130
FXUS66 KMFR 130411
AFDMFR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MEDFORD OR
911 PM PDT MON AUG 12 2013
.SHORT TERM...STRONG THUNDERSTORMS WHICH DEVELOPED EARLIER THIS
EVENING EAST OF THE CASCADES HAVE DECREASED IN STRENGTH AND
COVERAGE. THUNDERSTORM ACTIVITY IS PERSISTING NEAR FORT ROCK AS A
SHORTWAVE MOVES NORTHEAST OVER THE AREA. EXPECT THUNDERSTORMS TO
DIMINISH LATE THIS EVENING INTO TONIGHT. EARLIER STORMS BROUGHT SOME
LARGE SEVERE HAIL AND SIGNIFICANT HAIL ACCUMULATION TO THE AREAS
WEST OF FORT ROCK AND NEAR KENO. ADDITIONALLY THE LAKE AND
KLAMATH COUNTY AREAS HAVE RECEIVED AROUND 250 LIGHTNING STRIKES
DURING THE LATE AFTERNOON THROUGH 9 PM PDT. FOR THE REMAINDER OF
THIS EVENING EXPECT MUCH LOWER CHANCES FOR SEVERE THUNDERSTORMS
WITH MAINLY SMALL HAIL AND LIGHTNING BEING THE MAIN CONCERNS.
THEN THE FORECAST REMAINS ON TRACK FOR TOMORROW WITH MODELS
INDICATING A WARM AND DRY DAY OVER THE AREA. SHORTWAVES AND
POTENTIAL THUNDERSTORM ACTIVITY IS EXPECTED TO REMAIN EAST AND
NORTH OF CWA.
&&
.AVIATION...INLAND...CONDITIONAS ARE MAINLY VFR THIS EVENING. AREAS
OF SMOKE APPEAR TO BE OF MOST CONSEQUENCE EAST OF TILLER FROM THE
WHISKEY COMPLEX AND ACROSS WESTERN SISKIYOU COUNTY FROM THE
ORLEANS AND SALMON RIVER COMPLEXES. THROUGH THE EVENING LOW
PRESSURE MOVING THROUGH ALOFT WILL ASSIST IN THE CONTINUED
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS ACROSS KLAMATH AND LAKE
COUNTIES. THESE THUNDERSTORMS WILL BE CAPABLE OF GUSTY OUTFLOW
WINDS, SIGNIFICANT LIGHTNING, HAIL, AND LOCALIZED HEAVER RAINFALL.
OVERNIGHT EXPECT THE MARINE LAYER TO RETURN ALONG THE COOS COUNTY
COAST SPREADING INLAND TO AROUND ROSEBURG WITH A MIX OF MVFR/IFR CIGS.
&&
.PREV DISCUSSION... /ISSUED 307 PM PDT MON AUG 12 2013/
DISCUSSION...
VISIBLE SATELLITE IMAGERY AND KMAX RADAR RETURNS OVER THE LAST
HOUR INDICATE THAT SURFACE BASED CONVECTION IS BEGINNING TO
INITIATE ACROSS THE AREA. AT THE CURRENT TIME AREAS OF FOCUS
ARE CENTRAL SISKIYOU COUNTY, NORTH AND EASTERN LAKE COUNTY, AND
THE CASCADES NORTH-NORTHEAST OF CRATER LAKE NATIONAL PARK. WATER
VAPOR IMAGERY ALSO INDICATES THE UPPER LEVEL LOW PRESSURE WAVE
EXPECTED TO AID IN CONVECTIVE DEVELOPMENT ROTATING THROUGH
NORTHERN CALIFORNIA OUT INTO KLAMATH AND LAKE COUNTIES AT THE
CURRENT TIME. THIS IS CONSISTENT WITH MODEL GUIDANCE, AS WELL.
SPC MESOSCALE ANALYSIS INDICATES MOST UNSTABLE CAPE INCREASING
UNDER THIS WAVE, WEST OF THE PRIMARY CLOUD SHIELD ON THE EAST
SIDE. ADDITIONALLY, FAVORABLE OMEGA IS PUSHING OUT OF NORTHERN
CALIFORNIA AND INTO SOUTHERN OREGON AT THIS TIME. THUS, THE RED
FLAG WARNING FOR LIGHTNING ON THE EAST SIDE LOOKS ON TRACK AT THIS
TIME. DO HAVE SOME CONCERN THAT THE ACTIVITY IN NORTHERN
CALIFORNIA COULD GET A LITTLE BEYOND ISOLATED SHOULD CONVECTION
ORGANIZE THERE BEFORE ABOUT 00Z. THE PRIMARY THREAT FROM THESE
THUNDERSTORMS WILL BE MOSTLY DRY LIGHTNING. ANY HAIL SHOULD BE
SMALL AND WINDS SUB-SEVERE. RAINFALL WILL BE BRIEF DUE TO STEADY
SW TO NE 15-25KT STEERING FLOW.
ASIDE FROM THUNDERSTORMS THIS AFTERNOON AND EVENING ARE AREAS OF
SMOKE AND THE MARINE LAYER. PER SATELLITE, THE FIRES THAT REMAIN
ACTIVE ENOUGH TO BE A SMOKE PROBLEM ARE THE WHISKEY COMPLEX EAST
OF TILLER AND THE ORLEANS AND SALMON COMPLEXES IN NW CALIFORNIA.
HAVE ADDED AREAS OF SMOKE NEAR THESE FIRES AND ATTEMPTED TO
CAPTURE HAZE EFFECTS BEYOND SOURCES FOR OTHER LOCATIONS IN THE
FORECAST AREA FOR THE NEXT 48-60 HOURS. BEYOND THAT, WE WILL NEED
TO SEE HOW ACTIVE THESE FIRES ARE AND IF ANY OTHERS BECOME ACTIVE.
WITH WARM TO HOT AND DRY WEATHER EXPECTED TO CONTINUE, SUSPECT
FIRE AND SMOKE ACTIVITY WILL INCREASE ACROSS THE AREA. THE MARINE
LAYER TONIGHT THROUGH TUESDAY MORNING WILL AFFECT THE COASTLINE TO
ABOUT ROSEBURG OVERNIGHT. AS FAR AS ACTIVE FIRE PERIMETERS, EXPECT
MAIN EFFECTS TO BE ON THE DOUGLAS COMPLEX.
A WARMING AND DRYING TREND WILL PERSIST THROUGH WEDNESDAY BEFORE
A WEAKENING FRONTAL BOUNDARY ARRIVES THURSDAY INTO FRIDAY. EXPECT
THE MARINE LAYER INFLUENCE TO INCREASE DURING THIS TIME PERIOD,
AND THERE WILL BE A THREAT OF THUNDERSTORMS ON FRIDAY ALONG AND
NEAR THE MARBLE MOUNTAINS AND CASCADES.
THEREAFTER MODELS ARE ADVERTISING A BUILDING UPPER LEVEL HIGH FROM
THE FOUR CORNERS REGION. LONG TERM MODEL GUIDANCE SUGGESTS ABOVE
AVERAGE TEMPERATURES FOR THE MAJORITY OF WEEKS 2 AND 3. BTL
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...RED FLAG WARNING UNTIL 11 PM PDT THIS EVENING FOR
ORZ027-029>031.
CA...NONE.
PACIFIC COASTAL WATERS...NONE.
$$
CC