Weather Service Report

FXUS65 KREV 270403 AAA

Area Forecast Discussion...UPDATED
National Weather Service Reno NV
903 PM PDT Wed Jul 26 2017

Thunderstorms are winding down with some showers and an isolated
thunderstorm or two near and east of Highway 95. A quick update to
reflect the current trends. Otherwise, a bit of a break tomorrow
before thunderstorms increase again for the weekend. Looking at
the latest models, there could be an isolated storm or two 
tomorrow over the Sierra Crest in Mono County, but will let the
mid shift make that decision. Wallmann


.PREVIOUS DISCUSSION... /Issued 149 PM PDT Wed Jul 26 2017/ 


Thunderstorms are once again developing across northeast
California and northwest Nevada this afternoon and are expected to
continue into the evening. A drier air mass works into the region
overnight with tranquil weather expected for Thursday. Isolated 
storms will return on Friday with increasing thunderstorm coverage
possible heading into the weekend. Near average high temperatures
rise to above average for Friday and the weekend.


The upper level low which had been sitting off the northern 
California coast the past few days is shifting inland today. This is 
bringing increasing upper level divergence with thunderstorms 
already ongoing along the leading edge of the low. There is plenty 
of lingering moisture and instability with the shear across the 
region potentially helping storms to become organized. Locally 
severe storms are once again possible. 

Storm motions will be fast, but there is also still high PWATs 
across the region, likely leading to a hybrid of locally heavy 
rain and the potential for new fire starts from lightning. Flash 
flooding is less likely due to storm motion, however, if storms 
train over the same region or produce intense rainfall rates over 
steep terrain or recent burn scars, it is not out of the question.
The other concerns today are the potential for some larger hail 
in addition to accumulation smaller hail and gusty and erratic 
outflow winds over 50 mph.

Isolated nocturnal storms may linger across central Nevada into 
eastern Nevada overnight, but overall there will be a drier and 
more stable airmass moving into the region behind the upper low. 
This will likely keep any storms from developing on Thursday. This
break is short lived, however, as moisture once again advects 
northward around an area of high pressure bringing the return of 
isolated thunderstorms on Friday. What will need to be watched is 
how this interacts with a weak upper wave off the California 
coast. It is possible this could enhance the thunderstorm 
coverage, but will leave the forecast alone for now with slight 
chances mainly south of Highway 50 on Friday. -Dawn

LONG TERM...Saturday through Wednesday...

Upper level ridge expands westward across the southwest for the 
weekend into the early part of next week, bringing a warm up in high 
temperatures and potentially another push of modified monsoonal 
moisture. Signals are a bit mixed as far as how much moisture 
advects northward, with some operational runs as high as 0.80-1.0" 
PWATs, while others are more in the 0.5-0.75" range. Either way, it 
looks like thunderstorms will continue Saturday, with coverage 
increasing Sunday into Monday. If PWATs end up pushing the upper 
end of the range, it does increase the flash flood potential, but 
keep in mind this is only one possible scenario. There is a chance
that another weak low may move into northern California on 
Tuesday, which would keep thunderstorm chances in the forecast, 
but could change the character of the storms. -Dawn


Thunderstorms are firing off across northeast California and 
northwest Nevada again today. Storms will bring localized heavy 
rainfall, creating short-lived periods of IFR CIGS/VIS and obscuring 
terrain. Abundant lightning, small hail, gusty and erratic winds, 
blowing dust, and turbulence are also concerns. 

The greatest thunderstorm coverage is expected to be north of 
Interstate 80 this afternoon and evening, though isolated 
thunderstorm cells are possible elsewhere across the region. 

Chances for a storm to affect a terminal site:

KRNO/KCXP: 20 percent

KMMH/KTRK/KTVL: 10 percent

A drier air mass moves into the region overnight into Thursday with 
storms not expected on Thursday. This will be short-lived, however, 
with additional thunderstorm chances for the weekend. -Dawn


.REV Watches/Warnings/Advisories...


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