FXUS65 KREV 240348 AAA
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
848 PM PDT WED MAY 23 2012

.UPDATE...
QUICK UPDATE TO EXPIRE LAKE WIND ADVISORY FOR PYRAMID LAKE. WINDS
ARE SLOWLY DIMINISHING ACROSS WESTERN NEVADA THIS EVENING AND WILL
CONTINUE TO DO SO. THE REST OF THE FCST LOOKS IN GOOD SHAPE FOR
THE OVERNIGHT HOURS. AS FOR TOMORROW, WIND EVENT STILL LOOKS ON
TRACK ALTHOUGH SUSTAINED WIND SPEEDS WILL LIKELY NEED TO BE
INCREASED. GRADIENT WIND EVENT TYPICALLY LESS GUSTY WITH STRONGER
SUSTAINED WINDS, SIMILAR TO WHAT OCCURRED YESTERDAY. WILL NOT MAKE
ANY CHANGES NOW AND LET MID SHIFT TAKE ANOTHER QUICK LOOK AT THAT.
WALLMANN

&&

.PREVIOUS DISCUSSION... /ISSUED 314 PM PDT WED MAY 23 2012/

SHORT TERM...
MAIN FORECAST ADJUSTMENTS IN THE SHORT TERM INCLUDE: LOWERING SNOW
LEVEL A BIT MORE FRIDAY NIGHT AND SATURDAY (ESPECIALLY RENO-TAHOE
NORTH) AND INCREASING WINDS THURSDAY. THE FORECAST THROUGH MONDAY
INCLUDE A WINDY/DRY DAY TOMORROW AND THEN MUCH COLDER WITH RAIN AND
SNOW FRIDAY INTO SATURDAY FOLLOWED BY MUCH MILDER CONDITIONS BY
SUNDAY AND MONDAY.

ON THURSDAY AFTERNOON A COLD UPPER DISTURBANCE CURRENTLY OVER THE
GULF OF ALASKA WILL MOVE TO NEAR THE SOUTHERN OREGON COAST. TO THE
SOUTH OF THE LOW CORE, A 110-120 KT JET STREAK WILL MOVE OVER THE
NORTHERN SIERRA AND WESTERN NEVADA. UNDER THE JET STREAK, A DRY
SLOT WILL MOVE OVER THE SIERRA AND WESTERN/WEST-CENTRAL NEVADA IN
THE AFTERNOON AS STRONG WINDS ENSUE CARE OF A DEVELOPING SURFACE LOW
OVER CENTRAL AND EASTERN NEVADA. THIS WILL SET THE STAGE FOR ANOTHER
DRY AND WINDY DAY WITH FIRE WEATHER CONCERNS. SEE THE FIRE DISCUSSION
BELOW FOR DETAILS OF WINDS AND HUMIDITIES ON THURSDAY.

THURSDAY NIGHT AND FRIDAY, THE AFOREMENTIONED COLD UPPER LOW WILL
DROP OVER NORTHERN CALIFORNIA AND WESTERN NEVADA. AHEAD OF THE LOW
THURSDAY AFTERNOON AND EVENING THERE IS STILL A LOW CHANCE FOR A
THUNDERSTORM OR TWO NORTH OF SUSANVILLE AND GERLACH AS THE LEFT
EXIT REGION OF THE JET STREAK, COOLING TEMPS ALOFT, AND CONVERGENCE
ALONG A FRONTAL BOUNDARY ENCOURAGE CONVECTIVE DEVELOPMENT.

ON FRIDAY, MANY MODEL RUNS HAVE MOVED THE CORE OF THE UPPER LOW FROM
BETWEEN THE CENTRAL VALLEY-CALIFORNIA COAST TO BETWEEN THE CENTRAL
VALLEY-SIERRA FOOTHILLS. THIS IS KEY AS IT WILL BOTH BRING COLDER
AIR ALOFT INTO THE SIERRA AND FAR WESTERN NEVADA AND INCREASE THE
DEFORMATION AXIS FORCING ON THE EAST SIDE OF THE UPPER LOW. THIS
MEANS A BIT LOWER SNOW LEVELS OVER FAR WESTERN NEVADA AND NORTHEAST
CALIFORNIA THURSDAY NIGHT AND FRIDAY AS WELL AS EVER INCREASING
CHANCES FOR A SOLID RAIN/SNOW SHIELD ON THE NORTH SIDE OF THE
LOW`S DEFORMATION AXIS. THEREFORE, I HAVE NUDGED UP POP A BIT MORE
OVER WESTERN NEVADA AND NORTHEAST CALIFORNIA ON FRIDAY. AS FAR AS
SNOW LEVELS, NOTE THAT ARE NOW NEAR OR BELOW 5000 FEET NORTH AND
WEST OF RENO FRIDAY MORNING AND ONLY RISE TO AROUND 6000 FEET IN
THE AFTERNOON. HOWEVER, IT IS UNLIKELY THAT THE SNOW WILL HAVE MUCH
IMPACT BELOW 5500-6000 FEET (AND THEN ONLY NORTH OF TAHOE) FRIDAY
MORNING WITH NO IMPACT ANYWHERE BY FRIDAY AFTERNOON AS THE SUN WARMS
ROADS (EVEN IF IT IS CLOUDY).

FRIDAY NIGHT, WRAP AROUND PRECIP WILL CONTINUE AS THE UPPER LOW SLOWLY
PIVOTS INTO CENTRAL NEVADA. IF ANY PRECIP REMAINS FRIDAY NIGHT, THERE
COULD BE A LIGHT ACCUMULATION FOR HIGHER PASSES AFTER 9-10 PM. SNYDER

LONG TERM...SATURDAY THROUGH WEDNESDAY...
FOR SATURDAY, WRAP AROUND MOISTURE WILL CONTINUE OVER THE SIERRA
AND WESTERN NV WITH MAX TEMPS NOT QUITE AS CHILLY AS FRIDAY, BUT
STILL ABOUT 10 DEGREES BELOW NORMAL WITH 60S IN WRN NV AND LOWER-MID
50S FOR TAHOE. 700 MB TEMPS RANGE FROM -4 TO -6 DEGREES C FOR SAT
MORNING WHICH WOULD KEEP THE POSSIBILITY OF MIXED RAIN AND SNOW DOWN
TO LAKE LEVEL IN THE TAHOE BASIN. ACCUMULATIONS WILL PROBABLY BE
SPARSE AND LIMITED TO UNPAVED SURFACES BELOW 7000 FT SAT MORNING,
WITH SNOW LEVELS RISING ABOVE 7000 FT DURING THE AFTERNOON AS COLD
POOL ALOFT DEPARTS TO THE SOUTHEAST. THE REMAINDER OF WESTERN NV AND
EASTERN CA WILL BE CLOUDY WITH BRISK NORTHWEST WINDS AND ISOLATED TO
SCATTERED RAIN SHOWERS. ANY LINGERING PRECIP SAT EVENING WILL
DIMINISH QUICKLY WITH LOSS OF DIURNAL INSTABILITY AND DYNAMICS AS
UPPER LOW EXITS WESTERN NV.

DRY WEATHER AND A WARMING TREND WILL CONTINUE FOR THE REMAINDER OF
THE MEMORIAL DAY WEEKEND AND INTO NEXT WEEK AS UPPER LEVEL RIDGE
REBUILDS OVER THE WESTERN US. THE RIDGE WILL BE RATHER FLAT ON
SUNDAY WITH AREAS OF CIRRUS MAINLY NORTH OF I-80. HIGHS WILL RANGE
FROM THE LOWER TO MID 70S IN WESTERN NV AND MID 60S IN THE TAHOE
BASIN, WHICH IS NEAR NORMAL FOR LATE MAY.

FROM MEMORIAL DAY THROUGH WEDNESDAY, STEADY RISE IN 500 MB HEIGHTS
AND 700 MB TEMPS WILL BRING BACK ABOVE NORMAL TEMPS WITH MOST
VALLEYS PUSHING ABOVE 80 DEGREES MONDAY, THEN WELL INTO THE 80S BY
MIDWEEK. MAX TEMPS MAINLY IN THE 70S ARE EXPECTED EACH DAY IN THE
TAHOE BASIN. COMMON LATE DAY ZEPHYR BREEZES WITH LEE SIDE GUSTS
25-30 MPH ARE EXPECTED MONDAY, WITH WINDS TRENDING LIGHTER FOR
TUES-WED AS RIDGE AMPLIFIES OVER THE WESTERN US. MJD

AVIATION...
VFR CONDITIONS CONTINUE THROUGH THURSDAY. WEST-NORTHWEST WIND GUSTS
AT THE TERMINALS TODAY MAINLY BETWEEN 20-25 KT THEN DECREASING
BETWEEN 02Z-04Z.

COLDER LOW PRESSURE WILL DROP INTO THE PACIFIC NORTHWEST
THURSDAY AND REACH NORTHERN CALIFORNIA/NORTHWEST NEVADA AFTER 00Z
FRIDAY. AHEAD OF THE LOW WEST WINDS WILL INCREASE WITH GUSTS TO
30-35 KTS AT THE TERMINALS THURSDAY AFTERNOON/EVENING.

THE BEST POTENTIAL FOR SHOWERS WITH POSSIBLE NARROW BAND OF STEADIER
WRAP AROUND RAIN OR SNOW IS EXPECTED BETWEEN 12Z FRI AND 06Z SAT.
WHEN PRECIP IS OCCURRING, MVFR CONDITIONS WILL BE POSSIBLE AT TIMES
IN WESTERN NV WITH IFR VSBY/CIGS AT KTVL, KTRK AND KMMH. MJD

FIRE WEATHER...
BREEZY WINDS CONTINUE TODAY BUT WITH PEAK GUSTS BETWEEN 30 TO 35
MPH. WINDS SHOULD DECREASE OVERNIGHT WITH LIGHT NORTH FLOW ACROSS
THE REGION BEFORE WINDS INCREASE SIGNIFICANTLY THURSDAY.

AN ALMOST WINTER LIKE SYSTEM WILL DROP INTO THE PACIFIC NORTHWEST
THURSDAY AND REACH NORTHEAST CALIFORNIA/NORTHWEST NEVADA EARLY
FRIDAY MORNING. AHEAD OF THE SYSTEM MUCH DRIER AIR WILL REACH THE
SIERRA AND WESTERN NEVADA EARLY THURSDAY MORNING, WITH INCREASING
AFTERNOON WINDS. MAIN AREA OF CONCERN IS ALONG AND SOUTH OF
INTERSTATE 80 WHERE PEAK AFTERNOON GUSTS SHOULD REACH 40-45 MPH, WITH
LOCALLY HIGHER GUSTS UP TO 50 MPH SOUTH OF TOPAZ LAKE-HAWTHORNE. A
RED FLAG WARNING IS IN EFFECT FOR THE TAHOE BASIN, WESTERN NEVADA
BASIN AND RANGE, WESTERN NEVADA SIERRA FRONT, MINERAL, AND SOUTHERN
LYON AND MONO COUNTIES. CRITICAL CONDITIONS EXPECTED WITH HIGH
CONFIDENCE OF GUSTS 40 TO 45 MPH FOR THOSE AREAS LISTED IN THE RED
FLAG WARNING. AFTERNOON HUMIDITY IS EXPECTED TO LOWER TO BETWEEN
10 TO 15% FOR WESTERN NEVADA, WHILE THE TAHOE BASIN WILL BE BETWEEN
15 TO 20%.

AS THE LOW DROPS INTO NORTHERN CALIFORNIA FRIDAY, MODELS HAVE BEEN
CONSISTENT IN DEVELOPING A BAND OF RAIN AND SNOW NORTH OF US-50.
UNDER THIS BAND WETTING RAINS ARE LIKELY NORTH OF US-50, THOUGH SOME
RAIN/SNOW WILL IMPACT AREAS SOUTH OF US-50. THE LOW MAY NOT MOVE OUT
OF THE AREA UNTIL LATE SATURDAY, WHICH COULD ALLOW THE SYSTEM TO
PRODUCE HIGH END RAINFALL AMOUNTS NEAR 0.75 INCHES. BRONG/LINDAMAN

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY UNTIL 9 PM PDT THIS EVENING FOR PYRAMID LAKE
     IN NVZ004.

     LAKE WIND ADVISORY FROM 2 PM TO 9 PM PDT THURSDAY FOR PYRAMID
     LAKE IN NVZ004.

     RED FLAG WARNING FROM 11 AM TO 11 PM PDT THURSDAY NVZ450-453-459.

     LAKE WIND ADVISORY FROM NOON TO 11 PM PDT THURSDAY FOR LAKE
     TAHOE IN NVZ002.

CA...RED FLAG WARNING FROM 11 AM TO 11 PM PDT THURSDAY CAZ272-273.

     LAKE WIND ADVISORY FROM NOON TO 11 PM PDT THURSDAY FOR LAKE
     TAHOE IN CAZ072.

&&

$$

HTTP://WEATHER.GOV/RENO