textproduct: Reno

KEY MESSAGES

* A warming trend continues with near record high temperatures most likely today through Tuesday.

* Dry conditions are expected through the beginning of the week with typical afternoon west breezes most days.

* Some cooling returns by mid-late next week with isolated shower chances and periods of breezy winds.

DISCUSSION

The latest forecast guidance continues to show an upper ridge over the W CONUS today and into tomorrow. A shortwave trough is seen moving through the PacNW this afternoon and evening though keeping the general ridging pattern intact over the CWA. The upper ridge then will restrengthen Monday and Tuesday with a closed low traveling through the Pacific behind the ridge. With this pattern aloft, the current warming trend will continue through Tuesday. As a result, near record to record daytime high temperatures across the region are expected through Tuesday with temperatures climbing to around 15-20 degrees above seasonal normals (please see the Climate section for a list of the current temperature records at our two climate sites: Reno, NV and South Lake Tahoe, CA). Generally, the temperature forecast for the next three days shows highs in the upper 80s to middle 90s range in NE CA and W NV valleys while the Sierra communities will range between the upper 70s and the lower 80s. The latest NWS HeatRisk forecast continues to display an areawide minor category of HeatRisk early next week with the warmer valley portions of W NV being in the moderate category through Tuesday. Please remember to stay hydrated and limit exposure to the sun during the warmest parts of the day especially if you have outdoor plans and are sensitive to heat. Also, please use extra caution near rivers and resist the urge to enter them to cool off as area rivers still remain cold and could be flowing fast, presenting a risk of hypothermia.

The ridge pattern will also allow for generally dry conditions to prevail for the first half of this week. However, increased daytime heating could allow for brief pop-up showers though chances look to be less than 10%. The latest runs of a few of the CAMs show some isolated showers possible in Mineral County during the late afternoon and early evening hours today and tomorrow. It is also worth noting that the 00Z run of the RRFS is predicting some PM showers developing along the CA/NV border on Tuesday and moving north through the Tahoe area as well as Reno and Carson City. This model could be overdoing Tuesday afternoon convection, but will be monitoring this in case more models begin to agree. Afternoon winds are expected to be typical zephyr-type west-southwest breezes (gusts up to around 25 mph) through Tuesday.

The upper air pattern looks to change by Wednesday as the resident ridge moves east with the aforementioned low making landfall on the west coast. There is still is some uncertainty in the evolution of this low through the rest of the week as ensembles forecast the low opening up into a trough as it makes landfall while the deterministic models continue it as a closed low as it moves through the CWA. But overall, this pattern will cause temperatures to begin a slow cooling trend while staying above seasonal normals going through the latter half of the week. Precipitation chances return to the region on Wednesday onward, but there is low confidence in details at this time due to the model uncertainty. Timing on this system is also still quite uncertain as the ECMWF shows an increased potential for showers and thunderstorms on Wednesday while the GFS delays this until Thursday. Will be monitoring this later week system for better agreement in future model runs. -078

AVIATION

VFR conditions are expected at most TAF sites today and tonight. KTRK looks to be the exception as there is a ~20% chance for patchy shallow fog developing between 10/10-15Z, which could cause sub-VFR conditions. Afternoon winds at area terminals will be out of the southwest to west with gusts up to around 20-25 kts mainly between 10/20Z-11/04Z. While dry conditions prevail, the warmer temperatures through Tuesday could potentially bring density altitude concerns each afternoon, especially for the western NV terminals. -078

CLIMATE

Current record high temperatures for Reno, NV that have potential to be broken or tied (Today-Tuesday):

May 10: 88 F, set in 1934.

May 11: 90 F, set in 2001 and 2013.

May 12: 89 F, set in 1959 and 2013.

Current record high temperatures for South Lake Tahoe, CA that have potential to be broken or tied (Today-Tuesday):

May 10: 75 F, set in 2025.

May 11: 78 F, set in 2013.

May 12: 79 F, set in 1988 and 1996.

REV Watches/Warnings/Advisories

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