textproduct: Reno

KEY MESSAGES

* Breezy winds and low humidity will pose elevated fire weather and recreation concerns Friday and Saturday afternoons.

* Increasing temperatures into the weekend will bring areas of moderate to locally major HeatRisk for Saturday.

* A monsoon-type pattern may increase the potential for showers and thunderstorms next week.

DISCUSSION

High pressure currently over southern CA/AZ is projected to migrate to the Four Corners region by Saturday. The weak low pressure trough that was located near the west coast since Tuesday retreats northward today before becoming re-established along the coast for Friday-Saturday. The resulting effect of this weather pattern will be a slight decrease in the PM breezes today, before returning to increased gusts beyond the typical Friday- Saturday (see the Fire Weather section below for more details). Meanwhile, a slow warming trend will resume, with above average temperatures peaking Saturday in the triple digits for many western NV valleys and near 90 for Sierra communities, resulting in Moderate to isolated Major HeatRisk for lower elevations on Saturday. While dry conditions are expected to prevail for the next three days, a few higher resolution guidance scenarios show increased cumulus buildups and isolated showers (up to 10% chance) forming in far northeast CA-northwest NV this afternoon.

Later in the weekend through early-mid next week, the pattern begins to shift with flow aloft becoming more SW-S over the Sierra Sunday, with potential for deeper southerly flow at times from Monday-Wednesday. This would allow for monsoon-type moisture to push into the eastern Sierra and parts of western NV, with increasing instability leading to showers and t-storms mainly in the afternoon, but also could linger overnight. While the high pressure ridge is most likely to be centered over the central US with a low pressure trough near or just off the west coast, the eventual location of these features (along with upper level disturbances rotating around the ridge's western periphery) will determine the extent of the t-storm threat. In general, the most favored areas for storms extend from Mono-Mineral counties into the US-95 corridor of west central NV, with decreasing storm chances to the north and west.

Temperatures begin a downward trend starting Sunday with highs dipping to near mid-July averages (lower-mid 90s for western NV valleys and lower 80s near the Sierra) for early next week. A warmup may return later next week, but confidence remains on the lower side with how much heat returns to the region as we get to the second half of July. MJD

AVIATION

* Widespread VFR across the region through this weekend with SW-W gusts 20-25 kts for the main terminals (except a bit lighter for KTRK/KTVL) this afternoon mainly between 22-04Z, down slightly compared to yesterday. Winds edge upward Friday-Saturday, with afternoon gusts 25-30 kts for the main terminals. MJD

FIRE WEATHER

* Continued dry afternoons will prevail into this weekend, with minimum RH values dipping to the single digits for much of western NV (down to near 5% at times along/east of US-95) and eastern Lassen County, with 10-15% for the eastern Sierra/Tahoe Basin and near the OR border. Overnight humidity recovery will be poor for much of western NV and some midslope/thermal belt regions, with maximum RH values only around 20-30%.

* While winds today ease back a bit, SW-W flow increases over the Sierra Friday with 700 mb winds increasing to 25-30 kt. This would increase the potential for afternoon wind gusts pushing into the 30-35 mph range, producing elevated to locally critical conditions across parts of eastern Lassen/northern Washoe counties southward into the western NV Sierra Front. The duration of the gusty winds/low RH meeting critical levels still looks limited, but a few sites could see these conditions occur for more than 3 hours.

* For Saturday afternoon, similar wind speeds return with the enhanced (25-30 kt) 700 mb flow shifting northward. This would result in areas near the OR border having the best potential for gusty winds/low RH meeting critical levels for 3 or more hours, while a shorter duration of these combined dry and gusty conditions extends southward to the western NV Sierra Front. MJD

REV Watches/Warnings/Advisories

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