textproduct: Reno

KEY MESSAGES

* Monsoonal moisture increases today, bringing wetter storms and potential flash flooding concerns through Tuesday. Isolated dry thunderstorms are also possible today.

* A potential midweek break in storm activity is likely with storm chances persisting for Mono and Mineral. Winds increase for areas near the OR border.

* Monsoonal moisture may return this weekend and next week.

DISCUSSION

Light rain showers along with smoke from wildfires in NE CA continue across portions of the CWA, with accumulations generally between a trace to 0.01 inches. This activity is expected to continue through the night per CAMs. The monsoonal moisture continues its way up as the upper high near the Four Corners area and a trough in the East Pacific make a moisture highway from Sonora and southern Arizona towards Nevada and California, and into eastern Oregon and Idaho. PWs in the latest sounding were around 0.82" and we are expecting those values to increase today to around 1-1.25 inches through Tuesday. So, yes we have the moisture for showers and thunderstorms but we need instability and a lifting mechanism to get what's in the air on the ground. Smoke appears to continue around Reno and vicinity today. The HRRR smoke product shows more smoke pushed east towards Reno and the North Valleys this afternoon with subsided activity tonight, but the inversion may lock the smoke into the valleys again overnight reducing air quality.

Models are showing instability increasing this afternoon mainly in areas near the Sierra, then more widespread on Tuesday. Although values are kind of low MUCAPE ranging between 200-500 J/kg, but increase to 500-1000 J/kg by Tuesday. Shear is around 25-30 kts both days. Based on the above we are expecting storms today and tomorrow with better coverage tomorrow due to the higher instability. Hi-res models are showing storms lifting off from Mono and Mineral, and then moving north quickly this afternoon. Brief periods of heavy rain will be likely with any storm, and if any of them start to train or get anchored to a mountain could lead to flash flooding, especially in areas south of I-80 between western Mineral Co and the Sierra crest. The quick motion of these storm may also result in dry thunderstorms that could ignite new fires outside of rain cores or areas north of I-80. The storms on Tuesday will be slower and have greater coverage. So, the risk for heavy rain and potential flash flooding also expands to all areas south of I-80.

An upper trough just off the coast from the PacNW also starts to move inland and this may start to push the moisture east by Tuesday evening, but TBD on this as models are starting to diverge with the position of the low pressure system. This model divergence further increases Wednesday and beyond. However, the trend we are seeing is for drier conditions across much of the region except for Mono and Mineral counties which keep low POPs generally below 15% through Friday. Otherwise, the rest of the area remains dry with POPs below 5%. Temperatures will rise with less cloud cover and winds increase due to the potential approach of that upper trough. So, expect typical west breezes returning for the second half of the week, and some a bit more enhanced for mountain ridges and over NE CA with gusts having a 20-50% of exceeding 35 mph.

Even though models are disagreeing which brings us to have very low confidence of the out come for this weekend and next week, we may have another plume of monsoonal moisture during the aforementioned timeframe. This would potentially bring cooler and wetter conditions back, but we'll have to wait and see how the models trend over the rest of this work week.

-HC

AVIATION

Light SHRA today with a 15-40% chance of TSRA this afternoon, especially for TAF sites south of US-50 including KMEV, KHTH, KBAN and KMMH. Gusty winds up to 35 kts are possible near SHRA/TSRA. Otherwise, winds will be south to southwest 7-12 kts with gusts to 20 kts.

Shower and storm coverage increases Tuesday with similar TSRA potential to Monday on most sites after 18Z. Gusty outflow winds, heavier rain showers, small hail and terrain obscuration continue to be the main concerns.

-HRICH/HC

FIRE WEATHER

A monsoonal moisture surge continues through Tuesday ushering shower and thunderstorm chances back into the Eastern Sierra and western Nevada. Storms trend wetter today and Tuesday, increasing the potential for wetting rainfall. However, storm motions will remain on the faster side today, so new lightning ignitions are possible away from main rain cores. Storms will be slower on Tuesday limiting the fire risk.

Gusty and erratic outflow winds up to 45 mph could also accompany thunderstorms. Moreover, an increasingly unstable environment on today and Tuesday will be more favorable for deeper vertical plume growth/more active plume behavior on any new/existing fires that become intense.

Winds also appear to increase midweek with the approach of an upper trough leading to brief periods of elevated to critical conditions over portions of NE CA, especially over mountain ridges due to gusts to 30-35 mph, and a 20-50% chance of exceeding 35 mph.

HRICH/Salas/HC

REV Watches/Warnings/Advisories

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