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000
FXUS66 KMFR 051708
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
908 AM PST THU MAR 5 2015

.UPDATE...
AN UPDATE HAS BEEN MADE TO ADJUST FOR A SLOWER MARINE STRATUS AND
FOG SURGE IN THE COASTAL WATERS AND ALONG THE COAST. WHILE THIS
SURGE WILL EXPAND IN THE COASTAL WATERS OVER THE NEXT 24 HOURS, IT
IS LIKELY TO TAKE SUNRISE FRIDAY MORNING, AT THE EARLIEST, FOR
THE FOG AND STRATUS TO REACH THE BEACHES. BTL

&&

.DISCUSSION...
HIGH PRESSURE REMAINS FIRMLY ENTRENCHED ALONG THE WEST COAST.
MORNING FOG WILL DISSIPATE DURING THE MORNING YIELDING MOSTLY
CLEAR SKIES ACROSS THE ENTIRE AREA. SOME THIN CIRRUS CLOUDS
WILL STREAM OVERHEAD, ESPECIALLY OVER NORTHWESTERN SECTIONS OF
THE AREA. BTL

&&

.AVIATION...FOR THE 05/12Z TAF CYCLE...VFR AREA WIDE FOR THE NEXT 24
HOURS EXCEPT FOR AREAS OF IFR LOW CLOUDS AND FOG IN THE COQUILLE
VALLEY AND THE UMPQUA BASIN INCLUDING KRBG TOWARD SUNRISE.
HOWEVER...THIS SHOULD BURN OFF BY LATE MORNING. /SVEN

&&

.MARINE...UPDATED 445 AM PST, THURSDAY, 5 MAR, 2015...THE THERMAL
TROUGH THAT BROUGHT MODERATE NORTHERLY WINDS WILL SHIFT INLAND TODAY
BUT IS EXPECTED TO REDEVELOP THIS WEEKEND WITH LIGHT TO MODERATE
NORTHERLIES RETURNING. /SVEN

&&

.PREV DISCUSSION... /ISSUED 500 AM PST THU MAR 5 2015/

DISCUSSION...THE LARGE SCALE RIDGE CURRENTLY OVER THE PACIFIC
NORTHWEST WILL REMAIN IN PLACE FOR SEVERAL MORE DAYS. EXPECT DRY
CONDITIONS TO CONTINUE WITH A GRADUAL WARMING TREND INLAND...ALONG
WITH THE POSSIBILITY OF SOME MORNING FOG IN THE WEST SIDE VALLEYS.
MARINE STRATUS IS EXPECTED TO PUSH NORTHWARD ALONG THE COAST TODAY
INTO TONIGHT...BUT THE MARINE LAYER WILL BE SHALLOW DUE TO
SUBSIDENCE ALOFT, AND LOW CLOUDS AND FOG WILL BE LIMITED TO THE
OFFSHORE WATERS AND COASTAL AREAS. THE RETURN OF EASTERLY FLOW
SHOULD PUSH THE CLOUDS BACK OFFSHORE BY SATURDAY.

THE RIDGE, ALONG WITH A CLOSED LOW OVER THE BAJA PENINSULA, WILL
FORM A REX-TYPE PATTERN ALONG THE WEST COAST BY FRIDAY. GIVEN THE
SLOW PROGRESSION OF THE HEMISPHERICAL WAVE PATTERN, THIS IS NOT
UNEXPECTED. HOWEVER, THERE IS SOME QUESTION AS TO HOW THE MODELS
WILL HANDLE THE FEATURE, AS THE SYNOPTIC MODELS USUALLY HAVE A
HARD TIME WITH BLOCKS AND CLOSED LOWS. HAVE DECIDED TO TREND THE
FORECAST BEYOND FRIDAY TOWARDS THE MIDDLE-OF-THE-ROAD ECMWF
SOLUTION. THIS WILL NOT HAVE ANY DISCERNIBLE EFFECTS UNTIL THE
APPROACH OF A TROUGH BY MIDWEEK. UNTIL THEN, EXPECT THE DRY
CONDITIONS AND WARMING TREND TO CONTINUE. OVERNIGHT LOWS WILL BE
SLIGHTLY ABOVE SEASONAL NORMALS BY THIS WEEKEND...BUT INLAND HIGHS
WILL BE 10 TO 15 DEGREES ABOVE NORMAL BY THAT TIME.

TUESDAY IS WHEN THE NEXT CHANCE OF PRECIPITATION CREEPS INTO THE
FORECAST, IN ASSOCIATION WITH THE TROUGH MENTIONED ABOVE. THE
TIMING OF THE TROUGH IS STILL UNCERTAIN, ESPECIALLY CONSIDERING
THE BLOCKING PATTERN THAT PRECEDES IT, SO IT MIGHT NOT ACTUALLY
HAPPEN UNTIL NEXT WEDNESDAY OR THURSDAY. HOWEVER...MEDIUM-RANGE
MODELS ARE MAKING STRONG INDICATIONS THAT WET CONDITIONS WILL
DEVELOP IN THE 7-14 DAY PERIOD. -BPN

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

$$

BTL/BPN/SBN