Weather Lookup

Key Messages

* a pacific storm will bring rain, mountain snow and travel impacts, and thunderstorm chances through sunday morning.

* monday will be warmer and drier, with a return of increased winds and showers around midweek.

* dry weather is favored after the middle of next week, with a potential return of unsettled weather around veteran's day.

Discussion

Rain and high elevation snow will remain light and sporadic during the afternoon, with a low 10-20% chance of isolated thunderstorms along the E sierra and portions of W nevada. Showers become more widespread during the evening and overnight hours, greeting halloween festivities with wet, unpleasant weather. Be sure to make your evening plans accordingly, especially if traveling through the sierra.

A bulk of the rain and snow will fall overnight, with heaviest snowfall rates of 0.5-1"/hours along the sierra (above 7000 ft). Highest peaks in alpine and mono county may even see snowfall rates in excess of 1"/hour at times. Initially, snowfall and subsequent travel impacts will be confined above 7000 ft, but lowering snow levels will allow snow down to around 6000 ft sunday morning. As such, greatest snowfall totals of 4-8" (up to 12" locally) will favor higher sierra terrain, but light accumulations of a trace to 3" will be possible between 6000 and 7000 ft -- including donner pass and stretches of US-395 in mono county. Be prepared for slick, snow-covered roads if traveling around/across the sierra tonight or sunday morning.

One notable change to the forecast is that sunday morning's snow levels have trended higher in latest blended guidance, which suggests rain-snow lines only fall as low as 5500 ft. Thus, valley floors will likely just see rain with this storm. Foothill areas may still see snow falling -- or at least a rain-snow mix -- but very little to no accumulation is expected. Rain and snow will gradually clear out to the east as the morning progresses, but there is a 10- 20% chance of lingering showers south of US-50 sunday afternoon.

Transient high pressure will deliver warmer and drier weather monday before another pacific storm increases the potential for gusty winds and showers tuesday into wednesday. Looking ahead, ensembles favor a period of dry and mild weather after the middle of next week, but signal a return of wet, unsettled weather around veteran's day. -salas

Aviation

Low clouds and spotty -shra will maintain mountain obscuration impacts and brief periods of MVFR conditions at all area terminals through the afternoon. Thunderstorm chances increase to 10-20% in the afternoon, although ktrk-ktvl and krno-kcxp-kmev have a relatively higher likelihood of t-storm impacts through around 02- 04Z.

Showers increase in coverage and intensity after 00Z this evening, resulting in longer stints of MVFR conditions and mountain obscuration through sunday morning. Rain may briefly become a rain- snow mix after midnight at ktrk and ktvl, but shower activity should be wrapping up by then so any reductions to IFR conditions will be brief. At kmmh, rain will become a rain-snow mix -- or perhaps all snow -- as early as 04Z, creating periods of IFR conditions through sunday morning. A dusting of snow is possible on the kmmh runway by sunrise sunday morning.

Showers will taper off through the morning hours sunday, with additional light showers possible at ktvl and kmmh sunday afternoon. Elsewhere, expect VFR conditions to prevail sunday afternoon into monday.

-salas