Strong Wind in Nevada, March 6, 2014

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
846 PM PST WED MAR 5 2014

.UPDATE...
AN AREA OF LIGHT RAIN IS SPREADING ACROSS NORTHWEST NEVADA ALONG
AND NORTH OF INTERSTATE 80 THIS EVENING. AMOUNTS ACROSS NORTHWEST
NEVADA WILL BE LESS THAN 0.25 INCH, WITH MUCH HIGHER AMOUNTS ALONG
THE SIERRA CREST. GOOD INSTABILITY AND UPSLOPE FLOW HAS PRODUCED
SEVERAL THUNDERSTORMS ALONG THE WESTERN SLOPES NORTH OF INTERSTATE
80. THE STORMS ARE WEAKENING AS THEY CROSS THE SIERRA CREST BUT
STILL PRODUCING HEAVY RAIN IN WESTERN LASSEN AND EASTERN PLUMAS
COUNTIES. SNOW LEVELS APPEAR TO BE ABOVE 8000 FEET BASED ON
PROFILER AND RADAR DATA IN THE SACRAMENTO VALLEY. HOWEVER HEAVIER
SHOWERS COULD DROP SNOW LEVELS AS LOW AS 7500 FEET.

THE RIDGE WINDS AROUND TAHOE HAVE DROPPED OFF ABOUT 20 MPH OVER
THE LAST COUPLE HOURS WITH GUSTS NEAR AND BELOW 60 MPH. WILL NEED
TO WAIT UNTIL MIDNIGHT OR SO FOR THE FRONT TO APPROACH THE TAHOE
BASIN BEFORE ADVISORY LEVEL WINDS CAN MIX DOWN IN THE RENO-CARSON
AREA. THE CURRENT NORTH TO SOUTH PRESSURE GRADIENT TAKES AWAY
FROM THE DOWNSLOPE POTENTIAL ALONG HIGHWAY 395, THOUGH WILL HELP
FUNNEL WINDS THROUGH NORTH-SOUTH VALLEYS AND NEAR THE RENO
AIRPORT. FARTHER NORTH, WINDS ARE GUSTING UP TO 50 MPH IN THE
SURPRISE VALLEY, WHERE THE FRONT SHOULD PASS JUST AFTER MIDNIGHT.
BRONG

&&

.SYNOPSIS...

A FAST MOVING STORM SYSTEM WILL BRING RAIN TO THE SIERRA AND EASTERN
CALIFORNIA TONIGHT, WITH PRECIPITATION ENDING ON THURSDAY. STRONG
GUSTY WINDS WILL OCCUR ACROSS THE REGION TONIGHT AND THURSDAY.
DRY CONDITIONS WILL CONTINUE FRIDAY AND SATURDAY BEFORE ANOTHER
WEAK STORM MAY BRING SOME RAIN AND SNOW SUNDAY NIGHT INTO MONDAY.

&&

.PREVIOUS DISCUSSION... /ISSUED 152 PM PST WED MAR 5 2014/

SHORT TERM...

NO SIGNIFICANT CHANGES TO THE ONGOING FORECAST WITH THIS FIRST
STORM TONIGHT AND THURSDAY. MODEL GUIDANCE IS CONSISTENT WITH
PREVIOUS SOLUTIONS AND FORECAST CONFIDENCE IS MEDIUM TO HIGH.

IN THE SIERRA, PERIODS OF RAIN ARE EXPECTED TO DEVELOP TONIGHT AS
COLD FRONT AND UPPER JET APPROACH. RAIN MAY COME DOWN HEAVY AT
TIMES ESPECIALLY CLOSE TO THE CREST. WITH NEARLY ISOTHERMAL
SOUNDINGS BELOW 700MB - SNOW LEVELS WILL BE QUITE HIGH MOST OF
TONIGHT, ABOVE 8000-8500 FEET, LEADING TO SNOW ONLY AT THE HIGHEST
PEAKS. AS COOLER AIR MOVES IN AROUND DAYBREAK THURSDAY SNOW LEVELS
SHOULD FALL INTO THE 6000-7000 FT RANGE BUT PRECIP IS WINDING DOWN
BY THEN. SOME GUIDANCE SHOWS A SECONDARY WAVE HELPING REGENERATE
SHOWERS ALONG THE SIERRA NORTH OF MARKLEEVILLE THURSDAY, WITH SOME
LOCALIZED LIGHT SNOW ACCUMULATIONS ABOVE 6500 FT.

WHILE WE EXPECT SHADOWING IN THE LEE OF THE SIERRA WITH LIMITED
OBVIOUS FORCING FOR SPILLOVER, THE RECENT HRRR RUNS AND TO A
LESSER EXTENT ECMWF SHOW SOME OCCURRING BETWEEN 3-9Z. WE'RE SIDING
WITH THE MORE SHADOWED SOLUTIONS RIGHT NOW, BUT I JUST WANTED TO
NOTE THIS SPILLOVER IS A SLIGHT POSSIBILITY AND WORTH KEEPING AN
EYE ON.

PERHAPS THE BIGGER ISSUE WITH THIS STORM IS WIND IN THE LEE OF
THE SIERRA. RECENT GUIDANCE IS CONSISTENT IN SHOWING WINDS
INCREASING TONIGHT AS MOUNTAIN TOP FLOW NEARS 50 KNOTS. POTENTIAL
FOR SOME DOWNSLOPING ENHANCEMENT OF WINDS TONIGHT INTO THE 50-60
MPH RANGE FROM SURPRISE VALLEY TO RENO/MINDEN THEREFORE WILL
CONTINUE THE WIND ADVISORY. BUT FORECAST CONFIDENCE IN THIS IS
ONLY MEDIUM AS PREDICTABILITY OF THESE DOWNSLOPE EVENTS IS
NORMALLY TRICKY AT BEST. EVEN JUST SUBTLE CHANGES IN LAPSE RATES
ALOFT AND/OR WIND DIRECTION CAN ALTER THE OUTCOME. BEHIND THE
FRONT ON THURSDAY, GOOD MIXING AND A SOLID PRESSURE GRADIENT WILL
YIELD WIDESPREAD STRONG WINDS WITH GUSTS ON THE ORDER OF 40-50 MPH
ACROSS MUCH OF THE REGION. WILL EXTEND THE WIND ADVISORY FROM
SURPRISE VALLEY-RENO/MINDEN THROUGH TOMORROW TO ACCOUNT FOR THIS.
LAKE WIND ADVISORIES WILL ALSO BE POSTED FOR TAHOE/PYRAMID.

WINDS SHOULD SUBSIDE QUICKLY THURSDAY NIGHT AS HIGH PRESSURE
MOVES IN. FRIDAY/SATURDAY LOOK QUIET. DAYTIME TEMPS ON FRIDAY WILL
COOL INTO THE 50S (SEASONABLE) BUT THEN WARM INTO THE 60S SATURDAY
AS RIDGE BUILDS IN ALOFT WITH MOSTLY SUNNY SKIES. TEMPS SATURDAY
MORNING WILL BE THE COOLEST WE'VE SEEN IN ABOUT A WEEK - WITH
UPPER 20S IN WESTERN NV VALLEYS AND UPPER TEENS IN THE SIERRA
VALLEYS. CS

LONG TERM...

AN UPPER LEVEL TROUGH ACROSS THE EASTERN PACIFIC WILL PROVIDE A
CHANCE FOR RAIN AND HIGH SIERRA SNOWFALL SUNDAY INTO MONDAY NEXT
WEEK. RECENT MODEL GUIDANCE IS IN REASONABLE AGREEMENT IN DRAWING
A SUBTROPICAL MOISTURE PLUME ACROSS NORTHERN CALIFORNIA SUNDAY BUT
HAVE TRENDED SLOWER WITH THE PRECIPITATION ONSET. MAIN CHANGES TO
THE EXTENDED FORECAST WERE TO DECREASE POPS SUNDAY AND INCREASE
POPS MONDAY TO REFLECT THE DELAY. PRECIPITATION WILL BEGIN AS
EARLY AS SUNDAY MORNING MAINLY NORTH OF THE TAHOE BASIN INTO
LASSEN COUNTY. THIS LOOKS TO BE ANOTHER WARM SYSTEM WITH SNOW
LEVELS AROUND 8500 FEET SUNDAY FALLING TO 7500 ON MONDAY AS A JET
AND SURFACE FRONT MOVE THROUGH THE SIERRA AND WESTERN NEVADA. THIS
WILL ALLOW PRECIPITATION TO SPILL OVER INTO WESTERN NEVADA DURING
THE DAY ON MONDAY AS THE FRONT PASSES. STILL SOME MODEST
DISCREPANCIES IN RESOLVING THE SHORTWAVE'S PROGRESSION AMONGST
DETERMINISTIC GUIDANCE AND PUT FORECASTER CONFIDENCE AT MEDIUM
WITH THIS SYSTEM.

SHOWERS DIMINISH THROUGH MONDAY EVENING WITH LOWER FORECASTER
CONFIDENCE HEADING INTO NEXT WEEK WEDNESDAY. MEDIUM RANGE MODELS
AGREE ON A DRIER PERIOD THROUGH MIDWEEK BUT STILL HAVE SUBSTANTIAL
DIFFERENCES BEGINNING TUESDAY. THE GFS SHOWS A SHORTWAVE CUTTING
ACROSS NORTHERN NEVADA WHILE THE EC BUILDS A SHORTWAVE RIDGE. HAVE
SIDED TOWARDS THE EC AS SEVERAL GEFS MEMBERS KEEP THE TRACK OF THE
SHORTWAVE FURTHER NORTH AND HAVE KEEP US DRY IN THE FORECAST AS A
RESULT. OVERALL, LOOKING FOR MILD TEMPERATURES IN THE EXTENDED
FORECAST WITH HIGHS IN THE UPPER 60S BY SUNDAY ACROSS WESTERN
NEVADA AND BACK INTO THE UPPER 50S TUESDAY AFTER THE PASSAGE OF
THE FRONT. FUENTES

AVIATION...

PRIMARY FORECAST CONCERN IS STRONG WINDS BOTH AT THE SURFACE AND
ALOFT THROUGH THURSDAY. PERIODS OF MODERATE TO HEAVY RAINS LIKELY
FOR THE SIERRA AS WELL. OVERALL FORECAST CONFIDENCE IN THE TAFS IS
MEDIUM TO HIGH.

FOR RNO/CXP - S/SW WINDS TO INCREASE LATE THIS AFTERNOON AND
TONIGHT, WITH GUSTS 25-35 KTS. DOWNSLOPE ENHANCEMENT AT RNO IS
POSSIBLE, 30% CHANCE, WHICH COULD BRING GUSTS ABOVE 40 KTS AND
ERRATIC WIND DIRECTIONS AT TIMES BETWEEN 4Z-8Z TONIGHT. LLWS AND
TURBULENCE IS LIKELY TONIGHT ON APPROACH/DEPARTURE ROUTES WITH
SLIDE MOUNTAIN (10KFT MSL) FORECAST WINDS OF 50 KTS AND GUSTS TO
75 KTS. THURSDAY IS LOOKING TO BE A SOLID GRADIENT WIND DAY WITH
WIDESPREAD GUSTS 30-35 KTS. WINDS FORECAST TO SWITCH FROM S/SW TO
W/NW AFTER 18Z AS COLD FRONT MOVES IN. NO CIG/VSBY RESTRICTIONS
EXPECTED FROM PRECIPITATION AS THE LEE OF SIERRA SHOULD LARGELY BE
SHADOWED THOUGH THERE IS A SLIGHT CHANCE (20%) OF SOME SPILLOVER
SHOWERS BETWEEN 4-8Z.

FOR TRK/TVL - WHILE S/SW WINDS WILL BE GUSTY AT TIMES, MAIN ISSUE
IS PERIODS OF MVFR/IFR CIGS, VSBY, AND MOUNTAIN TOP OBSCURATION
DUE TO RAIN AFTER 3Z TONIGHT. FREEZING LEVELS WILL BE QUITE HIGH
TONIGHT, ABOVE 8000 FT MSL, LEADING TO RAIN AT TRK/TVL. A
RAIN/SNOW MIX IS POSSIBLE AFTER 12Z/THURSDAY AS STORM IS WINDING
DOWN. STRONG WINDS ALOFT WILL PRODUCE TURBULENCE AND LLWS IN THE
VICINITY OF BOTH TRK/TVL TONIGHT.

FOR MMH - TERMINAL IS ON THE PERIPHERY OF THIS INCOMING STORM
THOUGH GUSTY W/SW WINDS ARE LIKELY TONIGHT INTO THURSDAY WITH
TURBULENCE AND LLWS LIKELY. RAIN/SNOW SHOWERS ARE POSSIBLE
12-18Z/THURSDAY BUT THEY SHOULD BE LIGHT ENOUGH TO PRECLUDE
CIG/VSBY RESTRICTIONS. MOUNTAIN TOP OBSCURATION IS A GIVEN THOUGH.

CS

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY FROM 6 AM TO 6 PM PST THURSDAY FOR PYRAMID
     LAKE IN NVZ004.

     WIND ADVISORY UNTIL 4 PM PST THURSDAY NVZ003-005.

     LAKE WIND ADVISORY UNTIL 6 PM PST THURSDAY FOR LAKE TAHOE IN
     NVZ002.

CA...WIND ADVISORY UNTIL 4 PM PST THURSDAY CAZ070.

     LAKE WIND ADVISORY UNTIL 6 PM PST THURSDAY FOR LAKE TAHOE IN
     CAZ072.

&&

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