FXUS66 KMFR 051020
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
220 AM PST SUN FEB 5 2012

.DISCUSSION...THE BLOCKING PATTERN ACROSS THE WESTERN US IS
PREVENTING ANY SIGNIFICANT JET ENERGY TO PROGRESS INTO THE FORECAST
AREA FROM THE PACIFIC. THUS...ENERGY WILL STREAM TO THE NORTH AND
SOUTH...WITH NO SIGNIFICANT STORMS AFFECTING NORTHERN CALIFORNIA OR
SOUTHERN OREGON THROUGH THE NEXT WEEK. THE REX-TYPE BLOCK BREAKS
DOWN EARLY THIS WEEK WHICH OPENS THE DOOR FOR A MORE PROGRESSIVE
PATTERN LATER IN THE WEEK.

IN THE NEAR-TERM...ITS MAINLY A TEMPERATURE AND FOG FORECAST...AND
PERSISTENCE HAS YIELDED GOOD RESULTS SO WILL CONTINUE THAT TACK FOR
THE NEXT COUPLE DAYS. TEMPERATURES WILL CONTINUE TO BE 5 TO 10
DEGREES ABOVE NORMAL MOST PLACES TODAY...WITH JUST A BIT OF COOLING
IN WEST SIDE VALLEYS COURTESY OF INCREASING HIGH CLOUDS. MORNING FOG
AND FREEZING FOG IS EXPECTED IN THE UMPQUA BASIN AND THE ILLINOIS
VALLEY AGAIN. PATCHY FREEZING FOG IS LIKELY IN THE ROGUE RIVER
VALLEY NEAR GRANTS PASS BUT NOT MEDFORD WHERE EAST FLOW AND DROPPING
DEW POINTS ARE BEING OBSERVED FOR THE THIRD NIGHT IN A ROW...DESPITE
DECREASED OFFSHORE FLOW. SUNDAY AND MONDAY WILL FEATURE SOME HIGH
CLOUDS...AND ABOVE NORMAL TEMPERATURES. MEDFORD AREA HIGHS SHOULD
REACH NEAR 60 DEGREES WITH THE EAST SIDE IN THE MID TO UPPER 40S.

ON TUESDAY A FRONT WITH LITTLE UPPER SUPPORT WILL BRUSH THE FORECAST
AREA AS IT SHEARS APART...PRODUCING SOME LIGHT PRECIPITATION MAINLY
AT THE COAST AND WESTERN SISKIYOU COUNTY. SOUTH WINDS OVER HIGHER
TERRAIN AND ON THE EAST SIDE WILL INCREASE AHEAD OF THIS FRONT...AND
MID AND HIGH CLOUDS WILL INCREASE. HIGH TEMPERATURES BE CLOSER TO
NORMAL...IN RESPONSE TO THE CLOUD COVER.

ANOTHER RIDGE BUILDS OVERHEAD ON WEDNESDAY INTO THURSDAY. ITS A
LITTLE STRANGE THAT THE UPPER RANGE OF THE GFS TEMPERATURE GUIDANCE
IS ONLY 61 FOR THURSDAY IN MEDFORD. I HAVE LEFT THURSDAY
TEMPERATURES ALONE...BUT GIVEN WHAT WE HAVE SEEN THE PAST SEVERAL
DAYS AND 850MB READINGS PEAKING AT 9C+ LATER THIS WEEK...UPPER 60S
COULD BE IN THE CARDS FOR THE ROGUE VALLEY. AGRICULTURAL INTERESTS
SHOULD BE AWARE OF THE POSSIBILITY OF WELL ABOVE NORMAL TEMPERATURES
THURSDAY AND POSSIBLY FRIDAY.

THE NEXT CHANCE OF APPRECIABLE PRECIPITATION IS FRIDAY PER THE ECMWF
AND EVEN LATER FOR THE GFS. CONFIDENCE IS LOW IN THE EXTENDED.


&&

.AVIATION...GOOD FLYING WEATHER IS EXPECTED TODAY OVER MOST OF THE
FORECAST AREA. THE EXCEPTIONS ARE THE ILLINOIS VALLEY...ROGUE VALLEY
NEAR GRANTS PASS...AND UMPQUA BASIN WHERE FOG AND IFR CONDITIONS
WILL LIKELY LAST UNTIL LATE MORNING. ALL LOCATIONS WILL HAVE VFR
CONDITIONS THIS AFTERNOON...AND SIMILAR FOG FORMATION IS EXPECTED
LATE TONIGHT.


&&

.CLIMATE...A MAJOR CLIMATE INDEX...THE ARCTIC OSCILLATION...IS
SOLIDLY NEGATIVE FOR THE FIRST TIME THIS COOL SEASON. SOME PRELIMINARY
RESEARCH SUGGESTS THAT IF THIS INDEX REMAINS NEGATIVE THROUGH THE
REST OF THE WINTER ALONG WITH A NEGATIVE PACIFIC DECADAL
OSCILLATION...A CHANGE TO A WETTER PATTERN COULD OCCUR.
HOWEVER...THIS IS ONLY ONE PIECE TO A COMPLICATED PUZZLE...AND WE
REMAIN IN WHAT SEEMS TO BE A DRY PATTERN FOR THE NEXT 1-2 WEEKS.


&&

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

CA...NONE.
PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 10 PM PST THIS
EVENING FOR PZZ350-356-370-376.

$$

SK



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