Severe Thunderstorm Warning 2, NWS Portland, OR

NORTHWEST OREGON AND SOUTHWEST WASHINGTON FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
300 PM PDT MON SEP 30 2002

.SYNOPSIS...COOL MOIST AND UNSTABLE NORTHWEST ONSHORE FLOW WILL
DECREASE TONIGHT AS HIGH PRESSURE BUILDS OVER AREA. SNOW LEVELS WILL
BE NEAR THE PASSES. DRY WEATHER TUESDAY AND WEDNESDAY UNDER HIGH
PRESSURE. THE NEXT PACIFIC FRONTAL SYSTEM WILL SAG SOUTH INTO OUR
AREA LATE WEDNESDAY NIGHT AND THURSDAY...MOVING TO THE SOUTH THURSDAY
NIGHT. DRYING AGAIN FOR FRIDAY AND SATURDAY AS HIGH PRESSURE REBUILDS
ALONG THE COAST. SYSTEM WILL BEGIN PASSING BY TO THE NORTH SUNDAY AND
MONDAY...POSSIBLY INCREASING CLOUDS AGAIN EARLY NEXT WEEK.

.DISCUSSION...
.SHORT TERM...WILL CONTINUE THE UNSTABLE SHOWERY REGIME THIS EVENING
PER CURRENT NATIONAL WEATHER SERVICE DOPPLER RADAR AND LIGHTNING
DATA. SNOW LEVELS WILL REMAIN NEAR 4000 FEET TONIGHT WITH POSSIBLE
1 OR 2 INCH ACCUMULATIONS. MODELS SHOW THE ASSOCIATED COLD POOL
MOVING EAST AND DIGGING SOUTH WITH STABILIZATION OVER OUR AREA
TONIGHT. THE JET IS SLOW TO MOVE EAST...FINALLY MOVING EAST OF THE
CASCADES TUESDAY MORNING. MODELS STILL SHOW A LOT OF CLOUDS JAMMED UP
AGAINST THE CASCADES TONIGHT...WITH MORE BREAKS OUT NEAR THE COAST
RANGE. COULD SEE SOME PATCHY FROST. WITH AFTERNOON CLEARING LIKELY
TUESDAY...A BETTER CHANCE OF FROST EXISTS TUESDAY NIGHT. HAVE RENEWED
AND EXPANDED THE SPECIAL STATEMENT.

WEDNESDAY WILL AGAIN BE DRY AFTER SOME MORNING CLOUDS OR FOG. THE
NEXT SYSTEM IS STILL NORTH...THOUGH THE ONSHORE FLOW STARTS TO
INCREASE ON THE FAR NORTH COAST LATE IN THE DAY.

THE FRONT SAGS SOUTH WEDNESDAY NIGHT AND THURSDAY...A LITTLE SLOWER
THAN EARLIER PROGS. WILL GO WITH A CHANCE IN THE NORTH WEDNESDAY
NIGHT...THEN LIKELY POPS NORTH AND A CHANCE SOUTH THURSDAY. SNOW
LEVEL ARE MUCH HIGHER WITH THIS SYSTEM.

WILL HAVE TO REISSUE A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS THIS
EVENING.

.LONG TERM...MODELS SHOW DRY NORTHERLY FLOW FRIDAY AS A RIDGE BUILDS
ALONG THE COAST...CONTINUING SATURDAY. THE MODELS SHOW A COUPLE OF
SYSTEM SKIRTING BY TO THE NORTH EARLY NEXT WEEK SLOWLY SAGGING INTO
THE NORTHWEST...BUT FOR NOW WILL EASE INTO THE CHANGE AND MAINLY
GRADUALLY INCREASE THE CLOUDS. TOLLESON

AST 310147 PDX 510026 SLE 510016 EUG 510015

.PQR...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS CAPE SHOALWATER TO
        FLORENCE TONIGHT.

ORZ001>013-WAZ019>023-039-040-010600-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE PORTLAND OR
152 PM PDT MON SEP 30 2002

...ISOLATED EVENING THUNDERSTORMS OVER MOST OF SOUTHWEST WASHINGTON
AND NORTHWEST OREGON THIS EVENING...

...LOW SNOW LEVELS IN THE SOUTH WASHINGTON AND NORTH OREGON CASCADES
TONIGHT...

...POSSIBLE FROST IN THE VALLEYS OF SOUTHWEST WASHINGTON AND
NORTHWEST OREGON TUESDAY NIGHT...

SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE INTO THE EVENING
THEN DECREASE ACROSS SOUTHWEST WASHINGTON AND NORTHWEST OREGON.
HEAVY RAIN...SMALL HAIL...GUSTY WINDS TO 35 MPH...LIGHTNING...AND
LOCAL STREET FLOODING ARE POSSIBLE EARLY THIS EVENING.

SNOW LEVELS WILL REMAIN NEAR 4000 FEET IN THE SOUTH WASHINGTON AND
NORTH OREGON CASCADES TONIGHT. AN ADDITIONAL 1 OR 2 INCHES IS
POSSIBLE TONIGHT BEFORE THE SHOWERS DECREASE.

COOL AIR LEFT OVER FROM THE RECENT SYSTEM WILL DROP NIGHTTIME LOWS
INTO THE 30S THE NEXT 2 OR 3 NIGHTS. TONIGHT THERE WILL LIKELY BE
ENOUGH CLOUDS LEFT OVER THAT MOST MINIMUM TEMPERATURES WILL REMAIN
ABOVE FREEZING. ON TUESDAY NIGHT THERE SHOULD BE MUCH MORE CLEARING
SO THAT MORE AREAS MAY SEE THE FIRST FROST OF THE
SEASON....ESPECIALLY THOSE OUTLYING AREAS AWAY FROM METROPOLITAN
AREAS AND AWAY FROM THE COLUMBIA RIVER.

TOLLESON