Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 030958
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
258 AM PDT MON AUG 3 2015

.SYNOPSIS...
DECREASING MOISTURE IS EXPECTED TO KEEP THUNDERSTORMS ISOLATED
THIS AFTERNOON AND EVENING, WANING TO AREAS WELL NORTH OF
INTERSTATE 80 TUESDAY. THUNDERSTORM CHANCES RETURN ON FRIDAY AS
LOW PRESSURE APPROACHES THE SIERRA AND WESTERN NEVADA. AFTERNOON
TEMPERATURES WILL REMAIN AROUND AVERAGE THIS WEEK.

&&

.SHORT TERM...
REDUCED THUNDERSTORM COVERAGE TUESDAY AND ADDED A SLIGHT CHANCE OF
NOCTURNAL THUNDERSTORMS NORTH OF I-80 LATE TUESDAY NIGHT.

DRIER AIR ALOFT HAS WORKED INTO EASTERN CALIFORNIA AND FAR WESTERN
NEVADA BEHIND AN EXITING WAVE OVER EXTREME NORTHERN NEVADA AND
CALIFORNIA. SURFACE-BASED PWAT MEASUREMENTS (GPSMET.NOAA.GOV) AT
PLACERVILLE AND RENO HAVE FALLEN FROM NEAR ONE INCH YESTERDAY TO
0.6" TO 0.7" THIS MORNING, WITH MAMMOTH LAKES DECREASING TO AROUND
0.35". THERE ARE SCATTERED MID-LEVEL CLOUDS BETWEEN HAWTHORNE AND
RENO-TRUCKEE ON THE PERIPHERY OF A HIGH-LEVEL WAVE EXTENDING FROM
NORTHWEST CALIFORNIA, HOWEVER THE FORCING/INSTABILITY ALOFT IS
WEAK AND THE CLOUDS MUST BE THIN AS THEY ARE NOT EVEN SHOWING UP
IN THE COMPOSITE RADAR IMAGE.

THIS AFTERNOON, SOUTHWEST-WEST FLOW ALOFT WILL INCREASE BEHIND
THIS MORNING`S WAVES. WITH A THERMAL RIDGE DEVELOPING OVER CENTRAL
AND EASTERN NEVADA THIS AFTERNOON, WEST WINDS ARE EXPECTED TO KICK
OFF THE SIERRA AND FOCUS ISOLATED CONVECTION GENERALLY EAST OF
HIGHWAY 395 AND PERHAPS OVER NORTHERN LASSEN/WASHOE COUNTIES IN
THE TYPICAL CONVERGENCE ZONE THERE. PWATS HAVE FALLEN OFF AND
STORM MOTIONS WILL BE INCREASED OVER YESTERDAY SO, WHILE STORMS
WILL PRODUCE RAIN IT WILL BE IN A NARROWER SHAFT WITH A FEW
LIGHTNING STRIKES POSSIBLE ON STORM PERIPHERIES.

TUESDAY, I HAVE REDUCED COVERAGE OF ISOLATED STORMS TO NORTH OF A
LINE FROM SUSANVILLE TO ALONG THE CHURCHILL/PERSHING COUNTY BORDER.
NEITHER THE NAM NOR THE GFS SHOW MUCH, IF ANY, INSTABILITY FOR
DIURNAL THUNDERSTORMS. THE NAM INDICATES SUBSIDENCE WARMING ALOFT
SOUTH OF A SUSANVILLE TO LOVELOCK LINE TO AID IN STABILIZATION,
WITH UPPER FORCING FROM A WAVE APPROACHING THE CALIFORNIA COAST
LIMITED TO NORTHERN/NORTHWESTERN CALIFORNIA. WITH INSTABILITY WEAK
AT BEST, LITTLE UPPER FORCING AND FLOW ALOFT MODERATE-STRONG, I DO
NOT EXPECT ANY DEEP CONVECTION FOR MOST OF THE REGION. IF ANY
STORMS FORM NORTH OF SUSANVILLE-LOVELOCK, THEY WOULD TEND TO BE
DRY WITH FAST MOTIONS.

TURNING TO TUESDAY NIGHT, THE NAM IS NOW SHOWING UPPER LIFT MOVING
INTO NORTHEAST CALIFORNIA AND NORTHWEST NEVADA LATE WITH A LOW
CHANCE FOR ELEVATED CONVECTION. THE NAM POSITIONS THE JET STREAK
WITH THE LIFT/WAVE FARTHER SOUTH THAN THE GFS SO INSTABILITY ALOFT
IS A BIT HIGHER IN THE NAM THAN THE GFS. THIS BEARS WATCHING FOR
THE POSSIBILITY FOR ISOLATED, DRY NOCTURNAL THUNDERSTORMS NORTH
OF I-80 LATE TUESDAY NIGHT. HOWEVER, IF THE WEAKER FORCING (AS IN
THE GFS) PANS OUT IT MAY WIND UP JUST BEING SOME ACCAS.

WEDNESDAY LOOKS DRIER STILL AS TUESDAY NIGHT`S WAVE PASSES BY TO
THE NORTH AND WESTERLY FLOW INVADES THE SIERRA AND WESTERN NEVADA.
I HAVE LEFT A SLIGHT CHANCE OF SHOWERS/STORMS OVER THE SURPRISE
VALLEY AND FAR NORTHERN WASHOE COUNTY WITH THE NAM SCRAPING THAT
AREA WITH SOME MINIMAL QPF, ALTHOUGH THE GFS IS MUCH DRIER AND
CONVECTION MAY WIND UP BEING REMOVED IN THE NEXT FEW MODEL RUNS.
SNYDER

.LONG TERM...THURSDAY THROUGH SUNDAY...
FEW CHANGES MADE IN THE EXTENDED AS THE MAIN CONCERN CONTINUES TO BE
THE UPPER LOW FORECAST TO ARRIVE FRIDAY. AHEAD OF IT ON THURSDAY,
TYPICAL AFTERNOON WINDS ARE EXPECTED WITH TEMPS NEAR AVERAGE. THEN
THE UPPER LOW MOVES ONTO THE COAST FRIDAY MORNING AND MOVES THROUGH
THE SIERRA BY FRIDAY NIGHT. THE FORCING IS STRONG WITH THE LOW EVEN
THOUGH MOISTURE WILL BE MARGINAL. HAVE INCREASED POPS TO CHANCE
ACROSS NORTHEAST CALIFORNIA AND NORTHWEST NEVADA NORTH OF HIGHWAY
50. EC/GFS REMAIN CONSISTENT OVERALL WITH TIMING EVEN THOUGH EC IS
SLIGHTLY SLOWER. DEPENDING ON HOW QUICKLY IT MOVES THROUGH THERE
COULD BE A FEW THUNDERSTORMS OVERNIGHT FRIDAY NIGHT. LEFT THE
LINGERING STORMS FOR SATURDAY, BUT IT MAY WELL BE DRY. SUNDAY WILL
BE DRY WITH A RETURN TO SOUTHWEST FLOW AND A TYPICAL AFTERNOON
ZEPHYR.

TEMPERATURES THROUGH THE PERIOD WILL AVERAGE BELOW NORMAL. THURSDAY
IS THE WARMEST DAY, THEN COOLING BACK INTO THE 80S FOR WESTERN
NEVADA AND 70S SIERRA UNDER THE INFLUENCE OF THE LOW. A SLOW WARMING
TREND IS POSSIBLE SUNDAY, BUT IT STILL LOOKS TO BE COOLER THAN
NORMAL. WALLMANN

&&

.AVIATION...
VFR CONDITIONS THIS MORNING WITH MID AND HIGH CLOUDS LIFTING
NORTH INTO OREGON. DRIER AIR IS MOVING IN AND WHILE THUNDERSTORMS
ARE EXPECTED, MOST WILL BE ALONG KMMH-KHTH AND NORTH OF KSVE-
GERLACH. ABOUT A 25% CHANCE OF KMMH BEING AFFECTED WHILE KCXP/KRNO
ARE ONLY 15% AND LESS THAN 10% FOR KTRK/KTVL. MAIN THREATS WOULD
BE GUSTY OUTFLOWS TO 40 KTS AND POSSIBLY SOME SMALL HAIL.

TSTM THREAT SHOULD END BY 03Z AND VFR THEREAFTER. IT LOOKS DRIER TUE-
THU ALTHOUGH THERE IS A 15% CHANCE OF STORMS NORTH OF I-80 TUE.
WALLMANN

&&

.FIRE WEATHER...
A FEW MORE THUNDERSTORMS TODAY, BUT MOST LOOK TO BE OVER MONO-
MINERAL AND IN THE LASSEN CONVERGENCE ZONE NORTH OF SUSANVILLE AND
GERLACH. EVEN THEN EXPECTING ISOLATED STORMS AT BEST AND MOST
SHOULD BE WET. CONTINUED DRYING TUESDAY AS A PORTION OF THE UPPER
LOW OFF THE COAST MOVES THROUGH. THUNDERSTORM POTENTIAL LOOKS MUCH
LESS THAN THE PAST COUPLE DAYS WITH ISOLATED DRY STORMS AT BEST
NORTH OF GERLACH AND POSSIBLY LOVELOCK. WE WILL SEE A RETURN TO
THE ZEPHYR THE NEXT TWO DAYS WITH AFTERNOON WIND GUSTS 25 MPH OR
SO.

DRY SOUTHWEST FLOW CONTINUES WED/THU WITH LOWER HUMIDITY, MORE
SEASONABLE FOR EARLY AUGUST WITH MINS 10-20%. THE MAIN FOCUS THEN IS
THE UPPER LOW FOR FRIDAY. MODELS CONTINUE TO SHOW IT MOVING THROUGH
FRIDAY OR FRIDAY NIGHT. FORCING WITH THE LOW IS STRONG AND MOISTURE
MARGINAL. THIS COULD BE A SIGNIFICANT LIGHTNING OUTBREAK. HOWEVER,
THERE IS STILL A LOT OF UNCERTAINTY AS IT IS STILL 4-5 DAYS OUT.
MOISTURE COULD INCREASE A LITTLE FURTHER OR THE LOW COULD TAKE A
DIFFERENT TRACK. IT REMAINS SOMETHING TO WATCH BECAUSE OF THE
POTENTIAL. WALLMANN

&&

.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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