Area Forecast Discussion
Issued by NWS Reno, NV

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FXUS65 KREV 080913

Area Forecast Discussion
National Weather Service Reno NV
213 AM PDT Thu Jun 8 2023


Additional shower and thunderstorm chances continue today through
at least the early part of next week. Storm have the potential to
bring heavy rain and flash flood concerns, along with gusty and
erratic winds, small hail, and of course lightning. Temperatures
to remain near or slightly below normal.



* Our compact upper low begins filling and shifting eastward
  today, leaving a moist and unstable airmass with very light
  northerly flow over the region. All signs point toward
  increasing PWATs through the day, nearing the 90-95th percentile
  by 00z, based on SPC sounding climatology for KREV. CAPE values
  remain anomalously high as well, per the EC EFI, in particular
  for the Sierra from Alpine Co north, northeast CA and western

* Taking a look at the CAMs, the HRRR in particular has been
  rather bullish for the past 24 or so hours in developing
  thunderstorms through portions of the Sierra, northeast CA,
  and the western Nevada Sierra Front this afternoon and early
  evening. The HREF favors these areas in addition to northern
  Washoe County, with some hints extending into the western Nevada
  Basin and Range as well.

* Today would definitely favor heavy raining thunderstorms and flash
  flooding potential, especially given the antecedent conditions.
  Pay close attention to areas with steep terrain, waterways, and
  burn scars. While a lesser risk today as compared to yesterday,
  gusty and erratic outflows are still possible with gusts exceeding
  45 mph, which could once again kick up dust.

* The next trough dropping into the area will increase flow on
  Friday, with decreasing thunderstorm coverage compared to today,
  but still a 60% chance near the Oregon border and a 15-30%
  chance elsewhere. As this low settles over southern CA over the
  weekend, we`ll see the return of widespread showers and
  thunderstorms Saturday through Monday. The EC QPF EFI (extreme
  forecast index) and SOT (shift of tails) are picking up on the
  very wet pattern these days, so once again we`ll be on the look
  out for flash flood potential in addition to strong to severe

* Storm chances decrease the middle into the end of next week,
  based on blended guidance and lack of troughing over the region.
  However, there is still no signal for any strong ridging either,
  and moisture is still present, so 15-25% chances for afternoon
  showers and thunderstorms remain in place. Temperatures to stay
  near to below normal. -Dawn



* There`s a 50-60% chance of showers and thunderstorms this
  afternoon across the Sierra and lower valley terminals,
  particularly during the 20Z-03Z timeframe. These storms have a
  chance to produce strong gusts of 45+ kts, small hail, and
  localized heavy rain.

* There is a continued chance (60%) for patchy, shallow fog and
  attendant MVFR/IFR conditions for KTRK each morning through this
  weekend, particularly between the 10Z-15Z time-frame.

* Friday, there`s a 20% chance for showers in the afternoon for
  Sierra terminals, and a 30-40% chance for showers near KMMH.
  Increased chances (60-80%) for heavier, area-wide showers and
  thunderstorms Saturday through Monday.




* Little change to ongoing thinking with regards to current flood
  statements on area rivers.

* Prolonged moderate flooding will persist along the East Fork and
  Mainstem of the Walker River. The Walker at Mason hit major
  flood stage last night, but appears to have leveled off. Given
  the flows upstream and reservoir management, it is possible this
  was related to debris in the channel. High flows to continue
  along the west fork of the Walker and the east and west forks of
  the Carson as well, but the current forecast keeps the rivers
  below flood stage. Minor flooding is ongoing along the lower
  Humboldt at Imlay as the snowmelt flood wave makes its way
  slowly downstream. Flows at Imlay are expected to continue to
  rise gradually, but remain in minor flood stage.

* Creeks and streams areawide will continue to run high, cold, and
  fast; with some potentially out of banks especially throughout
  portions of Mono County. As a result, banks may be unstable and
  any debris can send flows into unexpected areas, so take caution
  near waterway edges.

* The wild card will continue to be thunderstorm chances and
  coverage, with storms in the forecast today through at least the
  early part of next week. Slower storm motions Thursday and
  through the weekend will likely elevate flash flood potential as
  storms will remain capable of heavy rainfall. Cooler temps along
  with cloud coverage from thunderstorms will help slow the
  diurnally driven snowmelt.



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