Weather Service Report


963 
FXUS66 KMFR 041315 AAA
AFDMFR

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

UPDATED AVIATION AND FIRE WEATHER SECTIONS.

.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 04/12Z 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 THIS 
EVENING. OVER THE WEST SIDE VALLEYS...AREAS OF MVFR VSBYS IN SMOKE 
WILL PERSIST THROUGH THIS EVENING. FROM THE CASCADES EAST AND 
SISKIYOUS SOUTH...VFR CONDITIONS WILL PREVAIL THROUGH THIS EVENING 
EXCEPT FOR LOCAL MVFR VSBYS IN SMOKE.  ISOLATED THUNDERSTORMS WILL 
OCCUR AGAIN THIS AFTERNOON AND EVENING  FROM SISKIYOU COUNTY NE INTO 
THE CASCADES AND KLAMATH/LAKE COUNTIES. 
/FB 

&&

.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 600 AM PDT TUESDAY 4 AUGUST 2015... FLOW 
ALOFT IS MORE SOUTHWESTERLY TODAY...AND THIS WILL MAKE FOR DRIER AND 
LESS UNSTABLE STABLE CONDITIONS. ISOLATED THUNDERSTORMS WILL DEVELOP 
FROM THE SISKIYOUS SOUTH AND CASCADES EAST AS A SHORT WAVE 
DISTURBANCE MOVES INTO NORTHERN CALIFORNIA. 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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