Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 272124
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
224 PM PDT SUN JUL 27 2014

.SYNOPSIS...
MOISTURE AND CLOUDS WILL INCREASE MONDAY AND THERE ARE VARYING
CHANCES FOR THUNDERSTORMS EACH AFTERNOON THROUGH THE WEEK. A
WEATHER IMPULSE COULD LEAD TO A FEW STRONGER THUNDERSTORMS ON
TUESDAY. TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY ABOVE NORMAL.

&&

.SHORT TERM...
DESPITE MOSTLY SOUTHERLY TRANSPORT WINDS, SOME SMOKE FROM THE
SAND AND EL PORTAL FIRES WILL CONTINUE TO CROSS THE CREST TO THE
EAST SIDE AT TIMES, CREATING HAZY CONDITIONS FOR SIERRA AND
SIERRA FRONT RANGE COMMUNITIES.

THIS AFTERNOON THE LEADING EDGE OF A MONSOONAL MOISTURE SURGE IS
MOVING INTO MONO AND MINERAL COUNTIES. INSTABILITY IS RATHER WEAK
BUT ISOLATED THUNDERSTORMS ARE POSSIBLE THROUGH MIDNIGHT FOR THOSE
TWO COUNTIES. AFTER MIDNIGHT, THE WESTERN EDGE OF THIS MOISTURE
SURGE SPREADS NORTH ACROSS MINERAL, CHURCHILL AND SOUTHERN PERSHING
COUNTIES. LOW LEVELS ARE QUITE DRY AND MID-LEVEL INSTABILITY
APPEARS TOO WEAK FOR THUNDERSTORMS, BUT ISOLATED SHOWERS ARE
POSSIBLE OVERNIGHT FOR THOSE THOSE AREAS.

MOISTURE CONTINUES TO INCREASE MONDAY WITH PRECIPITABLE WATER
VALUES RISING ABOVE 0.75 INCHES FOR THE SIERRA AND TO AROUND 1
INCH FOR WESTERN NV. DESPITE A NEARLY SATURATED TROPOSPHERE ABOVE
600 MB, MID-LEVEL LAPSE RATES AND FORCING FOR LIFT DO NOT LOOK
IMPRESSIVE. AS SUCH, FORECAST CONFIDENCE IS MEDIUM THAT SHOWERS
AND THUNDERSTORMS WILL NOT PRODUCE HEAVY RAIN MONDAY. THE LESS-
LIKELY ALTERNATIVE SCENARIO IS FOR BREAKS IN THE CLOUDS TO CREATE
SURFACE HEATING AND STRONGER INSTABILITY. THE MORE LIKELY OUTCOME
IS FOR THICK CLOUD COVER AND SHALLOW CONVECTION. AS SUCH, THE
FORECAST CALLS FOR SCATTERED SHOWERS AND A SLIGHT CHANCE FOR
THUNDERSTORMS SOUTH OF HIGHWAY 50, AND FOR AREAS NORTH OF HIGHWAY
50 A SLIGHT CHANCE FOR SHOWERS MAINLY EAST OF HIGHWAY 395.

MODELS INDICATE SOUTHWEST FLOW PUSHING MUCH OF THE UPPER-LEVEL
MOISTURE TOWARDS OREGON TUESDAY. MEANWHILE, AN UPPER-LEVEL JET
MAX MOVES FROM SOUTHERN CALIFORNIA TO ACROSS THE SIERRA WHILE A
WEAK COLD FRONT AT LOWER-LEVELS MOVES OUT OF OREGON INTO NORTHERN
CA/NV. FORECAST CONFIDENCE IN THESE FEATURES IS LOW, ESPECIALLY
REGARDING THEIR TIMING. BUT THIS PATTERN COULD LEAD TO A FEW
STRONGER THUNDERSTORMS TUESDAY ALONG THE COLD FRONTAL BOUNDARY.
FARTHER AWAY FROM THE COLD FRONT, ANOTHER CONCERN IS THAT
ELEVATED CONVECTION COULD LEAD TO NEW FIRE STARTS. BUT THE
POTENTIAL LOCATIONS FOR THESE THREATS IS UNCERTAIN AT THIS TIME.
JCM

.LONG TERM...WEDNESDAY THROUGH SUNDAY...

CONTINUED POSSIBILITY OF THUNDERSTORMS FROM MIDWEEK THROUGH NEXT
WEEKEND, ALTHOUGH THERE IS NOT MUCH CONFIDENCE HAVING MORE THAN
LOCALIZED POCKETS OF HEAVY RAINFALL ON ANY PARTICULAR DAY. DAYTIME
TEMPS WILL RISE TO A BIT ABOVE NORMAL WED-THURS, THEN ARE LIKELY TO
INCREASE A FEW MORE DEGREES FROM FRI-SUN WITH HIGHS IN THE MID-UPPER
90S EACH DAY FOR MOST LOWER ELEVATIONS.

FOR WEDNESDAY, WE KEPT THE LOW END CHANCE POPS ACROSS AREAS WEST OF
HIGHWAY 95, ALTHOUGH MUCH OF THE 12Z GUIDANCE TRENDED TOWARD A LOWER
THUNDERSTORM POTENTIAL FOR THE RENO-CARSON VICINITY EASTWARD ACROSS
WEST CENTRAL NV. THE NAM WAS MUCH MORE UNFAVORABLE FOR CONVECTION
ACROSS NEARLY ALL OF THE REGION, WITH STRONGER MID LEVEL CAP,
SUBSIDENCE BEHIND A SHORTWAVE DEPARTING TO THE NORTH, AND NOTABLY
LOWER PW VALUES COMPARED TO OTHER GUIDANCE.

ON THURSDAY, WEAK LOW PRESSURE OFF THE NORTHERN CA COAST MAY BEGIN
TO COME INTO PLAY AND SHIFT THE BETTER FOCUS FOR THUNDERSTORMS TO
AREAS NORTH OF SUSANVILLE-GERLACH. ELSEWHERE, SOME GENERAL
INSTABILITY REMAINS BUT FORCING APPEARS TO BE WEAK, SO THUNDERSTORM
MENTION WILL BE LIMITED TO SLIGHT CHANCE, EXCEPT FOR THE TAHOE BASIN
NORTHWARD TO PLUMAS COUNTY WHERE A BIT MORE WESTERLY FLOW WILL
PROBABLY INHIBIT THUNDERSTORM FORMATION.

FOR FRIDAY, THE WEAK LOW REMAINS NEAR THE NORTHERN CA COAST,
ALTHOUGH A BIT MORE MOISTURE MAY BE PULLED INTO PARTS OF WEST
CENTRAL NV MAINLY SOUTH AND EAST OF FALLON AS FLOW ALOFT TRIES TO
SHIFT A BIT MORE TO THE SOUTH. OTHERWISE, THUNDERSTORM POTENTIAL IS
NOT CHANGED VERY MUCH FROM THURSDAY.

FOR NEXT WEEKEND, LITTLE CHANGE WAS MADE TO THE PREVIOUS FORECAST,
KEEPING SLIGHT CHANCE THUNDER EACH DAY MAINLY EAST OF A
SUSANVILLE-RENO-MARKLEEVILLE LINE. LINGERING SHOWERS OVERNIGHT
REMAIN POSSIBLE ACROSS A SMALLER PORTION OF NORTHWEST AND WEST
CENTRAL NV. HOWEVER, THE 12Z ECMWF MADE A MORE AGGRESSIVE MOVE
TOWARD INCREASING CONVECTIVE POTENTIAL, TRACKING A VIGOROUS 500 MB
SHORTWAVE NORTHWARD ACROSS WESTERN NV FROM SAT NIGHT THROUGH SUN
NIGHT. THIS WAS A DEPARTURE FROM THE PREVIOUS ECMWF RUN, AND THESE
FEATURES ARE DIFFICULT TO PROJECT THIS FAR IN ADVANCE SO IT WAS NOT
FACTORED INTO THE CURRENT FORECAST. HOWEVER, IT WILL BE WORTH
WATCHING, AS THIS TYPE OF SHORTWAVE WAS A KEY INGREDIENT IN
PRODUCING MORE AREAS OF HEAVY RAINFALL AND FLASH FLOODING LAST
SUNDAY. MJD

&&

.AVIATION...

ISOLATED SHOWERS THRU TONIGHT WILL REMAIN MAINLY EAST AND SOUTH OF A
LOVELOCK-YERINGTON LINE FOR WESTERN NV, AND LIMITED TO MONO COUNTY
IN EASTERN CA. SHOWERS MAY DEVELOP ACROSS MUCH OF WESTERN NV AND
NORTHEAST CA ON MONDAY, BUT AVIATION IMPACTS SHOULD BE LIMITED. A
FEW BRIEF TSTMS ARE POSSIBLE TODAY AND MONDAY BTWN 21Z-04Z MAINLY
SOUTH OF HIGHWAY 50, WITH A 10% PROBABILITY OF AFFECTING THE KMMH
AIRPORT. WINDS WILL BE GENERALLY LIGHT FOR THE NEXT TWO DAYS. MJD

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

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





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