Area Forecast Discussion
Issued by NWS Medford, OR

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000
FXUS66 KMFR 041122
AFDMFR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
422 AM PDT TUE AUG 4 2015

.DISCUSSION...
BLM LIGHTNING DETECTED ANOTHER APPROXIMATE 950 CLOUD TO GROUND
LIGHTNING STRIKES ACROSS THE FORECAST AREA IN THE PAST 24 HOURS.
THE VAST MAJORITY OF THESE OCCURRED EAST OF THE CASCADE CREST.
FORTUNATELY, AS EVENING SET IN, THESE STORMS SLOWED AND LOCALLY
SIGNIFICANT RAIN FELL FROM THEM. SEVERAL LOCATIONS IN KLAMATH AND
LAKE COUNTIES REPORTED 0.10 TO 0.50" OF RAIN, WITH LOCALIZED
HEAVIER AMOUNTS OF NEARLY AN INCH IN CHILOQUIN AND ON THE NORTH
SIDE OF UPPER KLAMATH LAKE.

OVER THE LAST 4 DAYS WE HAVE HAD OVER 2600 LIGHTNING STRIKES
ACROSS THE MEDFORD FIRE WEATHER ZONE AREAS. MANY WILDFIRES HAVE
BEEN FOUND WITH MANY OF THEM LESS THAN 10 ACRES. HOWEVER, THE
STOUTS CREEK FIRE NEAR TILLER AND MILO, THE CABLE CROSSING FIRE
NEAR GLIDE, THE EAST KELSEY FIRE NORTHWEST OF GALICE, 3 FIRES IN
AND NEAR NORTHWESTERN SISKIYOU COUNTY, THE FROG FIRE IN WESTERN
MODOC COUNTY, AND 8 LARGE FIRES OUT OF OUR FIRE WEATHER ZONE AREAS
IN NORTHERN CALIFORNIA ARE ALL OVER 10 ACRES AND ARE CONTRIBUTING
TO SMOKE AND HAZE ACROSS THE FORECAST AREA. THE SMOKE AND HAZE IN
THE FORECAST HAS BEEN INPUT AND SCRUTINIZED IN THE FORECAST OUT
THROUGH DAY 3, THURSDAY, BASED ON OUTPUT PRIMARILY FROM THE BLUE
SKY 4KM NWRMC PACIFIC NORTHWEST 72 HOUR FORECAST MODEL GUIDANCE FROM
AIRFIRE. IN SHORT, AREAS SOUTH AND EAST OF ACTIVE FIRES ON THE
WEST SIDE WILL CONTINUE TO SEE MOSTLY SMOKY AND HAZY CONDITIONS AS
WILL NORTHERN CALIFORNIA, ESPECIALLY NORTH AND EAST OF THE FROG
FIRE AND IN WESTERN SISKIYOU COUNTY.

AS FAR AS WEATHER GOES TODAY, WE`RE KEEPING A CLOSE EYE ON A
SHORTWAVE TROUGH THAT WILL MOVE NORTHEASTWARD ACROSS NORTHERN
CALIFORNIA THIS AFTERNOON THROUGH TONIGHT. WE EXPECT MORE
THUNDERSTORMS, MAINLY FROM THE SISKIYOU AND CASCADE CRESTS SOUTH
AND EASTWARD THIS EVENING. WHILE THE SHORTWAVE LOOKS SOMEWHAT
IMPRESSIVE AT 500MB AND IN THE MODEL GUIDANCE, THERE WILL BE
SEVERAL FACTORS THAT WILL CAUSE THUNDERSTORM DEVELOPMENT TO BE
LATER AND MUTED COMPARED TO WHAT WE`VE SEEN THE LAST 2 DAYS.
FIRST, THE SHORTWAVE TROUGH ARRIVES IN THE EVENING AND OVERNIGHT
FOR OUR AREA. SECOND, SMOKE ACROSS NORTHERN CALIFORNIA HAS MUTED
DEVELOPMENT IN WESTERN SISKIYOU AND MODOC COUNTIES THE LAST 2 DAYS,
AND EXPECT SMOKE TO KEEP STORMS ISOLATED THERE AGAIN TODAY. BOTH
THE GFS20 AND NAM12 INDICATE THAT INSTABILITY WILL BE LESSER IN
THE AREA TODAY, AND 700MB COMPUTED CAPE IS SUBSTANTIALLY LESS
TODAY IN DURATION AND MAGNITUDE THAN WHAT WE SAW YESTERDAY. WE DO
STILL EXPECT ISOLATED THUNDERSTORMS THAT COULD BRIEFLY BECOME
SCATTERED FOR ABOUT 3 HOURS THIS EVENING IN PORTIONS OF CENTRAL
AND SOUTHERN KLAMATH AND LAKE COUNTIES. THESE STORMS ARE LIKELY TO
MOVE AT 10-15 KNOTS, BUT MAY SLOW ALONG A CONVERGENCE BOUNDARY
THIS EVENING. WFAS.NET INDICATES FUELS ARE LESS RECEPTIVE THAN
THEY WERE A FEW DAYS AGO IN THAT AREA AND SUSPECT THIS ALONG WITH
SOME RAIN WITH THESE STORMS SHOULD KEEP NEW FIRE STARTS LIMITED
COMPARED TO RECENT DAYS. ALL TOLD, SUSPECT LIGHTNING TO BE 400
STRIKES OR FEWER TODAY.

WEDNESDAY THROUGH THURSDAY WE`LL CATCH A BREAK FROM THE
THUNDERSTORM ACTION. FRIDAY MOISTURE AND INSTABILITY ARRIVE FROM
THE SOUTH AGAIN. MODELS DIFFER SUBSTANTIALLY WITH DETAILS OF
THIS. ALL IN ALL TEMPERATURES WILL BE NEAR DAILY NORMALS THE REST
OF THE WEEK INTO THE WEEKEND. BTL

&&

.AVIATION...FOR THE 04/06Z TAF CYCLE...ALONG THE COAST...AREAS OF
IFR CIGS/VSBYS WILL CLEAR TO VFR BY LATE MORNING...BUT WILL
REMAIN OFFSHORE. THE LOWER CONDITIONS WILL RETURN TO THE SAME
AREAS TUESDAY EVENING. OVER THE WEST SIDE VALLEYS...AREAS OF
MVFR VSBYS IN SMOKE WILL PERSIST THROUGH TUESDAY EVENING. FROM THE
CASCADES EAST AND SISKIYOUS SOUTH...VFR CONDITIONS WILL PREVAIL
THROUGH TUESDAY EVENING EXCEPT FOR LOCAL MVFR VSBYS IN SMOKE.
ISOLATED THUNDERSTORMS TUESDAY AFTERNOON AND EVENING.

&&

.MARINE...UPDATED 230 AM PDT TUESDAY 4 AUGUST 2015...HIGH PRESSURE
WILL BUILD IN FROM THE WEST. A THERMAL TROUGH WILL DEVELOP ALONG THE
COAST AND STRENGTHEN INTO THURSDAY. NORTH WINDS AND SEAS WILL BUILD
TODAY AND REMAIN MODERATE THROUGH THURSDAY MORNING...THEN STRENGTHEN
FURTHER THURSDAY AFTERNOON AND EVENING...POSSIBLY REACH GALE FORCE
OVER THE SOUTHERN WATERS THURSDAY AFTERNOON AND EVENING. THE THERMAL
TROUGH WILL WEAKEN FRIDAY INTO SATURDAY. NORTH WINDS AND SEAS WILL
ABATE AT THAT TIME. /FB

&&

.FIRE WEATHER...UPDATED 800 PM PDT MONDAY 3 AUGUST 2015...
THUNDERSTORMS ARE NOW DISSIPATING OVER THE AREA AND THE CURRENT
RED FLAG WARNING WILL EXPIRE LATER THIS EVENING. ON TUESDAY THE
FLOW ALOFT WILL BE MORE SOUTHWESTERLY...AND THIS WILL MAKE FOR
DRIER AND MORE STABLE CONDITIONS. ISOLATED THUNDERSTORMS WILL
DEVELOP FROM THE SISKIYOUS SOUTH AND CASCADES EAST. NORTHWEST
FLOW ALOFT WILL DEVELOP WEDNESDAY...WHICH WILL STABILIZE THE AREA
FROM WEST TO EAST AND BRING IN COOLER TEMPERATURES. THURSDAY WILL
BE DRY BUT WARMER. SOUTHERLY FLOW WILL RETURN TOWARDS THE END OF
THE WEEK...WITH A SLIGHT CHANCE OF THUNDERSTORMS FRIDAY THROUGH
THE WEEKEND.

&&

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

CA...NONE.

PACIFIC COASTAL WATERS...
- SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11
  PM PDT WEDNESDAY FOR PZZ356.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM THIS
  AFTERNOON TO 11 PM PDT WEDNESDAY FOR PZZ356.
- SMALL CRAFT ADVISORY FOR WINDS FROM 2 PM THIS AFTERNOON TO 11
  PM PDT THIS EVENING FOR PZZ370.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 2 PM THIS
  AFTERNOON TO 11 PM PDT THIS EVENING FOR PZZ370.
- SMALL CRAFT ADVISORY FOR WINDS FROM 11 AM THIS MORNING TO 5 PM
  PDT THURSDAY FOR PZZ376.
- SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS FROM 11 AM THIS MORNING
  TO 5 PM PDT THURSDAY FOR PZZ376.

$$

BTL/FJB/JRS


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