Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 020351
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
851 PM PDT SAT AUG 1 2015

.UPDATE...
CONVECTION IS STARTING TO CALM DOWN THIS EVENING. WHILE WE DID NOT
HAVE MUCH COVERAGE NORTH OF HIGHWAY 50...STRONG STORMS DEVELOPED
SOUTH OF PORTOLA AND BEGAN TO PROPAGATE NORTH ALONG A LOW LEVEL
CONVERGENCE BOUNDARY INTO LASSEN COUNTY BEFORE THEN PUSHING WEST
ON EITHER A DIFFERENT LOW LEVEL BOUNDARY OR IN RESPONSE TO
DEVELOPING EASTERLY FLOW IN THE MID LEVELS. EITHER WAY THE
CONVECTION WAS NOT RESPONDING TO DAYTIME HEATING AS MUCH AS LOW TO
MID LEVEL FORCING.

AM NOW SEEING GUSTY EAST-SOUTHEAST WINDS OVER LYON/MINERAL
COUNTIES THAT MAY BE A RESPONSE TO A MESO-HIGH OVER THE REGION
THAT HAS DEVELOPED DUE TO RAIN COOLED AIR. MODELS DO NOT
TYPICALLY PICK UP ON THIS VERY WELL AND IT WILL LIKELY NOT LAST
VERY LONG INTO THE EVENING.

LATEST NAM GUIDANCE IS NOT AS AGGRESSIVE WITH A WAVE MOVING UP
FROM THE SOUTH OVERNIGHT SO HAVE TRIMMED BACK POPS A BIT FOR THE
REMAINDER OF THE NIGHT. WILL MAINTAIN SLIGHT CHANCE POPS
OVERNIGHT. THESE SHOULD BE SHOWERS ALONG WITH A FEW THUNDERSTORMS
AS LOW TO MID LEVEL MOISTURE IS INCREASING. THIS INCREASED
MOISTURE AND PRESENCE OF CLOUDS SHOULD HOLD LOW TEMPERATURES WELL
ABOVE AVERAGE TONIGHT AND MAY LIMIT CONVECTIVE POTENTIAL EARLY
SUNDAY. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 302 PM PDT SAT AUG 1 2015/

SYNOPSIS...

SHOWERS AND THUNDERSTORMS CONTINUE THROUGH THE WEEKEND WITH GUSTY
OUTFLOW WINDS AND POSSIBLY A FEW LIGHTNING INDUCED FIRE STARTS.
LIGHTNING AND LOCALLY HEAVY RAINFALL WILL BE THE MAIN THREATS FROM
THIS WEEKEND`S STORMS. AFTERNOON TEMPERATURES WILL FALL TO NEAR
AVERAGE ON SUNDAY WITH THUNDERSTORM CHANCES CONTINUING MONDAY AND
TUESDAY.

SHORT TERM...

NUMEROUS THUNDERSTORMS CONTINUE TO DEVELOP ACROSS THE EASTERN
SIERRA AND WEST-CENTRAL NEVADA THIS AFTERNOON, MAINLY SOUTH OF
HIGHWAY 50. AN IMPRESSIVE 700 LIGHTNING STRIKES HAVE OCCURRED
OVER THE LAST FEW HOURS MAINLY IN ALPINE, MONO, SOUTHERN LYON AND
MINERAL COUNTIES. ABUNDANT LIGHTNING IS OCCURRING WITH THESE
STORMS AND ANYONE WITH OUTDOOR ACTIVITIES SHOULD TAKE SAFETY
PRECAUTIONS TO AVOID GETTING HIT BY LIGHTNING.

THESE STORMS ARE A MIX OF WET AND DRY, WITH NARROW RAIN CORES AND
SOME NEW LIGHTNING FIRES BEING IGNITED ALONG THE SIERRA FRONT. SEE
OUR FIRE WEATHER DISCUSSION BELOW FOR MORE DETAILS. MOISTURE WILL
CONTINUE TO INCREASE THROUGH THE AFTERNOON AND INTO THIS EVENING
WITH THESE STORMS PROGRESSIVELY BECOMING WETTER WITH LOCALLY HEAVY
RAINFALL POSSIBLE. GUSTY OUTFLOW WINDS UP TO 50 MPH ARE POSSIBLE
WITH THESE STORMS.

THUNDERSTORM ACTIVITY WILL CONTINUE THROUGH THIS EVENING,
SPREADING FURTHER NORTH THROUGH THE RENO-TAHOE AREA AND INTO
NORTHEASTERN CALIFORNIA. FURTHER NORTH OF RENO, PRECIPITABLE WATER
IS AROUND 0.65-0.75", MEANING THAT THOSE STORMS WILL HAVE LESS
RAINFALL AND POTENTIAL FOR NEW LIGHTNING FIRES. TONIGHT, A
MIDLEVEL DISTURBANCE WILL PUSH UP FROM SOUTHERN NEVADA HELPING TO
KEEP SCATTERED SHOWERS GOING AFTER MIDNIGHT, EVEN POSSIBLY A FEW
ISOLATED THUNDERSTORMS.

SCATTERED THUNDERSTORMS ARE EXPECTED AGAIN FOR SUNDAY AFTERNOON,
WITH STORMS BECOMING WETTER AS PWAT INCREASES TO NEAR 1.0" FOR
MOST LOCATIONS. UPPER LEVEL LAPSE RATES WILL STEEPEN DUE TO COLDER
AIR ALOFT FROM THE UPPER DISTURBANCE. STORMS WILL ALSO BECOME
SLOWER, PRODUCING LOCALLY HEAVY RAINFALL. THERE IS A THREAT OF
FLASH FLOODING AS WELL FOR STEEP TERRAIN AND RECENTLY BURNED
AREAS. THUNDERSTORMS WILL DEVELOP OFF THE EASTERN SIERRA AND THEN
PUSH INTO WESTERN NEVADA LATE IN THE AFTERNOON.

SOUTHWEST FLOW BEGINS TO DRY THINGS OUT ON MONDAY, ALTHOUGH
LINGERING MOISTURE WILL KEEP SOME THUNDERSTORM ACTIVITY IN THE
FORECAST FOR MAINLY FOR WESTERN NEVADA. PWATS WILL DROP OFF ON
MONDAY TO AROUND 0.75" WITH INCREASING STORM MOTIONS. STEEP UPPER
LEVEL LAPSE RATES AND INCOMING JET EXIT REGION WILL GET
THUNDERSTORMS GOING AGAIN IN THE AFTERNOON. COULD END UP BEING
ANOTHER HYBRID TYPE DAY WITH A MIX OF WET AND DRY LIGHTNING. HOON

LONG TERM...TUESDAY THROUGH SATURDAY...

A SHORTWAVE TRACKING ACROSS THE REGION TUESDAY WILL PROVIDE ANOTHER
ROUND OF MOISTURE AND INSTABILITY WITH A FAVORABLE JET POSITION
AIDING IN LIFT. WILL MAINTAIN THE SLIGHT CHANCE FOR THUNDERSTORMS
FOR AREAS MAINLY NORTH OF HIGHWAY 50, WHICH LINES UP WELL WITH THE
BEST DYNAMICS. WHILE INITIATION OVER THE SIERRA CREST IS POSSIBLE,
STORMS ARE LIKELY TO QUICKLY MOVE EAST INTO WESTERN NEVADA AS THE
AFTERNOON ZEPHYR MATERIALIZES. WHILE PWATS BRIEFLY RISE TO AROUND
0.75", STORM MOTIONS WILL BE FAST AND MOST OF THE MOISTURE WILL BE
CONFINED TO ABOVE 650 MB. THIS INCREASES THE CHANCE FOR STRONG AND
GUSTY OUTFLOW WINDS FROM ANY STORMS THAT DO DEVELOP AS WELL AS THE
POTENTIAL FOR LIGHTNING TO CAUSE NEW FIRE STARTS OUTSIDE OF THE RAIN
CORES.

FOR WEDNESDAY THROUGH FRIDAY, DRY SOUTHWEST FLOW RETURNS WITH
SLIGHTLY ENHANCED AFTERNOON ZEPHYR WINDS AND TEMPERATURES NEAR
NORMAL. BY SATURDAY BOTH THE GFS AND EC AGREE ON A COMPACT WAVE
PUSHING ACROSS THE NORTHERN SIERRA AND NORTHWEST NEVADA. THE
MOISTURE ISN`T ALL THAT IMPRESSIVE, BUT THERE IS ENOUGH PRESENT THAT
THUNDERSTORMS COULD DEVELOP AND ADDED A SLIGHT CHANCE OF STORMS TO
THE FORECAST THAT AFTERNOON. DJ

AVIATION...

THUNDERSTORMS ARE DEVELOPING THIS AFTERNOON WITH A 25 PERCENT CHANCE
A STORM MAY BRIEFLY IMPACT KMMH OR KTVL AND A 10 PERCENT CHANCE OF
STORMS IMPACTING OTHER TERMINALS. STORMS WILL PRODUCE GUSTY AND
ERRATIC OUTFLOW WINDS, TURBULENCE AND WIND SHEAR. CLOUD BASES ARE
BETWEEN 10-14 KFT AGL WITH TOPS 25-35 KFT AGL. IN THE STRONGEST
THUNDERSTORM CELLS, TOPS MAY REACH 50 KFT AGL. BRIEF HEAVY RAINFALL
IS POSSIBLE WHICH MAY LOWER CEILINGS AND VISIBILITY, THOUGH OVERALL
CONDITIONS WILL BE VFR. ADDITIONAL THUNDERSTORMS ARE EXPECTED ACROSS
THE SIERRA AND NORTHWEST NEVADA ON SUNDAY. DJ

FIRE WEATHER...

LIGHTNING ACTIVITY HAS BEEN ROBUST SOUTH OF INTERSTATE 80 EARLY THIS
AFTERNOON. THERE HAVE BEEN REPORTS OF NEW FIRES EVEN THOUGH CELLS
HAVE BEEN PRODUCING DECENT PRECIPITATION. THIS IS RESULTING FROM
STRIKES OUTSIDE THE STORM CORES WITH RECEPTIVE VEGETATION THAT IS
READY TO BURN. THIS ENERGY WILL MOVE NORTHWARD THIS EVENING INTO A
DRIER ENVIRONMENT NORTH OF INTERSTATE 80. DRY LIGHTNING WILL
CONTINUE TO BE A CONCERN WITH NEW FIRE STARTS QUITE POSSIBLE.

WETTER CONDITIONS ARE EXPECTED SUNDAY WITH WETTING RAINS LIKELY
WITHIN STORM FOOTPRINTS. STRIKES WILL BE POSSIBLE OUTSIDE OF THE
CORES WITH THE POTENTIAL OF A FEW NEW FIRE STARTS. HUMIDITY SHOULD
BE 15-30% DURING THE DAY LIMITING THE UPWARD FIRE-GROWTH POTENTIAL
SOMEWHAT. THUNDERSTORM COVERAGE HAS BEEN EXPANDED FOR MONDAY, BUT
THESE TOO APPEAR TO BE OF THE WETTER VARIETY.

DRY LIGHTNING WITH MORE ISOLATED COVERAGE WILL BE POSSIBLE TUESDAY
AS SOUTHWEST FLOW DEVELOPS; A WEAK WAVE WILL BE THE POTENTIAL
TRIGGER MECHANISM. DRY SUB-CLOUD LAYER WILL PROMOTE STRONGER OUTFLOW
WIND GUSTS WHICH WOULD BE A DANGER TO FIRE MITIGATION EFFORTS.
ADDITIONALLY, HOLDOVERS MAY BECOME A NUISANCE LATE NEXT WEEK AS
ZEPHYR WINDS INCREASE WITH SOME LOCALLY BREEZY CONDITIONS POSSIBLE
WEDNESDAY THROUGH THE END OF THE WEEK. BOYD

&&

.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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