Area Forecast Discussion
Issued by NWS Reno, NV

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162
FXUS65 KREV 230959
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
259 AM PDT Mon Jul 23 2018

.SYNOPSIS...

Showers and thunderstorms will persist early this week with the
best coverage along the eastern Sierra from Mono and Alpine
Counties northward to the Sierra Front of western Nevada. Locally
heavy rain will keep the flash flood potential around through
today with more localized potential Tuesday. High pressure will
build mid to late week for a decrease in thunderstorms and a
return to hot temperatures.

&&

.SHORT TERM...

The area will remain on the northwest side of an upper ridge the
next couple of days before the ridge finally shifts west mid to
late week and brings warming temperatures aloft and a decrease in
storm coverage. So we will see another round of thunderstorms
areawide today with a gradual decrease in the coverage by
Wednesday as temperatures slowly climb back to hot levels.

For today...cloud debris left over from the storms Sunday was
clearing from south to north and this will once again provide a
good setup for thunderstorms as temperatures heat up a degree or
two over Sunday`s high temperatures. PWAT values remain very high
(around 1" or a little more than +2 SD above the mean) and storms
will once again be capable of producing copious rainfall
especially where cells train. We have been watching an upper level
wave which was depicted better in the The GFS this morning,
approaching late this afternoon. This would bring an increase in
wind/shear aloft(above 500 MB) and given the deep updrafts (CAPE
values of 1500-2000 J/KG) storms could be longer lived and even
produce large hail in addition to the heavy rain. Given the heavy
rain of the past couple days, we have hoisted a flash flood watch
for the eastern Sierra with the best flash flood potential along
the Highway 395 corridor and generally west of Highway 95.

For Tue-Wed, we have pushed the coverage up and slight farther to
the north although areas north of Highway 50 and the Tahoe Basin
should see a gradual decrease in storms. Model soundings are
still showing abundant moisture and given the intense heating,
there is no reason why another round of slow moving thunderstorms
will not once again occur, especially along the eastern Sierra
south of Highway 50. There will also be a little more speed shear
to promote a few strong storms capable of producing flash
flooding. So remain vigilant each day through Wednesday and keep
an awareness of storm trends in your area. Hohmann

.LONG TERM...Thursday into next week...

The focus remains on the high over Arizona that will bring hot
temperatures and eventually some thunderstorms. The main changes
were to add thunderstorms to the forecast for the weekend into early
next week.

As the high continues to build over Arizona with a light southwest
flow aloft, drier air moves in. In addition, temps warm aloft with
near triple digit heat for western Nevada, well into the 80s for
Sierra valleys and 90s for NE California. The hottest days look to
be Friday-Saturday, a bit later than previous runs. That said, it
still doesn`t look as hot as last week. Temps will begin to cool
some Sunday into early next week as the flow becomes more south and
moisture moves back in.

As for thunderstorms, Thursday still looks to be confined to Mono-
western Mineral Counties with an afternoon zephyr wind to the north.
Friday may be the one day without thunderstorms, but I am no longer
certain as the moisture never really gets scoured out of the
southern areas. For the weekend, continued upslope convergence over
Mono-western Mineral Counties will likely produce isolated
thunderstorms for the weekend. As we move into early next weekend,
we are expecting storms to migrate northward as monsoon moisture
returns. X

&&

.AVIATION...

TSRA again the main concern with outflow winds to 45 kts and heavy
rains. Large hail a bigger concern today, but it will still be
isolated. As for the best chance, it remains along the 395 corridor
including the KMMH, KMEV, KCXP, KRNO, KRTS and KSVE terminals. Each
has a 60% chance of seeing a direct hit. Slightly less for KTVL-KTRK
at around 50% with KNFL-KLOL about 20-30%. The best chance looks to
be a little later today, from 22Z in the south to around 02Z in the
north. Tuesday will be another active storm day, but we are not
expecting the coverage to be as great.

As for the smoke from area fires, Ferguson still has the potential
biggest impact with the Oregon fires second. Some haze will be
around today, but the active thunderstorms will limit the impact.
Smoke threats do look to increase later in the week depending on the
flow. X

&&

.REV Watches/Warnings/Advisories...
NV...Flash Flood Watch from this afternoon through this evening
     NVZ001>003.

CA...Flash Flood Watch from this afternoon through this evening
     CAZ071>073.

&&

$$

For more information from the National Weather Service visit...
http://weather.gov/reno



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