Winter Storm in Oregon, November 18 to 22, 2001

NORTHWEST OREGON AND SOUTHWEST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
230 AM PST SUN NOV 18 2001

.SYNOPSIS...HIGH PRESSURE ALLOWING LOCALLY DENSE FOG TO DEVELOP ONCE
AGAIN THIS MORNING IN MOST LOWER VALLEYS.  FOG WILL LIFT BY MID
MORNING AS CLOUDS FROM THE FIRST IN A SERIES OF WEATHER SYSTEMS MOVES
ACROSS THE AREA.  THE FIRST SYSTEM WILL WEAKEN CONSIDERABLY PRODUCING
NOTHING MORE THAN A BAND OF MID AND HIGH CLOUDS...HOWEVER IT WILL
WEAKEN THE RIDGE AND PUSH IT E OF THE AREA.  A STRONGER SYSTEM WILL
AFFECT THE AREA MON AND MON NIGHT WITH INCREASING WIND AND RAIN.
STRONG W FLOW ACROSS THE W WILL CONTINUE THE WET WEATHER PATTERN INTO
THE EXTENDED.

.DISCUSSION...
.SHORT TERM...LOCALLY DENSE FOG HAS DEVELOPED AGAIN THIS MORNING IN
THE SHELTERED VALLEY LOCATIONS.  VISIBILITY REPORTED AS LOW AS A
QUARTER MILE AT SALEM AND PORTLAND BUT E WINDS NEAR THE GORGE HAVE
HAMPERED FOG DEVELOPMENT E OF PORTLAND.  EXPECT THE FOG TO HANG IN
UNTIL MID MORNING WHEN E WINDS INCREASE DUE TO LOWER PRESSURE
APPROACHING THE COAST.  THIS FIRST TROUGH PRODUCES LITTLE WEATHER BUT
WILL WEAKEN THE HIGH PRESSURE RIDGE CURRENTLY OVER THE AREA.  THE
NEXT TROUGH EXPECTED MON AND MON NIGHT STILL SHOWN BY THE ETA AND AVN
TO BE A BETTER WIND AND RAIN PRODUCER ALTHOUGH TIMING DIFFERENCES
STILL AN ISSUE.  THE ETA SHOWS THE FLOW NEARLY PARALLELING THE COAST
MON WHICH COULD DELAY PRECIPITATION INTO THE INTERIOR VALLEYS UNTIL
LATE MON AFTERNOON OR EVEN MON EVENING.  AVN APPEARS TO BE A LITTLE
TOO FAST WITH THIS SYSTEM SO HAVE MOSTLY FOLLOWED THE TIMING OF THE
ETA.  LIKELY POPS STILL LOOK FINE ALONG THE COAST BUT HAVE TRIMMED
BACK POPS MON FOR THE VALLEYS.  RAIN AT TIMES MON NIGHT WITH VERY
LITTLE BREAK INDICATED INTO THE EXTENDED.

.LONG TERM...THE NEW MRF STILL CONSISTENT IN SHOWING A SERIES OF
SYSTEMS EMBEDDED IN STRONG W FLOW.  WILL KEEP RAIN LIKELY IN THE
EXTENDED THROUGH FRI.  BY SAT...THE JET MAY SAG FAR ENOUGH S TO
TAPPER PRECIPITATION TO SHOWERS AS FLOW TURNS MORE NW.  MERCER

AST 23888 PDX 11387 SLE 11387 EUG 11387

.PQR...GALE WARNING,,,CAPE SHOALWATER TO FLORENCE.