Wildfire in Oregon, August 17 to 22, 2002

NORTHWEST OREGON AND SOUTHWEST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
900 AM PDT SAT AUG 17 2002

.SYNOPSIS...HIGH PRESSURE WILL REMAIN OVER THE NORTHEAST PACIFIC AS
WEAK WEATHER SYSTEMS SLIDE DOWN THE BRITISH COLUMBIA COAST AND OVER
THE AREA. THESE DISTURBANCES WILL INCREASE THE ONSHORE FLOW AND ALLOW
FOR LATE NIGHT AND MORNING CLOUDS OVER NORTHWEST OREGON THROUGH
WEDNESDAY.

.DISCUSSION...
.SHORT TERM...THE SHARP SHORTWAVE SHOWN NEAR VANCOUVER ISLAND THIS
MORNING IS ZIPPING DOWN THROUGH NORTHWEST FLOW ALOFT A BIT AHEAD OF
YESTERDAYS MODELS. MAIN ENERGY IS INLAND OVER BC AS SHOWN BY IR PICS
BUT WATER VAPOR IMAGERY SHOWS BLACKENING WEST OF VANCOUVER ISLAND AND
AN ORGANIZED LOW CLOUD FIELD. THIS FEATURE SHOULD PRODUCE SOME GUSTY
WINDS OVER THE COASTAL WATERS. LOW CEILING CLOUD DECK SHOULD LIFT
OVER THE NEXT FEW HOURS THEN EXPECT CLOUDS TO REDEVELOP ALONG THE
BEACHES THIS AFTERNOON AS ONSHORE FLOW INCREASES DUE TO THE
APPROACHING SHORT WAVE.  THIS DISTURBANCE MAY THICKEN THE MARINE
LAYER ENOUGH FOR SOME DRIZZLE ON THE NORTH COAST TONIGHT AND EARLY
SUNDAY MORNING. SUNDAY NIGHT AND MONDAY A STRONGER SHORT WAVE
SWINGS THROUGH WESTERN OREGON FOR INCREASED ONSHORE FLOW AND A MUCH
DEEPER MARINE LAYER...FOR A CHANCE OF DRIZZLE INLAND AS WELL. THE
LATEST AVN SHOWS A -16 DEG COLD POOL AT 500 MB MOVING INLAND AND WILL
HAVE TO KEEP AN EYE ON LAPSE RATES GETTING ANY STEEPER FOR THE
POSSIBILITY OF SHOWERS.  THE 12Z AVN AND ETA BOTH HAVE THE SPLIT
FARTHER NORTH MONDAY THAN YESTERDAYS MODELS SO MORE LIFT OVER THE
FORECAST AREA IN THE INFLUENCE OF THE SOUTHERN BRANCH.

.LONG TERM...THE ECMWF MEDIUM RANGE MODELS CONTINUE TO SHOW A RIDGE
BUILDING OVER NORTHWEST OREGON LATER WEDNESDAY THROUGH FRIDAY WITH
BOTH THE MRF AND EURO OPTING FOR A STRONG RIDGE SOLUTION.

AST 02222  PDX 00011  SLE 00011  EUG 00001

.PQR...SMALL CRAFT ADVISORY...CAPE SHOALWATER TO FLORENCE.