Area Forecast Discussion
Issued by NWS Reno, NV

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

000
FXUS65 KREV 152125
AFDREV

Area Forecast Discussion
National Weather Service Reno NV
225 PM PDT Sat Jun 15 2019

.SYNOPSIS...

Thunderstorms remain possible each day through Monday especially
near high terrain. As the airmass dries out starting Tuesday with
high pressure building overhead, temperatures trend upward and
humidities drop. Warm temperatures will result in high flows on
rivers and streams. Low pressure moving into the Pacific
Northwest late week will result in some cooling along with
increased winds.

&&

.DISCUSSION...

* No appreciable changes to ongoing forecast, though confidence
  continues to increase in a period of warmer temps Tuesday-
  Thursday followed by a cooldown with breezier conditions.

* Thunderstorms: The main issue over the next few days will be
  afternoon and evening t-storm risks. Isolated storms remain
  likely into this evening following SPC HREF guidance. Cells
  already forming near Lassen and south of Yerington. Additional
  storms could form further north to between Reno and Fernley.
  For Sunday and Monday coverage looks to increase vs today
  especially from Tahoe southward to Mammoth and east to Central
  Nevada. GFS showing a few shortwaves rolling through and HREF
  has a good concentration of storms in these areas at least for
  Sunday. Even a 10-30% neighborhood probability of at least 1"
  rain in 3 hours. Not bad. Typical t-storm hazards expected:
  strong outflow winds and dust, small hail, lightning, and brief
  heavy rains. Debris flows could be a concern on recent burn
  scars especially in Mono-Alpine-S Lyon Counties.

* Heat: GFS/EC ensemble guidance has been consistent in showing a
  pronounced resurgence of high pressure aloft over the west coast
  Monday-Wednesday. This will lead to even warmer temps and less
  t-storm risks with drier and more stable airmass. Highs 10-15
  degrees above normal Tuesday-Thursday but no records
  anticipated. Some heat health impacts are possible for sensitive
  groups without AC or those outdoors for prolonged periods
  during the daytime under sunny skies.

* Late Week Wind: Same ensemble guidance also shows fairly
  significant troughing swinging into the western states starting
  Thursday-Friday lasting into the following week (6/24). The
  height anomaly signals are respectable this far out so that
  increases confidence in this scenario panning out. Impacts would
  be cooler temps closer to normal or even a hair below along
  with an increase in winds. This pattern is not favorable for
  precip this time of year. So if our lower elevation vegetation
  dries enough the increased breezes late next week could become a
  fire weather concern.

-Chris

&&

.AVIATION...

Thunderstorms remain the primary aviation weather hazard through
Monday. Terrain driven storms over the Sierra and nearby high
terrain develop during the early afternoon hours each day the push
off to the east/southeast into the evening. Typical hazards with
strong outflow winds to 40 kts, small hail, lightning, and brief
periods of MVFR conditions in heavy rain.

For Sunday simulations showing weak upper wave that could enhance
t-storm coverage especially from TVL southward along the Sierra
and east into Central Nevada (MMH-TPH). SPC HREF guidance really
showing this especially 21z onward. Rough probabilities of t-storm
impacts at TAF sites look something like this:

RNO/CXP: Saturday 15%, Sunday 10%, Monday 5%
TRK/TVL: Saturday 30%, Sunday 40%, Monday 10%
MMH: Saturday 40%, Sunday 70%, Monday 60%

-Chris

&&

.HYDROLOGY...

* Changes: Some slight delays to reaching flood stages on Walker
  River so have updated flood warning to account for this.

* Walker: Even with warm temperatures, plenty of cloud cover
  Friday likely caused an under-performing snowmelt on the Walker
  River as evidenced by the weaker bump in flows last night @
  Coleville. This potentially could be an issue the next couple
  days with t-storms remaining in the forecast for the E Sierra.
  After a brief bump today, latest CNRFC forecast now doesn`t take
  Walker @ Mason above flood status until Monday. A bit of a
  delay from previous forecasts. 10-day probabilistic simulations
  show the W Walker peaking Wednesday-Thursday (later peak
  downstream) with a steady fall into the weekend with cooler
  temps expected.

* Humboldt: No big changes here. Still expecting a slow steady
  rise in levels through next week with mainly minor flood impacts
  as described in the flood advisory. Latest 10-day ensembles
  have the river at Imlay peaking out sometime the week of 6/24
  around 11.6 feet (flood stage is 10.3 ft, current 10.4 ft).

* All Other Rivers/Streams: With incoming heat, most rivers and
  streams will see a resurgence of flows this coming week with a
  peak roughly Wednesday or Thursday. Some bankfull conditions or
  minor spot flooding are possible but no major impacts
  anticipated as snow covered contributing area is diminishing
  quickly. Public safety concerns of fast, cold water however
  remain.

-Chris

&&

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

$$

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



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.