textproduct: Reno

KEY MESSAGES

* Cool and pleasant conditions this morning, lows near freezing in the Sierra valleys.

* Afternoon breezes return for the second half of this week with near normal summer temperatures and dry conditions for the holiday weekend.

DISCUSSION

Another chilly start, with another lobe of low pressure for today spinning into the base of the trough that has been positioned over the Western US over the weekend. The main concern for today will be the 10-30% chance for a shower over the Sierra this afternoon. There is a 15% chance that any given shower that forms could contain lightning, small hail or gusty winds, so if you are planning to recreate in the mountains south of US-50, keep an eye on the sky and plan ahead for shelter in case a storm develops. Instability is on the lower end, with MUCAPE values ranging 100-300 J/kg, but with a little help from topography, that may be enough to support storm development. Moisture will be limited with this low circulation, with PWAT only checking in around 0.3 inches, so these storms will offer little precipitation. Most CAMs are showing storms developing along the western slopes of the Sierra around 11 AM to noon today, then due to a lack of steering associated with light upper winds, the storms meander in a south- southwest direction after initiation. This would keep the majority of the action from the crest and westward, but there are a few solutions that show storms firing along and slightly east of the crest.

After this wave moves through, we remain under a general troughing pattern that will help to keep the temperatures closer to average into late week. The troughing pattern will allow for another shortwave to move through the meridional flow around Thursday, which will also be moisture-starved. The main influence we expect will be an enhanced zephyr for Thursday afternoon.

In the longer range forecast, the ridge builds back in over the west for the holiday weekend, bringing mid 90s to near 100 to western Nevada valleys and mid to upper 80s across the Sierra valleys. Long range guidance also hints at yet another low carving a path across the Pacific Northwest for the week following the holiday, but confidence is low due to varying solutions at this time scale.

AVIATION

* VFR conditions this morning, with potential (10-30%) for afternoon showers and storms to develop for KTVL/KBAN/KMMH between 19-20z. Showers and storms that develop may contain lightning, and may produce terrain obscurations.

HRICH

REV Watches/Warnings/Advisories

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