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 38 39 40 41 42
000
FXUS65 KREV 240306
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
806 PM PDT SAT MAY 23 2015

.UPDATE...
CONVECTIVE COVERAGE HAS DECREASED QUITE A BIT THIS EVENING AS THE
UPPER LOW THAT DROPPED THROUGH NRN CA EARLIER CONTINUES TO DIP
SOUTH TOWARD SRN CA THIS EVENING. MEANWHILE THE VORT LOBE OVER
CENTRAL NV IS SHOWING SIGNS OF WEAKENING...EVEN THOUGH IT IS
STILL STRONG ENOUGH TO PRODUCE SHOWERS AND THUNDERSTORMS IN NORTH
CENTRAL NV. WILL MAINTAIN HIGHER POPS FOR OUR FAR ERN AND SRN
AREAS LATE THIS EVENING...BUT WILL DECREASED POPS THE REMAINDER OF
THE EVENING FROM THE TAHOE BASIN NORTHWARD IN CA AND FAR WRN AND
NW NV.

AS CLEARING BEGINS LATE TONIGHT WE DO EXPECT FOG TO DEVELOP IN THE
FAVORED VALLEYS OF THE SIERRA FROM THE TAHOE BASIN NORTH. 20

&&

.PREVIOUS DISCUSSION... /ISSUED 221 PM PDT SAT MAY 23 2015/

SYNOPSIS...

SCATTERED TO NUMEROUS SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED
THIS AFTERNOON AND EVENING FOR EASTERN CALIFORNIA AND WESTERN
NEVADA. SHOWERS AND THUNDERSTORMS WILL DECREASE IN COVERAGE SUNDAY
AND MONDAY. TEMPERATURES BELOW AVERAGE TODAY WILL WARM TO AROUND
AVERAGE FOR SUNDAY AND MEMORIAL DAY.

SHORT TERM...

RADAR IMAGERY SHOWS TWO MAIN AREAS OF SHOWERS AND ISOLATED
THUNDERSTORMS THIS AFTERNOON. THE FIRST, OVER THE SIERRA AND
SIERRA FRONT RANGE, IS ASSOCIATED WITH A SMALL LOW PRESSURE MOVING
SOUTH THROUGH CALIFORNIA. THE SECOND AREA, OVER PERSHING AND
CHURCHILL COUNTIES, IS WRAPPING AROUND THE BROAD LOW PRESSURE
CENTERED OVER UTAH. BOTH CLUSTERS OF SHOWERS AND ISOLATED
THUNDERSTORMS ARE EXPECTED TO INCREASE IN COVERAGE AND SLOWLY
SHIFT SOUTH THROUGH THE REST OF THIS AFTERNOON AND EVENING. BY
MIDNIGHT, THE AIR MASS SHOULD STABILIZE NORTH OF I-80, BUT
ISOLATED SHOWERS COULD PERSIST OVERNIGHT FROM I-80 SOUTHWARD.

TONIGHT, AND ESPECIALLY SUNDAY NIGHT, THERE IS AN INCREASED
CHANCE FOR FOG AS CLOUD COVER DECREASES AND SURFACE MOISTURE
REMAINS HIGH. AREAS OF FOG ARE EXPECTED TO DEVELOP IN SIERRA
VALLEYS FROM I-80 NORTHWARD AFTER MIDNIGHT TONIGHT. THE POTENTIAL
FOR FOG EXPANDS SUNDAY NIGHT TO INCLUDE BOTH SIERRA AND WESTERN
NV VALLEYS, AS WELL AS NEAR LAKES AND STREAMS.

THE LOW PRESSURE ALOFT WILL SLOWLY SHIFT EASTWARD TONIGHT. THIS
WILL OPEN THE DOOR TO WEAK NORTHWEST FLOW ALOFT SUNDAY AFTERNOON,
WHICH ALONG WITH A WEAK DISTURBANCE ALOFT, COULD LEAD TO SLIGHTLY
STRONGER SHOWERS AND THUNDERSTORMS. THE GEOGRAPHIC COVERAGE OF
SHOWERS SHOULD BE REDUCED, BUT A FEW AFTERNOON STORMS COULD BECOME
STRONGER AND PRODUCE BRIEF HEAVY RAIN AND HAIL UP TO PENNY SIZE,
ESPECIALLY OVER THE MOUNTAINS.

THE FLOW ALOFT IS STILL WEAK BUT TURNS WESTERLY FOR MEMORIAL DAY.
A SLIGHTLY STRONGER DISTURBANCE ARRIVES MONDAY AFTERNOON WHICH
WILL AGAIN PROVIDE CHANCES FOR SHOWERS AND THUNDERSTORMS. CURRENT
MODEL GUIDANCE SHOWS THIS DISTURBANCE MOVING EAST INTO CENTRAL NV
MONDAY EVENING. THIS TIMING WOULD LEAD TO A ZEPHYR-LIKE PATTERN,
WITH SHOWERS AND THUNDERSTORMS DECREASING OVER THE SIERRA MONDAY
EVENING AS THE MAIN FOCUS FOR STORMS SHIFTS INTO WESTERN NEVADA.
JCM

LONG TERM...TUESDAY THROUGH SATURDAY...

ONLY A FEW MINOR ADJUSTMENTS WERE MADE TO THE EXTENDED FORECAST
BASED ON LATEST MODEL TRENDS. MEAN LONGWAVE TROUGHING WILL HAVE
SHIFTED MORE OVER THE INTERMOUNTAIN WEST BY TUESDAY. HOWEVER,
RIDGING REMAINS SLOW TO PUSH ONSHORE WITH THE AXIS REMAINING JUST
OFF THE CALIFORNIA COAST. THIS WILL KEEP WESTERN NEVADA IN THE
POSITION TO CONTINUE TO RECEIVE PIECES OF ENERGY OUT OF THE LONGWAVE
PATTERN RESULTING IN CONTINUED CHANCES OF SHOWERS THROUGH WEDNESDAY.
MAINTAINED THE DIURNAL PATTERN TO PRECIPITATION CHANCES WITH
ACTIVITY OCCURRING IN THE AFTERNOON HOURS. STILL, AS DISTURBANCES
ROLL THROUGH, SOME SHOWER ACTIVITY MAY CONTINUE INTO THE NOCTURNAL
HOURS. IT`S TOO UNCERTAIN AT THIS TIME TO NAIL DOWN SPECIFICS WHICH
WILL LIKELY CHANGE OVER THE NEXT FEW DAYS.

DID INCREASE PRECIPITATION CHANCE WEDNESDAY AS ANOTHER DECENT WAVE
MOVES THROUGH. CONSIDERING THE AMOUNT OF LATENT MOISTURE, IT SEEMED
PRUDENT TO BUMP PRECIPITATION CHANCES UP, ESPECIALLY SOUTH OF
HIGHWAY 50 WHERE FORCING IS PROJECTED TO BE HIGHER.

MID RANGE MODELS ARE IN BETTER AGREEMENT THAT RIDGING WILL MOVE
ONSHORE BY THURSDAY AND FRIDAY DRASTICALLY LIMITING PRECIPITATION
CHANCES. EXPECT CONDITIONS TO BECOME MUCH DRIER BY NEXT WEEKEND.
WE`LL BE WATCHING 700MB TEMPERATURES THROUGH THIS WEEK AS CURRENT
RUNS SUGGEST +8 TO +10C. THIS CORRELATES TO SURFACE HIGHS IN THE
MID/UPPER 80S FOR WESTERN NEVADA AND A STARK CONTRAST TO RECENT
TEMPERATURES. BOYD

AVIATION...

SHOWERS CONTINUE THIS AFTERNOON ACROSS MUCH OF NORTHEAST CALIFORNIA
AND NORTHWEST NEVADA. LCL MVFR CONDS CONTINUE IN -SHRA WITH CIGS
2-3000 FEET, BUT MOST 4-5000 FEET. CEILINGS COULD INTERMITTENTLY
DROP TO MVFR THROUGH THE EVENING AS SHOWERS MOVE OVER TERMINALS.

AFTER 00Z, BEHIND THE IMPULSE, MORE STABILIZATION WILL OCCUR WITH
POSSIBLE CLEARING. AT THIS POINT, CONFIDENCE IS LOW ON HOW MUCH
CLEARING WILL OCCUR WITH ONLY ISOLD -SHRA POSSIBLE AFTER 03Z. IF
SKIES CLEAR ENOUGH, EXPECT FG TO FORM IN MANY VALLEYS FROM THE
RECENT RAIN. KTRK/MARTIS VALLEY MOST LIKELY TO BE AFFECTED, BUT
KRNO/KLOL/KTVL MAY ALSO SEE FG WITH VIS NEAR OR BLO 1/4SM. POTENTIAL
FG FOR KTRK 60 PCT WITH OTHER AREAS 20-30 PCT.

PRECIPITATION CHANCES DROP SUNDAY THROUGH THE WEEK AS DRIER AIR AND
HIGH PRESSURE BEGIN TO INFLUENCE THE REGION. STILL, SOME MOUNTAIN
OBSCURATIONS ARE EXPECTED OVER THE NEXT COUPLE OF DAYS DUE TO A LOT
OF LINGERING MOISTURE. FOG FORMATION WILL LIKELY INCREASE EACH NIGHT
AS SKIES BECOME CLEARER, ESPECIALLY FOR SIERRA TERMINALS.
BOYD/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)


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