Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 200232
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
732 PM PDT TUE AUG 19 2014

.UPDATE...
CONVECTION IS FAIRLY MEAGER ACROSS MOST OF THE FORECAST AREA RIGHT
NOW. THERE DOES NOT APPEAR TO BE ENOUGH UPPER LEVEL FORCING TO
OVERCOME LOSS OF DAYTIME HEATING. FROM THE OVERALL PATTERN IT
APPEARS THE UPPER LEVEL DEFORMATION ZONE IS TRYING TO DEVELOP MORE
ACROSS THE SRN FORECAST AREA THEN NORTHEAST INTO CENTRAL AND
NORTHEAST NEVADA AS OPPOSED TO CLOSER TO THE CENTRAL PART OF OUR
FORECAST AREA. THERE IS A WEAK IMPULSE TRYING TO MOVE INTO NRN
CA...BUT CONVECTION WITH THIS IS SLIGHT. LATEST NAM GUIDANCE IS
NOT VERY ENTHUSIASTIC ABOUT SHOWERS OVER THE REGION TONIGHT GIVEN
POSITIONING OF DEFORMATION ZONE A BIT FARTHER EAST. FOR NOW WILL
LEAVE THE SLIGHT CHANCE SHOWERS WE HAVE GOING IN THE FORECAST
OVERNIGHT AND REEVALUATE LATER. WILL ADJUST CONVECTION FOR THE
EVENING AS WELL MORE TO THE EASTERN CWA. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 217 PM PDT TUE AUG 19 2014/

SYNOPSIS...
LOW PRESSURE MOVING SOUTH ALONG THE CALIFORNIA COAST WILL BRING
THE THREAT OF ISOLATED SHOWERS AND THUNDERSTORMS THE REST OF TODAY
AND WEDNESDAY. COOLER TEMPERATURES ARE LIKELY FOR FRIDAY AND THIS
WEEKEND AS LOW PRESSURE FROM THE GULF OF ALASKA MOVES INTO THE
PACIFIC NORTHWEST.

SHORT TERM...
LOW PRESSURE WILL CONTINUE TO MOVE SOUTH ALONG THE CALIFORNIA
COAST WITH A DEFORMATION ZONE SETTING UP OVER THE NORTHERN SIERRA
AND WESTERN NEVADA TONIGHT. THIS WILL BE THE BEST FOCUS FOR
THUNDERSTORMS THIS EVENING AND A FEW SHOWERS FOR TONIGHT AND
WEDNESDAY MORNING.

THROUGH THIS EVENING, SHOWERS AND THUNDERSTORMS WILL CONTINUE
NORTH OF SUSANVILLE TO PYRAMID LAKE TO FALLON UNDER THE
DEFORMATION ZONE. THE STRONGER STORMS WILL PRODUCE OUTFLOW WINDS
OF 40-50 MPH, BRIEF HEAVY RAINFALL AND SMALL HAIL. AS THE LOW
SHIFTS SOUTH THE DEFORMATION ZONE WILL REACH LAKE TAHOE TO RENO-
CARSON AND EAST TO LOVELOCK-FALLON. THIS SHOULD ALLOW A FEW
SHOWERS TO PERSIST OVERNIGHT AND EARLY WEDNESDAY MORNING. HOWEVER
ANY RAINFALL AMOUNTS WILL BE LIGHT DUE TO RELATIVELY DRY SURFACE
CONDITIONS.

AS THE LOW DROPS INTO SOUTHERN CALIFORNIA WEDNESDAY AFTERNOON,
WARMING ALOFT WILL LIMIT CONVECTIVE STRENGTH. HOWEVER THERE IS
STILL GOOD INSTABILITY BELOW 25000 FEET, SO THERE COULD BE A FEW
LOW TOPPED THUNDERSTORMS ALONG THE EASTERN SIERRA SOUTH OF HIGHWAY
50. THE NAM CONTINUES TO SHOW A FEW SHOWERS OR THUNDERSTORMS
DEVELOPING OVER RENO-TAHOE TO PYRAMID LAKE. HOWEVER DON`T HAVE
ENOUGH CONFIDENCE TO INCLUDE THIS IN THE FORECAST WITH LITTLE TO
NO SUPPORT FROM OTHER MODELS.

A FEW SHOWERS AND LOW TOPPED THUNDERSTORMS MAY ALSO OCCUR NORTH
OF CEDARVILLE-GERLACH-LOVELOCK LATE WEDNESDAY AFTERNOON TO EARLY
THURSDAY MORNING AS A SECONDARY WAVES SKIMS THE NORTHERN NEVADA
BORDER. BRONG

LONG TERM...FRIDAY THROUGH TUESDAY...
AN UPPER TROUGH WILL MOVE INTO WASHINGTON AND OREGON FRIDAY BEFORE
SLIDING EAST INTO THE NORTHERN ROCKIES OVER THE WEEKEND. THIS WILL
BRING DRY WEST-NORTHWEST FLOW ALOFT TO NORTHEAST CALIFORNIA AND
WESTERN NEVADA THROUGH EARLY NEXT WEEK WITH TEMPERATURES SLIGHTLY
BELOW AVERAGE LATE WEEK RISING BACK TO AROUND AVERAGE BY SUNDAY.

AS FAR AS MODEL DIFFERENCES, THE GFS/EC AND THEIR ENSEMBLES CONTINUE
TO SHOW DECENT AGREEMENT WITH THE LATE WEEK TROUGH. THE GEM ENSEMBLE
ALSO HAS SIMILAR DEPTH/TIMING WITH THE TROUGH ALTHOUGH THE 12Z
DETERMINISTIC GEM IS NOW MORE PROGRESSIVE AND FARTHER NORTHEAST THAN
PREVIOUS RUNS. THIS IS A FLOP FROM PREVIOUS SOLUTIONS WHICH SUPPORT
THE CURRENT GFS/EC RUNS SO THE 12Z GEM HAS BEEN IGNORED.

IMPACTS FROM THE LATE WEEK TROUGH WILL BE MINOR FOR MOST PEOPLE. THE
MAIN EXCEPTIONS WILL BE: LOW TEMPERATURES NEAR FREEZING BY SUNDAY
MORNING FOR EASTERN CALIFORNIA`S COLDER VALLEYS AND GUSTY WINDS ON
FRIDAY/FRIDAY NIGHT AS THE UPPER LOW SLIDES BY TO THE NORTH. THE
WINDS COULD BRING SOME CONCERN FOR THE FIRE WEATHER COMMUNITY,
ESPECIALLY NORTH OF HIGHWAY 50. SNYDER

AVIATION...
ISOLD TSTMS ARE EXPECTED INTO THIS EVENING FOR NORTHEAST CALIFORNIA
AND WESTERN NEVADA, MAINLY WELL NORTH AND EAST OF KRNO AND NEAR THE
SIERRA SOUTH OF HIGHWAY 50. MAIN THREATS WILL BE LIGHTNING, SFC WND
GUSTS TO 45 KTS AND SMALL HAIL (UP TO AROUND 0.50").

ISOLATED STORMS WILL ONCE AGAIN BE POSSIBLE WEDNESDAY AFTERNOON,
MAINLY AFTER 21Z/2 PM PDT. SNYDER

&&

.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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