Hazardous Seas Warning 39, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
125 PM PDT THU OCT 2 2008

.DISCUSSION...12Z NGM/NAM/GFS IN.

A COLD FRONT IS NOW MOVING THROUGH SOUTHERN OREGON. AS EXPECTED...THIS
FRONT IS WEAKENING AS IT LOSES UPPER LEVEL SUPPORT. MEASURABLE
RAIN HAS BEEN REPORTED BY MOST LOCATION FROM THE CASCADES
WEST...BUT NOTHING ON THE EAST SIDE.

THE UPPER LEVEL SUPPORT WAS LOST DUE TO A SHORTWAVE DIVING DOWN
THE BACKSIDE OF THE OFFSHORE UPPER TROUGH. THIS CAUSED THE
LONGWAVE TROUGH TO REDEEPEN OUT AROUND 140W...CUTTING OFF THE
ENERGY SOURCE TO THE LEADING WAVE.

PRECIPITATION ASSOCIATED WITH THIS FIRST WAVE WILL BE LIGHT EXCEPT
ALONG THE COAST...AND VERY LITTLE OF IT WILL FALL EAST OF THE
CASCADES. THE FRONT WILL STALL THIS EVENING OVER SOUTHWEST OREGON
AND NORTHERN CALIFORNIA.

HOWEVER...THE LONG WAVE TROUGH IS STILL OUT THERE...AND IT WILL
APPROACH THE COAST FRIDAY. FIRST THE STALLED COLD FRONT WILL LIFT
BACK NORTH AS A WARM FRONT LATE TONIGHT AND EARLY FRIDAY. THIS
WILL KEEP THE LIGHT PRECIPITATION GOING IN THE AREA THROUGH THE
NIGHT. THEN A MUCH STRONGER AND WETTER COLD FRONT WILL MOVE
ONSHORE FRIDAY AFTERNOON. AT THIS TIME IT DOES NOT APPEAR THAT
WINDS WILL MEET WARNING OR ADVISORY CRITERIA IN THE CWA...BUT IT
WILL BE STRONG AND GUSTY ALONG THE COAST...OVER THE RIDGES...IN
THE SHASTA VALLEY...AND EAST OF THE CASCADES. WETTING RAINS ARE
ALSO EXPECTED OVER JUST ABOUT THE ENTIRE MEDFORD CWA FRIDAY INTO
FRIDAY NIGHT. A SECONDARY FRONT WILL MOVE ONSHORE SATURDAY WITH
THE UPPER TROUGH...AND THIS WILL BRING ANOTHER ROUND OF HEAVIER
PRECIPITATION TO THE AREA.

THE UPPER TROUGH WILL FINALLY MOVE TO THE EAST SATURDAY AFTERNOON
AND EVENING...AND SHOWERS WILL DIMINISH AS IT PASSES. A RIDGE WILL
BUILD INTO THE AREA SATURDAY NIGHT INTO SUNDAY. THE LAST
STRAGGLING SHOWERS WILL END SUNDAY. A WEAK OFFSHORE FLOW EVENT
WILL OCCUR SUNDAY NIGHT.

THE RIDGE WILL HOLD OVER THE AREA THROUGH AT LEAST SUNDAY. THE
NEXT TROUGH WILL APPROACH THE COAST MONDAY NIGHT AND MOVE ONSHORE
TUESDAY. THE 02/12Z GFS IS ABOUT 12 HOURS FASTER WITH THE SURFACE
FRONT THAN THE 02/06Z RUN WAS. THE NEW RUSH PUSHES A FRONT ONSHORE
MONDAY EVENING.  IT STILL LOOKS TO BE A LIGHT PRECIPITATION EVENT
WITH ALMOST ALL OF THE RAIN FALLING FROM THE CASCADES WEST.  WILL
SMEAR THE POPS FROM MONDAY THROUGH TUESDAY TO ACCOUNT FOR THE
UNCERTAINTY.

ANOTHER RIDGE WILL FOLLOW THIS SYSTEM...AND THIS ONE WILL BE
STRONGER AND HANG AROUND A BIT LONGER. A MODERATE TO STRONG OFFSHORE
FLOW EVENT WILL DEVELOP TUESDAY NIGHT...PEAK WEDNESDAY NIGHT...AND
PERSIST THROUGH AT LEAST THURSDAY NIGHT.

&&

.AVIATION...AREAS OF MVFR CIGS/VSBYS HAVE DEVELOPED ALONG THE COAST
AND OVER THE UMPQUA VALLEY AND WILL PERSIST THROUGH TONIGHT. THE
REMAINDER OF THE AREA WILL REMAIN VFR.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.

CA...NONE.

PACIFIC COASTAL WATERS...GALE WATCH FROM FRIDAY MORNING THROUGH LATE
          FRIDAY NIGHT FOR PZZ350-PZZ356-PZZ370-PZZ376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 PM PDT THIS AFTERNOON FOR
          PZZ356-PZZ376.
     HAZARDOUS SEAS WATCH FROM FRIDAY MORNING THROUGH LATE FRIDAY
          NIGHT FOR PZZ350-PZZ356-PZZ370-PZZ376.
     HAZARDOUS SEAS WARNING UNTIL 3 PM PDT THIS AFTERNOON FOR PZZ356-
          PZZ376.
     SMALL CRAFT ADVISORY FOR WINDS UNTIL 9 PM PDT THIS EVENING FOR
          PZZ350-PZZ370.
     HAZARDOUS SEAS WARNING UNTIL 9 PM PDT THIS EVENING FOR PZZ350-
          PZZ370.

15/15/10