000 
FXUS66 KPQR 021632
AFDPQR

NORTHWEST OREGON AND SOUTHWEST WASHINGTON FORECAST
DISCUSSION...CORRECTED POPS
NATIONAL WEATHER SERVICE PORTLAND OR
830 AM PST SAT MAR 2 2002

.SYNOPSIS...A STRONG UPPER RIDGE ALONG 130W EXTENDS INTO THE GULF OF
ALASKA...WITH DRY NORTHERLY FLOW ALOFT TODAY AND TONIGHT OVER THE
FORECAST AREA. SURFACE HIGH PRESSURE IS EAST OF THE CASCADES WITH
OFFSHORE FLOW. THE RIDGE WILL FLATTEN SUNDAY WITH WEAKENING OFFSHORE
FLOW. A COLD UPPER TROUGH WILL DROP SOUTHWARD FROM THE GULF OF ALASKA
TOWARD THE PACIFIC NW MONDAY WITH GRADUALLY INCREASING ONSHORE FLOW.
THE ASSOCIATED FRONT WILL MOVE INTO THE FORECAST AREA MONDAY NIGHT
AND TUESDAY. SNOW LEVELS WILL DROP ESPECIALLY BEHIND THE FRONT DURING
THE MID WEEK PERIOD. MORE MOISTURE IS POSSIBLE LATE IN THE WEEK.

.DISCUSSION...
.SHORT TERM...OFFSHORE GRADIENTS INCREASING THIS MORNING WITH DRY
AIR MASS ALL LEVELS TODAY AND SUNDAY. OFFSHORE FLOW CONTINUES
INTO SUNDAY...BUT WEAKENS IN THE AFTERNOON AS THE SURFACE HIGH
PRESSURE EAST OF THE CASCADES ERODES DUE TO THE BROADENING AND
FLATTENING OF THE UPPER RIDGE. NEXT SYSTEM IS A COLD TROUGH DROPPING
DOWN THE B.C. COAST SUNDAY NIGHT AND MONDAY...WITH LOW LEVEL FLOW
TURNING ONSHORE MONDAY. FRONT ENTERS OUR AREA MONDAY NIGHT AND
TUESDAY. NEW ETA IS SLOWER DEVELOPING THE ONSHORE FLOW AND MAY NEED
TO SLOW DOWN SYSTEM. WILL WAIT FOR AVIATION MODEL BEFORE MAKING
ADJUSTMENTS. SNOW LEVELS INITIALLY DROP A LITTLE BELOW PASS
ELEVATIONS FOR TUESDAY.

.LONG TERM...MODELS CONTINUE TO KEEP THE COLD UPPER TROUGH OVER THE
PACIFIC NW THROUGH FRIDAY. THE PAST TWO RUNS HAVE HAD HIGHER
THICKNESSES THAN PREVIOUS SO SNOW LEVELS SHOULD REMAIN ABOVE 1500-
2000 FEET. MOISTURE FORM THE SOUTHERN BRANCH OF THE JETSTREAM COULD
BOOST QPF...AND A WINTER STORM WARNING MAY BE NECESSARY FOR THE
CASCADES...AND POSSIBLY THE COAST RANGE AT TIMES. LATEST MRF BRINGS
ANOTHER COLD SHOT OF PRECIPITATION FRIDAY. NO CHANGES TO CURRENT
FORECASTS. TOLLESON

AST 00014 PDX 00003 SLE 00002 EUG 00002

.PQR...SMALL CRAFT ADVISORY FOR CASCADE HEAD TO FLORENCE THIS
         AFTERNOON AND EVENING.