FXUS66 KMFR 160347
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
847 PM PDT MON MAR 15 2010

.EVENING DISCUSSION...MID TO HIGH CLOUDS INCREASE AHEAD OF THE COLD
FRONT THAT GIVES THE REGION A GLANCING BLOW TOMORROW. THIS INCREASED
CLOUD COVER WILL RESULT IN WARMER LOWS ON THE WEST SIDE TOMORROW
MORNING. CURRENT FORECAST LOOKS RIGHT ON TRACK AND WILL NOT UPDATE
THIS EVENING.

.SYNOPSIS...A RIDGE OF HIGH PRESSURE OVER THE WESTERN U.S. WILL
SHIFT EASTWARD TONIGHT. AS IT DOES...DEEPENING LOW PRESSURE OVER
THE PACIFIC WILL HEAD NORTHEASTWARD TOWARD BRITISH COLUMBIA AND
DRAG A COLD FRONT ONSHORE OVER WASHINGTON AND OREGON TUESDAY INTO
TUESDAY NIGHT. ANOTHER RIDGE OF HIGH PRESSURE WILL ESTABLISH
ITSELF JUST OFFSHORE WEDNESDAY THROUGH THURSDAY BEFORE MOVING
ONSHORE FRIDAY. THIS WILL PROMOTE A PERIOD OF DRY AND MILD WEATHER
INTO THE WEEKEND.

&&

.SHORT TERM...TONIGHT THROUGH THURSDAY...A RIDGE OF HIGH PRESSURE
EXTENDS FROM THE NORTHERN ROCKIES INTO SOUTHERN CALIFORNIA THIS
AFTERNOON. A DIGGING UPPER LEVEL DISTURBANCE LOCATED NEAR 40N/140W
IS RESULTING IN A DEEPENING AREA OF LOW PRESSURE NEAR 40N/135W.
THIS IS HELPING TO PUSH A PREVIOUSLY STALLED FRONT EASTWARD TOWARD
THE PAC NW. CLOUDS WILL BEGIN TO THICKEN AND LOWER TONIGHT INTO
EARLY TUESDAY MORNING BEFORE THE FRONT APPROACHES THE COAST AND
COMES ASHORE AROUND MIDDAY TUESDAY. THE CENTER OF LOW PRESSURE AND
MOST OF THE UPPER LEVEL SUPPORT FOR THIS FRONT WILL HEAD
NORTHEASTWARD INTO BRITISH COLUMBIA. THIS WILL RESULT IN THE FRONT
WEAKENING AS IT REACHES THE CWA AND KEEP RAIN AMOUNTS GENERALLY A
HALF AN INCH OR LESS. MOST OF THE PRECIPITATION WILL FALL OVER THE
COAST AND COASTAL RANGE WITH LESSER AMOUNTS OVER THE WEST SIDE
VALLEYS AND IN THE CASCADES.

THE WEAKENED FRONT WILL CROSS THE REST OF THE CWA TUESDAY
AFTERNOON INTO TUESDAY NIGHT. A FEW SHOWERS MAY LINGER INTO
WEDNESDAY MORNING BUT MOST OF THIS ACTIVITY IS EXPECTED TO REMAIN
NORTH OF THE CWA CLOSER TO THE UPPER LEVEL TROUGH. BY LATE
WEDNESDAY...A RIDGE OF HIGH PRESSURE WILL BEGIN TO BUILD OVER THE
PACIFIC NEAR 135W. THIS WILL RESULT IN OFFSHORE FLOW BEGINNING TO
DEVELOP. THE RIDGE WILL STRENGTHEN ON THURSDAY ALONG 130W WITH
OFFSHORE FLOW CONTINUING. MW

.LONG TERM...THURSDAY NIGHT THROUGH MONDAY...HIGH PRESSURE ALOFT
AND A LOW LEVEL OFF SHORE FLOW PATTERN ARE WELL ENTRENCHED BY
THURSDAY NIGHT. HOWEVER FRIDAY AS THE UPPER LEVEL RIDGE SHIFTS A
BIT EAST THE OFF SHORE FLOW PATTERN WEAKENS QUITE A BIT AND SHIFTS
INLAND ALLOWING LIGHT ON SHORE FLOW TO BEGIN FRIDAY NIGHT. STILL
SKIES WILL BE GENERALLY CLEAR AND THE DAYS GENERALLY SLIGHTLY
ABOVE NORMAL TEMPERATURE WISE THROUGH SUNDAY. BY SUNDAY NIGHT
THOUGH THE RIDGE WILL HAVE SHIFTED MUCH FURTHER EAST AND A COLD
FRONT WILL REACH THE COAST MONDAY MORNING. THE UPPER TROUGH WILL
MOVE THROUGH DURING THE DAY BRINGING LIGHT PRECIPITATION TO THE
REGION. MO

&&

.AVIATION...SCATTERED HIGH AND MID LEVEL CLOUDS AT THE COAST WILL
THICKEN AND LOWER TONIGHT BUT REMAIN VFR. RAIN WILL ARRIVE TUESDAY
MORNING WITH MVFR CIGS AT TIMES. VFR CONDITIONS ELSEWHERE WITH A
FEW HIGH AND MID LEVEL CLOUDS TONIGHT THICKENING AND LOWERING
TUESDAY MORNING.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...HIGH SURF ADVISORY FROM 5 AM TUESDAY TO 9 AM PDT WEDNESDAY FOR
ORZ021-022.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 11 PM
THIS EVENING TO 11 AM
PDT TUESDAY FOR PZZ350-356.
HAZARDOUS SEAS WARNING FROM 3 PM TUESDAY TO 9 AM PDT WEDNESDAY
FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 3 PM PDT TUESDAY
FOR PZZ350-356-370-376.
SMALL CRAFT ADVISORY FOR WINDS FROM 8 PM THIS EVENING TO 8 PM
PDT TUESDAY FOR PZZ370.
GALE WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY AFTERNOON
FOR PZZ376.
SMALL CRAFT ADVISORY FOR WINDS FROM 8 PM THIS EVENING TO 11 AM
PDT TUESDAY FOR PZZ376.
HAZARDOUS SEAS WATCH FROM WEDNESDAY AFTERNOON THROUGH THURSDAY
AFTERNOON FOR PZZ376.

$$

SVEN



Back to Main Forecast Discussion Page