textproduct: Reno

KEY MESSAGES

* West breezes will elevate fire weather concerns this afternoon, while smoke from ongoing fires persists across parts of northeast CA and western NV.

* Shower and thunderstorm chances extend to north of I-80 in parts of western NV this afternoon, with more widespread and wetter storms expected Wednesday and Thursday.

* Lingering heat will again ease today across west central NV, followed by notably cooler temperatures for the remainder of the week.

DISCUSSION

Today will continue the northward advance of afternoon showers and t-storms from the Sierra to western NV, with a few cells in far western NV pushing near or even north of I-80. There's a low-end risk of a storm or two building near the large fires north of Reno (Bug, Fred Mtn, Stallion), leading to erratic wind shifts, stronger outflow gusts and a lightning threat. Afternoon west breezes also return with gusts a bit lower compared to Monday, but still enough to produce fire weather concerns--for more details see the Fire Weather section below.

Otherwise, temperatures continue a slight decline from the recent heat event although with highs still above average in the mid- upper 90s for lower elevations and mid 80s near the Sierra. With the advancing moisture, this afternoon's storm activity will start to tilt toward wetter storms and brief heavy rainfall, but enough dry air below the cloud bases keeps the threat for outflow gusts of 45-55+ mph, especially for west central NV.

For Wednesday through Thursday, a developing low pressure off the CA coast adds more forcing and pulls in even more moisture, with PW values from 1.0"-1.2" across a larger chunk of western NV and the eastern Sierra. While this abundant moisture increases the risk for heavy rainfall capable of producing localized flash flooding, it also could lead to some areas clouding over more quickly and receiving a lighter rate of rain. Several guidance sources also indicate shower activity with embedded lightning continuing or redeveloping through Wednesday night and Thursday morning, with an increased potential of spreading to northeast CA- northwest NV. Temperatures both days will be notably cooler, especially on Thursday when the peak cloud cover and shower presence limits highs to the lower-mid 80s, with 70s near the Sierra and in places where thicker cloud cover and showers persist.

By Friday, shower and t-storm chances decrease as the midweek low is projected to lift out to the north of CA-NV. However, residual moisture and a lingering trough along the west coast leaves open the potential for another round of afternoon showers and isolated storms, currently favoring west central NV. Then from the weekend into early next week, an overall drier pattern appears to set up with southwest flow over the Sierra. A few brief late day showers or storms can't be ruled out (up to 10% chance) with leftover moisture, weak terrain-driven or upper level forcing, and afternoon warmth (although highs only in the mid 80s to near 90 in lower elevations). One wild card is the location of a larger scale low pressure off the west coast early next week--if it makes a closer approach to CA then shower and t-storm potential would increase. MJD

AVIATION

Shower and t-storm chances increase this afternoon to near 30% at KMMH and around 15% for the western NV terminals, but remain below 10% at KTRK-KTVL. Storm onset could occur as early as 19Z around KMMH and continue through 23-00Z, while for far western NV sites the storm potential ranges from 22-02Z. Outflow gusts of 30-40 kt could affect KMMH and the far western NV sites (10-15% chance), although the greater gust potential remains east of these terminals. Otherwise, afternoon W wind gusts 20-25 kt return for western NV terminals with onset 20-22Z and diminishing by 02-04Z. More frequent convection and greater terminal impacts are expected Wednesday and Thursday afternoons, with some activity potentially extending into Wednesday night and Thursday morning.

Smoke from local fires continues northeast of KRNO, while smoke from Oregon fires continues across northeast CA and northwest NV. P6SM surface visibility should prevail at the main terminals, although slantwise visibility and terrain obscuration may be reduced near and downwind of the smoke plumes. Deep afternoon mixing and west-southwest transport winds should improve surface conditions, followed by renewed smoke and haze overnight and Wednesday morning as winds and mixing diminish. MJD

FIRE WEATHER

While winds today will be weaker than Monday, W/SW gusts of 20-30 mph will overspread RH reductions to 10-15% from far NE California into NW Nevada -- including ongoing fires in Washoe County -- this afternoon. Nighttime recoveries remain poor for most areas in NE California and W Nevada as RH struggles to exceed 30-40%, extending burn periods into the overnight hours.

Shower and thunderstorm chances increase to 30-50% this afternoon across Mono, E. Douglas, Lyon, and Mineral counties. Lesser probabilities of 15-30% exist from the Greater Reno-Carson-Minden area east to west-central Nevada, with a low 10-15% chance of impacting the Bug, Fred Mtn, and Stallion wildfires. Expect strong outflow winds, lightning/new fires, and brief heavy rain with stronger showers and storms. Moreover, increasing mid-level moisture atop a dry, unstable airmass will yield a favorable environment for deep, impactful plume growth accompanying the more intense fires this afternoon. The more significant plume activity today will feature strong, near-fire inflow winds, and sudden/erratic downdraft gusts from collapsing plumes.

A pattern change will deliver cooler temperatures and higher humidities (including much-improved nighttime recoveries) Wednesday into the weekend. However, deeper moisture will encourage greater shower and thunderstorm activity Wednesday and Thursday. While isolated dry lightning will be possible, mostly wet showers and storms will increase the potential for beneficial wetting rains but also the likelihood of heavy rain/flooding impacts (i.e., muddy unpaved trails, obstructed roadways, etc) to fire suppression operations. -Salas

REV Watches/Warnings/Advisories

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