324 
FXUS66 KPQR 161645
AFDPQR

NORTHWEST OREGON AND SOUTHWEST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
830 AM PST SUN MAR 16 2003

.SYNOPSIS...A BROAD UPPER LEVEL TROUGH OVER THE EAST PACIFIC WILL
MAINTAIN A MOIST SOUTHWEST FLOW ALOFT OVER THE FORECAST AREA FOR THE
NEXT SEVERAL DAYS. THE AIR MASS WILL BE UNSTABLE...MAINLY IN THE
AFTERNOON AND EVENING HOURS SUNDAY. A WEAK PACIFIC COLD FRONT WILL
MOVE INLAND OVER THE FORECAST AREA ON MONDAY AND ANOTHER TUESDAY. A
STRONGER COLD FRONT WILL MOVE INLAND ACROSS THE AREA ON WEDNESDAY. A
SERIES OF PACIFIC WEATHER SYSTEMS WILL PARADE INLAND ACROSS THE
FORECAST AREA NEXT WEEK.

.DISCUSSION...
.SHORT TERM...A BROAD 500 MILLIBAR TROUGH OVER THE EASTERN PACIFIC
WILL MAINTAIN SOUTHWEST FLOW ALOFT OVER THE PACIFIC NORTHWEST AS IT
ROTATES WEAK SHORE WAVES INLAND OVER THE FORECAST AREA. SEVERAL WEAK
VORTICITY LOBES ARE VISIBLE OFFSHORE ON INFRA RED SATELLITE IMAGERY
ROTATING TOWARD THE COAST THIS MORNING AND THESE WILL ADD ADDITION
TRIGGER TO DAYTIME HEATING FOR CONVECTION IN A CONDITIONALLY UNSTABLE
AIR MASS THIS AFTERNOON. ONE VORTICITY LOBE TRIGGERED A FEW STRIKES
NEAR THE NORTH OREGON COAST ALREADY THIS MORNING AND HAS MOVED
ON...THE AIR MASS IS STABILIZING A BIT THIS MORNING AND THEN WILL
BECOME ACTIVE WITH SHOWERS AND A CHANCE OF A THUNDERSTORM THIS
AFTERNOON. A WEAK SHORTWAVE AND FRONT WILL MOVE INLAND MONDAY THEN A
ANOTHER WEAK FRONT WILL BRUSH ACROSS NORTHWEST OREGON ON TUESDAY. THE
UPPER LEVEL TROUGH WILL COME INLAND WITH A STRONGER FRONT ON
WEDNESDAY BUT IT WILL BE SPLITTING AS IT COMES WITH THE HEAVIEST
PRECIPITATION MOVING INTO CALIFORNIA AND BRITISH COLUMBIA.

.LONG TERM...NO CHANGES TO PREVIOUS DISCUSSION...A PROGRESSIVE
PATTERN CONTINUES LIKELY PRECIPITATION FOR THE EXTENDED PERIOD AS
SYSTEMS MOVE THROUGH ABOUT EVERY 24 HOURS.

AST 86757  PDX 76755  SLE 76755  EUG 76755

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

$$