textproduct: Reno

KEY MESSAGES

* Showers and afternoon thunderstorms expected today with gusty outflow winds and possible new fire starts from lightning.

* Monsoonal moisture increases Monday, bringing wetter storms and possible flash flooding concerns through Tuesday.

* Storm chances continue for the eastern Sierra and Mineral County Wednesday through Friday, though some uncertainty remains.

DISCUSSION

Clouds and showers are streaming north today, courtesy of a monsoonal surge of moisture. This initial push of moisture has brought some light showers to northeastern California, but many of the showers have only amounted to elevated virga. As the column of air moistens under the influence of inbound PWAT values ranging 0.6 to 0.8 inches, more precipitation may actually make it to the surface. This condition has already limited morning fire behavior on fires across Nevada and Lassen counties in NE CA. Should shower activity increase today to thunderstorms, we could see some gusty outflows that may impact fire operations, as well as new starts from any dry thunderstorms.

The thick upper to mid-level clouds over much of the area have already begun to limit the incoming solar influence that would be needed to increase instability over the northern extent of our region. If we see some clearing this afternoon, light showers may take on a more convective nature. In fact, recent CAMs are modeling a bit of clearing along the southern portion of the Sierra, seen and verified by current satellite and observations. Therefore, a round of showers looks to approach the southern Sierra later today, and may contain anything from light rain to virga, with embedded lightning potential increasing to 5-10% after 1 PM today. This encroaching plume of moisture makes it's way into southern Mono County for the afternoon hours, then heads toward Mineral County for the late afternoon into evening time frame. This might be the area and time frame to watch for dry thunderstorms with fast storm motions of 40-45 mph, and little to no measurable rainfall.

As this surge of moisture continues a northward trek, the PWATs are predicted to get as high as 1.00 inch as we start the new week. This will modify our main threat from the dry thunderstorm regime to a possible flooding theme instead. For contrast, the QPF shown by the NBM today offers no measurable precipitation as mentioned for today, but the overnight hours into Monday we start to see a few hundredths creeping up the Sierra. By Monday afternoon, we could see wetting rains, with some showers capable of producing isolated showers that may be heavy at times. Shower chances increase from the early day 20- 40% to around 30-70% with the highest chances over Mono County and into Mineral County into the evening and overnight into Tuesday.

Tuesday's forecast looks a bit more spicy as convection and the necessary instability that accompanies it moves into place over western Nevada and far northeastern California. Shower chances will be around 20-40% early Tuesday afternoon from Susanville to the Tahoe Basin and 50-70% from US-50 to southern Mono County. Then, the progression of the ridging pattern over the central US nudges just a bit to the east, allowing the monsoonal moisture to also follow suit. Showers will work to keep temperatures across the area in check, and around seasonal average.

A trough from the north enters the conversation for Wednesday, which will put us between the southwest flow of the monsoonal push and the southwest flow ahead of the incoming trough. As such, temperatures will climb once again as we go from midweek into the week's end. Once the upper low is drawn back into the flow north of our area, we will again be seeing high pressure over the Four Corners region. This invites the monsoonal flow back into the picture for the weekend, when we once again will contend with showers and storms. Check back daily for the latest in our forecast, as details should become clearer for midweek and beyond.

HRICH

AVIATION

* Light showers around the region today with thunderstorms possible this afternoon, especially for KMMH/KBAN. Gusty winds are possible in the vicinity of showers and thunderstorms, up to 35 kts possible. Otherwise, winds will be south to southwest 10-15 kts with gusts to 25 kts possible.

* Shower and storm chances increase Monday and Tuesday with greater potential for lightning as a 30% chance for KTRK/KTVL/KBAN/KMMH/KCXP/KMEV/KRNO arrives after 18z. Gusty outflow winds, heavier rain showers, small hail and terrain obscuration are all concerns for both days. HRICH

FIRE WEATHER

* A monsoonal moisture surge today through Tuesday will usher shower and thunderstorm chances back into the Eastern Sierra and western Nevada. First round of showers today will be on the dry side with the potential for starts outside of wetter rain cores, especially south of US-50. QPF has been light so far today, with most areas receiving less than 0.1". Surface RHs today will struggle to exceed 40% across western NV, with virga showers overhead. RHs may get a little higher in NE CA this afternoon, but QPF will remain low.

* Storms trend wetter on Monday and Tuesday, increasing the potential for wetting rainfall. However, storm motions will remain on the faster side, so new lightning ignitions are possible away from main rain cores. Gusty and erratic outflow winds up to 45 mph will also accompany thunderstorms. Moreover, an increasingly unstable environment on Monday and Tuesday will be more favorable for deeper vertical plume growth/more active plume behavior on any new/existing fires that become intense.

HRICH/Salas

REV Watches/Warnings/Advisories

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