Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 240300
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
800 PM PDT SAT MAY 23 2015

.DISCUSSION...24/00Z NAM IN.

A FAIRLY QUIET EVENING WEATHERWISE OVER THE MEDFORD CWA. THE
THUNDERSTORMS REMAINED SOUTHEAST OF THE AREA...AND THE SHOWERS
THAT DID DEVELOP OVER THE MEDFORD CWA ARE NOW DISSIPATING. PLENTY
OF CLOUDS AROUND THOUGH.

A LONG WAVE UPPER LEVEL RIDGE WILL BUILD INTO THE WEST COAST INTO
SUNDAY NIGHT. THIS WILL BRING IN WARMER AND MORE STABLE CONDITIONS
WITH WEAK OFFSHORE LOW LEVEL FLOW PEAKING SUNDAY NIGHT. SOME
ISOLATED SHOWERS AND THUNDERSTORMS MAY DEVELOP FROM THE CASCADES
EAST SUNDAY AFTERNOON AND EVENING...BUT COVERAGE WILL BE MUCH LESS
THAN WHAT OCCURRED EARLIER THIS WEEK.

MONDAY WILL BE THE WARMEST DAY ALONG THE COAST WITH THE CHETCO
EFFECT MAKING THE SOUTH COAST ESPECIALLY WARM. THE RIDGE WILL
WEAKEN MONDAY AS AN UPPER LOW MOVES INTO WASHINGTON STATE. THIS
WILL MAKE FOR A MORE UNSTABLE AIRMASS WITH THE COOLER AIR ALOFT
AND STRONG SURFACE HEATING...SO SHOWERS AND THUNDERSTORMS WILL BE
MORE WIDESPREAD MONDAY AFTERNOON AND EVENING...BUT STILL LIMITED
TO THE CASCADES EAST AND SISKIYOUS SOUTH.

DISCUSSION FROM THE SATURDAY AFTERNOON AFD...TUESDAY THROUGH
SATURDAY. THE THERMAL TROUGH MOVES INLAND TUESDAY WITH THE WARMEST
DAY OF THE STRETCH INLAND ON TUESDAY ALSO. SOUTHERLY FLOW WILL
BEGIN TO FEED WARM MOIST AIR FROM THE SACRAMENTO VALLEY WITH THE
CONVERGENCE ZONE OVER SISKIYOU AND MODOC COUNTY. THIS WILL BRING A
CHANCE OF THUNDERSTORMS TO THAT AREA. INSTABILITY SPREADS NORTH UP
THE CASCADES WEDNESDAY BUT WITH VERY WEAK STEERING WINDS ANY
STORMS THAT DO DEVELOP SHOULD STAY LATCHED TO THE HIGHER TERRAIN.
THIS INSTABILITY INCREASES UP THE CASCADE CREST ON THURSDAY.
THURSDAY EVENING INTO FRIDAY THE SOUTHERLY MOISTURE FEED INCREASES
AND SPREADS NORTH INTO THE ENTIRE FORECAST AREA. THERE ARE SOME
MINOR TIMING ISSUES BETWEEN THE GFS AND ECMWF WITH THE ECMWF
HAVING THE AXIS OF THE UPPER LEVEL TROUGH SLIGHTLY FARTHER WEST
FRIDAY.

&&

.AVIATION...FOR THE 24/00Z TAF CYCLE...ALONG THE COAST NORTH OF
CAPE BLANCO AND IN THE UMPQUA BASIN...AREAS OF MVFR CIGS AND LOCAL
IFR CIGS ALONG THE COAST WILL SPREAD INLAND TONIGHT...THEN BURN
BACK TO THE COAST BY SUNDAY AFTERNOON. ELSEWHERE...VFR CONDITIONS
WILL PREVAIL WITH AREAS OF HIGHER TERRAIN OBSCURED. SKIES WILL
CLEAR EAST OF THE CASCADES. HOWEVER...CLOUDS WILL REDEVELOP SUNDAY
WITH ISOLATED THUNDERSTORMS FROM THE CASCADES EAST SUNDAY
AFTERNOON AND EVENING.

&&

.MARINE...UPDATED 800 PM PDT SATURDAY 23 MAY 2015...HIGH PRESSURE
OFFSHORE AND A THERMAL TROUGH NEAR THE COAST WILL STRENGTHEN INTO
SUNDAY AFTERNOON...THEN GRADUALLY WEAKEN MONDAY NIGHT THROUGH
THURSDAY. THIS WILL BRING MODERATE TO STRONG NORTH WINDS TO THE
WATERS AND STEEP TO VERY STEEP WIND DRIVEN SEAS THROUGH WEDNESDAY
EVENING. THE STRONGEST WINDS AND HEAVIEST SEAS WILL OCCUR IN THE
AFTERNOONS AND EVENINGS SOUTH OF GOLD BEACH AND BETWEEN 10 NM AND 40
NM OFFSHORE.

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 11 PM
        PDT WEDNESDAY FOR PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 11 PM PDT
        WEDNESDAY FOR PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING FROM 2 PM SUNDAY TO 11 PM PDT MONDAY FOR
        PZZ376.
     GALE WARNING FROM 2 PM SUNDAY TO 11 PM PDT MONDAY FOR PZZ376.

$$

15/15/15



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