Area Forecast Discussion
Issued by NWS Medford, OR

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS66 KMFR 310414
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
914 PM PDT THU JUL 30 2015

.DISCUSSION...A WEAK SHORTWAVE AND SOME MID AND UPPER LEVEL
MOISTURE COMBINED WITH DAYTIME HEATING TO BRING ISOLATED
THUNDERSTORMS THIS EVENING TO NORTHERN CALIFORNIA. STORMS ARE
DIMINISHING AND EXPECT NO OVERNIGHT THUNDERSTORMS IN THIS AREA. IN
OREGON, MAINLY ONLY SAW SOME CUMULUS BUILD UPS EAST OF THE
CASCADES. EXCEPT IN EASTERN DOUGLAS COUNTY, WHERE A
PYROCUMULONIMBUS CLOUD FORMED IN THE AREA NEAR MILO JUST WEST OF
TILLER. THIS CLOUD PRODUCED LIGHTNING IN THE AREA. THE CLOUD WAS
A RESULT OF SIGNIFICANT BURNING CONDITIONS FROM A WILDFIRE THAT
DEVELOPED IN THE AREA. DRY AND UNSTABLE ATMOSPHERIC CONDITIONS
SUPPORTED THE WILDFIRE GROWTH.

ON FRIDAY, EXPECT ANOTHER HOT DAY OVER THE AREA. THE CHANCE FOR
THUNDERSTORMS WILL SPREAD FURTHER NORTH INTO PORTIONS OF SOUTHERN
OREGON AS ANOTHER SHORTWAVE IS FORECAST TO MOVE INTO THE AREA AND
SOME MID AND UPPER LEVEL MOISTURE MOVES UP FROM THE SOUTH. SIMILAR
TO TODAY, THE MOISTURE FOR THESE STORMS IS FAIRLY HIGH WITH A VERY
DRY SUB-CLOUD LAYER. SO EXPECT LITTLE PRECIPITATION WITH STORMS.

&&

.AVIATION...FOR THE 31/00Z TAF CYCLE...TWO WILDFIRES ARE BURNING
IN DOUGLAS COUNTY...ALTHOUGH MIXING HAS INCREASED DURING PEAK
HEATING SO VISIBILITY IS CURRENTLY ABOVE 6 MILES AT KRBG. STILL
EXPECTING HAZE AND SMOKE TO DEVELOP FOR THE OVERNIGHT HOURS IN
THE UMPQUA VALLEY, INCLUDING KRBG. AREAS ALONG THE COAST,
INCLUDING AT KOTH, WILL ALSO SEE SOME LOW CEILINGS AND FOG TONIGHT
WITH WEAK ONSHORE WIND. IFR AND LIFR CONDITIONS ARE EXPECTED FOR
COASTAL AREAS TONIGHT AND FRIDAY MORNING. /CC

&&

.MARINE...UPDATED 900 PM PDT THURSDAY 30 JULY 2015...A THERMAL
TROUGH NEAR THE COAST WILL CONTINUE TO WEAKEN THROUGH LATE FRIDAY.
NORTH WINDS AND CHOPPY, WIND-DRIVEN SEAS WILL CREATE SMALL CRAFT
ADVISORY SEAS IN THE OUTER WATERS THROUGH LATE FRIDAY EVENING.
WINDS AND SEAS AS ARE EXPECTED TO GRADUALLY LOWER THIS WEEKEND. A
THERMAL TROUGH AND STRONG GUSTY NORTH WINDS MAY RETURN AROUND
WEDNESDAY OF NEXT WEEK. /CC


&&

.PREV DISCUSSION... /ISSUED 520 PM PDT THU JUL 30 2015/

UPDATE...SOME ISOLATED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
OVER SOUTHWEST AND SOUTH-CENTRAL SISKIYOU COUNTY. THESE STORMS ARE
ASSOCIATED INCREASING MID AND UPPER LEVEL MOISTURE MOVING INTO
THE AREA ALONG WITH A SHORTWAVE DISTURBANCE. THESE STORMS ARE
EXPECTED TO LINGER THROUGH THE EVENING THEN DIMINISH. FURTHER
EAST, ISOLATED SHOWERS AND THUNDERSTORMS ARE ALSO POSSIBLE THIS
EVENING IN EASTERN SISKIYOU AND MODOC COUNTY. FURTHER NORTH IN
OREGON, EXPECT MAINLY JUST CUMULUS CLOUD DEVELOPMENT. HAVE UPDATED
THE FORECAST FOR THESE STORMS. ALSO EXPANDED THE RED FLAG WARNING
FOR DRY AND UNSTABLE FIRE WEATHER CONDITIONS IN CENTRAL DOUGLAS
COUNTYTO INCLUDE THE STOUT FIRE 11 MILES EAST OF CANYONVILLE.


PREV DISCUSSION... /ISSUED 307 PM PDT THU JUL 30 2015/

SHORT TERM...THE ATMOSPHERE WILL CONTINUE TO BE VERY WARM AND DRY
THROUGH FRIDAY. THE THERMAL TROUGH SHIFTS BACK AND FORTH BETWEEN
THE COAST AND INLAND. MEANWHILE MID TO HIGH LEVEL MOISTURE WILL
STREAM NORTHWARD ON FRIDAY. FOR MOST OF FRIDAY, THE WEATHER SHOULD
BE RELATIVELY QUIET WITH MAINLY CUMULUS BUILDUP. THUNDERSTORM
CHANCE WILL BE CONFINED MAINLY FOR MOUNTAINS DURING THE DAY.
HOWEVER, BOTH THE GFS AND NAM12 SHOW SHORT WAVE DISTURBANCE
APPROACHING SISKIYOU AND MODOC COUNTIES FROM THE SOUTH. THIS COULD
LEAD TO THUNDERSTORM DEVELOPMENT FROM FRIDAY EVENING THROUGH
FRIDAY NIGHT. DEPENDING ON HOW STRONG THIS SHORT WAVE IS, THE
STORM COULD CONTINUE INTO FRIDAY NIGHT. AT THIS POINT CONFIDENCE
IS ONLY MODERATE AS THERE IS ALSO MID LEVEL CAP THAT COULD PREVENT
THE CLOUDS FROM BUILDING INTO A THUNDERSTORM CLOUD.

ON SATURDAY A STRONGER SHORT WAVE TROUGH IS EXPECTED TO MOVE
THROUGH THE AREA. THUNDERSTORM CHANCE LOOKS GREATEST FROM THE
CASCADES EAST WITH THE EXCEPTION OF SISKIYOU COUNTY AND THE
SISKIYOU MOUNTAINS. THE OVERALL PATTERN CONTINUES INTO SUNDAY WITH
THUNDERSTORM CHANCES.

LONG TERM...(MONDAY THROUGH THURSDAY)
THE UPPER LEVEL FLOW TURNS TOWARD THE SW ON MONDAY AS ANOTHER
TROUGH APPROACHES THE COAST. THERE IS ALSO ANOTHER TROUGH DROPPING
INTO THE PACIFIC NW. THIS WILL HELP BRING DOWN TEMPERATURES WITH
HIGHS IN THE ROGUE VALLEY DOWN INTO THE 90S. THERE WILL STILL BE
PLENTY OF MOISTURE AND INSTABILITY FOR SHOWERS AND THUNDERSTORMS
IN OUR FORECAST AREA. /FB


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...FIRE WEATHER WATCH FROM FRIDAY AFTERNOON THROUGH SATURDAY
     EVENING FOR ORZ619>623.
     RED FLAG WARNING UNTIL 9 PM PDT FRIDAY FOR ORZ616.
     HEAT ADVISORY UNTIL 11 PM PDT SATURDAY FOR ORZ023.
     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 HAZARDOUS SEAS UNTIL 11 PM PDT FRIDAY
     FOR PZZ370-376.

$$

CC


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.