textproduct: Reno

KEY MESSAGES

* Elevated fire weather concerns linger this afternoon in northeast CA and northwest NV with breezy winds and low humidity.

* Seasonably warm conditions and areas of increased cloud cover prevail through this weekend with isolated showers and thunderstorms near the Eastern Sierra each afternoon.

* Periods of monsoonal moisture will keep shower and thunderstorm chances with potential for localized heavy rain next week. Best overall storm chances favor Monday afternoon through Wednesday.

DISCUSSION

A swath of thicker mid to high level cloud cover overnight through this morning brought spotty light rain showers and isolated lightning to parts of northeast CA, with streaks of virga also seen outside our windows earlier today. The subtle shortwave aloft that produced this more extensive cloud deck was not resolved very well with yesterday's higher resolution guidance.

For the rest of today, overall cloud cover from US-50 northward will decrease, with a short period of drier conditions dropping humidity to between 12-16% in northeast CA and far northwest NV. Afternoon breezes with gusts to 25 mph in these areas will produce a few hours of elevated fire weather concerns until sunset. South of US-50, a small area of instability leaves open a window for isolated showers and short-lived t-storms (up to 15% chance) mainly between 3-8 PM for parts of Mono, Mineral and Lyon counties.

Overnight into Sunday morning, another stream of increased moisture returns to northeast CA, bringing another chance of light rain showers near or after daybreak through late morning. Also given the few lightning strikes that occurred earlier today in eastern Lassen County, there's a 10% or less chance for a few strikes again around 18Z Sunday, but focusing toward the western parts of Lassen County.

For the rest of Sunday through Sunday night, low to mid level S-SE flow and the southward drift of the high pressure ridge from the Rockies to the Four Corners region bring a gradual expansion of deeper monsoonal moisture. This could bring a bit more favorable setup for isolated PM showers and t-storms again across the eastern Sierra of Mono County eastward to adjacent parts of southern Lyon and Mineral counties. However, the confidence is relatively low as the higher resolution guidance scenarios are not all on board with the instability being sufficient to support storm cell growth. If the cloud cover becomes too widespread after the initial storms form, we could see a relatively quick transition to lighter rain showers for Sunday evening and night as this activity moves north and west. Overall we only have chances for measurable rain at less than 10% through Sunday night, but passing sprinkles could occur across nearly any portion of western NV/northeast CA.

The monsoonal moisture push still appears to peak from Monday afternoon through Tuesday with increased risk for greater shower and t-storm coverage. For Monday the best instability and potential for showers and t-storms currently favors areas south of US-50, although isolated storms could extend farther north across western NV into Monday evening with lighter showers extending overnight.

Tuesday is where the concerns increase for more widespread rainfall affecting a greater extent of eastern CA-western NV, slower storm motions, abundant moisture and pockets of instability to hold the shower/storm activity together. This could be a similar outcome as last Monday when more areas got wet, although the overdeveloping cloud scenario continues to lurk as the PW values push above 1" in much of the region. At this time, we're giving an early heads-up notice for potential localized flash flood risks peaking on Tuesday.

Later in the week and into next weekend, the monsoon push appears to be gradually shifting eastward with storm risks decreasing initially for northeast CA Wednesday and then northwest NV southward across Tahoe and far western NV including the Reno- Carson vicinity from Thursday onward. However, this has been fluctuating with each day's guidance and the shower/storm chances could hang on longer, especially in west central NV along and east of US-95 and southward to Mono County. MJD

AVIATION

VFR conditions are expected this weekend for all area terminals, with periods of increased mid-high level cloud cover through Sunday. SW-W wind gusts this afternoon and Sunday mainly 15-20 kt except 20-25 kt at KRNO starting a bit later compared to recent days (after 22Z) then winding down between 03-05Z. A few showers may develop near KMMH each afternoon today and Sunday but only 10-15% chance of lightning within 5 NM of the terminal site.

For the early part of next week, shower and t-storm chances increase mainly south of US-50 Monday, with best overall chances at the main terminals on Tuesday. Impacts may include locally heavy rainfall, more frequent lightning and outflow gusts of 30+ kt. MJD

REV Watches/Warnings/Advisories

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