Sunrise 5:55 AM   Sunset 7:52 PM Moonrise 2:33 AM   Moonset 12:23 PM

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FXUS65 KREV 012226 AFDREV

Area Forecast Discussion National Weather Service Reno NV 326 PM PDT Wed May 1 2024

SYNOPSIS

Cooler daytime temperatures continue today behind the passage of a cold front earlier in the day. Following a brief warmup on Thursday and Friday, temperatures expect to cool down once again over the weekend with chances for valley rain and mountain snow returning along with some stronger winds on Saturday. The latest forecast beyond the weekend going into the beginning of next week calls for a warming trend across the region along with some lower precipitation chances.

DISCUSSION

At the beginning of the forecast period, the latest RAP analysis shows the CWA currently with a mostly northwesterly flow aloft being west of the axis of an upper air trough this afternoon with ridge trailing the trough over the Pacific Ocean. The current satellite imagery along with surface observations show dry conditions along with mostly light and variable winds with the exception of southern portions of Mineral and Mono Counties as they are experiencing some breezy north-northwesterly winds. Models show the trough moving eastward as the Pacific ridge advances toward the CWA on Thursday.
By Friday afternoon, the axis of the upper air ridge is projected to move over the CWA as an upper air low moves into the Pacific Northwest. At the surface, the dry conditions look to continue through the rest of today. While most of the region looks to stay dry on Thursday, northern portions of Washoe County as well eastern Modoc and northern Lassen Counties may see chances for light snow showers in the early morning that transition to light rain as it warms during the afternoon due to a surface low in OR projected to move eastward into ID during the day. Minimal amounts of rain and snow are anticipated with models showing a few hundredths of QPF at most in the locations that see the precipitation. By Thursday evening, these precipitation chances depart to the east with the passing system leaving dry conditions through the remainder of Thursday as well as on Friday. Warmer daytime temperatures compared to today's are expected on Thursday and especially Friday with models showing a possible warm front beginning to pass through the southern half of NV and northern CA by the late Friday afternoon hours. A good portion of the region may warm up to the middle 60s to the lower 70s during the day on Friday with higher elevations in the Sierra Mountains being slightly cooler.

On Friday night, model guidance shows the CWA starting to take a more southwesterly upper air flow as the upper air low moves toward the OR coast. By Saturday afternoon, models are in pretty good agreement with the low moving through onto the OR shore and towards the CWA On Sunday morning, forecast guidance has the low passing over the northern portion of the CWA before departing to the east in the afternoon causing a northwesterly flow over the CWA for the remainder of the day. With this upper air pattern, models have a surface low in the northeastern CONUS pushing cold front across the region on Saturday. This cold front will allow chances for light rain to move into the northwestern portions of the CWA on Friday night and then spread through the remainder of the CWA during Saturday. Snow levels continue to be near or above 7000 feet on Saturday afternoon. By the evening hours, the snow levels look to drop to around 5000 feet in northeastern CA and around 6000 feet in the Tahoe Basin which will allow for a bit more areas to see the P- type transition to snow. By Sunday morning, the colder temperatures and lower snow levels will allow for most of the area to see light snowfall if precipitation occurs. By Sunday evening, the precipitation chances are anticipated to depart out of the CWA to the northeast. When looking at the NBM snowfall probabilities from Friday night through Sunday, portions of Lassen County have less than a 10% chance of four inches of snow. Higher elevations in the Tahoe Basin as well as Mono and Alpine Counties see a 20-60% probability of four inches of snow. Will continue to monitor this as this may cause hazardous traveling conditions over the weekend for people going through mountain passes with roads becoming slick with some potential slushy snow. As for the latest QPF values for this event, it looks to range between around a tenth of an inch to around a little over an inch in western portions of the region.
Another concern during this event is the potential for some stronger southwesterly to west winds with the cold front passage on Saturday afternoon. The latest probabilities of 55 mph wind gusts within the southern half of the CWA ranges between 50-90%.
Will monitor this going forward as well in case a high wind product is needed this weekend.

Going through the beginning of next week, the northwesterly upper air flow continues with ensemble guidance showing the low opening up into a negatively tilted trough on Monday and Tuesday over the Rocky Mountains. As a result, warmer daytime temperatures are seen to begin the work week with a 10-20% chance for afternoon and evening isolated showers each day mostly for the northern half of the CWA

-078

AVIATION

VFR conditions are anticipated across the region at the REV terminals through the remainder of today and going into Thursday.
While most terminals may see light and variable winds, KMMH and KMEV see northwesterly winds around 10 kts through around 03-05Z when they begin to decrease. By Thursday afternoon, wind gusts up 25-30 kts are possible for the western NV terminals southward to KMMH while KTVL and KTRK may see gusts up to around 20 kts.

A cold front passing through the area is anticipated to produce increased aviation impacts Saturday-Saturday night due to gusty winds with areas of potential LLWS, increased precipitation chances with periods of lower CIGS/reduced VIS, and even some light snow for the Tahoe and Eastern Sierra terminals.

-078

REV Watches/Warnings/Advisories
NV...None.
CA...None.

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