Hazardous Seas Warning 32, NWS Medford, OR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
855 PM PDT SUN MAY 20 2012

.DISCUSSION...THE 18Z GFS AND 00Z NAM MODEL DATA SUPPORTS THE
CURRENT FORECAST OF A JOLT BACK TO MORE SPRING-LIKE WEATHER ON
MONDAY WITH A SIGNIFICANT COLD FRONT TO REACH THE COAST LATE IN
THE MORNING AND MOVE QUICKLY ACROSS OUR AREA THROUGH THE EVENING.
THE FRONT WILL PRODUCE BREEZY TO WINDY CONDITIONS WITH VERY LIGHT
RAIN LIKELY AT THE COAST IN THE MORNING THEN RAIN IN THE AFTERNOON
MAINLY FROM THE COAST INTO THE UMPQUA BASIN AND JOSEPHINE COUNTY.
RAIN WILL TURN TO SHOWERS IN THE EVENING WITH PRECIPITATION
LIKELY SPREADING ACROSS THE REMAINDER OF THE WEST SIDE AND ALSO
MUCH OF KLAMATH COUNTY. WITH THE THICKER/LOWER LEVEL CLOUD COVER
AND MUCH OF THE PRECIPITATION HOLDING OFF UNTIL THE
EVENING...THIS SHOULD ALLOW HIGH TEMPERATURES TO REACH LEVELS NEAR
OR SLIGHTLY ABOVE NORMAL.

SHOWERS WILL DIMINISH LATER MONDAY NIGHT. BUT, A SHORTWAVE TROUGH
WILL FOLLOW ON TUESDAY WITH A CHANCE OF SHOWERS MAINLY AT THE
COAST AND FROM THE UMPQUA BASIN NORTHWARD. A MOIST ONSHORE FLOW
WILL LINGER DURING MID-WEEK BUT THIS MOISTURE LOOKS MORE LIMITED
AND SHALLOW THAN IN PREVIOUS MODEL RUNS. THIS SHOULD KEEP SHOWERS
ON THE LIGHT SIDE AND MAINLY ALONG THE COAST INTO DOUGLAS COUNTY.
ALSO, THE GFS HAS TRENDED SLIGHTLY WEAKER WITH THE ARRIVAL OF THE
NEXT TROUGH AT THE END OF THE WEEK.

&&

.AVIATION...PLEASE NOTE...MEASURED OBSERVATIONS AT NORTH BEND WILL
NOT BE AVAILABLE FROM TUESDAY MAY 22RD THROUGH THURSDAY MAY 24TH.
MANUAL OBSERVATIONS WILL BE TAKEN DURING THIS TIME...BUT THEY WILL
BE ESTIMATES AND OBSERVATIONS WILL NOT BE AVAILABLE FROM 9 PM PDT
UNTIL 7 AM PDT.

WIDESPREAD IFR AND LOCAL MVFR CEILINGS HAVE SPREAD INTO THE COAST
AND WILL PERSIST OVERNIGHT. MVFR CEILINGS WILL ALSO SPREAD INTO
THE UMPQUA BASIN AFTER MIDNIGHT. ELSEWHERE, INLAND SITES WILL
REMAIN VFR THROUGH MONDAY MORNING WITH JUST SOME MID TO HIGH LEVEL
CLOUDS. THERE WILL BE SOME IMPROVEMENT IN COASTAL CEILINGS MONDAY
MORNING. BUT A COLD FRONT WILL ARRIVE BY THE AFTERNOON WITH MVFR
CEILINGS AND RAIN SPREADING INLAND...REACHING THE CASCADES BY
MONDAY EVENING.

&&

.PREV DISCUSSION... /ISSUED 204 PM PDT SUN MAY 20 2012/

SHORT TERM....A WEAK SHORTWAVE DISTURBANCE COMBINED WITH WEAK
DAYTIME INSTABILITY IS PRODUCING SOME CUMULUS CLOUDS...MAINLY
OVER THE CASCADES INTO SOUTHEAST OREGON. THERE IS VERY SLIGHT
CHANCE FOR ISOLATED THUNDERSTORMS. HOWEVER...DAYTIME HEATING MAY
NOT BE ENOUGH TO OVERCOME A WEAK CAP IN PLACE. HIGH CLOUDS ARE
ARE ALSO PRESENT OVER MUCH OF THE AREA THIS AFTERNOON WITH THE
LEAST AMOUNT OF HIGH CLOUDS IN SOUTHERN JOSEPHINE...WESTERN
SISKIYOU AND MODOC COUNTIES. THE HIGH CLOUDS ARE EXPECTED TO THIN
LATE THIS AFTERNOON INTO THE EVENING. HOWEVER...SOME CONTINUED HIGH
CLOUDS ARE EXPECTED AND MAY IMPEDE THE VIEWING OF THE ANNULAR
ECLIPSE THIS EVENING WHICH PEAKS NEAR 625 PDT TO 630 PDT WHEN THE
SUN IS ONLY 25 DEGREES ABOVE THE HORIZON. ALONG THE COAST...EXPECT
WIDESPREAD MARINE STRATUS TO PERSIST THROUGH TONIGHT AND INTO
TOMORROW MORNING.

MONDAY THROUGH WEDNESDAY...THE PATTERN  CHANGES TO A WETTER AND
COOLER REGIME. A FRONTAL SYSTEM WILL MOVE TOWARDS THE AREA TONIGHT
INTO MONDAY WITH THE WARM FRONT PUSHING INLAND TONIGHT FOLLOWED BY
THE COLD FRONT MONDAY AFTERNOON AND EVENING. MODELS ARE SHOWING
LITTLE PRECIPITATION OVER THE AREA WITH THE WARM FRONT...EXCEPT
NEAR THE COAST AND FOR AREAS JUST INLAND. THEN...THE COLD FRONT
WILL BRING A CHANCE FOR RAIN OVER MUCH OF THE CWA WITH RAIN LIKELY
FROM THE CASCADES WEST IN SOUTHERN OREGON AND INTO WESTERN
SISKIYOU COUNTY LATE MONDAY AFTERNOON AND EVENING. GUSTY SOUTHWEST
WINDS ARE EXPECTED ACROSS THE AREA MONDAY AFTERNOON AND EVENING. THE
STRONGEST WINDS WILL OCCUR OVER THE MOUNTAINS AND EAST OF THE
CASCADES WHERE GUSTS UP TO 40 MPH ARE POSSIBLE. BEHIND THE
FRONT...AN UPPER TROUGH SETTLES OVER THE REGION WITH ADDITIONAL
SHORTWAVE DISTURBANCES BRINGING CONTINUED CHANCES FOR RAIN TUESDAY
AND WEDNESDAY...ESPECIALLY FOR AREAS FROM THE CASCADES WEST.
COOLER TEMPERATURES ARE IN STORE DURING THIS PERIOD AS 500MB
HEIGHTS LOWER OVER THE REGION. HIGH TEMPERATURES TUESDAY AND
WEDNESDAY ARE EXPECTED IN THE 60S WEST OF THE CASCADES AND IN THE
UPPER 50S TO LOW 60S EAST OF THE CASCADES.

LONG TERM...THURSDAY THROUGH SUNDAY...THE COOL AND WET PATTERN
CONTINUES THURSDAY AND FRIDAY WITH MODELS SHOWING A UPPER LOW
DROPPING SOUTH OVER THE AREA LATE THURSDAY INTO FRIDAY. THIS WILL
BRING COLD SHOWERY CONDITIONS TO THE AREA. THE GFS IS QUICKER TO
EXIT THIS LOW TO THE SOUTHEAST THAN THE ECMWF AND BRINGS IN DRIER
CONDITIONS BY FRIDAY NIGHT AND SATURDAY. THE ECMWF KEEPS SHOWERS
OVER THE AREA THROUGH SATURDAY...DIMINISHING SATURDAY NIGHT AND
SUNDAY. HAVE GONE WITH A COMPROMISE OF CHANCE OF SHOWERS FRIDAY
WITH THE CHANCE OF SHOWERS DECREASING SATURDAY AND SUNDAY. AS THE
UPPER TROUGH EXITS TO THE EAST NEXT WEEKEND...EXPECT WARMER
CONDITIONS TO DEVELOP WITH A RETURN TO NORMAL OR SLIGHTLY ABOVE
NORMAL CONDITIONS BY SUNDAY. /CC

&&

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

CA...NONE.

PZ...GALE WATCH FROM 5 AM PDT MONDAY THROUGH MONDAY AFTERNOON FOR
     PZZ350-356.
     HAZARDOUS SEAS WATCH FROM 5 AM PDT MONDAY THROUGH MONDAY
     AFTERNOON FOR PZZ350-356.
     GALE WATCH FROM 2 AM PDT MONDAY THROUGH MONDAY AFTERNOON FOR
     PZZ370-376.
     HAZARDOUS SEAS WATCH FROM 2 AM PDT MONDAY THROUGH MONDAY
     AFTERNOON FOR PZZ370-376.

DW