textproduct: Reno

KEY MESSAGES

* Cooling trend continues today with increased southeast breezes for Mono and Mineral counties, and showers with embedded lightning this afternoon and evening.

* A slow moving storm will bring wetting rains and high elevation snow to the region Wednesday and Thursday.

* Cool but mainly dry Friday into the weekend. Unsettled pattern could bring a storm or two next week.

DISCUSSION

A storm currently off the CA coast will begin a sharp change to a cooler and wetter weather pattern starting today, with the main impacts expected from late Wednesday morning through Thursday night as this system moves slowly inland.

* For today, widespread cloud cover expands over CA-NV. Overall, winds will be lighter compared to Monday, except for Mineral and eastern Mono counties where increasing southeast flow brings wind gusts of 30-40 mph this afternoon. Bands of mainly light rain showers are also expected to form across the eastern Sierra and west central NV this afternoon, with embedded lightning strikes within these bands. These showers will generally move to the northwest across western NV and northeast CA through this evening. Precip amounts through tonight will be generally 0.10" or less with fast shower motions along with the transition from a dry to a wetter air mass.

* Confidence continues to grow in a widespread wetting rain event (70+% chance of rainfall totals exceeding 0.25") starting Wednesday, as larger areas of rain and thunderstorms develop around late morning/midday near the eastern Sierra and expand north and east through Wednesday afternoon-evening. Stronger forcing and instability (CAPE values up to 500 J/kg) and precipitable water values rising to 0.6-0.8" will support areas of more organized storms capable of producing locally heavy rainfall and minor accumulations of small hail.

* Additional shower bands with embedded lightning are projected to form Wednesday night mainly south of US-50, followed by another round of larger rain/thunderstorm areas through Thursday across much of the region with chilly daytime highs mainly in the upper 40s to upper 50s. As the low travels inland, wrap-around rain bands are also anticipated. Areas of west central NV near and east of US-95 most favored to see these bands through Thursday night, ending early Friday as the low exits to the eastern Great Basin.

* While this rain will include beneficial impacts such as greatly reducing fire potential, recharging the waterways, and easing the dust buildup from an overall dry early fall, areas with more persistent heavier showers/storms could receive total rainfall of 1-2" for this 2-day event. This could lead to flooding in poor drainage areas or on recent burn scars including the Hawk, Bull and Bug fires near Reno. With autumn leaf and needle drop happening, gutters and drains should be checked/cleared before the rain begins. Watch for slick roads as oils and other vehicle fluid deposits combine with the rainfall, leading to slower commutes from Wednesday afternoon through Thursday.

* For higher Sierra elevations (mainly above 8000-8500 ft), snow could impact higher passes/summits including Ebbetts, Tioga, Sonora, Carson and Mt Rose at times from Wednesday night through Thursday. These areas have a 80+% chance of at least 2" of snow and a 40-70% chance for at least 4", with higher-end scenarios producing up to 12" for higher peaks of the Sierra crest and White Mountains in Mono County. Although the majority of the Tahoe and eastern Sierra communities aren't expecting snow with this event, now is a good time to ensure your vehicle is ready for winter travel (good tire tread, wipers & battery, having chains handy and checking your survival kit).

* After this low exits quickly on Friday, overall dry and cool conditions prevail through the weekend, with highs mainly in the mid-upper 50s near the Sierra and lower-mid 60s for lower elevations--close to average for this point in October. Looking further ahead through next week, some longer range scenarios leave open the potential for more storms toward the end of October, including a slight risk for a heavier Sierra snowfall. At this point, the confidence for such an event is on the lower side. MJD

AVIATION

* FL100 wind gusts of 35-40 kt will produce areas of LLWS until around 16Z this morning near most of the main terminals (except KMMH). Otherwise, lighter E-SE winds are expected across the main terminals through the remainder of today. VFR conditions prevail although mid-high cloud cover increases. Isolated -SHRA after 21Z for the Sierra terminals and after 00Z for western NV sites could produce brief mountain top obscurations at times thru 06Z this evening.

* More widespread rain from Wednesday afternoon through Thursday brings longer periods of MVFR or IFR conditions and terrain obscurations to the main terminals. Thunderstorm chances peak at 20-25% between 20-02Z Wednesday afternoon-early evening. MJD

REV Watches/Warnings/Advisories

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