Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 030841
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
141 AM PDT WED JUN 3 2015

.SYNOPSIS...

THERE IS A LOW CHANCE FOR THUNDERSTORMS NORTH OF SUSANVILLE AND
GERLACH TODAY. THUNDERSTORM CHANCES EXPAND OVER THE SIERRA AND
WESTERN NEVADA THURSDAY AS LOW PRESSURE DROPS INTO CALIFORNIA.
CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUE THROUGH THE
WEEKEND.

&&

.SHORT TERM...

00Z GEFS SHOWS PRECIPITATION DEVELOPING LATE TONIGHT NORTH AND
EAST OF A SUSANVILLE-FALLON LINE. THIS IS ASSOCIATED WITH A
SOUTH-TO-NORTH JET EMERGING ALONG THE WEST SIDE OF AN UPPER LOW
LOCATED OVER CENTRAL CA. OOZ EC MODEL IS A LITTLE SLOWER WITH THIS
DEVELOPMENT, BUT SHOWS A SIMILAR FEATURE EARLY THURSDAY MORNING.
WE INTRODUCED A SLIGHT CHANCE FOR NOCTURNAL SHOWERS/THUNDERSTORMS
AFTER MIDNIGHT NORTH AND EAST OF SUSANVILLE-FALLON BASED ON THE
POTENTIAL FOR THIS CIRCULATION/LIFT IN THE LEFT-EXIT REGION OF
THE UPPER JET. THE JET SHIFTS EAST THURSDAY AFTERNOON/EVENING BUT
MODERATE 30 KT SHEAR IS STILL AVAILABLE THROUGH THE UPDRAFT LAYER
ALONG WITH MARGINAL INSTABILITY. THIS SHOULD LEAD TO SCATTERED
THUNDERSTORMS THURSDAY AFTERNOON/EVENING ACROSS WESTERN NV.
POSSIBLE THREATS EAST OF HIGHWAY 395 ARE BRIEF HEAVY RAIN, UP TO
PENNY SIZE HAIL, AND GUSTS TO 40 MPH.

AS THE UPPER COLD POOL OVER CALIFORNIA SHIFTS EAST THURSDAY
AFTERNOON, THERE WILL BE STRONGER INSTABILITY OVER THE SIERRA.
PRECIPITABLE WATER VALUES ARE ALSO HIGHER, LIKELY IN THE 0.50 TO
0.70 RANGE. WITH THE UPPER LOW NEARBY, STEERING FLOW FOR
THUNDERSTORMS WILL BE VARIABLE AND WEAK. AS SUCH, THERE IS
POTENTIAL THURSDAY AFTERNOON ACROSS THE SIERRA AND SIERRA FRONT
RANGE FOR SOME SLOW MOVING THUNDERSTORMS TO CREATE LOCALLY HEAVY
RAIN, MUD AND ROCKS TO WASH OVER ROADS, AND STREET FLOODING AND
PONDING OF WATER IN LOW-LYING AREAS. THIS POTENTIAL FOR LOCALLY
HEAVY RAIN WILL REMAIN IN PLACE OVER THE SIERRA FRIDAY AND COULD
SPREAD ACROSS WESTERN NEVADA AS WELL. JCM

.LONG TERM...SATURDAY THROUGH TUESDAY...

OVERALL THE FORECAST REASONING HAS CHANGED VERY LITTLE FOR THE
EXTENDED PERIOD THIS CYCLE SO ONLY MINOR TWEAKS WERE MADE TO THE
INHERITED FORECAST.

MEDIUM RANGE DETERMINISTIC MODELS AND MOST GEFS ENSEMBLE MEMBERS
LIFT A BROAD UPPER LOW FROM SRN CA ACROSS NV THROUGH SUNDAY. THE
MAIN DEFORMATION AXES APPEAR TO BE ON THE EAST AND NORTH SIDE OF
THIS LOW AND THOSE MAY BE THE BEST AREAS FOR WIDESPREAD CONVECTION
AND MODERATE TO LOCALLY HEAVY RAIN IN THUNDERSTORMS. BUT...THERE
IS A CHANCE FOR CONVECTION JUST ABOUT ANYWHERE IN THE CWA AND THIS
FAR OUT IT CAN BE VERY DIFFICULT TO NAIL DOWN THE BEST LOCATION
FOR MODERATE TO HEAVY BANDS OF PCPN TO FORM. MOISTURE IS PULLED UP
FROM THE SOUTH AHEAD OF THIS LOW...BUT THE DEEPEST MOISTURE WILL
RESIDE EAST OF THE CWA. STILL...MOISTURE IS PLENTIFUL ENOUGH FOR
SHOWERS AND THUNDERSTORMS EACH DAY EVEN IN WESTERN NV AND THE
SIERRA.

BY MONDAY THERE IS SOME DISAGREEMENT IN THE MODELS...MAINLY
REGARDING HOW FAST TO WEAKEN AND LIFT THE BROAD LOW OUT OF THE
AREA. MOST OF THE GEFS ENSEMBLE MEMBERS SHOW THE LOW SPLITTING
WITH A PIECE REMAINING WELL WEST OF THE WEST COAST AND THE OTHER
WEAKENING AND DRIFTING INTO THE INTERMOUNTAIN WEST. A FEW MEMBERS
KEEP THE LOW CLOSER TO OUR AREA. THE GFS AND ECMWF BOTH SPLIT THE
LOW BUT THE ECMWF HAS A MORE VIGOROUS SHORT WAVE MONDAY AFTERNOON
CLOSE TO THE REGION. THE GEM HOLDS THE LOW OVER US A BIT LONGER.
GIVEN THESE SUBTLE VARIATIONS WILL MAINTAIN SMALL CHANCE POPS
ACROSS THE FAR NORTHERN CWA MONDAY AND SLIGHT CHANCE OVER THE
SOUTH. THE BROAD TROUGH OFFSHORE EDGES A LITTLE CLOSER FOR TUESDAY
AND SOUTH TO SOUTHEAST FLOW IN THE LOWER TO MID LEVELS SHOULD KEEP
ENOUGH MOISTURE AROUND FOR AT LEAST SLIGHT CHANCE POPS FOR MOST OF
THE AREA.

TEMPS VARY EACH DAY DEPENDING ON CLOUD COVER BUT GENERALLY HIGHS ARE
AT OR SLIGHTLY ABOVE AVERAGE WHILE LOWS ARE ABOVE AVERAGE GIVEN CLOUD
COVER AND MOISTURE NOT ALLOWING FOR RADIATIONAL COOLING AT NIGHT. 20

&&

.AVIATION...

CLOUDS BEGIN TO INCREASE TODAY AS AN UPPER LEVEL LOW DROPS SOUTH
INTO THE REGION. AFTERNOON WIND GUSTS EAST OF THE SIERRA MAY REACH
25 KTS IN THE LOW LVLS TODAY. ISOLATED CONVECTION COULD DEVELOP
NORTH OF A SUSANVILLE TO GERLACH LINE THIS AFTERNOON AND EVENING.
CONVECTION IS ALSO POSSIBLE LATER TONIGHT EAST OF A SUSANVILLE TO
FALLON LINE AS AN UPPER LEVEL WAVE MOVES ACROSS THE REGION. OF
COURSE...TURBULENCE IS LIKELY NEAR ANY CONVECTION. OVERALL VFR
CONDITIONS WILL HOLD TODAY AS ANY CONVECTION WILL BE FAIRLY HIGH
BASED.

BY THURSDAY CONVECTION SHOULD BECOME MORE WIDESPREAD BY THE
AFTERNOON AND EVENING AND BASES WILL LOWER...BUT STILL MAINLY VFR.
MOUNTAIN TOPS COULD BE OBSCURED IN CONVECTION THURSDAY AND MODERATE
TO HEAVY RAIN IS POSSIBLE NEAR THE STRONGER THUNDERSTORMS. THIS WILL
BE THE CASE AGAIN FRIDAY WHEN CONVECTION COULD BE EVEN MORE
WIDESPREAD THAN THURSDAY. 20

&&

.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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