Dense Smoke in California, August 23 to 28, 2013

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
209 AM PDT FRI AUG 23 2013

.SYNOPSIS...
DRY AND STABLE SOUTHWEST FLOW MOVES INTO NORTHEAST CALIFORNIA AND
NORTHWEST NEVADA WITH BREEZY AFTERNOON AND EVENING WINDS THE NEXT
SEVERAL DAYS. THE STRONGEST WINDS LIKELY DEVELOP THIS WEEKEND AS A
SHORTWAVE PASSES ACROSS NORTHERN CALIFORNIA AND SOUTHERN OREGON.
AREAS OF SMOKE AND HAZE WILL CONTINUE ACROSS THE REGION DUE TO
SEVERAL ONGOING WILDFIRES.

&&

.SHORT TERM...
TWO MAIN CONCERNS FOR THE SHORT TERM FORECAST:
1. SMOKE AND HAZE FROM ONGOING WILDFIRES
2. DRY AND BREEZY CONDITIONS THIS WEEKEND

WITH MULTIPLE ONGOING WILDFIRES, SMOKE AND HAZE WILL CONTINUE TO
IMPACT THE SIERRA AND WESTERN NEVADA THROUGH THE WEEKEND. THE RIM
FIRE, JUST WEST OF YOSEMITE, WAS THE MAIN CULPRIT FOR THE SMOKEY
CONDITIONS YESTERDAY. THE FIRE GREW SUBSTANTIALLY WITH THE SMOKE
PLUME AND ASH BEING LOFTED OVER 25,000 FEET INTO THE ATMOSPHERE.
THERE WERE WIDESPREAD REPORTS OF DENSE SMOKE ACROSS THE SIERRA AND
WESTERN NEVADA. VISIBILITY REDUCTIONS DUE TO SMOKE WERE AS FAR EAST
AS LOVELOCK AND FALLON OVERNIGHT, AND SOME LOCATIONS IN CARSON CITY
REPORTED ASH FALLING OUT OF THE SKY. SIMILAR CONDITIONS ARE POSSIBLE
TODAY WITH SMOKE EXPECTED TO GRADUALLY WORSEN ACROSS THE REGION
THROUGH THE DAY. UNFORTUNATELY THE DIFFICULTY REMAINS WITH HOW
ACTIVE THE FIRE WILL BURN AND IF THE PLUME WILL BE LOFTED AS HIGH AS
IT WAS YESTERDAY. LEFT ONGOING FORECAST FOR SMOKE/HAZE THE SAME. THE
TWO OTHER FIRES THAT MAY CONTRIBUTE TO THE SMOKE ACROSS THE REGION
ARE THE SPRING PEAK FIRE (NEAR BODIE,CA) AND THE AMERICAN FIRE (WEST
OF SQUAW VALLEY), BUT FORTUNATELY THEY HAVE NOT BEEN BURNING AS
ACTIVELY AS THE RIM FIRE (AROUND 65,000 ACRES).

FOR THE WEEKEND, AN AREA OF LOW PRESSURE BEGINS TO DIG SOUTH IN THE
EASTERN PACIFIC WHICH WILL ALLOW SURFACE GRADIENTS TO INCREASE
ACROSS THE SIERRA AND WESTERN NEVADA. ON SATURDAY, A TYPICAL ZEPHYR
BREEZE IS EXPECTED WITH WIND GUSTS BETWEEN 20-30 MPH. BY SUNDAY, A
WEAK SHORTWAVE EJECTS ACROSS NORTHERN CALIFORNIA/SOUTHERN OREGON AND
MAY ENHANCE THE TYPICAL ZEPHYR WINDS WITH GUSTS UP TO 35 MPH
POSSIBLE IN SOME LOCATIONS. GFS IS A BIT MORE AGGRESSIVE THAN THE
NAM WITH THE WINDS FOR SUNDAY AFTERNOON AT THIS TIME, SO WILL HAVE
TO KEEP AN EYE ON THE MODEL TRENDS. GUSTY WINDS AND LOW RELATIVE
HUMIDITY VALUES MAY RESULT IN FIRE WEATHER CONCERNS FOR SUNDAY
AFTERNOON. LINDAMAN

.LONG TERM...MONDAY THROUGH THURSDAY...
NO CHANGES AS TROUGH WILL BE CENTERED OFF THE WEST COAST AND UPPER
RIDGE OVER THE CENTRAL SECTION OF THE COUNTRY. THIS WILL RESULT IN A
DRY SOUTHWEST FLOW ACROSS THE SIERRA AND WESTERN NV. AFTERNOON HIGHS
WILL STAY WITHIN A FEW DEGREES OF NORMAL FOR LATE AUGUST, MID 80S TO
LOW 90S FOR WESTERN NEVADA AND MID 70S TO LOW 80S FOR THE EASTERN
SIERRA. A STEADY-STATE THERMAL GRADIENT WIND SHOULD KICK UP EACH
AFTERNOON AND EVENING WITH PEAK GUSTS GENERALLY 25-30 MPH.

&&

.AVIATION...
SMOKE WILL BE THE MAIN ISSUE FOR THE TAHOE BASIN AND WESTERN NV AS
FIRES CONTINUE TO BURN WEST OF THE SIERRA CREST. FORECAST SOUTHWEST
FLOW ALOFT WILL BE FAVORABLE FOR BRINGING IN SMOKE OFF THE VERY
ACTIVE RIM FIRE NEAR YOSEMITE. THIS WILL REDUCE VISIBILITY FROM
3-5SM AT TIMES LATE EACH DAY WITH SOME IMPROVEMENT LATE IN THE
MORNING AND AFTERNOON. KMMH SHOULD ESCAPE MOST OF THE SMOKE. IF
THESE FIRES CONTINUE TO BURN, CONDITIONS MAY PERSIST THE NEXT FEW
DAYS OR SO. HOHMANN

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)