Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 302257 CCA
AFDREV

AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE RENO NV
311 PM PDT THU JUL 30 2015

.SYNOPSIS...

HIGH PRESSURE OVER THE DESERT SOUTHWEST WILL BRING ABOVE NORMAL
TEMPERATURES FOR THE NEXT FEW DAYS. INCREASING MONSOONAL MOISTURE
AND INSTABILITY WILL BRING ISOLATED TO SCATTERED THUNDERSTORMS
FRIDAY INTO NEXT WEEK, MAINLY FOR THE SIERRA AND IN FAR WESTERN
NEVADA. GUSTY OUTFLOW WINDS AND LIGHTNING FIRE STARTS ARE THE MAIN
CONCERNS FOR FRIDAY AND SATURDAY WITH LOCALLY HEAVY RAIN POSSIBLE
THIS WEEKEND.

&&

.SHORT TERM...

MONSOONAL MOISTURE CONTINUES TO PUSH AROUND THE HIGH PRESSURE OVER
THE GREAT BASIN OVER THE NEXT FEW DAYS. OVERALL, FORECASTER
CONFIDENCE IS ONLY MEDIUM REGARDING THUNDERSTORM TIMING AND COVERAGE
DUE TO INCONSISTENCIES IN MODEL GUIDANCE OVER THE LAST 48 HOURS.

TEMPERATURES UNDER THE RIDGE WILL PUSH TEMPERATURES WELL ABOVE
AVERAGE WITH HIGH TEMPS REACHING INTO THE MID TO UPPER 90S FOR
WESTERN NEVADA. HIGH TEMPERATURE FOR TODAY AT THE RENO-TAHOE
AIRPORT HAS ALREADY HIT 99 DEGREES. A FEW ISOLATED HIGH-BASED
THUNDERSTORMS CONTINUE TO DEVELOP OVER MONO COUNTY AND NORTH INTO
LASSEN COUNTY THIS AFTERNOON AND WILL CONTINUE INTO THE EVENING.
MODELS CONTINUE TO HIGHLIGHT A WEAK MID-LEVEL SHORTWAVE PUSHING
THROUGH TONIGHT WHICH LEAVES A SLIGHT CHANCE OF AN OVERNIGHT SHOWER
OR THUNDERSTORM IN MONO COUNTY.

MOISTURE CONTINUES TO INCREASE FRIDAY WITH THUNDERSTORM COVERAGE
INCREASING OVER MONO COUNTY AND NORTH INTO THE TAHOE BASIN AND
WESTERN NEVADA SIERRA FRONT. STORMS WILL HAVE 10-15KT STORM
MOTION, BUT THIS REALLY WON`T BE ENOUGH TO OVERCOME THE QUICKLY
INCREASING PRECIPITABLE WATER VALUES NEAR 0.75" BY LATE FRIDAY. SO,
STORMS ARE EXPECTED TO START OUT HIGH-BASED WITH LITTLE RAINFALL
INITIALLY, THEN TRANSITION TO WETTER STORMS THROUGH THE DAY AS THE
BOUNDARY LAYER MOISTENS UP. DRY SUB-CLOUD BOUNDARY LAYER WILL ALLOW
STRONG GUSTY OUTFLOW WINDS UP TO 50 MPH. PLEASE SEE FIRE WEATHER
SECTION BELOW FOR FIRE CONCERNS.

SHORTWAVE MOVING UP FROM THE SOUTH FRIDAY NIGHT INTO SATURDAY WILL
BRING ABUNDANT CLOUD COVER, WHICH MAY LIMIT THE AMOUNT OF
CONVECTION WE SEE SATURDAY AFTERNOON. LATEST MODELS ARE
SUGGESTING AT LEAST SOME CLEARING THAT WOULD ALLOW ISOLATED TO
SCATTERED THUNDERSTORMS TO DEVELOP IN THE SIERRA AND WESTERN
NEVADA. 500-300MB LAPSE RATES DO BECOME MORE UNSTABLE FOR SATURDAY,
AROUND 7.5 C/KM, SO THIS DAY HAS THE POTENTIAL TO GO EITHER WAY.
PRECIPITABLE WATER INCREASES TO NEAR 0.90" ON SATURDAY, SO STORMS
WILL BE PRETTY WET WITH LOCALLY HEAVY RAINFALL POSSIBLE. STAY TUNED
FOR ANY UPDATES TO THE SATURDAY FORECAST AS WE GET CLOSER.

THUNDERSTORM CHANCES CONTINUE SATURDAY NIGHT, SUNDAY AND SUNDAY
NIGHT AS SHORTWAVE ENERGY CONTINUES TO MOVE UP FROM THE SOUTH.
AGAIN, MODELS ARE HAVING RUN-TO-RUN INCONSITENCIES IN TIMING AND
PLACEMENT OF THE SHORTWAVES THIS WEEKEND, BUT OVERALL THE PATTERN
SUGGESTS DECENT THUNDERSTORM CHANCES THROUGH THE WEEKEND. HOON

.LONG TERM...MONDAY THROUGH THURSDAY...

THE FORECAST REMAINS LARGELY UNCHANGED NEXT WEEK. THE GFS IS STILL
FASTER BRINGING A JET SEGMENT INTO THE CENTRAL SIERRA AND NORTHERN
NV MONDAY AFTERNOON, WHILE THE EC IS A BIT FARTHER SOUTH, WEAKER AND
ABOUT 12 HOURS SLOWER. THE GFS IS A BIT SLOWER THAN PREVIOUS RUNS
AND THE EC IS A BIT FASTER, SO THINKING MODELS MAY BE TRYING TO
CONVERGE ON A SOLUTION POSSIBLY MONDAY NIGHT. THIS JET SEGMENT WILL
IMPACT HOW THUNDERSTORMS DEVELOP AND PROPAGATE MONDAY AFTERNOON.
FORECASTER CONFIDENCE IS MODERATE ON STORMS DEVELOPING, BUT LOW ON
HOW STRONG AND WIDESPREAD THEY MIGHT BE. IT DOES APPEAR THAT STORM
MOTIONS WILL BE FAST ENOUGH TO LIMIT THE FLASH FLOOD THREAT, BUT
THIS WOULD ALSO INCREASE THE RISK OF STRONG AND GUSTY OUTFLOW WINDS.

DRIER SOUTHWEST FLOW MOVES INTO THE SIERRA AND NORTHWEST NEVADA BY
TUESDAY, HELPING TO LIMIT THUNDERSTORMS CHANCES. THERE IS A SMALL
CHANCE SOME MOISTURE MAY LINGER NEAR THE OREGON BORDER TUESDAY, AND
SO WILL LEAVE A 10 PERCENT CHANCE FOR SHOWERS, BUT NO MENTION OF
WEATHER. MODELS ARE INDICATING A TROUGH MAY PUSH INTO THE NORTHWEST
AROUND THE THURSDAY-FRIDAY TIME FRAME, WITH ENHANCED AFTERNOON
ZEPHYR WINDS LIKELY AHEAD OF THE FEATURE TUESDAY-THURSDAY. HIGH
TEMPERATURES WILL BE NEAR NORMAL THROUGH THE WEEK, WHICH TRANSLATES
TO UPPER 80S TO MID 90S IN WESTERN NEVADA AND IN THE 70S AND LOW 80S
IN THE SIERRA. DJ

&&

.AVIATION...

VFR CONDITIONS THIS AFTERNOON WITH INCREASING MID TO HIGH LEVEL
CUMULUS CLOUDS FROM SOUTH TO NORTH ALONG THE SIERRA AND FOR MUCH OF
NEVADA. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS
AFTERNOON AND EARLY EVENING ALONG THE SIERRA AND SIERRA FRONT MAINLY
SOUTH OF HIGHWAY 50 WHICH COULD CAUSE GUSTY AND ERRATIC OUTFLOW
WINDS. CLOUD BASES ARE GENERALLY AROUND 09-12K FEET AGL WITH TOPS IN
THE BETTER BUILDUPS AS HIGH AS 30K FEET.

THUNDERSTORM CHANCES INCREASE AND SPREAD NORTHWARD ACROSS THE SIERRA
AND NORTHWEST NEVADA THROUGH THE WEEKEND WITH GUSTY WINDS, LOCALLY
HEAVY RAIN, LOWERING CIGS/VIS, AND SMALL HAIL POSSIBLE. DJ

&&

.FIRE WEATHER...

HIGH PRESSURE ACROSS THE WEST WILL PROVIDE VERY WARM TEMPERATURES
WITH POOR MID AND UPPER SLOPE HUMIDITY RECOVERY THROUGH FRIDAY.
THUNDERSTORM CHANCES WILL INCREASE THROUGH THE WEEKEND AS MOISTURE
IS TRANSPORTED NORTHWARD ACROSS THE SIERRA.

SCATTERED THUNDERSTORM COVERAGE WILL BE LIMITED TO NEAR THE SIERRA
CREST THROUGH ALPINE AND MONO COUNTIES FRIDAY AFTERNOON. LESSER
ISOLATED COVERAGE IS EXPECTED OVER THE TAHOE BASIN AND INTO WESTERN
NEVADA THROUGH MINERAL COUNTY. THESE WILL BE HYBRID TYPE STORMS (MIX
OF WET AND DRY STORMS) WITH STORM MOTIONS GENERALLY UNDER 15 KNOTS
AND ATMOSPHERIC MOISTURE INCREASING SUBSTANTIALLY OVER THE NEXT 24
HOURS. SOME UPPER LEVEL FORCING MAY ALLOW FOR A FEW STORMS TO
CONTINUE OVERNIGHT FRIDAY NIGHT INTO EARLY SATURDAY MORNING.

A FEW DRY LIGHTNING STRIKES AND FIRE STARTS ARE POSSIBLE OUTSIDE OF
THE MAIN STORM CORES FRIDAY BUT NOT ANTICIPATING A WIDESPREAD DRY
LIGHTNING OUTBREAK. AS MOISTURE INCREASES THROUGH THE WEEKEND, WE
WILL SEE THE THREAT FOR GUSTY OUTFLOW WINDS AND ISOLATED DRY
LIGHTNING STRIKES TRANSITION TO MORE OF A HEAVY RAINFALL AND
POSSIBLE FLASH FLOODING THREAT BY SATURDAY INTO SUNDAY. THE BEST
POTENTIAL AND COVERAGE FOR STORMS FOR SATURDAY AND SUNDAY WILL
REMAIN ALONG THE SIERRA AND MAINLY WEST OF ALTERNATE HWY 95 IN
WESTERN NEVADA. SHOWER AND STORM COVERAGE WILL DIMINISH BY MONDAY
WITH A DRIER AIRMASS WORKING ITS WAY ACROSS THE REGION. 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)


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