Wildfire and High Wind in California, February 6 to 12, 2015

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
707 PM PST THU FEB 5 2015

.UPDATE...
RADAR/SATELLITE TRENDS SHOW THE FIRST PART OF THIS WARM PACIFIC
STORM MOVING INTO NW CA AT THIS TIME. THERE ARE A FEW LIGHT
RETURNS SHOWING UP ON RADAR OVER NORTH CENTRAL CA...BUT THESE DO
NOT APPEAR TO BE REACHING THE GROUND YET. LATEST NAM GUIDANCE IS A
LITTLE SLOWER THAN PREVIOUSLY INDICATED WITH BRINGING MOST OF THE
PCPN IN TO OUR FORECAST AREA LATE TONIGHT. DECREASED POPS JUST
SLIGHTLY IN LINE WITH THIS LATEST GUIDANCE...BUT IT DOES NOT
CHANGE THE FORECAST THAT MUCH.

.HYDROLOGY...
LATEST MODEL GUIDANCE CONTINUES THE TREND OF BRINGING PERIODS OF
HEAVY PCPN INTO NORTHERN CA STARTING FRIDAY THEN SLIDING THIS
HEAVIER PCPN DOWN THE SPINE OF THE SIERRA THROUGH SATURDAY
EVENING. HIGH SNOW LEVELS WILL PROMOTE MORE RAIN THAN SNOW IN THIS
SYSTEM AND THE PERIODS OF HEAVIEST PCPN COULD PRODUCE ENOUGH HEAVY
RAIN TO INCREASE RUN OFF AND ELEVATE SMALL STREAMS...ESPECIALLY
FROM THE CARSON RIVER BASIN NORTH INTO NORTHEAST CA. THERE ARE
SOME THINGS THAT MAY LIMIT STREAM RISES...CHIEF AMONG THESE ARE
DRY SOILS AND ANTECEDENT VERY LOW FLOWS. STILL...WITH UPWARDS OF
2 TO 4 INCHES OF LIQUID POSSIBLE IN THE SIERRA AND CENTRAL PLUMAS
AND WESTERN LASSEN COUNTIES...SOME NEAR BANKFULL FLOWS ARE LIKELY
ON THE SMALLER STREAMS WITH ELEVATED FLOWS ON THE MAIN RIVERS.

WHILE NO SIGNIFICANT FLOODING CONCERNS EXIST AT THIS TIME...IT
WILL BE IMPORTANT FOR ANYONE NEAR SMALL STREAMS FROM MARKLEEVILLE
NORTH THROUGH THE TAHOE BASIN AND INTO NORTHEAST CA TO BE ALERT TO
THE POSSIBILITY OF RISING WATERS FROM LATE FRIDAY NIGHT THROUGH
SATURDAY.

THE SECOND SYSTEM SUNDAY NIGHT INTO MONDAY...WHILE LESS POTENT...
WILL BE MOVING ACROSS ALREADY SATURATED SOILS AND COULD CAUSE
MORE RAPID RISES EVEN WITH LESS RAINFALL.

WHILE WE DO NOT PLAN ANY FLOOD WATCHES AT THIS TIME...WE WILL BE
CAREFULLY MONITORING THE SITUATION AS THE RAIN STARTS FRIDAY AND
BECOMES HEAVY FRIDAY NIGHT INTO SATURDAY MORNING. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 305 PM PST THU FEB 5 2015/

SYNOPSIS...

A STRONG PACIFIC STORM WILL AFFECT THE REGION OVER THE NEXT COUPLE
DAYS WITH VERY STRONG WINDS BY FRIDAY. RAIN WILL BEGIN FRIDAY
MORNING OVER NORTHEAST CALIFORNIA WITH A PERIOD OF HEAVY RAIN AND
HIGH ELEVATION SNOW ALONG THE SIERRA CREST FRIDAY INTO SATURDAY
MORNING. AFTER A BRIEF BREAK SUNDAY ANOTHER STORM IS LIKELY SUNDAY
AND MONDAY WITH ADDITIONAL RAIN AND HIGH ELEVATION SNOW.

SHORT TERM...

PACIFIC STORM AND ASSOCIATED ATMOSPHERIC RIVER (AR) WILL CONTINUE TO
PUSH INLAND OVER THE NEXT COUPLE DAYS, BRINGING STRONG WINDS THROUGH
FRIDAY AND PERIODS OF HEAVY RAIN AND HIGH ELEVATION SNOW TO THE
SIERRA. GUSTY WINDS TODAY HAVE MIXED OUT THE VALLEYS WITH RENO
HITTING 70 DEGREES EARLIER THIS AFTERNOON. THIS BREAKS THE PREVIOUS
RECORD FOR THE DATE. THE PREVIOUS RECORD WAS 69 DEGREES SET BACK IN
1995. THERE HAVE ONLY BEEN THREE INSTANCES WHEN TEMPERATURES HAVE
HIT 70 DEGREES THIS EARLY OR EARLIER IN THE CALENDAR YEAR SINCE
RECORDS BEGAN IN RENO BACK IN 1893.

HERE ARE THE MAJOR UPDATES MADE TO THE FORECAST SINCE YESTERDAY...

*UPGRADED THE HIGH WIND WATCH FOR FRIDAY TO A HIGH WIND WARNING
FOR AREAS FROM NORTHERN WASHOE COUNTY SOUTH THROUGH MONO COUNTY. A
BLOWING DUST ADVISORY HAS BEEN ISSUED FOR PERSHING, CHURCHILL,
MINERAL, AND SOUTHERN LYON COUNTY FOR FRIDAY.

*SLOWED THE ONSET OF PRECIPITATION ON FRIDAY AS THE SYSTEM'S ARRIVAL
HAS BEEN TRENDING SLOWER BY ROUGHLY SIX HOURS. BULK OF THE
PRECIPITATION ACROSS THE SIERRA SHOULD OCCUR FRIDAY EVENING INTO
EARLY SATURDAY MORNING. ALSO DECREASED QPF EAST OF CREST WITH A
SHARPER WEST-EAST GRADIENT OCCURRING ON FRIDAY.

*CONTINUED TO INCREASE QPF AMOUNTS ALONG THE SIERRA CREST FOR TAHOE,
ALPINE, AND MONO COUNTIES AS MODELS TREND WETTER AND LONGER DURATION
FRIDAY NIGHT AND INTO SATURDAY AFTERNOON.

*SNOW LEVELS HAVE BEEN INCREASED FOR FRIDAY NIGHT INTO SATURDAY,
WITH THE MAJORITY OF THE SNOWFALL ABOVE THE 8000 FEET. SNOW AMOUNTS
FRIDAY THROUGH SATURDAY WILL BE ANYWHERE FROM 1 TO 2 FEET IN THE
SIERRA ABOVE 8000 FEET AND UP TO 3 FEET ALONG THE SIERRA CREST ABOVE
8500 FEET.

***STRONG WINDS TONIGHT, STRONGER DOWNSLOPE WINDS FRIDAY***

STRONG WINDS ARE ALREADY STARTING TO SURFACE IN THE EASTERN SIERRA
AND WESTERN NEVADA TODAY WITH GOOD MIXING, AS EVIDENCED BY OUR
RECORD HIGH TEMPERATURE IN RENO TODAY. 700MB WINDS HAVE INCREASED TO
AROUND 50KTS TODAY AND WILL CONTINUE TO INCREASE OVERNIGHT AND INTO
FRIDAY AS THE JET MOVES INTO NORTHERN CA. MODEL CROSS SECTIONS ARE
SHOWING A WELL DEVELOPED DOWNSLOPE WIND SIGNATURE IN THE LEE OF THE
SIERRA THAT WILL RESULT IN VERY STRONG AND DAMAGING WIND GUSTS
FRIDAY MORNING THROUGH FRIDAY NIGHT ALONG THE SIERRA FRONT. HIGH
WIND WARNINGS ARE IN PLACE, DUE TO EXPECTED WIDESPREAD WIND GUSTS UP
TO 60-70 MPH WITH POTENTIAL FOR LOCALIZED GUSTS 80+ MPH IN WIND
PRONE AREAS ALONG HIGHWAY 395. RIDGE WINDS WILL EASILY EXCEED 100
MPH DURING THIS PERIOD TOMORROW. AS FOR THE BASIN AND RANGE IN
PERSHING-CHURCHILL-MINERAL-SOUTHERN LYON COUNTIES, THE WINDS WILL BE
LESS AROUND 45-55 MPH. A BLOWING DUST ADVISORY HAS BEEN ISSUED FOR
THESE AREAS DUE TO THE IMPACTS OF BLOWING DUST ON THE CARSON AND
HUMBOLDT SINKS FROM THE PROLONGED DRY PERIOD. STRONG WINDS WILL
CREATE LOW VISIBILITY CONDITIONS ON HIGHWAY 50, 95, AND INTERSTATE
80 EAST OF RENO/CARSON CITY.

***PRECIPITATION/SNOW LEVEL FRIDAY/FRIDAY NIGHT***

MOISTURE PLUME IS ALREADY PUSHING INTO NORTHWESTERN CALIFORNIA
TODAY, AS EVIDENCED ON RADAR. THIS WILL PUSH INTO THE NORTHERN
SIERRA FRIDAY AFTERNOON, BUT THE BULK OF THE PRECIPITATION IS STILL
EXPECTED FRIDAY NIGHT INTO SATURDAY. THIS STORM HAS AN IMPRESSIVE
AR, WITH OVER 1.5" PRECIPITABLE WATER PUSHING INLAND FRIDAY NIGHT.
THIS STORM WILL PUSH A SOLID AMOUNT OF PRECIPITATION INTO THE SIERRA
FRIDAY THROUGH SATURDAY WITH A MORE LIMITED AMOUNT OF RAIN SPILLING
OVER INTO WESTERN NEVADA AFTER THE HIGH WIND EVENT AS THE MID LEVELS
OF THE ATMOSPHERE DESTABILIZE.

MODELS HAVE INCREASED QPF IN MONO COUNTY FRIDAY NIGHT AND EARLY
SATURDAY, AS WELL AS A SECOND PUNCH OF PRECIP IN THE NORTHERN SIERRA
FOR SATURDAY AFTERNOON AS WELL. WE'VE INCREASED QPF IN MOST OF THE
SIERRA FOLLOWING THESE TRENDS, WITH PRECIP AMOUNTS IN THE SIERRA
WILL BE ANYWHERE FROM 1.5" TO 3" OF RAINFALL FRIDAY THROUGH SATURDAY
AFTERNOON WITH LOCALLY UP TO 4 INCHES OF PRECIP ALONG THE CREST.

SNOW LEVELS WILL LIKELY FLUCTUATE BETWEEN 7500-8500 FEET DURING THE
EVENT WITH SOME SIGNIFICANT SNOWFALL IN THE HIGH SIERRA ABOVE 8500
FEET. SNOW AMOUNTS ABOVE 8000 FEET WILL BE UP TO 2 FEET OF HEAVY WET
SNOW, WITH LOCALIZED AMOUNTS OF 3+ FEET POSSIBLE ALONG THE SIERRA
CREST. SNOW RATIOS WILL BE A HEAVY AND WET SIERRA CEMENT...AROUND
7-8:1 OR SO. THE IMPACTS TO SIERRA HIGHWAYS WILL BE LOCALIZED TO THE
HIGHEST PASSES INCLUDING MOUNT ROSE SUMMIT, LUTHER PASS, CARSON PASS
AND CONWAY SUMMIT. ALTHOUGH, IF SNOW LEVELS DROP BY ABOUT 500 FEET,
DONNER SUMMIT AND ECHO SUMMIT MAY BE IMPACTED BY A FEW INCHES OF
HEAVY WET SLUSH AS WELL. IN THE DESERT VALLEYS OF NORTHEASTERN
CALIFORNIA AND WESTERN NEVADA, PRECIP AMOUNTS WILL BE MUCH LESS,
GENERALLY 0.25" TO 0.50" ALONG THE HIGHWAY 395 CORRIDOR AND LESSER
AMOUNTS AS YOU MOVE EAST.

RAINFALL DURING THE EARLY MORNING HOURS SATURDAY WILL LIKELY CAUSE
RISES IN AREA STREAMS AND RIVERS. NO FLOODING OF MAINSTEM RIVERS IS
EXPECTED, ALTHOUGH A FEW SMALL STREAMS IN THE SIERRA COULD PRODUCE
MINOR FLOODING BY SATURDAY MORNING. HOON

SUNDAY AND MONDAY...MAINLY MINOR ADJUSTMENTS WERE MADE TO THESE TWO
DAYS THAT ENCAPSULATE THE NEXT PASSING SYSTEM. THIS SYSTEM IS MORE
BAROCLINIC THAN THE FRIDAY/SATURDAY PORTION OF THE ATMOSPHERIC
RIVER. AS A RESULT OF THIS INCREASE IN BAROCLINICITY, FORCING IS
STRONGER AND PRECIPITATION SPILL-OVER INTO WESTERN NEVADA APPEARS
MORE FAVORABLE. AS SUCH, HAVE INCREASED PRECIPITATION CHANCES ALONG
THE CREST INTO WESTERN NEVADA. MODELS SEEM CONTINUE A HIGHER
PRECIPITATION EFFICIENCY DUE TO THE SUBTROPICAL TAP. STILL, 4 INCHES
OF LIQUID EQUIVALENT SEEMS OVERDONE CONSIDERING THE SPEED OF THIS
SYSTEM WHICH HAS TRENDED MORE PROGRESSIVE OVER THE LAST FOUR RUNS.
SETTLED ON ANOTHER 1.5 TO 2.5 INCHES OF LIQUID AT THE CREST OVER THE
2-DAY PERIOD AS A FIRST ESTIMATE.

AS FOR WESTERN NEVADA, TOTALS WILL TAPER DOWN TO AROUND 0.5-1 INCH
ALONG THE SIERRA FRONT WITH 0.10-0.25 INCHES WEST OF THE VIRGINIA
RANGE AND MAINLY A FEW HUNDREDTHS POSSIBLE OUT INTO THE GREAT BASIN.
WE COULD SEE MORE IF THE LOW SLOWS, BUT WILL START WITH THESE
TOTALS. THIS ADDITIONAL PRECIPITATION SHOULD HAVE AN IMPACT ON LOCAL
STREAM FLOWS WHICH WILL RESPOND MORE QUICKLY THAN FRIDAY AND
SATURDAY. THIS RESPONSE COULD BRIEFLY PUSH A FEW STREAMS OVER THEIR
BANKS, BUT DUE TO THE DRYNESS OF THE GROUND ONLY MINOR
INCONVENIENCES ARE EXPECTED.

THE HIGHEST ELEVATIONS COULD DO VERY WELL WITH SNOW, BUT ONLY ABOVE
8000 FEET INITIALLY. DID LOWER SNOW LEVELS MORE QUICKLY SUNDAY NIGHT
INTO MONDAY WITH THE FASTER SOLUTIONS. COULD SEE A DECENT PERIOD OF
SNOW DOWN TO LAKE LEVEL AS COLDER AIR MOVES INTO THE REGION UNDER
THE COLD CORE OF THE LOW LATE SUNDAY/EARLY MONDAY. THIS HAS
IMPLICATIONS FOR AREAS PASSES WHICH MAY BECOME SLICK WITH CHAIN
CONTROLS POSSIBLE. PRELIMINARY ESTIMATES DOWN TO LAKE LEVEL ARE
STILL ONLY A COUPLE TO 4 INCHES CONSIDERING HIGH COMPACTION RATES
BASED ON WET SURFACES. ALSO, LOWERED TEMPERATURES FOR MONDAY WHERE
HIGHS SHOULD COOL INTO THE MID 40S FOR SIERRA VALLEYS AND LOW/MID
50S FOR WESTERN NEVADA. THESE MAY NEED FURTHER ADJUSTMENT LOWER
DEPENDING ON HOW FAST COLDER AIR MOVES INTO THE REGION. BOYD

LONG TERM...TUESDAY THROUGH THURSDAY...

FOR NEXT TUESDAY THROUGH THURSDAY, DRY CONDITIONS RETURN TO THE
REGION AS HIGH PRESSURE REBUILDS OFF THE WEST COAST, THEN MOVES
INLAND OVER WESTERN NV BY THURSDAY. SHORTWAVE DIVING SOUTH ACROSS
EASTERN NV OR UTAH ON TUESDAY WILL BRING COOLER CONDITIONS AS LOW
LEVEL FLOW BECOMES NORTH AND NORTHEAST. HIGHS ON TUESDAY ARE
EXPECTED TO RANGE FROM THE MID 40S FOR THE SIERRA VALLEYS TO LOWER
50S IN WESTERN NV.

INVERSIONS WILL STRENGTHEN WEDNESDAY AND THURSDAY RESULTING IN A
QUICKER WARMING TREND IN HIGHER ELEVATIONS, WITH A SLOW WARMUP
EXPECTED FOR THE LOWER VALLEYS. GENERALLY LIGHT WINDS ARE EXPECTED
BOTH DAYS, EXCEPT FOR A POSSIBLE PERIOD OF INCREASED EAST RIDGE
WINDS ACROSS THE SIERRA ON WEDNESDAY. MJD

AVIATION...

SIGNIFICANT WIND-RELATED AVIATION CONCERNS WILL BE PRESENT TONIGHT
THROUGH FRIDAY EVENING, INCLUDING LLWS AND WIDESPREAD TURBULENCE
ESPECIALLY NEAR THE SIERRA. SHEAR INCREASES TONIGHT AS RIDGE LEVEL
WINDS INCREASE FROM THE SOUTHWEST, WHILE SURFACE WINDS PREVAIL FROM
THE SOUTH AND DECREASE SLIGHTLY. THE WORST WINDS WILL OCCUR FRIDAY
AS DOWNSLOPE SIGNATURES BECOME EVIDENT, WITH WIND GUSTS AT AREA
TERMINALS POSSIBLY AROUND 60 KT AT TIMES. THESE WINDS COULD BEGIN
BEFORE DAYBREAK IN THE TAHOE BASIN, THEN SPREAD INTO WESTERN NV AND
MONO COUNTY DURING THE MORNING AND CONTINUE THROUGH THE AFTERNOON.

BY FRIDAY NIGHT, RAIN WILL SPREAD ACROSS THE SIERRA AND THEN INTO
WESTERN NV, LEADING TO WET RUNWAYS AND LOWERING CIGS/VSBY TO MVFR
WITH MOUNTAIN OBSCURATIONS. RAIN MAY BECOME HEAVY ENOUGH FOR IFR
CIGS/VSBY AT KTVL/KTRK. SURFACE WINDS WILL DECREASE, BUT RIDGE LEVEL
WINDS WILL REMAIN STRONG SO SHEAR AND TURBULENCE CONCERNS WILL
CONTINUE. MJD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...HIGH WIND WARNING FROM 4 AM FRIDAY TO 4 AM PST SATURDAY
     NVZ002-003-005.

     WIND ADVISORY UNTIL 4 AM PST FRIDAY NVZ002-003-005.

     BLOWING DUST ADVISORY FROM 4 AM FRIDAY TO 4 AM PST SATURDAY
     NVZ001-004.

     LAKE WIND ADVISORY UNTIL 4 AM PST FRIDAY FOR PYRAMID LAKE IN
     NVZ004.

CA...HIGH WIND WARNING FROM 4 AM FRIDAY TO 4 AM PST SATURDAY
     CAZ070>073.

     WIND ADVISORY UNTIL 4 AM PST FRIDAY CAZ070>073.

&&

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