Wildfire in Oregon, August 13 to 31, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
906 AM PDT FRI AUG 13 2010

.DISCUSSION...
NO UPDATES NEEDED THIS MORNING AS THE FORECAST IS LOOKING GOOD. WE
WILL DELVE INTO THE HEAT AND THUNDERSTORM FORECASTS FOR THE
AFTERNOON PACKAGE. LUTZ

&&

.AVIATION...
LOW CLOUDS AND FOG OF THE IFR VARIETY ARE HANGING ALONG THE COAST
THIS MORNING. THIS WILL DISSIPATE FROM EAST TO WEST DURING THE
COURSE OF THE MORNING...THOUGH IT WILL LIKELY BE LATE MORNING TO
ABOUT NOON FOR NORTH BEND TO SCATTER OUT...AND UNTIL EARLY
AFTERNOON FOR THE MARINE LAYER TO RECEDE COMPLETELY TO THE OCEAN.
LATE THIS AFTERNOON AND EVENING A SURGE OF FOG AND VERY LOW
STRATUS IS LIKELY TO MOVE NORTHWARD FROM CRESCENT CITY AND
BROOKINGS...ONTO THE CURRY COAST...AND EVENTUALLY ONTO PORTIONS OF
THE COOS COAST OVERNIGHT. THIS WILL LEAD TO LIFR ALONG AT
ELEVATIONS BELOW 500 FEET MSL. LUTZ

&&

.PREV DISCUSSION... /ISSUED 243 AM PDT FRI AUG 13 2010/

SHORT TERM...A RIDGE CENTERED JUST OFFSHORE WILL CONTINUE TO
BUILD OVER THE REGION TODAY AND SATURDAY AND PERSIST INTO EARLY
NEXT WEEK BRINGING HOT TEMPERATURES TO INLAND AREAS. UNDER THE
RIDGE... A WEAK CUTOFF LOW IS CENTERED WELL OFF THE CENTRAL
CALIFORNIA COAST NEAR 35N AND 130W WHILE A SECOND LOW FURTHER
OFFSHORE IS NEAR 40N 150W. MODELS ARE CONTINUING TO SHOW THE LOW
OFF THE CENTRAL CALIFORNIA COAST MOVING SLOWLY NORTHWARD FRIDAY
NIGHT AND SATURDAY...THEN WEAKEN AND MOVE INLAND SUNDAY AS THE
SECOND LOW MOVES EASTWARD TOWARDS THE REGION.

THE BUILDING HIGH PRESSURE RIDGE TODAY WILL BRING CONTINUED DRY
AND WARMING CONDITIONS INLAND WITH AFTERNOON HIGH TEMPERATURES 5
TO 10 DEGREES ABOVE SEASONAL NORMS TODAY. MEANWHILE...ALONG THE
COAST THE MARINE STRATUS AND FOG IS EXPECTED TO GRADUALLY CLEAR
LATE THIS MORNING INTO THIS AFTERNOON WITH NEAR NORMAL AFTERNOON
TEMPERATURES TODAY. THEN...STRATUS AND FOG WILL RETURN AGAIN
FRIDAY EVENING AND SATURDAY TO THE COAST.

BY SATURDAY AFTERNOON...EXPECT SOME INCREASING  SOUTHERLY
MOISTURE IN THE MID LEVELS AS THE CUTOFF LOW MOVES NORTHWARD. THE
00Z NAM AND GFS ARE SHOWING SOME WEAK INSTABILITY OVER PORTIONS OF
THE CWA FOR INLAND AREAS. HOWEVER...HIGH PRESSURE IS EXPECTED TO
LIMIT CONVECTIVE POTENTIAL WITH ONLY CUMULUS CLOUDS EXPECTED TO
BUILD OVER HIGHER TERRAIN DURING THE AFTERNOON. ON
SUNDAY...MOISTURE AND INSTABILITY ARE FORECAST TO INCREASE. THIS
COMBINED WITH DAYTIME HEATING AND THE LOW MOVING INLAND SUNDAY
AFTERNOON MAY COMBINE TO BRING A SLIGHT CHANCE OF
THUNDERSTORMS. THE NAM...GFS...AND ECMWF HIGHLIGHT THE AREAS FROM
THE SOUTHERN CASCADES EASTWARD FOR BEST CHANCE OF ANY THUNDERSTORM
DEVELOPMENT.

LONG TERM...THE EXTENDED RANGE GFS AND ECMWF MODELS SHOW THE
SECOND UPPER LOW MOVING TOWARDS THE COAST MONDAY THEN GRADUALLY
SHIFTING INLAND TUESDAY INTO WEDNESDAY AS THE RIDGE WEAKENS AND
SHIFTS EASTWARD. THIS PATTERN MAY BRING ADDITIONAL MOISTURE INTO
THE CWA ON TUESDAY WITH SLIGHTLY COOLER CONDITIONS POSSIBLE AROUND
MID WEEK. HOWEVER...THERE REMAINS  UNCERTAINTY IN THIS TIME
PERIOD WITH ENSEMBLE RUNS SHOWING SIGNIFICANT VARIABILITY.

AVIATION...VFR WEATHER CONTINUES INLAND THROUGH FRIDAY NIGHT.
ALONG THE COAST WIDESPREAD IFR DECKS WILL PERSIST THROUGH THIS
MORNING FOR COASTAL AREAS AND INTO THE COQUILLE VALLEY WITH GRADUAL
CLEARING LATE THIS MORNING INTO THE EARLY AFTERNOON. EXPECT AREAS
OF VIS FALLING TO 1 TO 2 SM IN BR AND ISOLATED LOCATIONS WITH VIS DOWN
TO 1/2SM THROUGH 15Z THIS MORNING. THEN EXPECT WIDESPREAD IFR IN
CIGS AND VISIBILITIES TO RETURN TO THE COAST DURING THE EVENING
EVENING.

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...NONE.

BTL/JRS/CC