McGill, NV Weather

Key Messages

* Periods of valley rain and mountain snow continues thru Friday.

* Isolated thunderstorms expected Wednesday and Thursday afternoon and evening.

* Much cooler Friday, followed by a modest warming trend thru Monday.

Discussion

(Today through next Wednesday)

WEATHER PATTERN OVERVIEW: Large upper level closed low continues to slowly meander east and into California this morning. The low will concurrently weaken as it moves into Nevada today and Thursday, opening into a deep upper level trof. Trof axis looks to be centered over Nevada by Thursday night, after midnight. By Friday morning, most of the energy associated with the system will shift east into Utah as the trof splits into two pieces. The northern half lifting north into Montana and Alberta and a southern piece re- organizing into another closed low that will drift from Arizona into the four corners region Saturday.

Sensible weather wise, periods of showers and thunderstorms will continue thru Friday morning, with activity dissipating from west to east Friday afternoon and thru Friday night as the afore mentioned upper level trof progresses east into Utah. Areal coverage of showers and thunderstorms will again increase from the south, moving into central Nevada this afternoon and evening. The main push of showers and thunderstorms will occur Thursday as the main energy of the system passes overhead. Thunderstorms will be possible across the entire forecast area and there is a marginal risk of severe thunderstorms across eastern Nevada, including White Pine and Elko counties. The potential for severe thunderstorms across eastern Nevada on Thursday looks top be supported by adequate CAPE and mid level lapse rates, which will also be co- located with the main area of upper level lift. Gusty and erratic outflow winds, frequent cloud to ground lightning, and small hail are the primary hazards.

By Friday morning cooler air aloft will filter in from the northwest, and snow levels which had been around 10,000 feet for the majority of the event will lower to around 6,000 feet just as precipitation begins to dissipate across northern Nevada from west to east. Timing may allow for snowfall which had been restricted to the mountain summits to reach some of the higher elevation passes on NV225 Friday morning. That said, any valley snowfall within northwest Elko County will be limited to less than an inch. Storm total rainfall accumulation for the four day period that began Tuesday and will run thru Friday continues to look robust with most locations expected to receive between 0.25 inches and 0.75 inches. One inch or more of liquid equivalent is expected for the mountains thru Friday afternoon.

Beyond Friday, high pressure looks to quickly build in behind the trof, with the ridge firmly in control by Sunday. This will provide fair weather and a modest warming trend into next week Monday. Ridge looks to remain in control thru Wednesday of next week with fair weather continuing.

FORECAST CONFIDENCE & DEVIATIONS: There is high confidence for isolated to scattered showers and isolated thunderstorms today and tomorrow with the majority of the activity occurring on Thursday.

Aviation

Periods of -SHRA and/or VCSH will be present at all terminals thru at least Wednesday night as active weather persists across the region thru Friday. That said, CIGS are expected to remain within VFR category though brief reductions in VIS due to -SHRA on terminal may produce periods of MVFR. TS and/or VCTS may also impact terminals this afternoon as thunderstorms will be present across the forecast area. Breezy to locally windy conditions can also be expected this afternoon under generally southeast winds. The strongest winds will be present across the central Nevada terminals KTPH and KELY with gusts 25KT to 30KT.

Fire Weather

Upper level system continues to slowly move into the Great Basin from the west today and tomorrow, bringing rain showers, thunderstorms, and mountain snow to all FWZs. The next push of light showers and thunderstorms will move into central Nevada from the south around midday today. Shower and thunderstorm activity will increase Thursday as the main band of energy passes overhead, bringing additional activity north into the forecast area in the morning. The Storm Prediction Center has also issued a marginal risk for severe thunderstorms across FWZs 425, 438, 469, and 470 for Thursday afternoon. Gusty and erratic outflow winds, frequent cloud to ground lightning, and small hail are the primary hazards. Activity begins to dissipate from west to east Friday, eventually exiting Nevada Friday night. Widespread wetting rains are still expected over the four day period that began Tuesday and runs thru Friday with 0.25 inches to 0.75 inches of rainfall forecast across all FWZs, most of which is expected to fall on Thursday. Breezy to locally windy conditions will also be present each afternoon thru Friday, especially in central Nevada where gusts as high as 30-40 mph are expected. Much cooler temperatures will be in place by Friday though a modest warming trend will take place thru the weekend with dry and fair weather also present.