Area Forecast Discussion
Issued by NWS Reno, NV
Issued by NWS Reno, NV
542 FXUS65 KREV 301945 AFDREV Area Forecast Discussion National Weather Service Reno NV 1245 PM PDT Sun Jun 30 2024 .SYNOPSIS... * Breezy winds with a chance of showers and storms for northeast CA and northwest NV continue through early this evening. * Seasonable temperatures continue through Tuesday with breezy northwest winds Monday afternoon. * Temperatures rise to well above average from midweek through the July 4th holiday weekend, with Moderate to locally Major HeatRisk. Major HeatRisk areas may expand by next Saturday. && .DISCUSSION... Cumulus clouds have developed over northeast CA-northwest NV, in advance of a secondary upper level trough passage. A 15-25% chance of showers and thunderstorms continues through 8 PM this evening mainly north of a Susanville-Gerlach line, although a couple of stray cells could form a bit farther south into the west central NV Basin and Range. Potential hazards include dry lightning, gusty outflow winds and brief periods of rain or small hail. After today, dry weather will largely prevail throughout the upcoming week as northwest flow aloft and attendant large scale subsidence overspreads the region. However, on the hottest days for the July 4th holiday weekend, enhanced heating and terrain- driven lift may be sufficient to produce a few late day thunderstorms (5-10% chance) east of the Sierra crest into far western NV. A strong ridge of high pressure building near the CA coast will favor a notable warm-up from midweek through the holiday weekend as daytime temperatures rise 10-15 degrees above early July averages. The latest trend shows triple digit heat returning to some western NV valleys with highs pushing 90 for Sierra communities Wednesday and Thursday, then warming up even more with the peak heating next Saturday and Sunday. At this time, Saturday appears to be the overall hottest day, when the ridge center is most likely to be closest to western NV. The potential for highs of 105+ degrees has edged upward to 20-40% chances for Saturday, and 15-25% for next Sunday. The HeatRisk map also indicates expansion of the major category into some western NV communities for Saturday. Be sure to consider the upcoming heat risk when making plans for the holiday festivities, and review your safety precautions to keep yourself and loved ones safe from the heat! MJD && .AVIATION... Breezy surface winds with gusts 20-25 kt are expected at the main terminals each afternoon through Monday, prevailing from the west today then becoming more northwest on Monday. There is a 15% chance of showers and thunderstorms within 10 miles of KSVE thru 03Z early this evening, but remaining dry at the main Sierra and western NV terminals. A steady warming trend will likely lead to density altitude issues later this week. MJD && .FIRE WEATHER... Isolated thunderstorms with only sparse rainfall are likely to develop along and ahead of an upper level trough passage this afternoon for portions of Lassen County, the Surprise Valley and into northern Washoe and Pershing counties. Widely cured fine fuel beds in this region will be receptive to lightning ignitions, especially outside of main precipitation cores. A deep, well-mixed sub-cloud layer will support gusty outflow winds of 40-50 mph near any mature thunderstorms. Outside of thunderstorms, wind gusts around 25 mph are expected this afternoon and evening. For Monday afternoon, a brief 2-4 hour period of elevated to locally critical fire weather conditions will exist for eastern Lassen County into western NV north of I-80 as northwest wind gusts of 25-30 mph overlaps minimum daytime humidity of 10-15%. This area of dry and breezy conditions coincides with today`s thunderstorm risk, which may exacerbate any holdover lightning ignitions. The remainder of the week will feature widespread warming, yielding a prolonged period of above average temperatures, very low daytime humidities, poor overnight humidities, and deep mixing heights, although winds will generally be on the lighter side except for typical late day breezes. MJD && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$