Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 070406 AAA
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
906 PM PDT WED MAY 6 2015

.UPDATE...
PRECIPITATION BAND MOVING THROUGH THE TAHOE BASIN THIS EVENING
BROUGHT PERIODS OF IFR CIGS/VSBY AT KTVL AS SNOW LEVELS FELL TO
LAKE LEVEL IN THE HEAVIER SHOWERS. ROADS WERE GENERALLY WET BUT
WEBCAMS SHOWED A COUPLE INCHES OF SNOW AT ECHO SUMMIT. MAKE SURE
TO CHECK ROAD CONDITIONS IF HEADING OVER SIERRA PASSES. 00Z MODEL
DATA INCLUDING A HIGH RESOLUTION RUN (HRRR) INDICATE THAT SHOWERS
WILL BE CONFINED MAINLY TO THE NORTHERN SIERRA AND BE LIGHT THE
REST OF THE NIGHT. A QUICK LOOK INTO THU-FRI SUGGESTS THE FORECAST
IS ON TRACK WITH THE GFS/NAM SHOWING THE WRAP AROUND BAND OF RAIN
AND SNOW DEVELOPING THU-THU NIGHT, BUT POSSIBLY LINGERING LONGER
INTO FRIDAY. THE NIGHT SHIFT WILL LOOK MORE INTO THIS AND MAKE ANY
NECESSARY ADJUSTMENTS IN THE MORNING FORECAST PACKAGE.

A TIGHTENING GRADIENT DEVELOPS OVERNIGHT INTO THURSDAY WITH MOS
GUIDANCE IMPRESSIVE AT KLOL (NORTH WINDS 20-30KT). A LAKE WIND
ADVISORY WILL BE NEEDED FOR PYRAMID LAKE ON THURSDAY AND WILL BE
ISSUED WITH THE EARLY MORNING PACKAGE AS WELL. HOHMANN

&&

.PREVIOUS DISCUSSION... /ISSUED 319 PM PDT WED MAY 6 2015/

SYNOPSIS...

LOW PRESSURE DROPPING SOUTH FROM THE PACIFIC NORTHWEST WILL BRING A
COOLING TREND THROUGH TOMORROW, AND INCREASING CHANCES OF SHOWERS
FROM TONIGHT THROUGH FRIDAY, WITH SNOW LIKELY IN THE SIERRA. WARMER
CONDITIONS AND DECREASING SHOWER CHANCES RETURN FOR THE WEEKEND.

SHORT TERM...

A COOLER AND WETTER PATTERN IN STORE AS AN UPPER LOW BEGINS TO DROP
SOUTH FROM THE PACIFIC NORTHWEST. THE CORE OF LOW WILL DROP ACROSS
THE SIERRA THURSDAY MORNING ALLOWING SNOWLEVELS TO DROP NEAR
6,000 FEET MSL. TRAVEL IMPACTS ARE POSSIBLE IN THE SIERRA
PARTICULARLY ACROSS ALPINE AND MONO COUNTIES. SOME PASSES SUCH AS
EBBETTS, SONORA, MONITOR, AND TIOGA WHICH HAVE REOPENED MAY CLOSE
AGAIN THURSDAY-THURSDAY NIGHT AS HEAVIER SNOW BEGINS TO FALL. AS
SUCH, HAVE ISSUED A WINTER WEATHER ADVISORY FOR MONO COUNTY WITH
IMPACTS POSSIBLE THROUGH ALPINE COUNTY AND LESSENING SNOW AMOUNTS
NORTHWARD THROUGH THE TAHOE BASIN WHERE AN INCH OR TWO OF SNOW IS
POSSIBLE. BE SURE TO MONITOR THE LATEST FORECASTS AND ROAD
CONDITIONS IF YOU HAVE TRAVEL PLANS THROUGH THE SIERRA.

FOR THIS EVENING, WILL SEE A SWATH OF SHOWERS WITH ISOLATED STORMS
POSSIBLE ACROSS THE TAHOE BASIN AND EXTENDING INTO WESTERN NEVADA
MAINLY ALONG THE I-80 CORRIDOR THROUGH RENO. EXPECTING SHOWER
ACTIVITY TO LINGER ACROSS THE TAHOE BASIN OVERNIGHT, THEN WILL
BEGIN TO INTENSIFY THROUGH TOMORROW MORNING AS THE LOW DROPS
SOUTH. SNOW LEVELS WILL ALSO RAPIDLY FALL OVERNIGHT AS THE CORE OF
THE LOW MOVES ACROSS THE SIERRA. RAIN WILL BEGIN TO MIX WITH SNOW
BY MORNING BUT THE MAIN FOCUS FOR HEAVIER PRECIP WILL BE ACROSS
ALPINE INTO NORTHERN MONO COUNTY FROM LATE THURSDAY AFTERNOON
INTO EARLY EVENING. ALL TOLD SNOW ACCUMULATIONS OF 4 TO 8 INCHES
ARE POSSIBLE GENERALLY ABOVE 7,000 FEET ACROSS MONO/ALPINE WITH
LOCALLY UP TO 10 INCHES ALONG THE CREST. BELOW 7,000 FEET
ACCUMULATIONS SHOULD BE LIMITED ESPECIALLY WITH TIMING OF THE
HEAVIEST SNOW OCCURRING DURING THE DAYTIME HOURS ALONG WITH
WARMER ROAD SURFACES.

ON FRIDAY, THE LOW TAKES AN EASTWARD TURN ACROSS SOUTHERN NEVADA
WHICH PLACES A BAND OF WRAP AROUND PRECIPITATION NORTH OF THE LOW.
THIS WILL AGAIN PRODUCE A GOOD POTENTIAL FOR MOUNTAIN SNOWFALL AND
VALLEY RAIN ACROSS THE SIERRA PARTICULARLY SOUTH OF HWY 50.
SNOWLEVELS WILL BE A LITTLE HIGHER AROUND 7,500 FEET. ISOLATED
THUNDERSTORMS ARE POSSIBLE DURING THE AFTERNOON WITH THE INCREASED
INSTABILITY WITH PELLET SHOWERS AND SMALL HAIL POSSIBLE WITHIN
CONVECTIVE CELLS. FUENTES

LONG TERM...SATURDAY THROUGH WEDNESDAY...

ONLY MINOR CHANGES WERE MADE TO THE ONGOING FORECAST. UPPER LOW EXITS
THE REGION ON SATURDAY, BUT LINGERING MOISTURE AND INSTABILITY ON THE
BACK SIDE OF IT WILL KEEP CHANCES FOR ISOLATED SHOWERS AND
THUNDERSTORMS IN THE FORECAST FOR AREAS MAINLY SOUTH OF INTERSTATE 80
THROUGH SATURDAY EVENING. A BRIEF PERIOD OF WARMING AND DRYING FOLLOWS
SUNDAY UNDER A SHORTWAVE RIDGE WITH TEMPERATURES RETURNING TO NEAR OR
JUST SLIGHTLY ABOVE NORMAL.

THERE IS DECENT MODEL AGREEMENT THAT ANOTHER COLD LOW WILL DROP INTO
THE NORTHWEST EARLY NEXT WEEK, BUT THERE ARE DIFFERENCES IN EXACTLY HOW
FAR SOUTH THE LOW WILL MAKE IT. THE GFS HAS MAINTAINED A SOUTHERLY
TRACK, DROPPING THE LOW ACROSS THE SIERRA AND NORTHWEST NEVADA TUESDAY.
THE EC HAS BEEN A BIT MORE NORTHERLY, THOUGH THE LATEST 12Z RUN IS
TAKING IT FARTHER SOUTH, WITH SIMILAR PLACEMENT TO THE GFS. FOR NOW
WILL MAINTAIN CHANCES FOR SHOWERS AND AFTERNOON THUNDERSTORMS ALONG
WITH BELOW NORMAL TEMPERATURES FOR THE FIRST HALF OF NEXT WEEK. DJ

AVIATION...

SHOWERS HAVE DEVELOPED ACROSS NORTHEAST CALIFORNIA AND NORTHWEST
NEVADA, MAINLY NORTH OF INTERSTATE 80. THERE HAVE BEEN ISOLATED
THUNDERSTORMS MAINLY ALONG AND WEST OF THE SIERRA CREST, BUT CHANCES OF
A STORM IMPACTING TAF SITES IS LESS THAN 20 PERCENT. THE GREATEST RISK
IS GUSTY NORTHWEST WINDS TO 40 KTS, WHICH HAS BEEN OBSERVED WITH THESE
SHOWERS.

COLD FRONT WILL SHIFT THROUGH THE REGION TONIGHT FOLLOWED BY THE UPPER
LEVEL LOW. THIS WILL BRING ADDITIONAL CHANCES FOR SHOWERS OVERNIGHT WITH
SNOW LEVELS DROPPING TO AROUND 5500 FEET BY THURSDAY MORNING.
ACCUMULATING SNOW IS POSSIBLE FOR SIERRA TERMINALS, WITH THE BEST
CHANCES FOR KMMH AND KBAN. IF SNOW ACCUMULATES ON THE RUNWAY AT KTRK
AND/OR KTVL, IT WILL BE SHORT-LIVED EARLY THURSDAY MORNING, MELTING
DURING THE DAY. LIGHT RAIN SHOWERS ARE EXPECTED ACROSS WESTERN NEVADA,
INCLUDING KRNO AND KCXP. THIS COLD AND MOIST AIRMASS WILL INCREASE
ICING POTENTIAL ALOFT AS WELL.

WEST TO NORTHWEST WINDS TODAY WILL TRANSITION TO THE NORTHEAST BY
THURSDAY MORNING, WITH GUSTS OF 20 TO 30 KTS. DJ

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...WINTER WEATHER ADVISORY FROM 11 AM THURSDAY TO 5 AM PDT FRIDAY
     ABOVE 7000 FEET FOR CAZ073-273.

&&

$$

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


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