textproduct: Reno

KEY MESSAGES

* Increased breezes and low humidity will lead to elevated fire weather concerns this afternoon, especially for northeast California and northwest Nevada.

* Seasonably warm and mainly dry conditions prevail through this weekend with low chances for isolated showers and thunderstorms in the Eastern Sierra this afternoon.

* Periods of monsoonal moisture return next week, renewing chances for showers and thunderstorms, with potential for localized heavy rain.

DISCUSSION

For today, model guidance depicts an upper low over southern BC traveling eastward across SW Canada while opening up into a trough. As this happens, a high pressure ridge over the Rockies is forced southward and spreads a bit more into the western CONUS overnight. At the surface, dry conditions look to persist with afternoon minimum relative humidity values generally around or below 15% in NE CA and W NV. The latest NBM run also highlights portions of NE CA and N. Washoe County with around a 30-50% probability of seeing gusts reaching up to around 30 mph in the afternoon and early evening. With these increased winds and low RHs expected, NE CA and NW NV will see elevated fire weather concerns today. Please continue to avoid activities that can cause sparks in these conditions.

While mainly dry conditions are expected today, the latest CAMs do show Mono and southern Alpine Counties as well as adjacent portions of NV having around a 15% chance for isolated showers this afternoon due to diurnal heating. RRFS CAPE values in these areas reach up to between 100-200 J/kg, so there is similar chance for a few rumbles of thunder within these showers though not anticipating severe weather. Remember: when thunder roars, go indoors! It's also possible that rain may not reach the ground from these showers today with the dry air in the region. Overnight tonight into early Sunday, CAMs also show ~15% chances for isolated showers in NE CA and adjacent N. Washoe County as well. As for late Sunday afternoon and evening, the high pressure over the Four Corners region allows some moisture to enter into the region causing cloud cover to gradually increase. The latest CAM runs also have low chances (around 10% at most) for additional light showers generally south of US-50 though these chances could spread into portions of NE CA.

Going through next week, model guidance shows the upper ridge residing over the Western CONUS with high pressure building over the Four Corners region. This will allow monsoonal moisture to flow back into the region, which causes daily precipitation chances through the week. When looking at the latest GFS PWAT values, NE CA and W NV see amounts exceeding 1" on Monday and Tuesday with some portions of W NV reaching up to around 1.25". This signals that thunderstorms on these days will have the potential for heavy rainfall. Forecasted storm motions on these days also looks to be on the slower side at this time, so areas that see showers and storms within region may be in for possible flash flooding concerns. Will be monitoring this potential going forward to see if these trends continue, but please continue to watch for the latest forecast updates as details become more certain. Also: while the GFS does shows PWATs gradually trending downward on Wednesday through Friday, they stay within the range (>0.6") where storms could contain heavy rainfall leading to additional flooding concerns. -078

AVIATION

VFR conditions are expected today for all area TAF sites. Sierra Front terminals have westerly winds gusting up to around 15-20 kts this afternoon with KRNO potentially seeing gusts up to ~25 kts between 18/02-04Z. As for the Sierra terminals, KTRK and KMMH will have afternoon winds gusting up to 20 kts out of the southwest-to- west while lighter winds are expected at KTRK. There is also a ~15% chance for isolated showers and storms in the Eastern Sierra this afternoon. High temperatures around mid-July seasonal normals are also in the forecast which may allow for density altitude concerns going through this weekend. -078

REV Watches/Warnings/Advisories

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