000
FXUS66 KMFR 061121
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
321 AM PST TUE JAN 6 2009
.DISCUSSION...A STRONG 180KT JET AT 250MB IS ORIENTED FROM THE
GULF OF ALASKA SOUTHEASTWARD INTO THE INTERMOUNTAIN WEST. MOIST
AIR CONTINUES TO RIDE ALONG THIS JET OVER THE TOP OF A STRONG
RIDGE SITUATED OVER THE PACIFIC OCEAN NEAR 30N AND 135W. THIS IS
RESULTING IN A BROAD OVERRUNNING PATTERN INTO THE PACIFIC
NORTHWEST.
A SURFACE WARM FRONT WILL CAUSE PERIODS OF LIGHT RAIN WITH FAIRLY
HIGH SNOW LEVELS ACROSS SOUTHWESTERN OREGON THIS MORNING. WITH THE
JET AXIS DIRECTED DECIDEDLY TO OUR NORTH...PRECIPITATION AMOUNTS
WILL BE GENERALLY LIGHT WITH LESS THAN ONE QUARTER OF AN INCH IN
MOST AREAS...THE EXCEPTION BEING ALONG THE COAST AND IN THE
MOUNTAINS WHERE A FEW PLACES MAY RECEIVE A LITTLE MORE. WINDS MAY
ALSO PICK UP FOR A TIME AGAIN ON THE EAST SIDE THIS
AFTERNOON...ESPECIALLY IN THE VICINITY OF SUMMER LAKE AND ALONG
HIGHWAY 31. GUSTS OF 40 TO 50 MPH ARE POSSIBLE THERE...BUT THIS
SHOULD BE LOCALIZED. THE WARM FRONT WILL LIFT NORTH OF THE
FORECAST AREA THIS AFTERNOON THROUGH TONIGHT AND THIS WILL CAUSE
THE COVERAGE OF PRECIPITATION AS WELL AS AMOUNTS TO DIMINISH.
CLOUDS MAY EVEN BREAK FOR A TIME OVER PORTIONS OF NORTHERN
CALIFORNIA OVERNIGHT.
ON WEDNESDAY...MOST OF THE FORECAST AREA WILL BE UNDER A DRY WEST
TO SOUTHWESTERLY FLOW...BUT A FEW RAIN SHOWERS WILL LINGER OVER
THE HIGHER CASCADES AS WELL AS THE COOS COAST. TEMPERATURES WILL
BE MILD FOR JANUARY WITH HIGHS ON THE WEST SIDE GENERALLY IN THE
40S AND LOWER 50S...AND IN THE 40S ON THE EAST SIDE.
AN UPPER LEVEL TROUGH AND SURFACE COLD FRONT WILL MOVE THROUGH THE
AREA WEDNESDAY NIGHT INTO THURSDAY BRINGING ANOTHER ROUND OF
PRECIPITATION. GALES ARE EXPECTED OVER THE COASTAL
WATERS...ESPECIALLY NORTH OF CAPE BLANCO WITH THE FRONTAL
PASSAGE. SNOW LEVELS AHEAD OF THIS SYSTEM WILL REMAIN HIGH
(6500-7500 FT)...BUT WILL DROP TO NEAR 4500 FEET THURSDAY...THEN
TO 2500 TO 3500 FEET THURSDAY NIGHT. THE AIR MASS WILL DRY OUT
QUICKLY BEHIND THIS SYSTEM WITH ONLY A FEW SCATTERED SNOW SHOWERS
LINGERING IN THE MOUNTAINS THURSDAY NIGHT.
BEYOND THAT...ALL MODELS AND ENSEMBLE FORECASTS CONTINUE TO INDICATE
HIGH PRESSURE ALOFT BUILDING OVER THE EASTERN PACIFIC OCEAN FRIDAY
AND INTO NEXT WEEK. WE`LL HAVE TO KEEP AN EYE ON A JET STREAM
DISTURBANCE SKIRTING BY TO OUR NORTH SATURDAY NIGHT INTO
SUNDAY...BUT ASIDE FROM THAT...IT LOOKS LIKE A PROLONGED PERIOD OF
DRY WEATHER FOR SOUTHERN OREGON. UNFORTUNATELY...THIS WILL ALSO MEAN
AN EXTENDED PERIOD OF STAGNANT WEATHER WITH THE POTENTIAL FOR POOR
AIR QUALITY.
&&
.AVIATION...WARM FRONT DRAPED OVER THE REGION THIS MORNING WILL
BRING GENERALLY LIGHT PRECIPITATION IN THE FORM OF RAIN ON THE
WEST SIDE AND MIXED SNOW AND RAIN ON THE EAST SIDE. IFR AND
LOCALIZED LIFR CONDITIONS EXIST THIS MORNING ALONG THE
COAST...ESPECIALLY VICINITY OF KBOK. MVFR WITH LOCALIZED IFR
CONDITIONS INLAND WITH WIDESPREAD MOUNTAIN OBSCURATIONS. THE WARM
FRONT WILL LIFT NORTH OF THE AREA THIS AFTERNOON AND PRECIPITATION
WILL DECREASE. CIGS WILL ALSO GRADUALLY RISE TO MVFR AND EVEN VFR
IN SOME LOCATIONS LATE THIS AFTERNOON...THOUGH MOUNTAIN
OBSCURATIONS WILL PERSIST.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
CA...NONE.
PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 8 AM
PST THIS MORNING FOR PZZ356.
SMALL CRAFT ADVISORY FOR WINDS FROM 10 PM THIS EVENING TO 4 AM
PST THURSDAY FOR PZZ356-PZZ376.
HAZARDOUS SEAS WARNING FROM 4 AM WEDNESDAY TO 4 AM PST THURSDAY
FOR PZZ356-PZZ376.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 4 AM PST WEDNESDAY
FOR PZZ356-PZZ376.
SMALL CRAFT ADVISORY FOR WINDS UNTIL 10 PM PST THIS EVENING FOR
PZZ350-PZZ370.
HAZARDOUS SEAS WARNING FROM 10 PM THIS EVENING TO 4 AM PST
THURSDAY FOR PZZ350-PZZ370.
GALE WARNING FROM 10 PM THIS EVENING TO 4 AM PST THURSDAY FOR
PZZ350-PZZ370.
SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS
EVENING FOR PZZ350-PZZ370.
$$
SPILDE
