Area Forecast Discussion
Issued by NWS Reno, NV

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
000
FXUS65 KREV 250446 AAB
AFDREV

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE RENO NV
946 PM PDT THU APR 24 2014

.UPDATE...
SNOW LEVELS AT LEAST HAVE TEMPORARILY FALLEN TO 5000 TO 5500 FEET
IN WESTERN LASSEN COURTNAY BASED ON OBSERVATIONS AND WEBCAMS. SNOW
IS HAVING A HARD TIME STICKING HOWEVER, EVEN WITH A BIT HIGHER
INTENSITY FROM THE SHOWERS. WITH THIS BAND TO BE SHORT-LIVED AND
OVER BY 11 PM OR SO, AND THE UPSTREAM BAND NOT AS INTENSE, DECIDED
NOT TO ISSUE THE ADVISORY FOR LASSEN/PLUMAS. IT MAY GET SLUSHY AT
TIMES, BUT NOT LOOKING FOR THAT BIG AN IMPACT ON ROADS WITH
EXPECTED INTENSITY. HELP FROM THE METRO ROAD MODEL HELPED AS WELL.
OF COURSE, IF THE INTENSITY IS HIGHER THAN EXPECTED, THE SNOW WILL
OVERCOME THE WARM ROAD TEMPS AND STICK MUCH BETTER. ONLY BELIEVE
THAT TO BE A 10-20% CHANCE OF OCCURRING SO ONLY CHANGE TO THE
CURRENT FORECAST WAS TO LOWER SNOW LEVELS FASTER NORTH OF I-80
TONIGHT. WALLMANN

&&

.PREVIOUS DISCUSSION... /ISSUED 828 PM PDT THU APR 24 2014/

UPDATE...
QUICK UPDATE TO EXPIRE THE LAKE WIND FOR PYRAMID LAKE. WINDS ARE
DIMINISHING ACROSS WESTERN NV THIS EVENING WITH THE LOSS OF
HEATING. DO NOT EXPECT COMPLETE DECOUPLING HOWEVER AS THE WINDS
MOVE IN. STILL EXPECT A FEW GUSTS 40-45 MPH IN WIND PRONE AREAS
OVERNIGHT. WINDS ON TRACK AND HANDLE IT WELL WITH THE TAHOE
ADVISORY GOOD UNTIL 11 PM. WINDS ON THE LAKE ARE STILL 20-25 MPH.

AS FOR PRECIP, SOME THUNDERSTORMS THIS EVENING NEAR CHICO WITH A
BAND OF SHOWERS STRETCHING INTO LASSEN COUNTY AT TIMES. EXPECT
THESE SHOWERS TO BECOME MORE NUMEROUS OVERNIGHT AND SLOWLY PUSH
SOUTH. CURRENT PRECIP FORECAST LOOKS GOOD, BUT THERE IS SOME
UNCERTAINTY WITH HOW MUCH SNOW WILL FALL ACROSS LASSEN/PLUMAS AS
SNOW LEVELS FALL. AT THIS POINT, IT LOOKS TO BE JUST A COUPLE
INCHES, BUT WILL MONITOR TO SEE IF THE SNOW LEVELS FALL FASTER
THIS EVENING. IF SO, WILL HOIST A WINTER WEATHER ADVISORY, BUT
THAT LOOKS UNLIKELY AT THIS TIME. WALLMANN

PREVIOUS DISCUSSION... /ISSUED 243 PM PDT THU APR 24 2014/

SYNOPSIS...
LIGHT PRECIPITATION OVER NORTHERN CALIFORNIA SPREADS EAST AND
SOUTH AND BECOMES HEAVIER OVERNIGHT AND FRIDAY AS LOW PRESSURE
APPROACHES THE CALIFORNIA COAST. A STRONG COLD FRONT WILL MOVE
THROUGH THE REGION FRIDAY, BRINGING WELL BELOW AVERAGE
TEMPERATURES, RAIN AND SNOW, AND HIGHER ELEVATION TRAVEL IMPACTS.
HIGH PRESSURE RETURNS EARLY NEXT WEEK FOR MUCH WARMER AND DRIER
CONDITIONS.

SHORT TERM...
MINIMAL CHANGES WERE MADE IN THE SHORT TERM FORECAST AS FORECAST
MODELS ARE IN BETTER AGREEMENT TODAY THAN PREVIOUS DAYS AND ARE IN
LINE WITH THE TREND THAT DEVELOPED OVERNIGHT. THE GFS HAS TRENDED
TOWARD THE ECMWF SOLUTION...BUT HAS NOT FULLY GONE TO THE ECMWF.

AN INITIAL BURST OF HEAVIER PRECIPITATION SHOULD DEVELOP THIS
EVENING AND OVERNIGHT ACROSS NORTHEAST CALIFORNIA AND FAR
NORTHWEST NEVADA AND SPREAD INTO THE TAHOE BASIN BEFORE SUNRISE.
RELATIVELY HIGH SNOW LEVELS AT THE ONSET OF THE PRECIPITATION
SHOULD KEEP ACCUMULATIONS CONFINED TO THE HIGHER ELEVATIONS MOST
OF THE NIGHT...BUT AS THE SNOW MOVES INTO THE TAHOE BASIN TRAVEL
IMPACTS ARE LIKELY OVER THE HIGHER PASSES. THUS WE HAVE LEFT THE
WINTER WEATHER ADVISORY IN PLACE FOR TAHOE TONIGHT AND FRIDAY. IT
IS HIGHLY LIKELY THAT SNOW WILL STRUGGLE TO ACCUMULATE FRIDAY DUE
TO SURFACE HEATING BROUGHT ON BY A HIGHER LATE APRIL SUN
ANGLE...BUT PRECIPITATION RATES WILL INCREASE AGAIN IN THE SECOND
BURST FRIDAY EVENING.

AHEAD OF THE FIRST BURST OF PRECIPITATION...GUSTY WINDS WILL
CONTINUE ALONG AND EAST OF THE SIERRA THIS EVENING AND OVERNIGHT.
MID LEVEL FLOW PEAKS IN THE LATE EVENING. WHILE THIS IS NOT A
CLASSIC HIGH WIND SIGNATURE...AND NO SIGNIFICANT DOWN SLOPE
COMPONENT IS EXPECTED...GUSTS IN WIND PRONE AREAS COULD REACH 60
MPH BRIEFLY IN THE LATE EVENING AND EARLY OVERNIGHT HOURS ALONG
THE I-580/HWY 395 CORRIDOR FROM NORTHWEST OF RENO THROUGH ABOUT
LEE VINING AND ALONG HIGHWAY 95 FROM FERNLEY TO HAWTHORNE. A LAKE
WIND ADVISORY WILL REMAIN IN EFFECT FOR PYRAMID LAKE THROUGH THE
LAKE`S CLOSURE AT 8 PM THIS EVENING AND A LAKE WIND ADVISORY WILL
BE IN EFFECT FOR LAKE TAHOE UNTIL 11 PM WHEN THE WINTER WEATHER
ADVISORY STARTS.

THE SECOND BURST OF PRECIPITATION IS WITH THE UPPER LOW BEHIND THE
SFC FRONT LATE FRIDAY AFTERNOON INTO FRIDAY EVENING. AS MENTIONED
ABOVE...THE TAHOE BASIN SHOULD SEE ANOTHER ROUND OF ACCUMULATING
SNOW WITH THIS FEATURE. THE BULK OF THE HEAVIEST SNOW SHOULD SHIFT
TO MONO COUNTY BY THE MIDDLE OF FRIDAY EVENING...WITH ACCUMULATIONS
NEAR THE SIERRA CREST APPROACHING 1 FOOT OR MORE. AN ADVISORY WAS
ISSUED FOR MONO COUNTY EARLIER AND ACCUMULATING SNOW STILL LOOKS
LIKE A GOOD BET THERE...ESPECIALLY SINCE THE HEAVIEST WILL FALL
FRIDAY EVENING AND OVERNIGHT.

BY SATURDAY THE SYSTEM MOVES EAST WITH LINGERING SHOWERS. ANOTHER
WEAK SYSTEM TRIES TO BRING LIGHT PRECIPITATION TO THE NORTHERN
PARTS OF THE FORECAST AREA SATURDAY NIGHT...BUT IS SHUNTED TO THE
NORTH BY A BUILDING EAST PACIFIC RIDGE BY SUNDAY NIGHT. TEMPS WILL
BE WELL BELOW AVERAGE FRIDAY AND SATURDAY...AND THEN BEGIN TO
CLIMB BACK TO NEAR SEASONAL LEVELS BY SUNDAY. 20

LONG TERM...MONDAY THROUGH THURSDAY...
AN UPPER LEVEL RIDGE WILL BECOME ESTABLISHED ALONG THE WEST COAST
PROVIDING US WITH A DRY AND WARMER PATTERN. HIGH TEMPERATURES WILL
WARM BACK INTO THE 70S BY MONDAY ACROSS WESTERN NEVADA WITH MID 70S
TO NEAR 80 POSSIBLE BY WEDNESDAY. ACROSS SIERRA VALLEYS TEMPERATURES
WILL WARM INTO THE MID 60S TO NEAR 70 BY MIDWEEK. LIGHT WINDS WITH
PERIODS OF HIGH CLOUDS WILL BE IN PLACE AS THE RIDGE BUILDS ACROSS
WESTERN NEVADA.

HIGH UNCERTAINTY CREEPS INTO THE FORECAST BEYOND WEDNESDAY AS MODELS
ARE SHOWING DISAGREEMENT WITH THE BREAKDOWN/DISPLACEMENT OF THE
RIDGE ACROSS THE WEST. THE UPPER LEVEL FLOW ACROSS THE PACIFIC BASIN
INTO NORTH AMERICA BECOMES HIGHLY AMPLIFIED AND BLOCKED WITH THE
GFS ADVERTISING A QUICKER BREAKDOWN WITH A SHORTWAVE TROUGH
PUSHING INTO THE PACIFIC NORTHWEST BY LATE THURSDAY. THE EC
DEVELOPS AN OMEGA BLOCK WITH A SLOWER BREAKDOWN BUT PLACES US IN
AN AREA BETWEEN THE TRANSITION OF THE BLOCKING RIDGE AND CUT-OFF
LOW ACROSS THE MID-WEST. WILL FAVOR THE EC SOLUTION IN THE
FORECAST WITH THE LONGWAVE PATTERN FAVORING A RIDGE ACROSS THE
WEST EVEN IN THE GFS. NONETHELESS, UNCERTAINTY IN THE SYNOPTIC
SCALE PATTERN AND VERY LARGE ENSEMBLE SPREAD IS LEADING TO BELOW
NORMAL CONFIDENCE MAINLY IN THE TEMPERATURES FORECAST FOR THE
SECOND HALF OF NEXT WEEK. FUENTES

AVIATION...
PEAK SURFACE GUSTS OF 30-40 KTS LIKELY WITH TURBULENT APPROACHES
THROUGH ABOUT 05Z. BRIEF PERIODS OF LOW LEVEL WIND SHEAR POSSIBLE AT
KNRO THROUGH 00Z FRIDAY BUT SHOULD DECREASE AS SURFACE WINDS SHIFT
MORE WESTERLY THROUGH THE AFTERNOON. GUSTY CONDITIONS RETURNING
AFTER 18Z FRIDAY FOR THE RENO-TAHOE TERMINALS. MOUNTAIN WAVES WILL
CONTINUE THROUGH MOST OF FRIDAY ACROSS MONO/MINERAL COUNTIES.

RAIN AND SNOW WILL REACH AREAS NORTH OF SUSANVILLE-GERLACH BY 00Z
FRIDAY. SNOW WILL BEING AT THE TAHOE TERMINALS AROUND 12Z FRIDAY. A
COUPLE INCHES OF ACCUMULATIONS ARE LIKELY IN THE MORNING, WITH SNOW
AND MVFR/IFR CONDITIONS PERSISTING THROUGH 06Z SATURDAY. FOR
RENO-CARSON CITY MAIN PRECIPITATION TYPE WILL BE RAIN WITH A
RAIN/SNOW MIX POSSIBLE BETWEEN SAT 06-12Z BUT NO RUNWAY
ACCUMULATIONS EXPECTED.

AT KMMH, SHOWERS WILL BANK UP ALONG THE SIERRA CREST ON FRIDAY WITH
BEST CHANCE OF ACCUMULATING SNOW AND IFR CONDITIONS BETWEEN 00-12Z
SATURDAY.  TF/BRONG

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...LAKE WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR LAKE TAHOE
     IN NVZ002.

     WINTER WEATHER ADVISORY UNTIL 11 PM PDT FRIDAY NVZ002.

CA...WINTER WEATHER ADVISORY FROM 5 PM FRIDAY TO 11 AM PDT SATURDAY
     CAZ073.

     LAKE WIND ADVISORY UNTIL 11 PM PDT THIS EVENING FOR LAKE TAHOE
     IN CAZ072.

     WINTER WEATHER ADVISORY UNTIL 11 PM PDT FRIDAY CAZ072.

&&

$$

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







USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.