National Weather Service Weather Forecast Office

• Home
• Site Map
• News
• Organization
• Search for: NWS All NOAA 

000
FXUS66 KPQR 170947
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
246 AM PDT MON JUN 17 2013

.SYNOPSIS...AN UPPER LEVEL LOW WILL GRADUALLY MOVE TOWARDS THE
PACIFIC NORTHWEST COAST TODAY...INCREASING CLOUD COVER AND SHOWERS
THROUGH TONIGHT. THE LOW WILL MAKE ITS MAIN PUSH ONSHORE TUESDAY AND
TUESDAY NIGHT WITH A GOOD INCREASE IN SHOWERS...THEN LINGER OVER
WESTERN OREGON WEDNESDAY FOR CONTINUED UNSETTLED WEATHER. WE WILL
LIKELY SEE SOME INSTABILITY AT TIMES WITH THIS LOW FOR AN OCCASIONAL
THUNDERSTORM. THE MAIN ENERGY WITH THE LOW WILL MOVE EAST DURING THE
LATTER PART OF THE WEEK...BUT WEAKER LOW PRESSURE ALOFT WILL MAINTAIN
ONSHORE FLOW TO KEEP NIGHT AND MORNING CLOUDS AROUND...BUT WITH A
DECREASING CHANCE OF SHOWERS.
&&

.SHORT TERM...A CLOUD BAND ASSOCIATED WITH THE UPPER LOW OVER THE
EAST PACIFIC HAS DISSIPATED FOR THE MOST PART EARLY THIS MORNING. LOW
STRATUS ALONG THE COAST AND REMNANTS OF SOME MID-HIGH CLOUDS OVER THE
NORTH VALLEY SHOULD LIFT BRIEFLY LATER THIS MORNING...BEFORE CLOUDS
SPREAD ACROSS THE REGION AS A SHORTWAVE MOVES NORTH OVER THE AREA.

THE UPPER LEVEL LOW IS CURRENTLY ROTATING AROUND 45N/135W...AND WILL
CONTINUE TO APPROACH THE COAST THIS AFTERNOON AND EVENING. MODELS ARE
STILL SHOWING A SHORTWAVE WRAP AROUND THE LOW AND LIFT TO THE
NORTHEAST LATER TODAY. THIS SHORTWAVE WILL SPUR ON SOME CONVECTIVE
ACTIVITY OVER THE NORTHEAST PORTION OF THE FORECAST AREA THIS
AFTERNOON AS LIFTED INDICES DIP NEAR -1. ITS LOOKING LIKE THE BEST
THREAT FOR THUNDERSTORM FORMATION MAY BE OVER THE SW WASHINGTON
CASCADES.

TUESDAY WILL SEE ANOTHER DECENT THREAT FOR CONVECTION AS UPPER LEVEL
FLOW TURNS A LITTLE MORE SOUTH-SOUTHEASTERLY...BRINGING THE THREAT
FOR THUNDERSTORMS OVER THE VALLEY. AS THE LOW MOVES ONSHORE LATE
TUESDAY NIGHT AND WEDNESDAY...EXPECT INCREASING SHOWERS. YET ANOTHER
CHANCE FOR THUNDERSTORMS OVER THE NE PORTION OF THE CWA IS EXPECTED
WEDNESDAY AFTERNOON...BUT NOW ITS NOT LOOKING QUITE AS PROMISING AS
PREVIOUS DAYS. WILL KEEP THE THREAT IN THE FORECAST RIGHT NOW GIVEN
THE VERY UNSETTLED ENVIRONMENT AS THE MAIN COLD POOL MOVES ACROSS THE
PACIFIC NORTHWEST.

THE LOW PUSHES INTO SOUTHEAST WASHINGTON LATE WEDNESDAY NIGHT AND
THURSDAY...BUT EXPECT SHOWERS TO CONTINUE TO WRAP AROUND THE LOW.
EXPECT THE BULK OF THE SHOWERS TO IMPACT THE NORTHERN FORECAST
ZONES...GRADUALLY DECREASING OVER THE SOUTHERN ZONES BY THURSDAY
AFTERNOON.

EXPECT BELOW NORMAL TEMPERATURES THROUGH MUCH OF THE SHORT TERM
PERIOD AS UNSETTLED WEATHER REMAINS ACROSS THE REGION. /27

.LONG TERM...THURSDAY NIGHT THROUGH SUNDAY...THE UPPER LEVEL LOW THAT
BROUGHT COOL AND UNSETTLED WEATHER ACROSS THE REGION DURING THE FIRST
HALF OF THE WEEK WILL REACH THE CANADIAN BORDER LATE THURSDAY INTO
FRIDAY. EXPECT ONLY A SLIGHT CHANCE OF SHOWERS IN NORTHERN ZONES OF
THE CWA AND INTO WASHINGTON STATE THROUGH LATE FRIDAY. MUCH OF THE
REGION LOOKS TO BE DRY SATURDAY AS A WEAK RIDGE BUILDS IN.
UNCERTAINTY INCREASES ON SUNDAY AS THE MODELS ARE ADVERTISING A
LARGE TROUGH SETTING UP OVER THE EASTERN PACIFIC...LIKELY BRINGING
ANOTHER ROUND OF WET WEATHER TO THE REGION LATE SUNDAY. BURGESS/27
&&

.AVIATION...MARINE STRATUS A LITTLE SLOWER TO PUSH INLAND TONIGHT,
SO EXPECT A LITTLE LESS COVERAGE OVER THE INLAND VALLEYS LATER THIS
MORNING.  THE MVFR MARINE CLOUDS THAT DO PUSH INLAND WILL FOLLOW THE
NORMAL PATHS ALONG THE COLUMBIA RIVER AND THROUGH COASTAL GAMES.
LOWER CLOUDS WILL BURN OFF QUICKLY OVER THE INTERIOR LATER THIS
MORNING WITH A RETURN TO VFR CONDITIONS. COASTAL STRATUS SHOULD
RETREAT OFF SHORE BY THIS AFTERNOON. CLOUDS ARE GOING TO BE QUITE
VARIABLE OVER THE NEXT 24 HRS AS BANDS ROTATING AROUND UPPER LOW
MOVE OVER THE FORECAST AREA...BUT THE GENERAL TREND WILL BE LOWERING
CIGS AND INCREASING CHANCE OF RAIN AS LARGE LOW PRESSURE AREA DRIFTS
CLOSER.  MODELS HINTING AT SOME INSTABILITY OVER NORTH COAST RANGE
LATER THIS AFTERNOON. LOOK FOR A BETTER CHANCE OF RAIN OVER MUCH OF
THE AREA ON TUESDAY.

KPDX AND APPROACHES...VFR CONDITIONS SHOULD CONTINUE FOR NEXT FEW
HOURS...BUT MVFR CIGS WILL LIKELY RETURNING AROUND 13Z THIS
MORNING...LASTING THROUGH ABOUT 18Z. VFR CONDITIONS SHOULD THEN BE
NORM FOR THE REMAINDER OF THE DAYTIME HOURS MONDAY. THE MODELS
SUGGEST CONVECTION IS A POSSIBILITY LATER THIS AFTERNOON AND EVENING
IN THE VICINITY OF PDX. TODD
&&

.MARINE...A BROAD AREA OF LOW PRESSURE WILL CONTINUE TO SLOWLY TRACK
TOWARDS THE COAST THROUGH WEDNESDAY. WINDS MAY BRIEFLY INCREASE THIS
AFTERNOON AND AGAIN TUESDAY AS WEAK FRONTS PUSH INTO THE COAST.
SMALL CRAFT ADVISORY CRITERIA POSSIBLE WITH FRONTAL BAND ON TUESDAY
WITH SOME GUSTS OF 25 KT.

A MIXED SWELL AROUND 2 FT EXISTS SO OPTED TO HIGHLIGHT THE SWELL
TRAIN WITH THE LONGER PERIOD. REGARDLESS...A SHORTER PERIOD WESTERLY
SWELL WILL GROW LATE MONDAY SO THAT SEAS SHOULD RISE INTO THE 4 TO 6
FT RANGE FROM MONDAY NIGHT THROUGH TUESDAY NIGHT.

WEAK HIGH PRESSURE WILL THEN SLOWLY BUILD AGAIN OVER THE NORTHEAST
PACIFIC LATE IN THE WEEK WITH NORTHERLY WINDS GENERALLY 20 KT OR LESS
AND SEAS DROPPING BACK DOWN INTO THE 2 TO 4 FT RANGE. TODD
&&

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