Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 131021
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
321 AM PDT SUN JUL 13 2014

.DISCUSSION...SATELLITE IMAGERY DEPICTS A NICE PLUME OF MOISTURE
FEEDING INTO THE REGION FROM THE SOUTHWEST. WHILE INCREASED CLOUDS
WILL HELP KEEP TEMPERATURES A BIT COOLER THAN YESTERDAY...THE
MOISTURE WILL PROVIDE THE FUEL NECESSARY TO PRODUCE THUNDERSTORMS
OVER THE AREA TODAY. ALL OF THE OTHER NECESSARY INGREDIENTS ARE
PRESENT AS WELL...INSTABILITY...DIVERGENCE ALOFT...AND A
TRIGGERING TROUGH THAT IS FORECAST TO SKIRT ACROSS THE
NORTHWESTERN SECTIONS OF THE CWA LATER THIS MORNING AND INTO THIS
AFTERNOON. HAVE GOOD CONFIDENCE IN THUNDERSTORM DEVELOPMENT
TODAY...BUT HAVE SHIFTED POPS A BIT TO THE NORTH TO ACCOUNT FOR
THE LATEST TRENDS IN MODEL SOLUTIONS...MOSTLY IN REGARDS TO THE
LOCATIONS OF BEST JET DYNAMICS AND MID LEVEL SUPPORT. HAVE A
NAGGING FEELING THAT INCREASED CLOUDINESS MAY INHIBIT HEATING
ENOUGH TO SUPPRESS SOME CONVECTION TODAY...BUT WITH GOOD FLOW
ALOFT...ANY EARLY DEVELOPMENT SHOULD QUICKLY MOVE OUT OF THE WAY.
SHOULD THINGS GO ACCORDING TO PLAN...CONVECTION WILL LIKELY BEGIN
AS ISOLATED SHOWERS OVER THE KALMIOPSIS..THE UMPQUA BASIN...AND
THE CASCADES THIS MORNING...THEN SPREADING TO THE NORTHEAST AND
BECOMING SCATTERED OVER THE CASCADES AND THE EAST SIDE THIS
AFTERNOON AND EVENING. DRY AIR AND SUBSIDENCE WILL PUSH INTO THE
AREA BEHIND THE TROUGH...EFFECTIVELY SHUTTING DOWN ANY CONVECTION
OVER THE WEST SIDE BY EARLY AFTERNOON. THE BEST ENERGY AND
MOISTURE...AND THEREFORE THUNDERSTORMS...WILL SHUNT OFF TO THE
NORTHEAST BY LATE THIS EVENING.

THE TROUGH WILL MOVE EAST AND ATTEMPT TO JOIN WITH ITS MUCH BIGGER
BROTHER OVER THE CENTRAL AND EASTERN CONUS...FORCING THE RIDGE OVER
THE WESTERN CONUS TO RETROGRADE. THIS WILL ALLOW VERY WARM AIR TO
MOVE INTO THE REGION FORM THE SOUTHEAST...AND THE RESULT WILL BE
VERY WARM TEMPERATURES...10 TO 15 DEGREES ABOVE NORMAL FOR THIS TIME
OF YEAR...AND RECORD HIGH TEMPERATURES ARE IN THE FORECAST FOR MANY
LOCATIONS TUESDAY. AS THE RIDGE WORKS WEST...AND TROUGHING CONTINUES
TO THE EAST...THE FORECAST AREA WILL LIE UNDER WEAK NORTHWEST FLOW.
A TROUGH WITHIN THE FLOW WILL DIG INTO THE AREA LATE IN THE
WEEK...AND THE LOWERED HEIGHTS ALOFT SHOULD HELP SQUASH
TEMPERATURES DOWN CLOSER TO SEASONAL NORMALS THROUGH THE REMAINDER
OF THE WEEK. UNFORTUNATELY...THIS WONT PROVIDE TOO MUCH RELIEF AS
THIS IS NORMALLY THE HOTTEST TIME OF THE YEAR. THE TROUGH MAY ALSO
HELP PRODUCE SOME INCREASED CHANCES OF PRECIPITATION...MOSTLY TO THE
SOUTH OVER NORTHERN CALIFORNIA...WHERE MODEL SOLUTIONS ARE SHOWING
SOME WEAK MID LEVEL ENERGY. UNCERTAINTY IS MUCH TOO HIGH FOR
ANYTHING MORE THAN SLIGHT CHANCE OF THUNDER DURING THE AFTERNOON AND
EVENINGS THROUGH THE REMAINDER OF THE TERM.  -BPN


&&

.AVIATION...BASED ON THE 13/06Z TAFS...ALONG THE COAST EXPECT IFR
CIGS THROUGH THE NIGHT THAT MAY IMPROVE TO MVFR OR EVEN VFR IN SOME
AREAS SUNDAY. IN THE UMPQUA BASIN...AREAS OF MVFR CIGS WILL DEVELOP
OVERNIGHT AND MAY REACH KRBG TOWARD DAWN THEN IMPROVE TO VFR SUNDAY
MORNING. ELSEWHERE, VFR IS EXPECTED, THOUGH ISOLATED SHOWERS AND
THUNDERSTORMS DEVELOP IN NORTHERN DOUGLAS COUNTY SUNDAY MORNING,
THEN BECOME MORE NUMEROUS NEAR THE CASCADES AND ACROSS NORTHERN
KLAMATH AND LAKE COUNTIES DURING THE MIDDAY AND AFTERNOON. -SPILDE


&&

.MARINE...UPDATED SUNDAY 13 JULY 300 AM PDT...A WEAK
PRESSURE PATTERN WITH OFFSHORE HIGH PRESSURE WILL PERSIST TODAY.
A THERMAL TROUGH WILL THEN DEVELOP NEAR THE COAST BRINGING A
RETURN OF STRONG NORTH WINDS AND STEEP SEAS BEGINNING MONDAY.
THE TROUGH WILL WEAKEN TUESDAY AND WEDNESDAY...BUT NORTH WINDS
AND STEEP SEAS WILL PERSIST IN THE AFTERNOONS AND EVENINGS THROUGH
THURSDAY AND BEYOND. -RES


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM THIS MORNING TO 8 PM PDT THIS
     EVENING FOR ORZ617-623>625.

CA...NONE.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM
     MONDAY TO 11 AM PDT TUESDAY FOR PZZ350-356.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM MONDAY TO 8 PM
     PDT TUESDAY FOR PZZ350.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 AM MONDAY TO 8 PM
     PDT TUESDAY FOR PZZ356.
     SMALL CRAFT ADVISORY FOR WINDS FROM 5 AM MONDAY TO 11 AM PDT
     WEDNESDAY FOR PZZ376.
     HAZARDOUS SEAS WARNING FROM 2 PM MONDAY TO 8 PM PDT TUESDAY FOR
     PZZ376.
     GALE WARNING FROM 2 PM MONDAY TO 11 AM PDT TUESDAY FOR PZZ376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 AM MONDAY TO 5 PM
     PDT WEDNESDAY FOR PZZ376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM MONDAY TO 11 AM PDT
     WEDNESDAY FOR PZZ370.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM MONDAY TO 5 PM
     PDT WEDNESDAY FOR PZZ370.

$$

BPN/RES/MAS





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