Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 020315
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
759 PM PDT SAT AUG 1 2015

.DISCUSSION...02/00Z NAM IN.

A FAIRLY TYPICAL THUNDERSTORM PATTERN REMAINS IN PLACE OVER THE
MEDFORD CWA WITH SOUTHERLY FLOW ALOFT ADVECTING MONSOONAL MOISTURE
INTO THE AREA. THUNDERSTORMS DEVELOPED FRIDAY AFTERNOON...MOSTLY
FROM THE OREGON CASCADES EAST AND OVER THE SISKIYOUS. SOME OF THE
SISKIYOU THUNDERSTORMS MOVED OVER CURRY...JOSEPHINE...AND JACKSON
COUNTIES. THESE STORMS REMAIN MOSTLY DRY...BUT WETTER THAN FRIDAY.
THERE IS MORE REPORTED PRECIPITATION...BUT AMOUNTS REMAIN LIGHT.
AT THIS TIME...THE REMAINING THUNDERSTORM ACTIVITY IS EAST OF THE
CASCADES.

IN ADDITION...TWO FIRES IN DOUGLAS COUNTY ARE STILL VERY ACTIVE
IN THE HOT AND UNSTABLE CONDITIONS...AND MOST OF THE WEST SIDE IS
VERY SMOKY.

ANOTHER STORY IS THE HEAT...MEDFORD PEAKED AT A TOASTY 104F. 5
DEGREES COOLER THAN FRIDAY BUT STILL A RECORD HIGH FOR THIS DATE.

THE CONVECTION TODAY IS MOSTLY DUE TO SURFACE HEATING...BUT THERE
IS A WEAK SHORT WAVE ALOFT MOVING THROUGH. SUNDAY WILL BE A
DIFFERENT STORY THOUGH...AS SHORT WAVES WILL MOVE OVER THE EAST
SIDE DURING MAXIMUM SURFACE HEATING. EXPECT A CHANCE OF THUNDERSTORMS
OVER MOST OF THE MEDFORD CWA...WITH A SLIGHT CHANCE NEAR THE
COAST.

AFTER THAT WAVE MOVES THROUGH...FLOW ALOFT WILL BECOME
SOUTHWESTERLY AS A TROUGH APPROACHES THE COAST. THIS WILL CAUSE
THE AREA OF MOST FAVORABLE CONVECTION TO MOVE EAST. MONDAY
THUNDERSTORMS WILL BE LIMITED TO THE CASCADES EAST...AND MAYBE A
FEW OVER SISKIYOU COUNTY. IT WILL BE NOTABLY COOLER OVER THE AREA
AS WELL.

EXTENDED DISCUSSION FROM THE SATURDAY AFTERNOON AFD...WITH HEIGHTS
LOWERING MONDAY-WEDNESDAY NEXT WEEK, EXPECT ABOUT 10-15 DEGREES
OF COOLING OVER THE AREA. SO...INSTEAD OF READINGS WELL INTO THE
100S...WE EXPECT HIGHS IN THE UPPER 80S TO LOWER 90S IN MEDFORD.
THE FLOW ALOFT WILL SHIFT MORE TOWARD THE WEST- SOUTHWEST AND THE
THUNDER THREAT WILL SHIFT EASTWARD, MAINLY FROM THE CASCADES EAST
MONDAY AND TUESDAY. WESTERLY FLOW ALOFT SHOULD ARRIVE WEDNESDAY TO
KICK MOST OF THE MOISTURE EASTWARD SUCH THAT THE ENTIRE FORECAST
AREA WILL BE DRY. LATE NEXT WEEK...MODELS ARE SHOWING ANOTHER
UPPER LOW HEADING TOWARD THE CENTRAL CALIFORNIA COAST. THIS MAY
BACK THE FLOW ENOUGH TO ALLOW FOR INCREASING THUNDER CHANCES...AT
LEAST ACROSS THE EAST SIDE AND IN NORTHEAST CALIFORNIA...FRIDAY OR
SATURDAY. SPILDE

&&

.AVIATION...FOR THE 02/00Z TAF CYCLE...ALONG THE COAST...AREAS OF
IFR CIGS/VIS ALONG THE COAST SOUTH OF BANDON IS EXPECTED TO PERSIST
INTO TONIGHT. THE LOWER CONDITIONS WILL MOVE BACK NORTH INTO KOTH
BETWEEN 2-3Z. INLAND AWAY FROM THE COAST, TWO CONCERNS EXIST. FIRST,
ISOLATED TO SCATTERED AFTERNOON AND EVENING DRY THUNDERSTORMS WILL
BRING GUSTY WINDS, BUT CONDITIONS WILL REMAIN VFR. THE EXCEPTION
WILL A REDUCTION IN VISIBILITY AND LIMITED VERTICAL VISIBILITY IN
SMOKE DOWNWIND OF THE FIRES IN THE UMPQUA. THIS INCLUDES KMFR AND
POSSIBLY KRBG. -PETRUCELLI

&&

.MARINE...UPDATED 2 PM PDT SATURDAY 1 AUGUST 2015...A WEAK
THERMAL TROUGH NEAR THE COAST AND OFFSHORE HIGH PRESSURE WILL
PERSIST THROUGH THE START OF NEXT WEEK. THIS WILL RESULT IN A
CONTINUATION OF LIGHT WINDS AND LIGHT CHOP OVER THE WATERS.
OFFSHORE HIGH PRESSURE IS EXPECTED TO STRENGTHEN AND A THERMAL
TROUGH REDEVELOPS ALONG THE COAST LATER TUESDAY AND SMALL CRAFT
FOR WINDS AND SEAS ARE LIKELY TO RETURN. WINDS AND SEAS INCREASE
THROUGH THE REMAINDER OF NEXT WEEK AS THESE FEATURES STRENGTHEN.
-PETRUCELLI

&&

.FIRE WEATHER...UPDATED 800 PM PDT SATURDAY 1 AUGUST 2015...AN
UPPER TROUGH WILL REMAIN OFFSHORE AND CONTINUE TO PUMP MID LEVEL
MOISTURE AND INSTABILITY OVER OUR AREA THROUGH SUNDAY EVENING.
THERE WILL BE SEVERAL DISTURBANCES MOVING OVER THE AREA AS WELL
AND THE LOW LEVELS ARE STILL VERY DRY...SO ALL BUT THE STRONGEST
STORMS WILL LIKELY PRODUCE ONLY LIGHT RAIN. ALL OF THIS WILL
RESULT IN A PERSISTENT CHANCE FOR MOSTLY DRY THUNDERSTORMS OVER
MUCH OF OUR AREA THROUGH SUNDAY MORNING. STORMS BECOME WETTER
SUNDAY EVENING AND MONDAY. THE MONSOONAL FLOW SHIFTS EAST BY
TUESDAY WITH THUNDERSTORMS MOSTLY CONFINED TO THE FAR EAST SIDE.
BY WEDNESDAY STABLE ONSHORE FLOW MOVES IN WITH HIGH TEMPERATURES
AROUND TWENTY DEGREES LOWER THAN TODAY`S HIGHS.

INSTABILITY REMAINS OVER THE REGION ON SUNDAY...BUT THE BIGGEST AREA
OF UNCERTAINTY WILL BE THE MORNING CLOUD COVER WITH THUNDERSTORMS
POSSIBLY PERSISTING THROUGH TONIGHT. IF THERE IS EXTENSIVE CLOUD
COVER THE SURFACE HEATING WILL BE INHIBITED...REDUCING INSTABILITY
TOMORROW AS WELL AS THE THUNDERSTORM COVERAGE. CURRENTLY THERE
LOOKS TO BE ENOUGH OF A PAUSE TO ALLOW FULL HEATING...AND WITH A
STRONG SHORT WAVE MOVING THROUGH IN THE AFTERNOON THERE SHOULD BE
MORE EXTENSIVE COVERAGE AS IT MOVES THROUGH. SVEN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM SUNDAY TO 5 AM PDT MONDAY FOR
        ORZ625.
     RED FLAG WARNING UNTIL 11 PM PDT SUNDAY FOR
        ORZ615>617-619-620-622.
     HEAT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORZ023.
     RED FLAG WARNING UNTIL 11 PM PDT SUNDAY FOR ORZ621-623.
     HEAT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR ORZ024-026.
     RED FLAG WARNING UNTIL 5 AM PDT MONDAY FOR ORZ624.

CA...RED FLAG WARNING UNTIL 11 PM PDT SUNDAY FOR CAZ280-281-284.
     HEAT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR CAZ080-081.
     RED FLAG WARNING UNTIL 11 PM PDT SUNDAY FOR CAZ285.

PACIFIC COASTAL WATERS...NONE.

$$

15/15/15


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