Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 300109
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
609 PM PDT WED JUL 29 2015

.UPDATED FOR AVIATION...

&&

.PREV DISCUSSION... /ISSUED 304 PM PDT WED JUL 29 2015/

SHORT TERM...TEMPERATURES ARE RUNNING ABOUT 10 DEGREES WARMER
TODAY THAN YESTERDAY WITH HUMIDITY ABOUT 5 TO 10 PERCENT DRIER.
THE THERMAL TROUGH WHICH HAD SHIFTED INLAND WILL BE MOVING BACK TO
THE COAST AGAIN TONIGHT BUT THE PRESSURE GRADIENT IS MUCH LIGHTER
SO WINDS WILL NOT BE AS STRONG. THE THERMAL TROUGH WILL MOVE
FURTHER INLAND THURSDAY AND IS FORECAST TO MOVE EAST OF THE
CASCADES OVER THE KLAMATH AND TULELAKE BASINS BY THURSDAY EVENING.
THIS MEANS HIGH TEMPERATURES WILL BE QUITE WARM ON BOTH SIDES OF
THE CASCADES...WITH 105-110 RANGE FOR THE ROGUE VALLEY AND NEAR
95 FOR THE KLAMATH BASIN.

MID LEVEL MOISTURE WILL START TO MOVE INTO SISKIYOU COUNTY FRIDAY.
SO FAR MOISTURE WILL BE QUITE HIGH WITH CLOUD BASE NEAR 500MB. A
MODERATELY STRONG SHORT WAVE TROUGH IS FORECAST TO MOVE NORTH AND
THEN NW OFFSHORE. FORECAST SOUNDING FOR THE AREA SHOWED THERE IS
ENOUGH LIFT BUT THE LIFT DOES NOT APPEAR STRONG ENOUGH FOR
THUNDERSTORMS TO BE WIDESPREAD. WE HAVE CONTINUED WITH SLIGHT
CHANCE OR ISOLATED THUNDERSTORMS IN THE FORECAST.

CONDITIONS LOOK MORE FAVORABLE FOR GREATER THUNDERSTORM COVERAGE
ON SATURDAY AS THE ATMOSPHERE MOISTENS A BIT MORE. MOS GUIDANCE
FOR TERMINALS IN NORTHERN CALIFORNIA AND AT KMFR SHOWS HIGHER
CHANCE FOR THUNDERSTORMS FOR SATURDAY AND SUNDAY...WITH
THUNDERSTORM CHANCE INCREASING TO 25-40 PERCENT FOR SAT THROUGH
MONDAY...AND AREAL COVERAGE ENCOMPASSING SISKIYOU COUNTY...THE
ROGUE VALLEY AND THE KLAMATH BASIN.

LONG TERM...(SUNDAY THROUGH WEDNESDAY)
MOISTURE AXIS SHIFTS SLIGHTLY EAST ON SUNDAY AND THUNDERSTORM
CHANCES EXPANDS EAST INTO THE GOOSE LAKE BASIN AND MODOC COUNTY.
THERE MAY BE A BRIEF BREAK ON MONDAY BEFORE STEERING FLOW SHIFTS
TO SOUTHWEST AND ANOTHE ROUND OF MOISTURE MOVES INTO THE AREA.
THERE IS A CHANCE THAT IN THE SECOND HALF OF NEXT WEEK A TROUGH
WILL MOVE INTO THE PACIFIC NORTHWEST. WHILE SOUTHERN OREGON AND
NORTHERN CALIFORNIA WILL BE TOO FAR SOUTH...THIS TROUGH COULD BE
ENOUGH TO PUSH THE HIGH TEMPERATURES IN THE ROGUE VALLEY INTO THE
90S. /FB

AVIATION...FOR THE 30/00Z TAF CYCLE...THE THERMAL TROUGH WILL
BRING GUSTY NORTH WINDS TO THE COAST THIS AFTERNOON THROUGH EARLY
EVENING WITH GUSTS UP TO 30 KT. AFTER WINDS DIE DOWN LATER TONIGHT
AND FLOW TURNS MORE ONSHORE WITH SOME SOUTHERLY WINDS..LOW CLOUDS
ARE EXPECTED TO MOVE INTO KOTH WITH MVFR VIS. KRBG MAY SEE SOME
SMOKE FROM NEARBY FIRES LATER TONIGHT. /CZS

MARINE...UPDATED 230 PM PDT WEDNESDAY 29 JULY 2015...A THERMAL
TROUGH NEAR THE COAST WILL KEEP AREAS OF STRONG NORTH WINDS AND
STEEP TO VERY STEEP SEAS OVER THE WATERS THROUGH WEDNESDAY EVENING.
THE THERMAL TROUGH WILL GRADUALLY WEAKEN WEDNESDAY NIGHT THROUGH
FRIDAY...WHEN IT WILL MOVE INLAND. THE THERMAL TROUGH WILL STILL
PRODUCE A SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS THROUGH FRIDAY.
ALSO OF NOTE A MONSOONAL PUSH CONVERGING ONTO A WEAK COLD FRONT
COULD CREATE MORE HAZARDS IN THE OUTER WATERS ON SATURDAY. /CZS

FIRE WEATHER...UPDATED 200 PM PDT WEDNESDAY 29 JULY 2015...VERY HOT
AND DRY CONDITIONS CONTINUE THROUGH THE END OF THE WEEK...WITH
HAINES 6 DRY AND UNSTABLE CONDITIONS AFFECTING SOME INLAND AREAS
THURSDAY AND FRIDAY...INCLUDING THE CABLE CROSSING FIRE. POOR TO
MODERATE RECOVERIES WILL CONTINUE THROUGH FRIDAY MORNING...WITH
LOWER OVERNIGHT WIND SPEEDS LESS THAN PREVIOUS NIGHTS. TEMPERATURES
WILL REMAIN ABOUT 10 TO 15 DEGREES ABOVE NORMAL THROUGH FRIDAY.
TEMPERATURES WILL LOWER GRADUALLY SATURDAY INTO NEXT WEEK WITH
INCREASING CLOUD COVER AND A COOLING AIR MASS. THUS...HUMIDITIES
WILL ALSO GRADUALLY INCREASE OVER THE WEEKEND AND INTO NEXT WEEK.

THUNDERSTORMS MAY DEVELOP OVER THE FORECAST AREA AS EARLY AS FRIDAY
AFTERNOON...BUT MODELS HAVE BEEN TRENDING WEAKER WITH AN IMPULSE
THAT IS NOW EXPECTED TO STAY MAINLY SOUTH AND WEST OF THE
FORECAST AREA. THEREFORE...CONFIDENCE ON ANY THUNDERSTORM ACTIVITY
FOR FRIDAY IS LOW. THAT SAID...ANY THUNDERSTORMS THAT FORM FRIDAY
WILL FEATURE VERY LITTLE RAIN WITH THEM. BETTER TRIGGERS FOR
THUNDERSTORMS...AND MORE UNSTABLE CONDITIONS...EXIST SUNDAY AND
MONDAY. WE ARE VERY COGNIZANT OF THE FACT THAT ANY LIGHTNING THAT
OCCURS THIS WEEKEND OR EARLY NEXT WEEK WILL BE ON THE HEELS OF
EXTREMELY DRY AND HOT CONDITIONS...SO THE POTENTIAL FOR FIRE
STARTS WILL BE ENHANCED.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING FROM 11 AM TO 8 PM PDT THURSDAY FOR ORZ616.
     HEAT ADVISORY UNTIL 11 PM PDT SATURDAY FOR ORZ023.
     HEAT ADVISORY UNTIL 1 PM PDT THURSDAY FOR ORZ022.
     HEAT ADVISORY UNTIL 11 PM PDT SATURDAY FOR ORZ024-026.

CA...HEAT ADVISORY UNTIL 11 PM PDT SATURDAY FOR CAZ080-081.

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR WINDS UNTIL 5 AM PDT THURSDAY FOR
     PZZ350-356-370-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 5 AM PDT THURSDAY
     FOR PZZ350-356-370-376.
     HAZARDOUS SEAS WARNING UNTIL 5 AM PDT THURSDAY FOR PZZ376.

$$

FJB/NSK/CZS


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