Area Forecast Discussion
Issued by NWS Medford, OR

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FXUS66 KMFR 162205
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
305 PM PDT TUE SEP 16 2014

.DISCUSSION...CURRENT VISIBLE SATELLITE SHOWS SOME HIGH CLOUDS
APPROACHING THE AREA...MAINLY OFF THE COAST AND OVER NORTHERN
CALIFORNIA. THE REST OF THE AREA HAS CLEAR SKIES...ASIDE FROM
SMOKY/HAZY CONDITIONS ASSOCIATED WITH LOCAL WILDFIRES. CURRENT
TEMPERATURES ARE RANGING ABOUT 5 TO 10 DEGREES COOLER THAN THIS
TIME YESTERDAY. WATER VAPOR IMAGERY IS SHOWING THE NEXT UPPER
LEVEL TROUGH LOCATED OUT AROUND 38N 139W. THE TROUGH IS EXPECTED
TO AFFECT THE AREA BY LATE WEDNESDAY MORNING. THIS SYSTEM WILL
BRING AN INCREASE IN CLOUD COVER OVERNIGHT KEEPING TEMPERATURES A
FEW DEGREES WARMER THAN LAST NIGHT. EXPECT THINGS TO REMAIN DRY
OVERNIGHT AND INTO THE MORNING.

BY LATE WEDNESDAY MORNING...PRECIPITATION CHANCES INCREASE FOR THE
COAST AND GRADUALLY INCREASE INLAND THROUGHOUT THE DAY. GIVEN THE
SOUTHERLY FLOW ALOFT...EXPECT SOME DOWNSLOPING TO OCCUR OFF THE
SISKIYOUS, SO WE PROBABLY MISS OUT ON THE RAIN HERE IN THE ROGUE
VALLEY FOR A WHILE. 700MB WINDS OF 35-45KT WILL BRING SOME STRONG
GUSTY WINDS TO THE EAST SIDE AND IN PORTIONS OF NORTHERN
CALIFORNIA. AS A RESULT, WE HAVE ISSUED A RED FLAG WARNING. FOR
MORE DETAILS PLEASE SEE RFWMFR.

THE UPPER LOW WILL CONTINUE TO MOVE INLAND WEDNESDAY NIGHT INTO
THURSDAY BRINGING MORE RAIN TO THE COAST WITH INCREASING RAIN
CHANCES FARTHER INLAND. THERE WILL ALSO BE A SLIGHT CHANCE FOR
THUNDERSTORMS FROM THE CASCADES EASTWARD THURSDAY AFTERNOON INTO
THE EVENING. RAIN AMOUNTS COULD REACH 0.75 OF AN INCH ALONG THE
SOUTH COAST NEAR BROOKINGS AND MAY ALSO BRING WETTING RAIN TO
PORTIONS OF WESTERN SISKIYOU COUNTY WHERE WILDFIRES HAVE BEEN
BURNING MUCH OF THE PAST 2 MONTHS. FARTHER INLAND, MOUNTAIN
LOCATIONS COULD HAVE 0.10-0.25 OF AN INCH, BUT VALLEYS WILL MOSTLY
HAVE 0.10 OF AN INCH OR LESS. DUE TO THE INCREASED CLOUD COVER AND
PRECIPITATION POTENTIAL, TEMPERATURES WILL ALSO BE COOLER IN THE
WEST SIDE VALLEYS...NOT CLIMBING OUT OF THE 70S.

THIS UPPER LOW WILL THEN MOVE TO THE SOUTHEAST...FOLLOWING THE
CALIFORNIA COAST WHERE IT WILL CUT OFF FROM THE MAIN FLOW. MODELS
HAVE THIS LOW FAR ENOUGH SOUTH SO THAT THUNDERSTORMS WILL NOT BE A
CONCERN FOR OUR AREA. AFTER THIS LOW EXITS TO THE SOUTHEAST A
RIDGE WILL DEVELOP RESULTING IN A QUICK WARM-UP WITH TEMPERATURES
CLIMBING TO ABOVE NORMAL BY SATURDAY. A THERMAL TROUGH WILL ALSO
DEVELOP WITH A SHORT LIVED OFFSHORE FLOW EVENT FRIDAY NIGHT INTO
SATURDAY. OFFSHORE FLOW WEAKENS SATURDAY NIGHT AND A STRATUS
SURGE WILL CREEP NORTHWARD UP THE COAST BY SUNDAY MORNING.

MODELS ARE SHOWING A TROUGH APPROACHING THE COAST TOWARDS THE
MIDDLE OF NEXT WEEK. HOWEVER...CONSIDERING THE DIFFERENCES IN
MODEL SOLUTIONS...CONFIDENCE IS LOW ON THE TIMING AND DETAILS OF
THIS SYSTEM. THE ECMWF IS QUICKER BRINGING RAIN TO THE COAST BY
TUESDAY NIGHT WHILE THE GFS KEEPS THE SYSTEM FURTHER OFFSHORE AT
THE SAME TIME. -MND/SPILDE

&&

.AVIATION...BASED ON THE 16/18Z TAF CYCLE...UPPER LEVEL CLOUDS WILL
INCREASE TONIGHT BUT, WITH ONE EXCEPTION, VFR CONDITIONS WILL
PREVAIL THROUGH WEDNESDAY MORNING. THE EXCEPTION IS PERSISTENT AREAS
OF MVFR VSBYS IN SMOKE FROM WILDFIRES...MOSTLY OVER SISKIYOU COUNTY
AND JOSEPHINE COUNTY. DW

&&

.MARINE...UPDATED 230 PM PDT TUE 16 SEP 2014...THE MAIN CHANGE TO
THE MARINE FORECAST WAS TO INTRODUCE A DECREASING TREND TO NORTHERLY
WINDS SATURDAY EVENING WITH A SUBSEQUENT CHANGE TO LIGHT TO MODERATE
SOUTHERLY WINDS FOR THE REMAINDER OF THE WEEKEND AS AN AREA OF LOW
PRESSURE IS EXPECTED TO DEVELOP ALONG THE THERMAL TROUGH AND TRACK
NORTH THROUGH THE WATERS BEFORE DISSIPATING ON SUNDAY.

FIRST, MIXED SOUTHWEST AND NORTHWEST LONG PERIOD SWELLS WILL REMAIN
DOMINANT INTO WEDNESDAY MORNING. LOW PRESSURE AND AN ASSOCIATED COLD
FRONT ARRIVING FROM THE SOUTHWEST WILL BRING RAIN WEDNESDAY
AFTERNOON THROUGH THURSDAY WITH MODERATE SOUTHERLY WINDS AND
BUILDING SEAS. A DEVELOPING THERMAL TROUGH WILL LEAD TO INCREASED
NORTH WINDS WITH STEEP WIND WAVES FRIDAY THROUGH FRIDAY NIGHT.
BESIDES THE AFOREMENTIONED WIND CHANGES FOR THE WEEKEND, SEAS WILL
TRANSITION BACK TO BEING DOMINATED BY A MODERATE NORTHWEST SWELL.
WINDS AND SEAS ARE EXPECTED TO REMAIN WEAK TO MODERATE THROUGH EARLY
NEXT WEEK. /DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM TO 9 PM PDT WEDNESDAY FOR
     ORZ624-625.

CA...RED FLAG WARNING FROM 11 AM TO 9 PM PDT WEDNESDAY FOR
     CAZ284-285.
     RED FLAG WARNING UNTIL 9 PM PDT WEDNESDAY FOR CAZ281.

PACIFIC COASTAL WATERS...NONE.

$$

MND/BTL/MAS/DW




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