Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 030316
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
816 PM PDT SUN AUG 2 2015

.UPDATE...
WITH THE EXCEPTION OF FAR SOUTHERN MINERAL COUNTY THE CONVECTION
HAS LARGELY ENDED FOR THE TIME BEING THIS EVENING. DRIER AIR IS
SEEN TRYING TO PUSH INTO MONO COUNTY AND MAYBE EAST INTO MINERAL
COUNTY. THIS COULD EXPLAIN THE PERSISTENT CELLS IN THAT AREA ALONG
A MOISTURE GRADIENT. THERE ALSO APPEARS TO BE A FEATURE LIFTING
NORTH ACROSS WESTERN NEVADA AND NORTHEAST CALIFORNIA THAT IS
ENDING CONVECTION BEHIND THIS EVENING.

EARLIER MODELS SHOWED A PV WAVE MOVING NORTH LATE TONIGHT WITH A
FEW ELEVATED THUNDERSTORMS POSSIBLE. THIS STILL CANNOT BE
COMPLETELY COUNTED OUT.

HAVE MADE ADJUSTMENTS TO POPS THE REMAINDER OF THIS EVENING AND
OVERNIGHT SHOWING LESS CHANCE FOR CONVECTION AND PUSHING THOSE
CHANCES MORE TO THE EAST AND NORTH. THIS IS BANKING ON DRIER AIR
PUSHING INTO THE AREA FROM THE SOUTHWEST LATER TONIGHT. ALSO
ADJUSTED A FEW MAX RH VALUES TO ACCOUNT FOR THIS AS WELL. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 234 PM PDT SUN AUG 2 2015/

SYNOPSIS...

SCATTERED SHOWERS AND THUNDERSTORMS CONTINUE THROUGH THIS EVENING
WITH LIGHTNING AND LOCALLY HEAVY RAINFALL. 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...

SHOWERS AND THUNDERSTORMS A BIT SLOW TO DEVELOP THIS AFTERNOON,
BUT ARE STARTING TO POP IN THE TAHOE BASIN AND SIERRA FRONT WHERE
MOSTLY CLEAR SKIES HAVE LED TO THE BEST SURFACE HEATING. SOME
SHOWERS CONTINUE TO PUSH NORTH OF RENO TO NEAR SUSANVILLE WITH
ABUNDANT CLOUD COVER. MESOSCALE MODELS STILL SUGGEST THAT
THUNDERSTORMS WILL DEVELOP NORTH OF RENO INTO LASSEN AND NORTHERN
WASHOE COUNTIES LATE THIS AFTERNOON AND INTO THE EVENING HOURS.
INCREASING SHEAR ALOFT MAY HELP TO MAKE A FEW OF THESE STORMS
STRONG OR EVEN SEVERE. DEEP MOISTURE (PRECIPITABLE WATER NEAR
1.0") WILL LEAD TO LOCALLY HEAVY RAINFALL AS WELL.

THERE IS A SLIGHT CHANCE THAT SHOWERS AND THUNDERSTORMS MAY
CONTINUE AFTER MIDNIGHT AND INTO THE EARLY MORNING HOURS DUE TO A
WEAK UPPER LEVEL WAVE AND STEEP UPPER LAPSE RATES. NOT SUPER
CONFIDENT ON THIS EVENT AS THE PV WAVE LOOKS TO BE FAIRLY WEAK.
WE DON`T THINK IT`LL BE ANYTHING LIKE WE SAW LAST NIGHT FOR
LIGHTNING, BUT THERE IS A SLIGHT CHANCE OF THUNDERSTORM ACTIVITY
OVERNIGHT.

BY MONDAY, THUNDERSTORM ACTIVITY REALLY STARTS TO DROP OFF AS
SOUTHWEST FLOW DRIES OUT THE REGION. WE LOWERED STORM CHANCES FOR
MONDAY TO ISOLATED, WITH A MIX OF WET AND DRY STORMS LIKELY. AS
PRECIPITIABLE WATER VALUES DROP TO AROUND 0.75" AND STORM MOTIONS
INCREASING, THIS WILL ALLOW FOR MORE NARROW RAIN CORES AND SOME
DRY LIGHTNING STRIKES. SEE FIRE WEATHER DISCUSSION FOR MORE
DETAILS ON FIRE IMPACTS.

FOR TUESDAY, AGAIN WE WILL SEE A CHANCE OF AFTERNOON THUNDERSTORMS
IN WESTERN NEVADA, BUT WITH AN UPPER LEVEL WAVE AND JET NOSE MOVING
THROUGH NORTHERN CA, WE COULD SEE INCREASING COVERAGE OF
THUNDERSTORMS. HOON

LONG TERM...WEDNESDAY THROUGH SUNDAY...

A WARMING TREND WILL PREVAIL AS AN UPPER LOW DEPARTS WEDNESDAY AND
SHORTWAVE RIDGING BECOMES ESTABLISHED BY THURSDAY. A DRIER SOUTHWEST
FLOW WILL BECOME ESTABLISHED WEDNESDAY AND THURSDAY ACROSS MUCH OF
THE REGION WITH A STRAY SHOWER OR STORM POSSIBLE ACROSS FAR NORTHERN
WASHOE COUNTY WEDNESDAY.

THE FOCUS IN THE EXTENDED FORECAST WILL BE ON A DEVELOPING CLOSED
LOW WHICH MAY PROVIDE A SOLID POTENTIAL FOR THUNDERSTORMS BY FRIDAY
ACROSS THE SIERRA AND WESTERN NEVADA. UNCERTAINTY HINGES ON THE
POSITION AND TIMING OF THE CLOSED LOW. THE GFS AND EC SHOW GOOD
AGREEMENT IN THE LATEST 12Z RUNS. HOWEVER, JUDGING THE INHERENT
UNCERTAINTIES IN FORECASTING CLOSED LOW SYSTEMS ALONG WITH ONLY
MODEST ENSEMBLE SPREADS, WILL CONTINUE TO MENTION JUST ABOUT A 20%
FOR STORMS AND INCREASED CLOUD COVER. IF THE POSITION OF THE LOW
REMAINS WHERE ITS CURRENTLY DEPICTED BY THE GFS/EC IT WOULD PLACE
THE NORTHERN SIERRA AND WESTERN NEVADA IN A FAVORABLE AREA OF
DIVERGENCE ALOFT AND EVEN LEFT EXIT JET DYNAMICS. ORGANIZED
CONVECTION MAY ALSO BE A POSSIBILITY GIVEN SUFFICIENT MOISTURE AND
INSTABILITY COMBINED WITH GOOD DYNAMIC FORCING. OVERALL CONFIDENCE
IS LOW-MEDIUM UNTIL BETTER CONFIDENCE IS ESTABLISHED WITH PLACEMENT
OF THE LOW.

OVERALL, HIGH TEMPERATURES LOOK TO PEAK ON THURSDAY WITH LOWER TO
MID 90S POSSIBLE ACROSS WESTERN NEVADA AND LOWER 80S ACROSS SIERRA
VALLEYS. NUMERICAL GUIDANCE KEEPS FRIDAY`S LOW PROGRESSIVE WHICH
WILL LINGER SOME SHOWER ACTIVITY INTO SATURDAY WITH OTHERWISE COOLER
AND NEAR SEASONABLE TEMPERATURES EXPECTED FOR THE REMAINDER OF THE
WEEKEND. FUENTES

AVIATION...

ISOLATED STORMS CONTINUE ACROSS THE SIERRA AND WESTERN NEVADA
THROUGH LATE AFTERNOON. AS OF 21Z, ISOLATED -SHRA/-TSRA CONTINUE
NEAR KTVL AND KTRK. EXPECTING ACTIVITY TO MOVE NORTH OF OF KTVL BY
00Z AND NORTH OF KCXP/KRNO/KTRK AFTER 02Z. BRIEF IFR CONDITIONS
POSSIBLE WITHIN SHOWER AND STORM ACTIVITY. EXPECT VFR CONDITIONS
OVERNIGHT WITH LESS STORMS FOR MONDAY. ONLY A 15-20% CHANCE OF
STORMS IMPACTING THE KRNO/KCXP/KMMH TERMINALS AND LESS THAN 10% FOR
KTRK/KTVL. FUENTES

FIRE WEATHER...

NO MAJOR SHIFTS IN THE THOUGHT PROCESS ABOUT EXPECTED FIRE WEATHER
CONDITIONS FOR THIS WEEK. WHILE CONDITIONS BECOME DRIER THROUGH
TUESDAY AND THUNDERSTORMS ARE EXPECTED EACH AFTERNOON, THE
INGREDIENTS ARE NOT LINING UP FOR MORE THAN ISOLATED COVERAGE. PWATS
WILL FAVOR HYBRIDIZED THUNDERSTORMS MONDAY AS WEAK FORCING MOVES
THROUGH THE REGION. THIS FORCING IS OUT OF PHASE WITH OTHER
INSTABILITY ENHANCING FACTORS, HENCE THE MORE ISOLATED COVERAGE.
STILL, STORM MOVEMENT FAVORS DRIER THUNDERSTORMS AND A FEW NEW FIRE
STARTS WILL BE POSSIBLE. AS FOR TUESDAY, FORCING PARAMETERS ARE
BETTER, BUT MOISTURE BECOMES MORE ANEMIC WITH PWATS BACK DOWN TO
0.6". AGAIN, WHILE SUPPORTIVE OF SOME DRIER THUNDERSTORM ACTIVITY,
IT IS NOT FAVORABLE FOR MORE EXTENSIVE COVERAGE. OUTFLOW POTENTIAL
DOES INCREASE, HOWEVER, AS THE SUB-CLOUD LAYER DRIES OUT FURTHER.

THE NEXT THREAT WILL COME WEDNESDAY AND THURSDAY AFTERNOONS AS
ZEPHYR WINDS INCREASE; THURSDAY WILL BE THE BREEZIER DAY WITH GUSTS
UP TO 30 MPH. ANY HOLDOVERS MAY BECOME A NUISANCE AS RELATIVE
HUMIDITIES BOTTOM OUT DURING LOCALLY BREEZY CONDITIONS.

ANOTHER WAVE APPROACHES FRIDAY BRINGING THE POTENTIAL FOR DRY
LIGHTNING BACK INTO THE FORECAST. WITH 3 DAYS OF DRYING OUT, DECENT
SOUTHWESTERLY FLOW, AND STRONGER SYSTEM DYNAMICS, THERE IS A
MODERATE POTENTIAL FOR DRY LIGHTNING ACROSS THE SIERRA AND WESTERN
NEVADA. HOWEVER, CONSIDERING HOW FAR OUT THIS IS, CONDITIONS WILL
LIKELY CHANGE ONE WAY OR ANOTHER; JUST A CONSIDERATION FOR PLANNING
PURPOSES AT THIS POINT. 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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