textproduct: Reno

KEY MESSAGES

* Dry weather with unseasonably warm temperatures will prevail early this week with enhanced afternoon breezes today and Tuesday.

* Pattern shifts to cooler and wetter conditions by midweek with valley rain and high elevation snow.

* Isolated to scattered thunderstorms are possible Thursday and Friday, though confidence remains low on the extent of the impacts.

DISCUSSION

According to the latest RAP upper air analysis, an upper ridge continues to reside over the Western CONUS this morning. However, a weak shortwave is also seen just off the coast of S CA. Forecast guidance shows the shortwave progressing through S CA today and into AZ by this evening. This pattern aloft will cause temperatures to continue their warming trend today as daytime highs in the lower to middle 70s for the W NV valleys and in the lower to middle 60s for Sierra communities are forecast today. Dry conditions are anticipated to continue while winds increase a bit in the afternoon with breezy gusts up to 20 mph in the region and up to around 30 mph in the higher elevations of the Sierra.

For Tuesday, models show the upper ridge still over the region though it is now between low pressure over the Pacific and another low over SW Canada. This will allow for daytime high temperatures around 10-15 degrees above normal to continue another day in the region (mostly similar to those temperatures experienced on Monday). Also, breezy afternoon winds similar to those for Monday are forecast on Tuesday as well along with more dry weather.

On Wednesday, the Pacific upper low is projected to move towards N CA which will push the resident ridge to the east. With this pattern change aloft, area temperatures start a cooling trend though the current forecast daytime high temperatures still look to be ~5-10 degrees above normal. Light precipitation chances (15-35%) return to the region as well in the afternoon for NE CA, the Tahoe region, and N Washoe County. While the higher end chances look to be closer to the OR border, rain looks to be the primary precipitation type with snow levels over 9000 ft. However, any rain would have to overcome the lower dry layer to reach the surface. An isolated thunderstorm or two may be possible in the aforementioned areas during the afternoon though not anticipating severe weather.

Through the rest of the work week, forecast guidance has the low moving closer to the CA coast which will cause precipitation chances to increase and become more widespread. While details remain uncertain at this time, model forecast soundings as well as the latest ECMWF Extreme Weather Index (EFI) for CAPE show the potential for thunderstorms within the area. Thunderstorms on Thursday still look to be more isolated while Friday shows signs for thunderstorms to be a bit more scattered within the region. The cooling trend continues with forecast temperatures being around seasonal normals going into the weekend. As such, snow levels may come down to around 8000 ft on Friday which could allow for measurable snow in the higher elevations of the Sierra. Please continue to watch for further forecast updates for the latter half of the week especially if you have outdoor plans as active weather looks to be on the way. Extended forecast guidance then shows the upper low being absorbed into a larger PacNW trough over the weekend allowing precipitation chances to continue. -078

AVIATION

VFR conditions continue today for all area TAF sites. Dry conditions are expected in the region through Tuesday with afternoon breezes up to 15-20 kts in the forecast. Precipitation chances may return to a portion of the region on Wednesday due to an approaching low. The chances are then forecast to increase and become more widespread through the remainder of the week. -078

REV Watches/Warnings/Advisories

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