textproduct: Reno

KEY MESSAGES

* Isolated shower and very isolated thunderstorm chances, mainly for portions of western Nevada and the Sierra, on Thursday afternoon.

* Gusty to strong winds return Friday afternoon through Sunday morning with impacts to fire weather, aviation, and recreation with winds peaking on Saturday.

* A significant cooling trend is expected for Friday through early next week.

DISCUSSION

Generally fair weather along with warm temperatures continue through Thursday. Afternoon temperatures in valleys remain in the low-90s and Sierra valleys in the mid-80s, while lows remain in the 60s western NV and upper-40s to upper-50s Sierra. Winds will be generally light, but these are expected to increase by Friday as an upper level trough descending from BC into the northern East Pacific and subsequently back into the PacNW tightens the pressure gradient. Gusts of 15-25 mph will be expected across the region on Friday. This potentially leads to some aviation and recreation impacts on Fri afternoon. If the trend persists, choppy lake waters are possible, which may lead to Lake Wind Advisories for most lakes.

By Saturday, the low pushes into the PacNW further tightening the pressure gradient and resulting in the strongest winds of the week. Deterministic models at 700mb have winds along the Sierra and Sierra Front around 35-60 kts along with an inversion around that same level. This setup can potentially lead to strong gusty winds in ridgetops and downslope winds over wind-prone areas, especially over the US-395 corridor. Ensemble data is hinting at west to southwest gusts of 35-45 mph for most areas, and 50-65 mph for wind prone areas. The probability of exceeding 55 mph currently stands at 10-50%, with the higher probabilities around wind prone areas and ridgetops. If this trend persists, we are looking at Wind Advisories for most of western Nevada, NE CA, and the Tahoe Basin, as well as a low potential for High Wind Warnings for the Sierra Front and Mono on Saturday.

Winds will slowly subside on Saturday night into Sunday morning. We will also have a 10-30% chance for showers in areas near the OR border including the Surprise Valley on Saturday afternoon and evening. Temperatures will drop behind the cold front on Saturday.

Conditions appear to be relatively fair next week as we remain somewhere in between a ridge to our south and a trough to our north. Model guidance also has plenty of uncertainty with these systems, but the trend is looking dry with typical winds and a gradual warming up.

-HC

AVIATION

Mostly VFR conditions with high to mid level clouds prevail through the 24-hr period. There is a 10-20% chance of rain for western NV and Sierra sites from 18Z Thur - 03Z Fri that could lead to lower CIGS and VIS. Winds will be generally below 10 kts this afternoon, but increase tomorrow from 18-03Z to 10-15 kts with gusts up to 20-25 kts. Otherwise, winds will be light and VRB.

Gusty winds with turbulence and LLWS return Friday afternoon through Sunday morning.

-HC

FIRE WEATHER

An approaching upper level storm system brings strong winds to most of the region on Friday and Saturday. Isolated elevated to near critical conditions are expected on Friday for portions of northern Washoe, eastern Lassen, Churchill and northern Lyon counties. The minimum relative humidity will be around 10-15% with winds gusting to 25-35 mph in the late afternoon and evening. No products are expected as the areas are very isolated and the timing is expected to be short, but it will be highlighted in the Fire Forecast.

By Saturday, winds will increase significantly with gusts to 35-45 mph and over 55 mph in wind prone areas. Min RH actually increases slightly to 10-20%. However, the strong winds will overcome any increases with RH, as we have not received significant amounts of precipitation across much of the area. Therefore, if the trend continues we will be issuing Fire Weather Watches tomorrow to account for the enhanced fire weather risk across western NV, eastern Lassen and potentially for Mono. Although, we are still debating Mono. We are not considering fire products from western Lassen/Plumas down to the Tahoe Basin.

Conditions will improve by Sunday morning as the winds slowly come down on Saturday night.

-HC

REV Watches/Warnings/Advisories

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