Area Forecast Discussion
Issued by NWS Reno, NV

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000
FXUS65 KREV 301007
AFDREV

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE RENO NV
307 AM PDT WED JUL 30 2014

.SYNOPSIS...
ABUNDANT MOISTURE WILL CONTINUE PUSHING NORTH THROUGH THE WEEK. AN
UPPER LEVEL DISTURBANCE LIFTS NORTHEAST OVER THE REGION TODAY AND
INTERACTS WITH DEEP MOISTURE TO PRODUCE LOCALLY HEAVY RAIN, AND
EVEN THE POTENTIAL FOR FLASH FLOODING FROM MONO COUNTY NORTH AND
EAST INTO MINERAL, CHURCHILL AND PERSHING COUNTIES. FASTER STORM
MOTIONS BY THURSDAY COULD RESULT IN GUSTY OUTFLOW WINDS ALONG WITH
A FEW DRY LIGHTNING STRIKES, MAINLY OVER THE NORTHERN PART OF THE
FORECAST AREA, WHILE LOCALLY HEAVY RAINS AREA POSSIBLE SOUTH OF
INTERSTATE 80.

&&

.SHORT TERM...
ISOLATED LIGHT SHOWERS CONTINUE ACROSS THE SIERRA THIS MORNING WITH
AMPLE MOISTURE REMAINING ACROSS THE REGION. DEEP MOISTURE WILL
COMBINE WITH BETTER INSTABILITY (LI~-3, HLTT>35, SFC CAPES >
800J/KG) OVER THE SIERRA AND AREAS MAINLY SOUTH OF HWY 50 IN
WESTERN NEVADA TODAY. THIS WILL ALSO BE THE FAVORED REGIONS FOR
ADDITIONAL FORCING VIA UPPER LEVEL LIFT FROM A WEAK COUPLED JET
THIS AFTERNOON AND THEN BY A VORTICITY MAX IMPULSE THAT WILL PUSH
THROUGH LATE EVENING INTO THURSDAY MORNING. THE COMBINATION OF
THESE FEATURES ALONG WITH SLOW STORM MOTIONS HAS PROMPTED THE
ISSUANCE OF A FLASH FLOOD WATCH TODAY FOR MONO, MINERAL, AND
EASTERN PORTIONS OF PERSHING AND CHURCHILL COUNTIES. THESE AREAS
HAVE A HIGHER PROBABILITY FOR DEVELOPING FLASH FLOODING TODAY BUT
AREAS OUTSIDE OF THE WATCH STILL ARE STILL VULNERABLE TO ISOLATED
AREAS OF FLASH FLOODING.

OVERALL NO SIGNIFICANT CHANGE TO THE FORECAST FOR TODAY. MODELS HAVE
TRENDED SLOWER AND FURTHER SOUTHEAST WITH THE VORTICITY CENTER,
MAINLY CARRYING IT NEAR MINERAL AND ESMERALDA COUNTIES BY LATE
EVENING. LOOKING MORE LIKE THIS WILL BE RESPONSIBLE FOR TRIGGERING
SHOWERS AND STORMS OVERNIGHT WHILE THE DAYTIME STORMS WILL HAVE TO
RELY ON DAYTIME HEATING AND WEAK UPPER LEVEL JET FORCING. SOME
HIGH LEVEL CLOUDS ARE STREAMING NORTH FROM CENTRAL CALIFORNIA BUT
HI-RES MODELS STILL LOOK TO FOCUS CONVECTION ACROSS THE SIERRA
EARLY AFTERNOON THEN SHIFT INTO MINERAL AND THEN ACROSS EASTERN
PERSHING/CHURCHILL COUNTIES. ONGOING FORECAST SEEMS TO HANDLE THIS
PROGRESSION WELL AND NO CHANGES PLANNED AT THIS TIME.

BY THURSDAY, DRIER AIR STARTS TO FILTER ACROSS THE SIERRA BUT WITH
PWATS > 0.6", STILL PLENTY OF MOISTURE REMAINING FOR ANOTHER DAY OF
SHOWERS AND STORMS. THE DRIER AIR WILL ALLOW FOR REDUCED CLOUD COVER
EARLIER IN THE DAY ALLOWING FOR BETTER SURFACE BASED HEATING AND
INSTABILITY. DID INCREASE POPS ACROSS THE SIERRA AND WESTERN NEVADA
AS A RESULT. WITH DRIER AIR IN PLACE, COULD SEE INCREASED THREAT FOR
GUSTY OUTFLOW WINDS AND DRY LIGHTNING STRIKES. DRIER AIR WILL
CONTINUE TO PUSH ACROSS THE SIERRA INTO FRIDAY WHICH HAS PROMPTED
LESSER CHANCES FOR PRECIPITATION. HAVE TRENDED THE FORECAST DRIER
WITH THE BEST CHANCES ON FRIDAY STAYING MAINLY EAST OF HIGHWAY 395
OVER WESTERN NEVADA AND ACROSS MONO COUNTY. FUENTES


.LONG TERM...SATURDAY THROUGH TUESDAY...

THE FOUR CORNERS RIDGE OVER THE SOUTHWESTERN U.S. WILL GIVE WAVE TO
WEAK AND DISORGANIZED TROUGHING OVER NORTHERN CALIFORNIA THIS
WEEKEND. THIS WILL INCREASE DRIER SOUTHWEST FLOW OVER THE SIERRA AND
WESTERN NEVADA. LATEST MODEL RUNS HAVE REALLY BEEN BACKING OFF ON
THE THUNDERSTORM POTENTIAL FOR SATURDAY THROUGH MONDAY, AS SOUTHWEST
FLOW DROPS THE PRECIPITABLE WATER TO LESS THAN 0.5". THIS WOULD BE
DIFFICULT TO SEE ANY THUNDERSTORM DEVELOPMENT IF THE ATMOSPHERE
BECOMES THAT DRY (NOT TO MENTION THE STRONG CAPPING IN LATEST GFS
SOUNDINGS).

FOR NOW, LEFT IN THE MENTION OF SLIGHT CHANCE THUNDERSTORMS IN
WESTERN NEVADA FOR SATURDAY AND SUNDAY, BUT REALLY STARTED TRIMMING
BACK ON THE CHANCES. THE ECMWF STILL HAS CONVECTION IN WESTERN
NEVADA, SO WE WILL KEEP IT IN FOR NOW. WE`VE BEEN SAYING FOR DAYS
THAT THIS PATTERN IS VERY UNCERTAIN AND THE MODELS ARE DEFINITELY
SHOWING THEIR INCONSISTENCY. SINCE THERE IS NO MAJOR SHORTWAVE
DURING THE EXTENDED AND ONLY WEAK DISORGANIZED FLOW, THIS IS MAKING
FOR A VERY UNCERTAIN FORECAST.

MODELS SHOW THE TROUGH OFF THE CA COAST STARTING TO ELONGATE TO THE
SOUTH, TURNING THE FLOW OVER THE SIERRA TO A SOUTH-SOUTHEASTERLY
DIRECTION. THIS WOULD BE MORE FAVORABLE FOR THUNDERSTORM CHANCES
CREEPING BACK INTO THE SIERRA AND ALONG THE SIERRA FRONT MONDAY AND
TUESDAY. THAT BEING SAID, THERE IS VERY LOW FORECAST CONFIDENCE
GOING INTO NEXT WEEK. HOON

&&

.AVIATION...

SHOWERS AND THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND EVENING
WITH GREATER COVERAGE THAN MONDAY. HEAVY RAINFALL IS EXPECTED WITH
THUNDERSTORMS TODAY, ESPECIALLY AT KMMH-KBAN-KNFL-KLOL WITH 50%
CHANCE OF THUNDERSTORMS OVER THE TERMINALS TODAY. FURTHER NORTH,
INCLUDING KRNO-KCXP-KTRK-KTVL, THERE IS A 30% CHANCE OF
THUNDERSTORMS THROUGH THIS EARLY EVENING.

ALONG WITH LOCALLY HEAVY RAINFALL, FREQUENT LIGHTNING, SMALL HAIL
AND DOWNBURST WINDS UP TO 30KT CAN BE EXPECTED WITH THESE
THUNDERSTORMS. ADDITIONAL ISOLATED TO SCATTERED THUNDERSTORMS ARE
EXPECTED IN THE SIERRA AND WESTERN NEVADA THURSDAY AND FRIDAY. HOON

&&


.REV WATCHES/WARNINGS/ADVISORIES...
NV...FLASH FLOOD WATCH FROM 2 PM PDT THIS AFTERNOON THROUGH THIS
     EVENING NVZ004.

     FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING
     NVZ001.

CA...FLASH FLOOD WATCH FROM NOON PDT TODAY THROUGH THIS EVENING
     CAZ073.

&&

$$

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






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