Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 021003
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
303 AM PDT SUN AUG 2 2015

.SYNOPSIS...
PLENTY OF MOISTURE WILL BRING ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS TODAY TO NORTHEAST CALIFORNIA AND WESTERN NEVADA,
WITH LIGHTNING AND LOCALLY HEAVY RAINFALL THE MAIN THREATS FROM
THUNDERSTORMS. THUNDERSTORM COVERAGE IS EXPECTED TO WANE MONDAY
THROUGH WEDNESDAY AS DRIER AIR WORKS INTO THE REGION. AFTERNOON
TEMPERATURES WILL REMAIN AROUND AVERAGE THIS WEEK.

&&

.SHORT TERM...
MAIN CHANGES TO THE SHORT TERM FORECAST TO CUT BACK THUNDERSTORMS
TO MORE DIURNALLY-DRIVEN (AFTERNOON AND EVENING) TIMING FOR MONDAY
AND TUESDAY.

THE COMPLEX OF SHOWERS AND THUNDERSTORMS WHICH MOVED THROUGH
WESTERN NEVADA LAST EVENING HAS PUSHED OFF TO WEST OF THE SIERRA
CREST THIS MORNING, WITH JUST A FEW SHOWERS LEFT OVER NORTH OF
HIGHWAY 70 IN NORTHEAST CALIFORNIA. LOOKING DOWN INTO SOUTHERN
AND CENTRAL NEVADA, ANOTHER UPPER DISTURBANCE IS WORKING NORTH
PER INFRARED SATELLITE INDICATIONS OF COOLING CLOUD TOPS OVER
ESMERALDA AND NYE COUNTIES. THE IMPULSE IS PROGGED BY THE 08Z HRRR
TO FIRE UP SHOWERS SOUTH OF HIGHWAY 50 IN THE NEXT FEW HOURS,
WHICH MAKES SENSE GIVEN THE APPROACHING COOLING CLOUD TOPS AND THE
RATHER MOIST ATMOSPHERE. ELSEWHERE SOUTH AND WEST OF AN ALTURAS TO
RENO TO FALLON LINE, A FEW STRAY SHOWERS OR EVEN A VERY ISOLATED
LIGHTNING STRIKE CANNOT BE RULED OUT THIS MORNING.

THIS AFTERNOON, THE HRRR AND NAM HAVE TRENDED TOWARDS FOCUSING THE
BEST SHOT AT CONVECTION NORTH OF HIGHWAY 50 AHEAD THE INCOMING
UPPER DISTURBANCE. THOSE MODELS HAVE ALSO REDUCED THEIR AFTERNOON
PRECIPITATION FORECAST FOR MONO AND MINERAL COUNTIES AS THEY
FOCUS THE FORCING FARTHER NORTH. HOWEVER, PLENTY OF MOISTURE
REMAINS FOR AREAS SOUTH OF HIGHWAY 50 AND THE NAM SHOWS SOME
WESTERLY WINDS IN THE AFTERNOON WHICH COULD PROVIDE FOCUS FOR
SCATTERED DEEP CONVECTION. THEREFORE, I HAVE HELD OFF ON REDUCING
POP WHOLESALE FOR MONO/MINERAL COUNTIES FOR THIS AFTERNOON AND
EVENING.

AS FAR AS THE NATURE OF THUNDERSTORMS THIS AFTERNOON, THE RELATIVELY
HIGH MOISTURE BROUGHT INTO THE REGION SINCE YESTERDAY (PWAT NEAR
1" IN RENO CURRENTLY) SHOULD ALLOW FOR MODERATE TO HEAVY RAIN
UNDER STORM CORES DESPITE SOME MODEST STORM MOTION OF UP TO 10-15
KTS. IN FACT, IF STORMS GET HUNG UP ON TERRAIN OR TRAIN OVER THE
SAME AREA LOCALIZED FLOODING WILL BE POSSIBLE GIVEN THE HEAVY RAIN
POTENTIAL WITH THE HIGH PWATS.

LATE TONIGHT, AS THE UPPER DISTURBANCE CONTINUES TO TREK SLOWLY
THROUGH NORTHERN NEVADA, SHOWERS AND A FEW THUNDERSTORMS WILL BE
POSSIBLE IN THE BASIN AND RANGE AND OVER EXTREME NORTHEAST
CALIFORNIA.

MONDAY AND TUESDAY, THUNDERSTORM COVERAGE SHOULD WANE AS PWATS
FALL OFF SOME WITH DRIER WESTERLY FLOW IMPINGING ON THE REGION.
ALSO, WITH WEAKER UPPER FORCING AS COMPARED TO THE PAST COUPLE
DAYS, STORMS WILL NEED TO RELY ON DAYTIME HEATING TO DEVELOP.
THEREFORE, I HAVE CUT BACK THE THUNDERSTORM TIMING TO MORE
DIURNALLY-DEPENDENT TIMES. STORM FLOW WILL INCREASE FOR MONDAY
AND TUESDAY, WHICH MAY BRING HYBRID WET/DRY STORMS BACK INTO PLAY
VERSUS THE WETTER STORMS EXPECTED FOR TODAY. SEE THE FIRE WEATHER
SECTION FOR MORE ON THE CONCERNS WITH CONVECTION ON MONDAY AND
TUESDAY. SNYDER

.LONG TERM...WEDNESDAY THROUGH SATURDAY...
FEW CHANGES MADE TO THE LONG TERM WITH THE FIRST PART OF THE
UPPER LOW EXITING ON WEDNESDAY WITH THE MAIN LOW NOW FORECAST TO
MOVE THROUGH FRIDAY INTO SATURDAY. HAVE ADDED A SLIGHT CHANCE OF
THUNDERSTORMS NORTH OF SUSANVILLE AND GERLACH WEDNESDAY WITH
RESIDUAL MOISTURE AND INSTABILITY. AREAS FURTHER SOUTH WILL BE TOO
STABLE. A BREAK IS EXPECTED THURSDAY BEFORE THE MAIN LOW MOVES IN
LATE FRIDAY INTO SATURDAY. THIS LOW WILL TRACK FURTHER SOUTH AND
IT WILL BE COOLER ALOFT WITH IT. WHILE MOISTURE WILL NOT BE GREAT,
THE COOLER TEMPS ALOFT WILL BE CONDUCIVE FOR CONVECTION AT LEAST
NORTH OF HIGHWAY 50. ADDED THUNDERSTORMS FRIDAY AND FRIDAY NIGHT
FOR THESE AREAS. STRONG FORCING WILL CONTINUE OVERNIGHT WITH
ANOTHER ROUND OF CONVECTION POSSIBLE. THE STORMS MAY CONTINUE INTO
SATURDAY AS THE UPPER LOW MOVES ACROSS.

TEMPERATURES WILL REMAIN NEAR TO A LITTLE BELOW AVERAGE FOR EARLY
AUGUST. THE WARMEST TEMPERATURES ARE LIKELY THURSDAY BETWEEN SYSTEMS
WITH HIGHS ONLY IN THE 80S FRIDAY AND SATURDAY FOR WESTERN NV AND
70S IN THE SIERRA. A TYPICAL AFTERNOON ZEPHYR IS EXPECTED WEDNESDAY
BEHIND THE FIRST SYSTEM ONLY TO SEE THE FLOW BACK TO THE SOUTH AHEAD
OF THE MAIN UPPER LOW. THE WINDS WILL BE LIGHTER WITH PERHAPS A
LIGHT AFTERNOON ZEPHYR FOR THURSDAY. WALLMANN

&&

.AVIATION...
SCATTERED THUNDERSTORMS HAVE MOVED WEST OF THE SIERRA CREST EARLY
THIS MORNING. ABUNDANT MID AND HIGH CLOUDS ALONG WITH ISOLATED
SHOWERS REMAIN, BUT CONDITIONS WILL STILL BE VFR. A FEW THUNDERSTORMS
ARE POSSIBLE THIS MORNING 13-18Z NEAR KMMH AND KHTH, ABOUT A 10%
CHANCE. FOR THE AFTERNOON, EXPECT STORMS TO FIRE AROUND 19Z AND
LAST THRU 02Z NEAR HIGHWAY 395 AND 05Z FURTHER EAST. CHANCE OF
IMPACT AT KTRK/KTVL/KRNO/KCXP ABOUT 35% WITH SMALL HAIL AND SFC
WND GUSTS TO 40 KTS. LESSER CHANCE FOR KMMH THIS AFTERNOON AT
AROUND 25%.

EXPECT VFR CONDITIONS OVERNIGHT WITH LESS STORMS FOR MONDAY. ONLY A
20% CHANCE OF STORMS AFFECTING TERMINALS AND LESS THAN 10% FOR
KTRK/KTVL. WALLMANN

&&

.FIRE WEATHER...
ISOLATED SHOWERS CONTINUE AFTER THE SCATTERED STORMS FROM EARLIER
THIS MORNING HAVE MOVED WEST OF THE SIERRA CREST. MORE STORMS ARE
EXPECTED TO FIRE THIS AFTERNOON AND WITH MOISTURE UP, STORMS ARE
EXPECTED TO BE WET. SOME AREAS ALREADY RECEIVED UP TO 3/4" OF RAIN
YESTERDAY FROM STORMS AND THE SAME IS POSSIBLE TODAY. EVEN SO, A FEW
SMALL FIRES OUTSIDE STORM CORES ARE POSSIBLE FROM LIGHTNING STRIKES.

A LITTLE DRIER MONDAY AS SOUTHWEST FLOW INCREASES. IT ALSO APPEARS
TO STABILIZE A BIT WITH ONLY ISOLATED THUNDERSTORMS AT BEST EXCEPT
OVER MINERAL COUNTY. STORMS WILL BE MORE HYBRID WET/DRY, BUT WITH
LOWER COVERAGE DO NOT THINK ANY WATCHES/WARNINGS ARE NECESSARY.

TUESDAY MORNING INTO TUESDAY NIGHT A PIECE OF THE UPPER LOW OFF THE
COAST WILL MOVE THROUGH AND THE FORCING WILL BE STRONG MOISTURE
REMAINS WITH PW AROUND 0.6", BUT LAPSE RATES ALOFT ARE ACTUALLY
SOMEWHAT STABLE. THERE ARE DIFFERENCES IN THE MODELS WITH THE EC/GFS
DRIER AND MORE STABLE WHILE THE NAM SHOWS A SLUG OF MOISTURE NEAR
600 MB THAT WOULD BE ENOUGH TO GENERATE CONVECTION AS EARLY AS
TUESDAY MORNING. IF THE NAM IS RIGHT, A DECENT DRY LIGHTNING
OUTBREAK IS POSSIBLE FOR WESTERN NV, WHILE IT WOULD BE ONLY ISOLATED
AT BEST WITH THE EC/GFS. LEANING TOWARD THE EC/GFS FOR NOW, BUT WILL
BE MONITORED.

THE NEXT CONCERN WOULD BE WHEN THE UPPER LOW FINALLY MOVES ONSHORE
LATER THURSDAY NIGHT INTO FRIDAY. IT WILL BE MORE UNSTABLE WITH
COOLER TEMPS ALOFT WITH ONLY MARGINAL MOISTURE. MORE DRY LIGHTNING
IS POSSIBLE WITH THIS LOW AS WELL. 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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