Area Forecast Discussion
Issued by NWS Reno, NV

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
000
FXUS65 KREV 190027
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
527 PM PDT SAT APR 18 2015

.UPDATE...
JUST A QUICK UPDATE EARLY THIS EVENING TO ADD ISOLATED SHOWERS
OVER FAR NRN AND NE LASSEN COUNTY AND PARTS OF NRN WASHOE COUNTY.
A WEAK AREA OF PV ADVECTION ALOFT IS MOVING INTO THAT AREA AND IS
HELPING DEVELOP A FEW HIGH BASED SHOWERS. LOW LVL FORECAST
INSTABILITY DOES NOT APPEAR ROBUST ENOUGH TO PRODUCE DEEP
CONVECTION SO WILL NOT MENTION THUNDERSTORMS IN THESE AREAS.
THUNDER SHOULD BE CONFINED TO THE SIERRA AND POINTS WEST THIS
EVENING. THIS PV ADVECTION AREA MAY BE STRONG ENOUGH TO KEEP A
LITTLE CONVECTION GOING INTO THE LATE EVENING SO WE WILL BE
WATCHING THIS IF WE NEED TO EXTENDED POPS TONIGHT. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 241 PM PDT SAT APR 18 2015/

SYNOPSIS...
WARM AFTERNOON TEMPERATURES WILL PERSIST THROUGH EARLY NEXT WEEK.
ISOLATED AFTERNOON SHOWERS, AND A FEW THUNDERSTORMS, WILL DEVELOP
OVER THE SIERRA THIS WEEKEND. LOW PRESSURE WILL MOVE INTO EASTERN
CALIFORNIA AND WESTERN NEVADA BY THE MIDDLE OF NEXT WEEK WITH
INCREASING CHANCES FOR PRECIPITATION AND COOLER TEMPERATURES.

SHORT TERM...

SO, BEING ABOUT A MONTH AHEAD IN TERMS OF TEMPERATURES IT SHOULD
NOT SURPRISE THAT WE`RE ALSO AHEAD OF SCHEDULE IN SEEING PATTERNS
FAVORABLE FOR THUNDERSTORMS. PLUS AFTER SEEING HUMIDITIES IN THE
SINGLE DIGITS YESTERDAY AND AGAIN TODAY (RNO 5% FRIDAY), AN
INCREASE IN MOISTURE WILL BE MOST WELCOME! FORECAST CONFIDENCE IN
TSTM POTENTIAL THROUGH TUESDAY IS MEDIUM, WITH PRIMARY
UNCERTAINTIES BEING SUBTLE AND LESS PREDICTABLE FEATURES LIKE
SHORTWAVES AND CLOUD COVER THAT COULD IMPACT CONVECTIVE
INITIATION.

12Z REV SOUNDING SHOWED SLIGHTLY INCREASED MOISTURE AND INSTABILITY
ALOFT COMPARED TO FRIDAY, AND MODEL GUIDANCE INCLUDING THE HRRR
CORRESPONDINGLY SHOWS VERY ISOLATED SHOWERS/TSTMS OVER THE SIERRA
LATE THIS AFTERNOON. SHORTWAVE DROPPING IN FROM THE NORTH COULD
ALSO HELP IN TSTM INITIATION THE FAR NORTHERN SIERRA GIVEN IT`S
APPROACH AROUND 0-3Z. FOR SUNDAY, GUIDANCE HIGHLIGHTS THE SIERRA
FROM TAHOE SOUTHWARD FOR THE BEST ALIGNMENT OF INSTABILITY AND
MOISTURE FOR ISOLATED TSTMS. 3-6 KM AGL STEERING FLOW IS LIGHT BUT
EASTERLY SO MOST ACTIVITY THAT DEVELOPS RIGHT ALONG THE CREST
WOULD TEND TO FLOAT WEST OUT OF OUR AREA SOON THEREAFTER.

MONDAY AND TUESDAY ARE LOOKING TO BE THE MOST OPTIMAL FOR SHOWERS
AND TSTMS OVER BIGGER PARTS OF OUR CWA. TOO SOON TO TELL IF THERE
WILL BE SHORTWAVE ENHANCEMENTS IN PLAY, BUT GFS/SREF INSTABILITY
AND MOISTURE PARAMETERS ARE POINTING TOWARD SOMEWHAT ACTIVE DAYS
WITH SCATTERED SHOWERS AND TSTMS. MONDAY THE BEST CHANCES ARE OVER
MUCH OF THE SIERRA AND ADJACENT HIGH TERRAIN IN FAR WRN NV WITH
LIGHT/NO STEERING FLOW. ON TUESDAY THE SAME AREAS SHOULD BE THE
PRIMARY FOCUS BUT THERE`S MORE POTENTIAL FOR WIDESPREAD SHOWERS
GIVEN PROXIMITY OF AN APPROACHING UPPER TROUGH ALONG THE CA
COASTLINE. NOT REALLY ANTICIPATING NOTABLE SEVERE WEATHER WITH ANY
OF THESE TSTMS, DUE TO WEAK SHEAR, BUT THE USUAL IMPACTS OF
LIGHTNING, +RA, AND GUSTY WINDS ARE CERTAINLY POSSIBLE. CS

LONG TERM...WEDNESDAY THROUGH SATURDAY...

A COOLER AND WETTER PATTERN WILL PREVAIL FOR THE SECOND HALF OF
NEXT WEEK AS AN UPPER LEVEL LOW REMAINS ACROSS THE WESTERN U.S.
LATEST MODEL GUIDANCE IS IN GENERAL AGREEMENT WITH POSITIONING THE
CORE OF THE LOW OFF THE SOUTHERN CALIFORNIA COAST BY WEDNESDAY
WHICH LEAVES THE SIERRA AND WESTERN NEVADA UNDER THE INFLUENCE OF
SOME DEFORMATION FORCING NORTHEAST OF THE LOW. AS SUCH, CONTINUED
TO TREND PRECIPITATION CHANCES HIGHER AND EXPECT THIS DAY TO BE
OUR BEST SHOT FOR WIDESPREAD SHOWERS. ISOLATED THUNDERSTORMS ARE
POSSIBLE THIS DAY BUT LOW LEVEL INSTABILITY MAY BE WEAK DUE TO
EXTENSIVE CLOUD COVER RESULTING IN LESS SURFACE HEATING. MOST
PRECIPITATION LOOKS TO BE IN THE FORM OF LIQUID BELOW 8,000 FEET
AS THE COLD CORE OF THE LOW HAS TRENDED FARTHER WEST. SHOWERS WILL
CONTINUE THURSDAY AS THE LOW SLOWLY SHIFTS EAST.

THE GREATER POINT OF UNCERTAINTY WILL BEGIN FRIDAY AS THE EC
BRINGS IN ANOTHER TROUGH TO THE WEST COAST WHILE THE GFS
TRANSITIONS TO A DRIER ZONAL FLOW ACROSS THE WEST COAST. ENSEMBLE
SPREADS FROM THE GEFS AND ECMWF ENSEMBLES ARE SUBSTANTIAL BY THIS
TIME SO CONFIDENCE IS LOW END IN REGARDS TO PRECIPITATION CHANCES.
HAVE MAINTAINED THE PRECIPITATION CHANCES IN THE SLIGHT CHANCE
CATEGORY. EXPECTING COOLER CONDITIONS DURING THIS PERIOD BUT
OVERALL SEASONABLE. LOOKING FOR HIGH TEMPERATURES GENERALLY IN THE
MID 60S ACROSS WESTERN NEVADA WITH MID 50S IN THE SIERRA INTO NEXT
WEEKEND. FUENTES

AVIATION...

HIGH PRESSURE WITH LIGHT WINDS AND VFR CONDITIONS THRU SUNDAY. A
FEW SHOWERS POSSIBLE NEAR THE SIERRA CREST THROUGH 03Z THIS
EVENING. ISOLATED -SHRA AND -TSRA ARE POSSIBLE MAINLY FOR KMMH
SUNDAY AFTERNOON FROM 21-03Z WITH BRIEF PERIODS OF MVFR/IFR
CONDITIONS AND ERRATIC OUTFLOW WINDS POSSIBLE NEAR AND WITHIN
SHOWERS AND STORMS. FUENTES

&&

.REV WATCHES/WARNINGS/ADVISORIES...
NV...NONE.
CA...NONE.
&&

$$

FOR MORE INFORMATION FROM THE NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/RENO (ALL LOWER CASE)






USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.