES...VFR NEXT 24 HRS. CIGS AROUND 5000 FT WILL
INCREASE WITH WEAK FRONTAL PASSAGE FROM 12Z-15Z FRI. /27

&&

.MARINE...A WEAK FRONT WILL DECAY AS IT MOVES ACROSS THE WATERS
THIS EVENING. HIGH PRESSURE WILL REBUILD FRIDAY AND NORTHERLY
WINDS WILL RETURN. HIGH PRESSURE WILL HOLD OVER THE NE PACIFIC
INTO NEXT WEEK. A THERMAL TROUGH OVER NORTHERN CALIFORNIA WILL
RESULT IN A TIGHTER PRESSURE GRADIENT OVER THE WATERS AT TIMES
ESPECIALLY IN THE AFTERNOONS AND EVENINGS...AND S OF CASCADE HEAD.
TJ

&&

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



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