textproduct: Reno

KEY MESSAGES

* Warm weather prevails through the weekend with low shower and storm chances from Tahoe southward each afternoon. * A heatwave will induce moderate to locally major HeatRisk Monday through Wednesday.

* A pattern change may bring cooler temperatures, breezy afternoon winds, and increased shower and storm chances late next week.

DISCUSSION

A very warm weekend is underway with temperatures expected to climb into 80s to low-90s in the afternoons today and Sunday. Strong differential heating and weak synoptic ascent will support a low 10- 30% chance of showers and isolated thunderstorms each afternoon this weekend from the Tahoe Basin southward into Mono, Mineral, and far S. Lyon counties. A few showers or perhaps a stray t-storm may sneak into the Greater Reno-Carson-Minden area as shown in the more aggressive CAMs, but confidence is low. If you have outdoor plans in this area, but sure you have ways to receive weather alerts.

Broad high pressure will overspread the western states early next week, culminating in daytime highs near/in excess of 90F and 100F for Sierra communities and lower NE CA/W NV valleys, respectively, between Monday and Thursday. Such heat will yield widespread moderate HeatRisk with major HeatRisk spreading into W Nevada valleys -- partly due to minimal nighttime relief as lows only fall to the mid/upper 60s. Be sure to make your plans accordingly, and practice your heat safety precautions if your plans do take you outdoors. Low chances (10-20%) of afternoon showers and storms are maintained Monday through Wednesday given the extent of warming surface temperatures, but coverage should be limited by subsident flow.

A cooling trend begins after Wednesday as high pressure aloft weakens, returning temperatures closer to seasonal averages by next weekend. Thunderstorm potential trends upwards during the latter half of next week as low pressure approaches from the west. Still a bit too far out to give details with much confidence, but certainly worth keeping a close eye on if you have outdoor plans next week. Winds may also get a boost from this pattern change, but shoudn't be much stronger than our typical afternoon breeze. However, the increasing potential for thunderstorms and breezy winds will heighten fire concerns late next week (more in the fire weather section).

-Salas

AVIATION

Showers and isolated thunderstorms continue to be the main concern this weekend, mainly for KMMH where odds of a t-storm within 10 miles are 20-30%. Expect gusty/erratic winds, brief downpours, and occasional lightning with any storm. Otherwise, widespread VFR conditions and typical afternoon breezes prevail.

Density altitude concerns arise Monday through Thursday when temperatures become 10-20 degrees above average. Greatest concern will be for western Nevada terminals where temperatures flirt with the triple digits.

-Salas

FIRE WEATHER

An extended period of very warm/hot and dry conditions is expected through next Thursday. Monday through Wednesday features the hottest temperatures (10-20F above normal) with RH reductions to the teens and single digits. Furthermore, nighttime recoveries will remain poor away from higher elevations over the several days. Isolated thunderstorms will be possible from Tahoe southward each afternoon into next week, raising localized concerns for lightning ignitions and strong outflow winds.

While winds aren't anticipated to deviate much stronger than our typical afternoon breezes during this hot/dry period, Tuesday stands out as having the strongest breezes from E Lassen County into far western Nevada. A brief 1-3 hour overlap of critical wind/RH may unfold across these areas in the afternoon as a result.

A critical ridge breakdown takes place after Wednesday, increasing the potential for thunderstorms and new lightning ignitions/strong outflow winds, and increased afternoon breezes during the second half of next week. It's important to note that vegetation will have had several days to dry out under antecedent hot and very dry weather, compounding the potential fire threat late next week.

-Salas

REV Watches/Warnings/Advisories

NV...None. CA...None.