Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 312151
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
251 PM PDT FRI JUL 31 2015

.SYNOPSIS...

MOISTURE WILL SPREAD NORTH THROUGH THE WEEKEND BRINGING A CHANCE
FOR SHOWERS AND THUNDERSTORMS WITH GUSTY OUTFLOW WINDS AND
POSSIBLY SOME LIGHTNING INDUCED FIRE STARTS. THE BEST OVERALL
SHOWER AND THUNDERSTORM POTENTIAL IS EXPECTED THIS WEEKEND, WITH
LOCALLY HEAVY RAINFALL AND FLOODING BECOMING THE MAIN THREATS.


&&

.SHORT TERM...

ABUNDANT CLOUD COVER CONTINUES TO PUSH ACROSS THE SIERRA AND
WESTERN NEVADA THIS AFTERNOON, LIMITING THE INSTABILITY. WE ARE
STILL CALLING FOR SCATTERED SHOWERS (MAINLY VIRGA) AND ISOLATED
THUNDERSTORMS TO OCCUR THROUGH THIS EVENING. A COUPLE OF THUNDER
CELLS HAVE DEVELOPED WEST OF THE SIERRA CREST, PRODUCING LIGHTNING
AND LITTLE TO NO RAINFALL. A FEW BREAKS IN THE CLOUD COVER THIS
AFTERNOON OVER THE SIERRA WILL ALLOW FOR A FEW MORE THUNDERSTORMS
TO DEVELOP MAINLY ALONG AND WEST OF HIGHWAY 395.

SHORTWAVE WILL CONTINUE TO PUSH ACROSS WESTERN NEVADA TONIGHT
KEEPING CONVECTION AND CLOUDS AROUND PAST MIDNIGHT. SHOULD SEE
SOME CLEARING BY SATURDAY MORNING WHICH WILL HELP FOR
THUNDERSTORM DEVELOPMENT ON SATURDAY. INCREASING MOISTURE AND
STEEPENING UPPER LEVEL LAPSE RATES WILL ALSO ADD TO THE
INSTABILITY WITH STORMS DEVELOPING IN THE SIERRA AND WESTERN
NEVADA SIERRA FRONT SATURDAY AFTERNOON AND EVENING. STORMS WILL BE
A HYBRID OF WET/DRY WITH LOCALLY HEAVY RAINFALL POSSIBLE
UNDERNEATH THE CORES AND DRY LIGHTNING POSSIBLE ALONG THE
PERIPHERY. AS MOISTURE CONTINUES TO INCREASE THROUGH THE DAY,
STORMS WILL BECOME PROGRESSIVELY WETTER BY THE EVENING. GUSTY
OUTFLOW WINDS UP TO 50 MPH AND SMALL HAIL WILL BE POSSIBLE.

ANOTHER SHORTWAVE TRACKS INTO WESTERN NEVADA SATURDAY NIGHT,
BRINGING MORE CLOUDS AND SHOWERS TO THE REGION. SOME LIGHTNING MAY
BE POSSIBLE SATURDAY NIGHT, BUT OVERALL WE ARE MAINLY EXPECTING
WETTING RAINS WITH SCATTERED SHOWER ACTIVITY (POSSIBLY EVEN A
MESOSCALE RAIN BAND WITH SOME LOCALLY HEAVY RAIN).

BY SUNDAY, LINGERING MOISTURE AND COLD AIR ALOFT WILL ALLOW FOR
ANOTHER DAY OF SCATTERED SHOWERS AND THUNDERSTORMS. DUE TO THE
HIGH AMOUNT OF MOISTURE AND UNSTABLE AIR, IT WON`T TAKE VERY MUCH
HEATING TO GET CONVECTION GOING. IN FACT, THE LATEST MOS ONLY
SHOWS A HIGH TEMPERATURE IN RENO OF 81 DEGREES ON SUNDAY. WE HAVE
LOWERED THE FORECAST TEMPERATURE ACCORDINGLY, BUT MAY NEED TO BE
LOWERED EVEN MORE. SOME STORMS MAY BECOME STRONG OR SEVERE ON
SUNDAY WITH HEAVY RAINFALL POSSIBLE. HOON

.LONG TERM...MONDAY THROUGH FRIDAY...

ONLY MINOR CHANGES WERE MADE AS BETTER AGREEMENT BETWEEN MEDIUM
RANGE MODELS AND ENSEMBLES HAVE INCREASED FORECASTER CONFIDENCE TO
MODERATE FOR THE PERIOD. DRIER SOUTHWEST FLOW BEGINS TO PUSH INTO
THE SIERRA AND NORTHWEST NEVADA ON MONDAY, THOUGH ENOUGH MOISTURE
LINGERS FOR A SLIGHT CHANCE OF THUNDERSTORMS IN THE AFTERNOON. WITH
THE AFTERNOON ZEPHYR EXPECTED TO DEVELOP, STORMS WILL LIKELY
INITIATE ALONG AND AHEAD OF THE LEADING EDGE, WHICH MAY KEEP THE
TAHOE BASIN OUT OF ANY DEVELOPMENT.

A SHORTWAVE TRACKING ACROSS THE REGION TUESDAY WILL PROVIDE ANOTHER
ROUND OF MOISTURE AND INSTABILITY WITH A FAVORABLE JET POSITION
AIDING IN LIFT. HAVE ADDED A SLIGHT CHANCE FOR THUNDERSTORMS FOR
AREAS MAINLY NORTH OF HIGHWAY 50, WHICH LINES UP WELL WITH THE BEST
DYNAMICS. WHILE INITIATION OVER THE SIERRA CREST IS POSSIBLE, STORMS
ARE LIKELY TO QUICKLY MOVE EAST INTO WESTERN NEVADA AS THE AFTERNOON
ZEPHYR MATERIALIZES. WHILE PWATS BRIEFLY RISE TO AROUND 0.80", STORM
MOTIONS WILL BE FAST AND MOST OF THE MOISTURE WILL BE CONFINED TO
ABOVE 650 MB. THIS INCREASES THE CHANCE FOR STRONG AND GUSTY OUTFLOW
WINDS FROM ANY STORMS THAT DO DEVELOP.

FOR WEDNESDAY THROUGH FRIDAY, DRY SOUTHWEST FLOW RETURNS WITH THE
POTENTIAL FOR ANOTHER TROUGH TO IMPACT THE WEST LATE IN THE WEEK OR
NEXT WEEKEND. THE GFS IS FARTHER SOUTH WITH THIS FEATURE THAN THE EC
AND WOULD LIKELY YIELD ADDITIONAL CHANCES FOR SHOWERS AND
THUNDERSTORMS, WHILE THE EC WOULD BE DRY. HAVE CHANCES FOR SHOWERS
AROUND 10 PERCENT, BUT WILL NOT MENTION WEATHER AT THIS TIME. BOTH
SOLUTIONS WOULD ALLOW FOR ENHANCED AFTERNOON WINDS TO DEVELOP WITH
TEMPERATURES NEAR NORMAL FOR THIS TIME OF THE YEAR. DJ

&&

.AVIATION...

WIDESPREAD BROKEN TO OVERCAST CIGS (BASES 120-150 AGL AND TOPS 180-
250 AGL) OVER THE EASTERN SIERRA AND NORTHWEST NEVADA HAVE LIMITED
THUNDERSTORMS FROM FORMING. THERE HAVE BEEN A FEW SMALL POCKETS OF
CLEARING, BUT WILL KEEP CHANCES FOR THUNDERSTORM IMPACTING ANY
TERMINALS AT 10 PERCENT THIS AFTERNOON. THE RADAR IS SHOWING LIGHT
SHOWERS, BUT MOST SURFACE OBSERVATIONS HAVE SHOWN A TRACE OF RAIN AT
BEST. THESE MAINLY VIRGA SHOWERS COULD PRODUCE TURBULENT CONDITIONS
AND WIND SHEAR.

CHANCES FOR SHOWERS AND THUNDERSTORMS INCREASE SATURDAY WITH
LOWERING CIGS AND VIS POSSIBLE IN THE HEAVIER SHOWERS, ALONG WITH
GUSTY WINDS AND SMALL HAIL. STORMS MAY CONTINUE OVERNIGHT INTO
SUNDAY MORNING AND IF THERE IS ENOUGH CLOUD COVER SUNDAY WE MAY JUST
END UP WITH MORE SHOWERS AND LESS THUNDERSTORMS. HOWEVER, IF THERE
IS CLEARING SUNDAY, HEAVY RAINING THUNDERSTORMS ARE POSSIBLE. DJ

&&

.FIRE WEATHER...

DRY SUB-CLOUD LAYER CONDITIONS CONTINUE TO RESULT IN MOSTLY VIRGA
FROM AFTERNOON SHOWERS. THUNDERSTORMS HAVE BEEN MUCH MORE ISOLATED
DUE TO A BLANKETING CLOUD LAYER THAT HAS INHIBITED SURFACE BASED
INSTABILITY. STILL, ISOLATED THUNDERSTORMS ARE EXPECTED TO
CONTINUE THIS EVENING. ANY THUNDERSTORM WILL BE CAPABLE OF PRODUCING
GUSTY OUTFLOW IN THE 40-50 MPH RANGE AS WELL AS DRY LIGHTNING.
SHOWER AND THUNDERSTORMS ACTIVITY WILL DIMINISH OVERNIGHT AS HEATING
CEASES.

SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED AGAIN SATURDAY.
HOWEVER, THESE CELLS WILL BE HYBRIDIZED STARTING DRY AND RAPIDLY
TRANSITIONING TO WET AS DEEP LAYER MOISTURE INCREASES FROM SOUTH TO
NORTH. LOCATIONS NORTH OF A SUSANVILLE TO GERLACH LINE CAN EXPECT A
COUPLE HOURS OF DRIER STORMS AS MOISTURE WILL BE SLOW TO MOVE NORTH
OF THIS LINE. THESE LOCATIONS ALSO WILL BE IN AN AREA THAT WOULD
EXPERIENCE MORE RAPID FIRE DEVELOPMENT WITH HAINES VALUES AT A 5 OR
6. AS A VORTICITY LOBE MOVES THOUGH THE REGION, SHOWER AND
THUNDERSTORM ACTIVITY WILL LIKELY CONTINUE INTO THE OVERNIGHT HOURS.

SUNDAY WILL BRING MUCH WETTER CONDITIONS AS ATMOSPHERIC MOISTURE
INCREASES. THUNDERSTORMS WILL BE WET AND MAY BE ABLE TO PRODUCE
LOCALIZED FLASH FLOODING. SOUTHWEST FLOW WILL INCREASE SUNDAY
SOUTH OF HIGHWAY 50 SUGGESTING THAT THUNDERSTORM OUTFLOW COULD BE
STRONGER APPROACHING SEVERE. RECOVERIES WILL BE MUCH BETTER SUNDAY
WITH AFTERNOON HUMIDITY REMAINING MOSTLY ABOVE 35% IN THE
SIERRA; WESTERN NEVADA SHOULD REMAIN AROUND AND ABOVE 20%. SOUTHWEST
FLOW BEGINS TO DRY THE REGION BY TUESDAY THROUGH THE REST OF NEXT
WEEK. BOYD

&&

.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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