Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 301000
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
300 AM PDT THU JUL 30 2015

.SYNOPSIS...

HIGH PRESSURE OVER THE DESERT SOUTHWEST WILL BRING ABOVE NORMAL
TEMPERATURES FOR THE NEXT FEW DAYS. INCREASING MOISTURE AND
INSTABILITY WILL BRING A CHANCE FOR THUNDERSTORMS FRIDAY THROUGH
MONDAY, MAINLY FOR THE SIERRA AND IN FAR WESTERN NEVADA. GUSTY
OUTFLOW WINDS AND LIGHTNING FIRE STARTS ARE MAIN CONCERNS FOR
FRIDAY AND SATURDAY WITH LOCALLY HEAVY RAIN POSSIBLE THIS WEEKEND.

&&

.SHORT TERM...

THE WARMING TREND CONTINUES TODAY AS HIGH PRESSURE EXPANDS FARTHER
WEST ACROSS THE GREAT BASIN, WITH HIGHS LIKELY REACHING 100
DEGREES IN WEST CENTRAL NV AND COMING CLOSE TO 100 FOR RENO-
SPARKS. AFTERNOON CUMULUS WILL INCREASE ESPECIALLY NEAR THE SIERRA
AND INTO NORTHEAST CA. THERE IS A SMALL POSSIBILITY FOR A COUPLE
OF HIGH BASED THUNDERSTORMS FORMING LATE IN THE DAY IN SOUTHERN
MONO COUNTY, ALTHOUGH THE MAJORITY OF THE MODEL GUIDANCE KEEPS
BETTER CONVECTIVE CHANCES FARTHER SOUTH.

LATE TONIGHT AND INTO FRIDAY MORNING, SHORTWAVE MOVING NORTH
ACROSS CALIFORNIA MAY BRING SOME ELEVATED INSTABILITY FOR
GENERATING A FEW LATE NIGHT THUNDERSTORMS FOR MONO COUNTY SOUTH OF
BRIDGEPORT, THEN ADVANCING NORTH TO NEAR HIGHWAY 50 BY FRIDAY
MORNING.

FOR THE REMAINDER OF FRIDAY, ANY MORNING CONVECTION SOUTH OF
HIGHWAY 50 COULD EVENTUALLY LEAD TO A LOWER POTENTIAL FOR
AFTERNOON THUNDERSTORMS NORTH OF HIGHWAY 50. MODEL GUIDANCE
SPREADS A RELATIVELY BROAD AREA OF MID-HIGH LEVEL CLOUD COVER
NORTHWARD ACROSS WESTERN NV AND NORTHEAST CA, WHICH WOULD LIMIT
INSTABILITY AND INHIBIT CONVECTION. SOME HIGH BASED SHOWERS AND
THUNDERSTORMS MAY BE ABLE TO REDEVELOP IN THE AFTERNOON SOUTH AND
WEST OF A PORTOLA-RENO-YERINGTON LINE WHERE SKIES HAVE A BETTER
POTENTIAL FOR CLEARING, BUT AS THESE CELLS MOVE NORTH INTO
MARGINAL INSTABILITY BY LATE AFTERNOON/EARLY EVENING, THEY MAY
STRUGGLE TO MAINTAIN THEIR INTENSITY. NOT MUCH MEASURABLE RAINFALL
IS LIKELY TO REACH THE GROUND ON FRIDAY, BUT WE DID INCLUDE
MENTION OF SHOWERS BECAUSE OF THE MARGINAL INSTABILITY NORTH OF
HIGHWAY 50 WHICH COULD LEAD TO FEWER THUNDERSTORMS. HOWEVER, THERE
REMAINS POTENTIAL FOR STRONG OUTFLOW WIND GUSTS ABOVE 50 MPH EVEN
FROM WEAK-LOOKING SHOWERS, DUE TO THE DRY AND DEEP SUB-CLOUD
LAYER OVER MUCH OF THE REGION.

FOR FRIDAY NIGHT, SOME ELEVATED INSTABILITY WITH PRESENCE OF MID
LEVEL MOISTURE AND LEFTOVER OUTFLOW INTERACTIONS COULD STILL KICK
OFF ISOLATED CELLS AFTER MIDNIGHT. HOWEVER, CONFIDENCE IS LOW FOR
DETERMINING THE LOCATION OR EVEN THE DEVELOPMENT POTENTIAL FOR
LATE NIGHT CONVECTION.

FOR SATURDAY, THE OVERALL THUNDERSTORM POTENTIAL INCREASES AS
MORE INSTABILITY AND MOISTURE SHOULD BE PRESENT, AND MORE AREAS
ARE LIKELY TO START THE DAY WITH MOSTLY CLEAR SKIES. PRECIPITABLE
WATER VALUES INCREASE TO BETWEEN 0.70 AND 0.90 INCH, ALTHOUGH
MODEL SOUNDINGS STILL SHOW RELATIVELY HIGH CLOUD BASES AND
INCREASING DOWNDRAFT CAPE VALUES, SO WE COULD STILL BE DEALING
WITH STRONG OUTFLOW WIND GUSTS AND SPOTTY RAINFALL AMOUNTS,
RESULTING IN ELEVATED FIRE WEATHER CONCERNS IF LIGHTNING PRODUCES
NEW FIRE STARTS. ANOTHER UPPER LEVEL SHORTWAVE MOVING NORTHWARD
ACROSS CALIFORNIA MAY KEEP SOME SHOWER AND ISOLATED THUNDERSTORM
ACTIVITY GOING OVERNIGHT INTO SUNDAY MORNING. MJD

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

SHORTWAVE WILL BE LIFTING NORTHWARD AND OUT OF AREA SUNDAY WITH
PARTLY CLOUDY SKIES AND SURFACE HEATING LIKELY TO COMMENCE FOR
ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IN THE AFTERNOON. THE
ECMWF IS SLOWEST IN CLEARING THE MID AND HIGH LEVEL CLOUDS, WHICH
COULD HAMPER LATER DEVELOPMENT ACROSS NORTHERN AREAS DESPITE PWAT
VALUES APPROACHING AN INCH. FARTHER SOUTH IN WAKE OF THE UPPER
LEVEL WAVE, PWATS DO DRY OUT A BIT WITH VALUES DROPPING TO
0.50-0.60 INCH ALONG THE SIERRA AND FAR WESTERN NV. LOWERING
PWAT, RELATIVELY HIGH CLOUD BASES AND MODERATE STORM MOTIONS
SUGGEST A LOW FLASH FLOOD POTENTIAL WITH MORE LIGHTNING AND
OUTFLOW WIND POTENTIAL. HOWEVER IT MUST BE NOTED THAT CONFIDENCE
IN THE DETAILS REMAINS ONLY MEDIUM. COVERAGE WAS KEPT AT SCATTERED
SOUTH OF I-80 WITH MORE ISOLATED COVERAGE NORTH FOR NOW.

EARLY NEXT WEEK, THE FLOW TRENDS SOUTHWESTERLY AND BEGINS TO
INCREASE. THIS WILL LEAD TO EVEN FASTER STORM MOTIONS WITH STORMS
PUSHING OFF THE SIERRA AND FOCUSING MORE INTO WESTERN NV ON
MONDAY, AND POSSIBLY MOVING COMPLETELY OUT OF THE EASTERN SIERRA
AND WESTERN NV TUE-WED. WE MAINTAINED SOME LOW POPS BUT WITHOUT A
MENTION OF WEATHER BOTH TUE-WED AS THE GFS WAS SHOWING SOME QPF
SIGNATURES LINGERING ACROSS WESTERN NV. STORMS WILL HAVE HIGHER
STORM BASES AND OUTFLOW WINDS WILL CONTINUE TO BE A THREAT FROM
STRONGER STORMS IN THIS PATTERN. THE GFS/ECMWF BOTH AGREE ON A
MUCH DRIER PATTERN FOR THE LAST HALF OF NEXT WEEK AS A DEEP
ATMOSPHERIC DRY SLOT PUSHES INTO CA-NV. HOHMANN

&&

.AVIATION...

LIGHT WINDS AND VFR CONDITIONS WILL PERSIST TODAY WITH ONLY A SLIGHT
CHANCE OF A HIGH BASED SHOWER OR THUNDERSTORM DEVELOPING AROUND KMMH
LATE IN THE DAY.

THUNDERSTORM POTENTIAL WILL INCREASE FRI-SUN WITH GUSTY OUTFLOW
WINDS THE PRIMARY THREAT. THERE COULD BE A FEW NIGHTTIME STORMS AS
WELL FRIDAY AND SATURDAY NIGHT. HOHMANN

&&

.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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