Area Forecast Discussion
Issued by NWS Portland, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KPQR 291050
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
242 AM PST THU JAN 29 2015


.SYNOPSIS...A VERY WEAK STORM SYSTEM WILL BRING SOME PASSING CLOUDS
TODAY AND PERHAPS A SPRINKLE OR TWO. PATCHY VALLEY FOG AND LOW CLOUDS
SHOULD GIVE WAY TO CLEARING SKIES THIS AFTERNOON FOR MOST LOCATIONS.
BUILDING HIGH PRESSURE AND OFFSHORE FLOW SHOULD PRODUCE RELATIVELY
MILD TEMPERATURES...AREAS OF VALLEY FOG AND EAST WINDS NEAR THE MOUTH
OF THE COLUMBIA RIVER GORGE THROUGH SATURDAY NIGHT. A WEAKENING STORM
SYSTEM WILL LIKELY BRING A SHOT OF RAIN TO THE AREA LATE SUNDAY AND
MONDAY BEFORE HIGH PRESSURE LIKELY BRINGS ANOTHER BOUT OF DRY WEATHER
MIDWEEK NEXT WEEK.


&&


.SHORT TERM...INFRARED SATELLITE IMAGERY EARLY THIS MORNING REVEALS A
MESS OF MID AND HIGH LEVEL CLOUDS STREAMING NORTHEASTWARD AHEAD OF A
WEAK UPPER LEVEL TROUGH SLIDING ACROSS THE REGION. UNDERNEATH THESE
CLOUDS...ENOUGH RADIATIONAL COOLING HAS DEVELOPED TO ALLOW PATCHY FOG
AND LOW STRATUS TO FORM IN THE WILLAMETTE VALLEY. IN
ADDITION...DOPPLER RADAR INDICATES A FEW VIRGA SHOWERS ARE MOVING
NORTHEASTWARD ACROSS THE AREA AND MODELS SUGGEST THIS WILL CONTINUE
THROUGH THE MORNING HOURS. IN THE OFF CHANCE A FEW OF THESE SHOWERS
MATERIALIZE...ADDED A MENTION OF BRIEF SPRINKLES TO THE FORECAST
THROUGH THIS MORNING EVEN THOUGH MOST LOCATIONS SHOULD REMAIN DRY.

SHORTWAVE RIDGING WILL BEGIN TO SHIFT OVER THE REGION TONIGHT...WHICH
SHOULD BRING MOSTLY CLEAR SKIES AND CONTINUED MILD TEMPERATURES.
HOWEVER...THE WILLAMETTE VALLEY...LOWER COLUMBIA RIVER VALLEY AND THE
HOOD RIVER VALLEY WILL SEE AREAS OF FOG AND LOW CLOUDS RETURN
THURSDAY AND FRIDAY NIGHTS.

AN EASTERLY CROSS CASCADE PRESSURE GRADIENT IS ALREADY HOVERING
AROUND 6MB BETWEEN TROUTDALE AND THE DALLES...AND RESULTING IN 30 TO
40 MPH GUSTS NEAR TROUTDALE AND 50 TO 60 MPH GUSTS IN THE WINDIEST
SPOTS IN THE WESTERN COLUMBIA RIVER GORGE. PRESSURE GRADIENTS MAY
STRENGTHEN A BIT MORE...BUT SHOULD GENERALLY HOLD STEADY THROUGH
SATURDAY AND PRODUCE SIMILAR WIND SPEEDS THROUGH THAT TIME. EAST
WINDS MAY STRENGTHEN A BIT AND BECOME A LITTLE MORE WIDESPREAD
ACROSS THE PORTLAND METRO AREA SATURDAY NIGHT AS THE COLD POOL EAST
OF THE CASCADES DEEPENS SLIGHTLY AND THE INVERSION STRENGTHENS
TEMPORARILY.

A WEAKENING FRONT STILL LOOKS ON TRACK TO ENTER THE FORECAST AREA ON
SUNDAY...OR PERHAPS MORE LIKELY SUNDAY NIGHT. GIVEN THE WEAKENING
NATURE OF THE FRONT AND THE RIDGING THAT WILL BE IN PLACE
BEFOREHAND...POPS WERE TRENDED TOWARDS THE IDEA THAT A SLOWER SYSTEM
IS MORE LIKELY. /NEUMAN


.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...AS WE ENTER A MORE ZONAL
FLOW PATTERN...MODELS CONTINUE TO DISAGREE ON PRECIPITATION
DISTRIBUTION AND TIMING SUNDAY NIGHT AND MONDAY A WARM FRONT SPREADS
INTO THE REGION. CONTINUED THE IDEA THAT RAIN IS LIKELY DURING THIS
PERIOD...BUT DETAILS STILL REMAIN FAIRLY UNCERTAIN. DESPITE THESE
DIFFERENCES...BOTH THE GFS AND EC AGREE SHORTWAVE RIDGING WILL PUSH
BACK INTO THE REGION EARLY TO MID NEXT WEEK. POPS WERE TRENDED
DOWNWARD DURING THIS PERIOD...BUT DID NOT GO COMPLETELY DRY JUST YET
GIVEN UNCERTAINTY. ANOTHER FRONT MAY PUSH INTO THE REGION LATE IN
THE WEEK SO POPS WERE TRENDED BACK UPWARDS TOWARDS DAY 7. /NEUMAN


&&


.AVIATION...OFFSHORE WINDS ALONG THE COAST HAVE WEAKENED OVER
KAST...WHICH HAS ALLOWED FOG TO DEVELOP AT THE TAF SITE DROPPING
VIS TO IFR/LIFR. WINDS DON`T LOOK TO INCREASE AT THIS SITE UNTIL
LATER THIS MORNING SO HAVE ADDED FOG TO THE TAF THROUGH MID-
MORNING. KONP HAS OFFSHORE WINDS STILL...WHICH WILL KEEP THIS SITE
VFR THROUGH TONIGHT. SHORTWAVE TROUGH MOVING ACROSS THE AREA IS
KEEPING THE INVERSION FROM SETTING UP OVER THE INLAND SITES. THIS
IS KEEPING WIDESPREAD DENSE FOG FROM DEVELOPING. EXPECT KTTD TO
REMAIN VFR AS EAST WINDS CONTINUE OUT OF THE GORGE THROUGH
TOMORROW NIGHT. PATCHY FOG IS BEING OBSERVED OVER THE REST OF THE
NORTH WILLAMETTE VALLEY...AS KHIO IS OCCASIONALLY DROPPING TO
IFR/LIFR. THIS COULD SPREAD TO PDX LATER THIS MORNING AS THE
SHORTWAVE MOVES OFF TO THE EAST...BUT THINKING MORE THAT KPDX WILL
STAY VFR THROUGH TODAY. FURTHER SOUTH...FOG HAS DEVELOPED AROUND
KEUG...BRINGING CIGS AND VIS DOWN TO LIFR. THIS SHOULD CONTINUE
UNTIL IT STARTS TO LIFT EARLY THIS AFTERNOON. KSLE HAS BEEN UNDER
A STRATUS DECK AROUND FL010...WHICH HAS LIFTED A BIT OVER THE LAST
COUPLE HOURS AND STARTED TO BREAK UP AROUND FL015. CLEARING WILL
ALLOW FOR FOG TO SPREAD NORTHWARD FROM KEUG... BRINGING KSLE DOWN
TO IFR/LIFR BY AROUND 15Z THIS MORNING. THIS SHOULD BURN OFF BY
LATE THIS MORNING. ALL SITES SHOULD IMPROVE TO VFR BY THIS
AFTERNOON.

KPDX AND APPROACHES...VFR CONDITIONS ARE EXPECTED THROUGH
TODAY...WITH A CHANCE OF PATCHY FOG AROUND 14-17Z BRINGING CIGS
AND VIS DOWN TO IFR. IF IFR CONDITIONS DO DEVELOP...CIGS AND VIS
SHOULD IMPROVE BACK TO VFR BY 17-18Z AND STAY VFR THROUGH THIS
AFTERNOON. EAST WINDS OUT OF THE GORGE ARE EXPECTED TO REACH KPDX
BY 18Z AND PERSIST THROUGH TONIGHT...WHICH SHOULD KEEP CONDITIONS
VFR THROUGH TONIGHT. -MCCOY


&&


.MARINE...HIGH PRESSURE REMAINS OVER THE WATERS TODAY AND FRIDAY.
THE NEXT FRONTAL SYSTEM LOOKS TO MOVE THROUGH SATURDAY NIGHT
THROUGH SUNDAY MORNING. MODELS HAVE INCREASED WINDS A BIT IN THIS
SYSTEM AS IT MOVES THROUGH THE WATERS...NOW FORECASTING MARGINAL
SMALL CRAFT ADVISORY WINDS. WILL CONTINUE TO MONITOR THIS AS IT
GETS CLOSER. WITH INCREASED WINDS...SEAS STILL ONLY GET UP TO
AROUND 9 FT...BUT ANY MORE INCREASE IN WINDS COULD BRING SEAS UP
OVER 10 FT. AS OF NOW...SEAS ARE NOT FORECAST TO REACH OVER 10 FT
THROUGH THE WEEKEND. A MORE ACTIVE WEATHER PATTERN APPEARS
POSSIBLE TO SET UP FOR NEXT WEEK...STARTING WITH THIS SYSTEM LATE
SATURDAY/EARLY SUNDAY. CONFIDENCE IN THE DETAILS IS LOW AT THIS
TIME. -MCCOY


&&


.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.


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.