textproduct: Reno

KEY MESSAGES

* Shower and thunderstorm chances are in the forecast this afternoon and evening, especially for the Sierra and south of US-50.

* Warmer and generally dry conditions are expected mid-week with temperatures 5 to 10 degrees above average. * Increased winds and cooler temperatures return towards the end of the work week.

DISCUSSION

The latest forecast guidance projects low pressure currently over central CA traveling east-northeastward into the Great Basin later today. Current radar imagery shows that a few showers and thunderstorms have already developed within the CWA. Going through the rest of today, the forecast calls for around a 15-50% chance for showers generally for the Sierra and portions of the region south of US-50 with the higher end chances in Mono and Mineral Counties. Coverage also extends a bit north into western Lassen County where there is a ~15% chance for precipitation. When looking at CAM convective parameters, CAPE values will be around 250-500 J/kg today, which will allow for a 10-15% chance for thunderstorms to develop within the showers. Storms that form today will be capable of occasional lightning strikes, outflow wind gusts up to 45 mph (which could blow dust near desert sinks), and brief periods of heavy rainfall. Some models are also showing potential snow with these showers in portions of the Sierra above 10.5 kft though amounts range from a trace to under 1 inch. Please be weather aware today especially if you have outdoor plans. Elsewhere, dry conditions look to persist through the day.

Model guidance shows the low progressing off to the northeast on Tuesday as a weak ridge feature moves over the region in its wake going into Wednesday. The trajectory of the low may allow for some lingering isolated shower chances (~15%) in far NE CA and adjacent Washoe County as well in the NV Basin and Range during Tuesday afternoon. Dry conditions will follow late Tuesday through Wednesday. Daytime high temperatures will climb to around 5-10 degrees above seasonal normals by Wednesday with NE CA and W NV valleys topping out in the middle to upper 80s with Sierra communities in the 70s.

While Thursday has similar temperatures to those on Wednesday in the forecast, model guidance shows an upper trough moving into Pac NW beginning late Thursday. This feature will cause a tighter pressure gradient at the surface, which allows for stronger winds on Thursday and Friday compared to the lighter winds experienced earlier in the week. The latest forecast calls for gusts up to around 25-35 mph with a 30-60% chance of exceeding 35 mph in the Sierra front on both days. Precipitation chances remain uncertain, but the forecast is currently showing the dry pattern persisting through the latter half of the week. Temperatures begin to trend cooler on Friday as a potential dry cool front associated with the aforementioned trough moves through the region, causing daytime highs to become around 5 degrees below seasonal averages by the beginning of next week. -078

AVIATION

Most area TAF sites expect to see VFR conditions for the rest of today and tonight. KMMH could see sub-VFR conditions as there is a 20-50% chance for showers and thunderstorms in the Sierra and south of US-50 going through around 22/05Z with higher end chances in Mono and Mineral Counties. Storms that occur in the region could produce erratic outflow wind gusts up to around 40 kts and brief periods of heavy rainfall. Lesser precipitation chances (~15%) are seen tomorrow afternoon for areas along the OR border and in the NV Basin and Range. -078

REV Watches/Warnings/Advisories

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