Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 05/06/19

Area Forecast Discussion

National Weather Service Reno NV

 326 PM PDT Sun May 5 2019

.SYNOPSIS...

Showers and thunderstorms are expected today and Monday as low
pressure moves into southern California. Unsettled weather
continues next week with additional chances of showers and
isolated afternoon thunderstorms. Temperatures will remain close
to seasonal averages this week, and possibly becoming warmer than
average by next week.

&&

.SHORT TERM...

* Main message continues to be that thunderstorms could impact
  those with outdoor plans today and early this week. Have a plan
  for getting to shelter and don`t get caught out on a lake.

* Fast, cold, and high flows will continue on rivers; no flooding
  expected at this time.

A cut-off low moving inland over central California is helping to
bring in cooler temperatures aloft and instability over the
Sierra, northeast California and the western Nevada. Showers and
thunderstorms have already developed across much of the forecast
area this afternoon and will continue through the afternoon and
evening. Modest instability and steep lapse rates will help to
strengthen a few of the heavier showers into thunderstorms with
cloud-to-ground lightning, gusty outflow winds, and small hail.
Showers will continue overnight tonight as the low pressure
continues to slowly push eastward bringing a weak shortwave aloft.

By Monday, instability will increase even more with modified
totals up to 33-36, LI`s around -2 to -5, and CAPE around
800-1200 J/kg. These storms will have a steady northeast to
southwest movement tomorrow, but with precipitable water
increasing to near 0.70", these storms will be wetter and capable
of producing localized heavy rainfall in few places.

The main threat area for thunderstorms tomorrow will be along the
Eastern Sierra and western Nevada Sierra Front along the Highway
395 corridor all the way up into Lassen-Plumas. By Monday night,
we will see a stratiform deformation area setting up over western
Nevada as the low pressure pushes across southern Nevada. This
deformation zone will have some heavier rainfall, with some areas
seeing up to 0.50" Monday night. At this time, the best chances
for the heavier rainfall will be south of Highway 50, mainly south
of Carson City/Fallon down towards Mono County.

Low pressure continues to move across Southern Nevada and into
NM/UT by Tuesday, taking the majority of moisture and instability
out of the area and bringing some gustier northwest winds to the
region. A few lingering showers will be around on Tuesday, with a
slight chance of seeing thunder along the Sierra, Tahoe Basin and
south into Mono-Mineral Counties. Wednesday will be even less
coverage for showers, with only the High Sierra in Mono County
really seeing a slight chance.

A shortwave dropping out of the Pacific northwest will move into
northern Nevada Wednesday night, with slight potential for
nocturnal showers/thunderstorms. There is very low confidence in
this feature, so we will leave it out of the official forecast for
now. -Hoon

.LONG TERM...Thursday through next weekend...

Main changes to the forecast were to decrease POP coverage north of
Interstate 80 Thursday afternoon, increase POP coverage over the
Tahoe Basin Saturday afternoon, and increasing coverage of POPs
over Mono County next Sunday afternoon.

For Thursday, a cyclonic vorticity maximum will round the base of
an upper-level trough over the intermountain west, which will
provide mid-level cooling and synoptic lift to develop convection
during the morning and afternoon. However, POP coverage will be
limited to areas south of Interstate 80. Increased cloud cover
during the day will also limit the highs to near normal values
across the region.

For Friday and Saturday, medium range deterministic models have
trended toward different solutions regarding the placement and
timing of a cutoff low over southern California. Similar to the
previous shift, we confined chances for showers and thunderstorms
south of US Highway 50 Friday and Saturday. Both the GFS and
ECMWF show southwest-northeast oriented ridge moving over the
northern portion of the forecast area by Saturday. Temperatures
were slightly increased Saturday north of US Highway 50 due to
this feature.

For next Sunday, much of the forecast area will be under the
influence of an upper-level ridge, which will keep temperatures
5-10 degrees above normal. The central and southern Sierra could
see showers and thunderstorms also as moisture wraps around the
low over the southwest US.

As said in the previous discussion, model solutions typically do
not handle closed lows well in the long term. Therefore, this
forecast will likely change. -Johnston

&&

.AVIATION...

Showers and thunderstorms have developed over much of the forecast
area this afternoon. Gusty outflow winds, along with brief
reductions in visibility could be possible. Light-to-moderate
mountain wave turbulence will also be possible this afternoon into
Monday.

For Monday, shower and thunderstorm chances will continue to spread
north. The best chances for heavier showers will be Monday afternoon
through the overnight hours from TRK through WMC.

Aircraft icing will also be a possibility with character mainly
light and mixed today with areas of light-moderate by Monday
afternoon/evening. Some clear icing will be possible as
precipitation becomes more stratiform Monday over and in the
vicinity of RNO-CXP-LOL-NFL.

Weather will continue to be unsettled through this week, with
afternoon and evening chances for thunderstorms possible each day
this week. -Johnston/Boyd

&&

.REV Watches/Warnings/Advisories...
NV...None.
CA...None.
&&

$$

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