Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 011021
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
321 AM PDT SAT AUG 1 2015

.SYNOPSIS...
MOISTURE IS ON THE INCREASE THIS WEEKEND, BRINGING CHANCES FOR
SHOWERS AND THUNDERSTORMS 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 TAPERING OFF BY WEDNESDAY.

&&

.SHORT TERM...
LOOKING AT THE INFRARED SATELLITE THIS MORNING, CONSIDERABLE
CLOUD COVER REMAINS NEAR AND NORTH OF I-80. FARTHER SOUTH,
ADDITIONAL CLOUD COVER IS WORKING INTO SOUTHERN/EASTERN MINERAL
AND MONO COUNTIES WITH A SUBTLE UPPER WAVE APPROACHING FROM INYO
COUNTY. THE CLOUDS NORTH OF I-80 HAVE NOT PRODUCED MUCH IN THE
WAY OF SHOWERS PER RADAR RETURNS AND ARE SPREADING OUT AS IF THEY
ARE CAPPED OFF. HOWEVER, WITH THE WAVE APPROACHING FROM THE SOUTH
ENOUGH DEPTH COULD BE HAD FOR ISOLATED LIGHT SHOWERS OR SPRINKLES
THIS MORNING. I ALSO LEFT IN A SLIGHT CHANCE OF THUNDER WITH THE
INCOMING FORCING, ALTHOUGH NO LIGHTNING HAS BEEN NOTED SO FAR.

THIS AFTERNOON, CLEARING BEHIND THE WAVE IS EXPECTED TO ALLOW FOR
SCATTERED SHOWERS AND THUNDERSTORMS TO DEVELOP SOUTH OF HIGHWAY 50
AND IN/NEAR THE SIERRA. THE PWAT IN RENO IS ALREADY AROUND 0.75"
AND SOUNDING MODEL PROGS SHOW PWATS IN THE 0.75" TO 0.9" RANGE
THIS AFTERNOON FOR MANY AREAS. THE EXCEPTION MAY BE ACROSS
NORTHERN WASHOE, NORTHEAST LASSEN AND NORTHERN PERSHING COUNTIES
WHERE PWATS MAY REMAIN CLOSER TO 0.5" THIS AFTERNOON. WITH THAT IN
MIND, ANY THUNDERSTORMS NORTH OF A SUSANVILLE TO PYRAMID LAKE TO
LOVELOCK LINE TODAY MAY PRODUCE MUCH LESS RAINFALL THAN AREAS
FARTHER SOUTH. IN ADDITION, THE GUSTIEST OUTFLOW WINDS WILL TEND
TO BE UP NORTH (ESPECIALLY IF CLEARING DEVELOPS) WITH THE DRIEST
LOW LEVELS.

LATE TONIGHT AND EARLY SUNDAY, I HAVE LEFT THE RESIDUAL SHOWERS
AND SLIGHT CHANCE OF THUNDERSTORMS AS MODELS SHOW SIGNS OF AN
UPPER WAVE MOVING THROUGH NORTHERN NEVADA. THIS WAVE IS NOT
READILY VISIBLE IN SATELLITE IMAGERY BUT COULD BE HIDING OVER FAR
SOUTHEAST CALIFORNIA EARLY THIS MORNING (PER CLOUDS IN THE INFRARED).

SUNDAY AFTERNOON, PLENTY OF MOISTURE WILL IN PLACE FOR SCATTERED,
DIURNALLY-LINKED SHOWERS AND THUNDERSTORMS. SOME STORMS COULD
CERTAINLY CONTAIN HEAVY RAINFALL GIVEN PWATS BETWEEN 0.8" AND 1" FOR
MOST LOCATIONS IN WESTERN NEVADA AND NORTHEAST CALIFORNIA. UPPER
FLOW LOOKS TO BE IN THE 10-20 KT RANGE, HOWEVER STORM INTERACTIONS
COULD MAKE FOR SLOWER OR TRAINING CONVECTION WITH A LOCALIZED
THREAT FOR FLASH FLOODING IN STEEP TERRAIN OR ON BURN SCARS.

MONDAY WILL BRING IN DRIER SOUTHWEST FLOW ALOFT WITH A REDUCTION
IN STORM COVERAGE (BEST SHOT SOUTH OF HIGHWAY 50). SNYDER

.LONG TERM...TUESDAY THROUGH FRIDAY...
FEW CHANGES WERE MADE TO THE LONG TERM WITH THE MODELS IN DECENT
AGREEMENT ALTHOUGH THEY HAVE CHANGED LATE NEXT WEEK FROM 24 HOURS
AGO. BOTH GFS/EC SHOW THE LOW FOR TUESDAY NOW AND HAVE IT MOVING
ACROSS DURING THE AFTERNOON. HAVE KEPT IN THE SLIGHT CHANCE OF
THUNDERSTORMS THE DAY SHIFT ADDED NORTH OF HIGHWAY 50. THE MODELS
ARE A BIT DRIER THOUGH WITH PW 2/3 INCH OR LESS. THE FORCING IS
STRONG AND THERE IS A GOOD MOIST LAYER AT 600 MB SO THINK WE WILL
SEE SOMETHING AT LEAST.

BEHIND THE LOW A GENERAL SOUTHWEST FLOW WILL CONTINUE FOR WED/THU
WITH DRY CONDITIONS AND A TYPICAL AFTERNOON ZEPHYR. HOWEVER, THE
MODELS ARE FURTHER NORTH WITH THE PACIFIC TROUGH OVERALL WITH ONLY A
WEAK LOW DEVELOPING OFF THE COAST. FOR US, THIS CHANGE THESE TWO
DAYS REALLY DOESN`T IMPACT THE FORECAST MUCH. BY FRIDAY, BOTH GFS/EC
AND MANY ENSEMBLE MEMBERS BRING THE LOW TOWARD THE SIERRA AND
WESTERN NEVADA. HAVE LEFT FRIDAY DRY FOR NOW, BUT IF THE MODELS
CONTINUE, THUNDERSTORMS WOULD BE POSSIBLE AS IT MOVES ACROSS. THE
TRAJECTORY OF THE LOW WOULD ALSO LIMIT MUCH MOISTURE BEING PULLED
NORTH FROM THE MONSOON SO STORMS COULD BE DRIER AND A FIRE WEATHER
CONCERN. WILL CONTINUE TO MONITOR AS THIS IS STILL A FEW DAYS OUT.
TEMPERATURES WILL CONTINUE TO HOVER NEAR OR JUST BELOW
AVERAGE FOR EARLY AUGUST. WALLMANN

&&

.AVIATION...
SOME MID-HIGH CLOUD COVER REMAINS THIS MORNING, BUT IT APPEARS
LESS DENSE THAN YESTERDAY. IT ALSO APPEARS MUCH OF THE CLOUD COVER
WILL MOVE INTO NORTHERN NEVADA AND OREGON BY MID-MORNING. EXPECT
SCATTERED SHOWERS AND THUNDERSTORMS SOUTH OF A KSVE-GERLACH LINE
20-04Z WITH GUSTY OUTFLOW WINDS AND SMALL HAIL THE MAIN THREATS.
OTHERWISE WINDS WILL REMAIN LIGHT WITH VFR CONDITIONS.

STORMS ARE POSSIBLE AGAIN ON SUNDAY WITH SIMILAR TIMING AND THREATS.
COVERAGE WILL AGAIN DEPEND ON JUST HOW MUCH CLOUD COVER THERE IS
DURING THE MORNING HOURS. WITH A LITTLE MORE MOISTURE, CLOUD BASES
WILL LOWER WITH SOME MTN OBSCURATION POSSIBLE OVER THE HIGHER
SIERRA PEAKS. WALLMANN

&&

.FIRE WEATHER...
LESS CLOUD COVER THIS MORNING THUS FAR SO IT APPEARS WE WILL HAVE
AN ACTIVE DAY WITH SCATTERED THUNDERSTORMS AT LEAST SOUTH OF A
PORTOLA TO RENO TO FALLON LINE. NORTH OF THIS LINE, MORE ISOLATED
STORMS ARE LIKELY. THE ONLY EXCEPTION WILL BE LASSEN COUNTY WHERE
A FEW MORE STORMS ARE POSSIBLE WITH ENOUGH CLEARING. STORMS MAY
BEGIN DRY SOUTH OF THE LINE MENTIONED ABOVE BUT THEY WILL QUICKLY
TRANSITION TO WET AS MOISTURE SIGNIFICANTLY INCREASES. NORTH,
DRIER AIR REMAINS IN PLACE THE REST OF THE DAY.

THE ONE AREA WE WILL WATCH WILL BE EASTERN PLUMAS AND LASSEN
COUNTIES WHERE THERE COULD BE ENOUGH COVERAGE PROVIDED ENOUGH
CLEARING FOR HEATING THIS MORNING. AS OF THIS WRITING, PLAN ON
WAITING UNTIL THE LAST MINUTE TO DECIDE ON A RED FLAG FOR ZONES
271/278. I WOULD LIKE TO SEE THE RENO SOUNDING THIS MORNING AND
EXTENT OF CLOUD COVER ON VISIBLE SATELLITE IMAGERY. IR IMAGERY CAN
BE A BIT DECEIVING AND IT IS HARD TO SEE JUST HOW MANY BREAKS THERE
ARE IN THE CLOUD DECK.

BY SUNDAY, ENOUGH MOISTURE WILL BE IN PLACE ACROSS ALL ZONES FOR
WETTING RAINS FROM THE STORMS ALTHOUGH A FEW SMALL FIRE STARTS ARE
POSSIBLE OUTSIDE STORM CORES. MONDAY WE WILL SEE SLOW DRYING WITH A
FEW MORE STORMS POSSIBLE, BUT THESE LOOK TO BE WET AS WELL.

NEXT WEEK, THERE ARE TWO WAVES OF CONCERN. THE FIRST IS TUESDAY AS
THE UPPER LOW CURRENTLY OFF THE COAST FINALLY MOVES THROUGH. ENOUGH
DRYING WILL HAVE TAKEN PLACE BY THEN IN THE LOW LEVELS WHERE
THUNDERSTORMS WILL BE MUCH DRIER. MODELS SHOW ANOTHER LOW IS
POSSIBLE FRIDAY/SATURDAY AND THIS WOULD ALSO HAVE LIMITED LOW LEVEL
MOISTURE BUT PLENTY OF MID-LEVEL MOISTURE FOR THUNDERSTORMS. THESE
SYSTEMS ARE STILL SEVERAL DAYS OUT SO A LOT CAN CHANGE, BUT IF
CURRENT MODEL RUNS HOLD WE COULD HAVE SOME DRY LIGHTNING. 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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