Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 211010
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
310 AM PDT THU AUG 21 2014

.SYNOPSIS...
LOW PRESSURE WILL MOVE INTO THE PACIFIC NORTHWEST AND BRING
INCREASING WINDS AND THE POTENTIAL FOR CRITICAL FIRE WEATHER
CONDITIONS ON FRIDAY. COOLER TEMPERATURES WILL REACH THE AREA FOR
SATURDAY WITH DRY CONDITIONS FOR MOST OF NEXT WEEK.

&&

.SHORT TERM...
LINGERING CLOUD COVER ACROSS PERSHING AND CHURCHILL COUNTIES WILL
DIMINISH THROUGH THE MORNING AS AN UPPER TROUGH SHIFTS EASTWARD.
EXPECTING MOSTLY CLEAR AND DRY CONDITIONS TODAY WITH TEMPERATURES
IN THE UPPER 80S AND LOWER 90S ACROSS WESTERN NEVADA WITH UPPER
70S ACROSS SIERRA VALLEYS.

MAIN WEATHER CONCERN WILL OCCUR ON FRIDAY AS ANOTHER UPPER LEVEL
LOW DROPS ACROSS THE PACIFIC NORTHWEST. THE MAIN IMPACT
ACCOMPANYING THE LOW LOCALLY WILL BE LOW HUMIDITY AND GUSTY
WINDS. GLOBAL MODELS IN GOOD AGREEMENT WITH THIS PATTERN AND
CONFIDENCE IS HIGH THAT GUSTY WINDS AND LOW RH WILL PRODUCE
CRITICAL FIRE WEATHER CONDITIONS ACROSS PORTIONS OF WESTERN NEVADA
AND FAR NORTHEASTERN CALIFORNIA ON FRIDAY AFTERNOON (SEE FIRE
WEATHER DISCUSSION SECTION FOR ADDITIONAL DETAILS). STRONGER WINDS
WILL BE LOCATED ROUGHLY NORTH OF HWY 50 WITH PEAK GUSTS MAINLY
BETWEEN 30-40 MPH WITH ABOUT 30 MPH TO THE SOUTH. THIS WILL RESULT
IN HAZARDOUS BOATING CONDITIONS ON FRIDAY ACROSS AREA LAKES WITH
LAKE WIND ADVISORIES A GOOD POSSIBILITY. DRY CONDITIONS AND STRONG
WINDS WILL ALSO PRODUCE AREAS OF BLOWING DUST FRIDAY OVER AND
DOWNWIND OF DRY LAKE BEDS AND DESERT AREAS INCLUDING THE BLACK
ROCK DESERT.

THE LOW WILL SHIFT EAST AND WILL FORCE A WEAK SURFACE FRONT
ACROSS THE REGION SATURDAY MORNING WHICH WILL PROVIDE SOME GUSTY
NORTH WINDS PARTICULARLY NORTH OF INTERSTATE 80. COOLER TEMPERATURES
WILL ALSO ACCOMPANY THE FRONTAL BOUNDARY WITH HIGHS ONLY REACHING
THE LOW TO MID 80S BY SATURDAY ACROSS WESTERN NEVADA AND MID 70S
ACROSS SIERRA VALLEYS. FUENTES


.LONG TERM...SUNDAY THROUGH WEDNESDAY...
ONLY MINOR CHANGES TO THE INHERITED EXTENDED FORECAST THIS CYCLE.
MODELS ARE STARTING TO SHOW DIVERGENCE IN SOLUTIONS FOR THE EARLY
PART OF THE FORECAST BUT ARE MORE SIMILAR TOWARD DAY 7.

BROAD UPPER TROUGH OVER THE WRN U.S. IS SHOWN BY MOST MODELS AT THE
START OF THE PERIOD THEN BEGINS TO SLIDE EAST BY MONDAY. OPERATIONAL
GFS AND GEM ARE STARTING TO BUILD A RIDGE TO THE WEST OF THE REGION
BY LATE MONDAY BUT ECMWF IS DIGGING A LOW INTO THE BASE OF THE UPPER
TROUGH AND RETROGRADING IT OVER THE REGION MONDAY NIGHT AND TUESDAY.
NORMALLY THIS WOULD BE REJECTED OUT OF HAND AS IT IS AN OUTLIER...
BUT A FEW OF THE GEFS ENSEMBLE MEMBERS SHOW A SIMILAR SOLUTION. WITH
A LITTLE SUPPORT FROM THE GEFS WILL NOT COMPLETELY REJECT THIS
SOLUTION AND WILL INCREASE CLOUDS A BIT AND BUMP UP POPS...BUT STILL
BELOW 10 PERCENT. RIDGE THEN BUILDS IN THE ECMWF FORECAST BY
WEDNESDAY.

THE PRESENCE OR LACK OF THIS LOW WOULD HAVE A DRAMATIC EFFECT ON
POPS AND TEMPS WITH EC COOLER AND WETTER. FOR NOW WILL LEAVE TEMPS
LARGELY UNCHANGED AS CONFIDENCE IN THIS SOLUTION IS FAIRLY LOW.
OVERALL...WILL SEE BELOW NORMAL TEMPS AT THE START OF THE EXTENDED
PERIOD...THEN ABOVE NORMAL TEMPS BY THE END. 20
&&

.AVIATION...
TYPICAL WEST WINDS BY THIS AFTERNOON WITH LEE SIDE TERMINALS
GUSTING TO AROUND 25 KTS AFTER 20-21 UTC. VFR CONDITIONS WITH FEW
CLOUDS THROUGH TONIGHT.

STRONGER WINDS ARE LIKELY FRIDAY AS AN UPPER LOW STARTS TO DROP
TOWARD THE REGION. COULD SEE GUSTS AS HIGH AS 35 KTS IN SOME AREAS
FRIDAY AFTERNOON WITH BLOWING DUST REDUCING VISIBILITIES NEAR THE
SFC IN AREAS EAST OF PRIMARY DUST SOURCES. 20
&&

.FIRE WEATHER...
INCOMING UPPER LEVEL TROUGH OF LOW PRESSURE WITH STRONG JET SUPPORT
PUSHES A DRY SURFACE BOUNDARY SOUTH BY EARLY FRIDAY. WINDS NEAR THE
SURFACE SHOULD INCREASE BY LATE MORNING WITH GUSTS IN THE 30-40 MPH
RANGE BY AFTERNOON...MAINLY NORTH OF HIGHWAY 50. THERE IS A DRY SLOT
ALOFT SHOWING UP AS WELL. THIS DRY AIR SHOULD MIX TO THE SURFACE
RESULTING IN SURFACE RH VALUES LESS THAN 15 PERCENT IN MANY VALLEYS.

THE STRONGEST WINDS AND LOWEST RH VALUES SHOULD BE OVER PORTIONS OF
NORTHEAST CALIFORNIA AND WESTERN AND NORTHWEST NEVADA WHERE CRITICAL
CONDITIONS ARE POSSIBLE BY EARLY FRIDAY AFTERNOON. FUELS HAVE HAD
TIME TO DRY FROM PREVIOUS RAINS OF TWO WEEKS AGO AS WELL. HAVE LEFT
FIRE WEATHER WATCH IN PLACE AND WILL LET DAY SHIFT TAKE A LOOK AT
THIS FOR UPGRADE PURPOSES.

WINDS SHOULD DECREASE LATE FRIDAY NIGHT AS UPPER LEVEL TROUGH SHIFTS
EAST BUT RH VALUES ARE NOT LIKELY TO RECOVER VERY QUICKLY. THERE
COULD BE A BRIEF PERIOD OF GUSTY NORTH WINDS OVER THE FAR NORTHERN
PARTS OF THE FORECAST AREA FRIDAY NIGHT. 20
&&


.REV WATCHES/WARNINGS/ADVISORIES...
NV...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
     NVZ450-453-458.

CA...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING
     CAZ270-278.

&&

$$

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





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