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 241656
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
955 AM PDT THU APR 24 2014

.SYNOPSIS...A COLD FRONT HAD MOVED INTO THE CASCADES THIS MORNING AND
WILL MOVE EAST OF THE CASCADES LATER THIS MORNING. A BROAD AND COOL
UPPER LOW WILL REMAIN JUST OFF THE COAST AND SPREAD SHOWERS ONSHORE
AT TIMES TODAY AND TONIGHT. THE UPPER LOW/TROUGH WILL MOVE ONSHORE
AND THROUGH SOUTHWEST WASHINGTON AND NORTHWEST OREGON FRIDAY FOR MORE
SHOWERS AND POSSIBLE AFTERNOON THUNDERSTORMS...THEN EAST OF THE AREA
FRIDAY NIGHT FOR DECREASING SHOWERS. THERE SHOULD BE A BRIEF BREAK IN
THE WET WEATHER SATURDAY. ANOTHER SIGNIFICANT FRONTAL SYSTEM IS
EXPECTED LATE SATURDAY ON THE COAST WITH RAIN SPREADING INLAND
SATURDAY NIGHT.
&&

.SHORT TERM...A STRONG COLD FRONT/SQUALL LINE MOVED THROUGH THE
PORTLAND METRO AREA DURING THE MORNING COMMUTE TODAY...AND WAS NOW IN
THE CASCADES...AND WILL BE EAST OF THE CASCADE BY AFTERNOON. SNOW
LEVELS HAVE RISEN WELL ABOVE THE PASSES. THE RAIN WAS HEAVY
ESPECIALLY IN THE HIGHER TERRAIN...WITH SOME 24 HOUR AMOUNTS ABOVE 3
INCHES IN OUR NORTHERN MOUNTAINS. DID BRIEFLY HIT FLOOD STAGE AT THE
GRAYS RIVER AT ROSBURG IN WAHKIAKUM COUNTY. NO OTHER RIVERS ARE
EXPECTED TO REACH FLOOD STAGE. A COOL BROAD UPPER LOW OR TROUGH WAS
OFF THE COAST AND WILL SPREAD SHOWERS INTO OUR AREA AT TIMES TODAY
AND TONIGHT. SNOW LEVELS WILL DROP BACK DOWN TO NEAR OR BELOW THE
PASSES LATER TODAY AND ESPECIALLY TONIGHT...AND CONTINUE BELOW THE
PASSES ON FRIDAY. HOWEVER...A LACK OF ORGANIZED ONSHORE FLOW WILL
LIMIT ACCUMULATIONS BELOW SNOW ADVISORY THRESHOLDS.

WITH SOME COOLING ALOFT TODAY...WE WILL PROBABLY SEE SOME HEAVIER
SHOWERS DEVELOP AT TIMES THIS AFTERNOON AND EVENING...WITH SOME SMALL
HAIL POSSIBLE. MODEL SOUNDINGS AND WITH THE MAIN COLD POOL ALOFT
REMAINING OFFSHORE...THE CHANCE OF THUNDER IS SMALL TODAY.

THE MAIN UPPER TROUGH/LOW COMES ONSHORE FRIDAY WITH ITS ASSOCIATED
COLD POOL ALOFT...TEMPS AT 500 MB BETWEEN MINUS 30 AND MINUS 32
DEGREES C. THIS SHOULD GIVE A DECENT CHANCE OF THUNDERSTORMS FRIDAY
AFTERNOON AND EVENING. SOME OF THESE SHOWERS WILL LIKELY BE HEAVY AT
TIMES.

THE UPPER TROUGH MOVES EAST FRIDAY NIGHT WITH DECREASING SHOWERS
LATER FRIDAY NIGHT.

THE NEXT SIGNIFICANT FRONT COMES IN LATE SATURDAY AND ESPECIALLY
SATURDAY NIGHT WITH A DECENT SHOT OF RAIN AND MORE BREEZY CONDITIONS.
TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
SATURDAY NIGHT THROUGH WEDNESDAY...THE LATEST MEDIUM RANGE FORECAST
MODELS CONTINUE TO ADVERTISE A FRONTAL SYSTEM MOVING ONSHORE SAT
NIGHT AND EARLY SUN. KEPT CATEGORICAL POPS FOR THIS TIME
PERIOD...WITH A TRANSITION TO SHOWERS LATER IN THE DAY SUNDAY BEHIND
THE TRAILING COLD FRONT. A WEAK WARM FRONT MAY BRUSH THE FORECAST
AREA WITH SOME LIGHT PRECIPITATION ON MON...BUT THE TREND WILL BE
TOWARD DRIER WEATHER AS UPPER LEVEL RIDGING BUILDS OVER THE PAC NW.
RIGHT NOW...CONFIDENCE IS PRETTY HIGH THAT TUE WILL BE WARM AND DRY
WITH THE RIDGE DIRECTLY OVERHEAD...AND HIGH TEMPS WERE RAISED
SIGNIFICANTLY WITH THE LATEST FORECAST PACKAGE. MODEL UNCERTAINTY
BEGINS TO INCREASE WED...AS THE 12Z GFS AND SOME OF ITS ENSEMBLES
INDICATE THAT A TROF OVER THE NE PAC WILL SPLIT...WITH THE NORTHERN
ENERGY PUSHING INTO THE PAC NW WED AS AN OPEN TROF. THE 12Z ECMWF
MAINTAINS A NE PAC CLOSED LOW THAT HARDLY MOVES THROUGH THE END OF
THE WEEK...ALLOWING RIDGING TO REMAIN IN PLACE OVER THE PAC NW FOR
SEVERAL DAYS. HAVE KEPT SOME LOW CHANCE POPS ON WED DUE TO THIS
UNCERTAINTY. PYLE
&&

.AVIATION...COLD FRONT PUSHING UP AND OVER THE CASCADES AS OF 8 AM.
WORST CONDITIONS OVER THE CASCADES THROUGH 17Z WHERE MTNS WILL BE
OBSCURED IN CLOUDS AND PRECIP...ALONG WITH AN ISOLATED TSTM OR TWO.
UNSETTLED AIR MASS OVER THE PAC WILL SPREAD SHOWERS ACROSS THE REGION
TODAY. OVERALL...MOSTLY VFR WITH POCKETS OF MVFR UNDER THE SHOWERS
THROUGH TONIGHT.

KPDX AND APPROACHES...VFR CONDITIONS WITH OCCASIONAL BRIEF MVFR CIGS
DUE TO SHOWERS. SHOWERS WILL BE INCREASING AFTER 18Z. NOT MUCH CHANGE
THROUGH TONIGHT. ROCKEY.
&&

.MARINE...MUCH MORE QUIET THIS AM. 996 MB LOW OFF VANCOUVER ISLAND
THIS AM WILL WEAKEN AS IT PUSHES FURTHER INTO CENTRAL BRITISH
COLUMBIA TODAY. STILL HAVE ENOUGH PRES GRADIENT AROUND THE LOW TO POP
FREQUENT GUSTS 20 TO 30 KT...MAINLY N OF CASCADE HEAD TODAY INTO THIS
EVENING. OTHERWISE WILL HAVE SHOWERS WITH OCCASIONAL GUSTS NEAR/UNDER
THOSE SHOWERS.

SEAS RUNNING 10 TO 12 FT TODAY...BUT WILL SLOWLY SUBSIDE THROUGH FRI.
HIGHEST SEAS WILL BE OVER THE OUTER WATERS. SEAS SHOULD DROP BELOW 10
FT OVER MOST ALL AREAS EARLY FRI AM.

NEXT FRONT WILL ARRIVE LATE SAT...WITH S WINDS 20 TO 30 KT AND SEAS
BUILDING BACK INTO THE LOWER TEENS. ROCKEY.
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS THROUGH THIS EVENING ON ALL
 COASTAL WATERS.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS TODAY THROUGH FRI
 ON ALL COASTAL WATERS.
     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA BAR CONDITIONS
 TODAY...AND AGAIN 12 AM TO 5 AM FRI.

&&

$$

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..


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