000
FXUS66 KMFR 131237
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
537 AM PDT THU JUN 13 2013

.DISCUSSION...MODELS CONTINUE ON TRACK...BOTH RUN TO RUN AND MODEL
TO MODEL THROUGH THE WEEKEND. A COLD POOL WITH 500 MB TEMPS IN THE
-22 TO -25 C OVER THE NORTHERN CASCADES AND OVER TO THE NORTHERN
EAST SIDE COMBINES WITH WEAK MOISTURE TO BRING WEAK INSTABILITY TO
THAT SAME AREA THIS AFTERNOON AS THE COLD FRONT MOVES INTO THE
REGION BRINGING PRECIPITATION TO MOSTLY. HOWEVER...WITH DEW POINTS IN
THE LOWER 40S IN THAT AREA HAVE GONE WITH A SLIGHT CHANCE INSTEAD
OF ISOLATED AS AM THINKING ONLY OF A SLIGHT CHANCE OF A
THUNDERSTORM DEVELOPING RATHER THAN BASING ON COVERAGE.

A WEAK UPPER LEVEL RIDGE BUILDS IN QUICKLY BEHIND THE EXITING
SYSTEM FRIDAY BRINGING A RAPID WARM-UP. A DEEPENING UPPER LEVEL
LOW APPROACHES FROM OFFSHORE OF VANCOUVER ISLAND SATURDAY...AND
WITH LOW PRESSURE IN CENTRAL CALIFORNIA AND HIGH PRESSURE IN THE
GREAT BASIN SEMI-MONSOONAL MOISTURE BEGINS TO FEED INTO THE REGION
INLAND. SATURDAY CONTINUES TO LOOK TO BE A DAY OF PRIMING THE PUMP
FOR SUNDAY`S CONVECTION...BUT WITH COMPUTED FROM 850 LI`S AROUND
-1 AND 700-500 RH AROUND 60 PERCENT IN THE NORTHERN CASCADES
HAVING A CELL DEVELOP ENOUGH TO DROP SOME LIGHTNING BEFORE IT
MOVES NORTH OUT OF THE AREA IS DEFINITELY NOT OUT OF THE QUESTION.
AM SKEPTICAL OF THE GFS SOLUTION ON SUNDAY. THE ECMWF MAINTAINS
THE CLOSER TO SHORE SOLUTION OF THE UPPER LOW A LITTLE BEYOND 132
W WITH THE GFS NOW PUTTING THIS LOW AROUND 136 W. THIS SHOULD
CONTINUE TO INCREASE THE SOUTHERLY THETA E FEED INTO THE REGION
WITH MORE INSTABILITY WITH GREATER COVERAGE. WITH THIS IN MIND
WILL NOT CHANGE THE CONVECTIVE FORECAST FOR SUNDAY.


&&

BASED ON THE 13/12Z TAF CYCLE.

AN AREA OF LOW PRESSURE WITH AN ASSOCIATED COLD CORE ALOFT WILL BE
TRACKING ACROSS PRIMARILY NORTHERN PORTIONS OF THE FORECAST AREA
TODAY. THIS LOW WILL BRING MVFR AND OCCASIONAL IFR CONDITIONS TO
PORTIONS OF COOS AND DOUGLAS COUNTIES THIS MORNING, IMPROVING TO
MVFR TO VFR IN THE AFTERNOON AND EVENING. ELSEWHERE VFR CLOUD DECKS
ARE EXPECTED WHERE THERE WILL BE CLOUDS, EXCEPT JUST WEST OF THE
OREGON CASCADES AND SISKIYOUS AND OVER NORTHERN KLAMATH AND LAKE
COUNTIES WHERE TEMPORARY MVFR CONDITIONS ARE POSSIBLE IN SHOWERS AND
ISOLATED THUNDERSTORMS. ACROSS THE HIGHER TERRAIN FROM THE SISKIYOUS
NORTHWARD PARTIAL TERRAIN OBSCURATIONS ARE POSSIBLE THROUGH DAY
TODAY IN SHOWERS. EXPECT PARTIAL CLEARING THIS EVENING TO BE
FOLLOWED BY AREAS OF WEST SIDE MVFR TO LOCAL IFR BY SUNRISE ON
FRIDAY. BTL

&&

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

PACIFIC COASTAL WATERS...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS
UNTIL 5 AM PDT EARLY
     THIS MORNING FOR PZZ356-376.
     SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 5 PM THIS
AFTERNOON
     TO 5 PM PDT FRIDAY FOR PZZ310-356-376.
     SMALL CRAFT ADVISORY FOR WINDS FROM 5 PM THIS AFTERNOON TO 5 AM
     PDT SATURDAY FOR PZZ376.
     HAZARDOUS SEAS WATCH FROM FRIDAY AFTERNOON THROUGH FRIDAY
     EVENING FOR PZZ376.

$$

SVEN/BTL