textproduct: Reno

KEY MESSAGES

* Dominant high pressure continues to bring historic March warmth this week.

* The warm temperatures have accelerated snowmelt, leading to rivers running fast and cold.

* Dry and mild weather is favored through the weekend, but a pattern change featuring breezy ridges, temperature moderation back to near seasonal averages and chances for precipitation arrives next week.

DISCUSSION

At the risk of sounding like a broken record about breaking records, we are anticipating the historic warmth to continue to build across the southwest. As the ridge axis (592 dam) continues to move across California and Nevada today, our high afternoon temperatures will challenge the all-time highest temperature recorded in March at Reno- Tahoe International Airport, at 83F degrees set March 31st, 1966. The record set for South Lake Tahoe is 71F, achieved on March 30th of 2015. Our forecast highs for Reno and South Lake Tahoe today are 85 and 72, respectively. So, all of this heat arriving mid- March is anomalous, at least two weeks earlier than previous record holding dates. For more on this historic March warmth, see our climate section at the bottom of this discussion.

We hold strong onto this warming pattern through the rest of the work week, with our warmest day slated to occur on Friday. The weekend will bring a shift as the high pressure pattern moves further inland, with the ridge axis migrating over the Intermountain West. This eastward progression will bring the periphery of the ridge closer to our region, which will allow some brush-by style activity. Showers look to be held north of the southern Oregon/Idaho borders, with breezy northerly winds and a moderation of afternoon high temperatures that will feel more like late May instead of late June.

Our next best opportunity for precipitation appears late March, around the 24th or 25th. At this time, ensemble guidance shows a shortwave moving across the Pacific northwest, which suggests another brush-by system. However, a deviation in the track of that system could bring showers into view, but confidence is low on precipitation amounts. HRICH

AVIATION

Benign weather remains the norm for most terminals through Friday, with light winds and VFR conditions dominating. KTRK is the lone outlier, facing a low-end risk of intermittent morning BR and FG. Warming will result in increased density altitude for the region. Anticipate some degradation in slantwise visibility during the morning hours due to haze lingering beneath sharp temperature inversions.

-Johnston

CLIMATE

New record highs were set on 3/17 for both Reno and South Lake Tahoe, surpassing the previous records by 4 degrees. However, the morning was cooler with no new records for warmest lows.

Both area climate sites (Reno at KRNO and South Lake Tahoe at KTVL) are on track to set new record high temperatures each day through Saturday. Although with less certainty, some record warm lows may also be set.

Current record high temperatures for Reno and South Lake Tahoe:

Date Reno NV South Lake Tahoe CA ---- ------------ ------------------- 3/18 77F in 1947 63F in 2004 3/19 77F in 1997 65F in 2015 3/20 81F in 2004 68F in 1997 3/21 80F in 2004 68F in 1997

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Current record warmest low temperatures for Reno and South Lake Tahoe:

Date Reno NV South Lake Tahoe CA ---- ------------ ------------------- 3/18 47F in 1945 37F in 2021 3/19 46F in 2013 38F in 2013 3/20 47F in 2013 35F in 2013 3/21 46F in 2015 38F in 1972

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Warmest daily March temperatures on record:

Reno, NV: 83F on 3/31/1966

South Lake Tahoe, CA: 71F on 3/30/2015

REV Watches/Warnings/Advisories

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