textproduct: Reno

KEY MESSAGES

* Dry conditions and mostly clear skies persist with cold temperatures today and just below zero wind chills near the Sierra crest with gusty breezes. * The next impactful storm arrives on Monday night with rain and high elevation mountain snow through Wednesday. Flooding potential persists with this weak atmospheric river event, but flooding confidence remains low.

* Warmer and drier conditions return late this week into the weekend. Although, there are hints of a weak system early next week.

DISCUSSION

A massive upper low pressure area remains in the Eastern Pacific while the upper ridge axis affecting our area starts to slowly move east towards the Four Corners. The ridge appears to mostly remain stationary which will allow shortwaves to affect the PacNW down into northern California and Nevada.

The first wave will be today as a weak shortwave ejected from that low in the E Pacific skirts through northern CA into OR. This will lead to increased winds, especially in the higher elevations of the Sierra (ridgetop) where winds to 80 mph are likely today. NE CA from northwestern Lassen into the Surprise Valley will have the strongest gusts to 35 to 45 mph this afternoon with a 40-70% chance of winds greater than 40 mph. Otherwise, the rest of the region will have more typical winds in the 20-35 mph range with wind-prone areas up to 40 mph. Rain chances up to 20% are mostly restricted to western Lassen. Monday will have similar conditions but with rain chances up to 30% in the same general vicinity, and weaker winds.

The low splits on Tuesday sending a shortwave towards British Columbia at the same time the AR reaches the West Coast. Integrated Water Vapor has this AR classified as weak for Sierra foothill/Sierra Front areas with values ranging from 250-350 kg/ms. Anyway, this AR brings a warm airmass, and the latest model runs are showing higher snow levels to 9 to 10 kft. Therefore, this will be mostly a rain event with snow restricted to areas above 10 kft. Those areas could see 2 to 4 inches of snow with a 20-50% chance of exceeding 4" in the highest peaks by Wednesday night.

Rain will be the main concern as we have a hefty snowpack from our last storm. Rain over snow will lead to quicker runoff, especially for urban areas. So, make sure that paths are clear of snow to reduce the risk of water ponding on low lying areas. Rivers and streams will see rises, especially over NE CA from the Susan, Middle Fork of the Feather and the Pit River. Chances for river flooding are still low for Minor Flood Stage at 5% starting on Tuesday.

Strong winds are also expected with this system on Tuesday as 700 mb winds reach 50 to 60 kts. This will lead to Sierra crest gusts around 100+ mph, while gusts of 35-45 mph are likely in wind-prone areas. Winds slowly subside on Wednesday as another ridge slowly takes over.

Drier and warmer conditions continue late this week into the weekend, which will keep high flows in rivers and streams as temperatures rise to 10 to 15 degrees above normal for late February.

-HC

AVIATION

VFR conditions continue through the period. The probability for FZFG near KTRK is very low due to strong winds aloft. Ridgetop level winds of 50-75 kts are likely to continue through 18Z. Then winds slowly subside as they move north towards NE CA. At the surface, light and VRB winds persist for Sierra Front terminals and KMMH. South to southwest winds of 10-15 kts with gusts up to 25-30 kts are likely at KTRK-KTVL and for the NV Basin and Range. LLWS and turbulence continue through the overnight hours ending around 18-20Z. However, isolated LLWS is possible again after 00Z this evening.

-HC

REV Watches/Warnings/Advisories

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