textproduct: Elko

KEY MESSAGES

* Subtropical moisture will help to fuel afternoon and evening thunderstorms through the middle of next week

* Some showers and thunderstorms could produce brief moderate to heavy rain with the main threat of debris flows on recently burned areas * Cooling trend begins today as mid-level moisture and increasing cloud cover continues its northward trajectory

DISCUSSION

(This afternoon through next Saturday)

WEATHER PATTERN OVERVIEW: Subtropical moisture from southerly monsoonal flow caused by high pressure over the four corners area, will bring chances for isolated/scattered thunderstorms this afternoon and evening across central and northern Nevada lasting into mid-week. Today is the strongest chances for thunderstorms as PWAT values across the area ranging above 0.8 to 1 inch of moisture, with ample instability. Periods of brief moderate to heavy rain from thunderstorms possible with the main threat of thunderstorms over recently burned areas that could produce debris flow. Humboldt county is the exception this afternoon as the thunderstorms will be mainly dry due to fast storm motions that will limit rainfall in the area. Tomorrow, thunderstorm chances continue in the afternoon with it more centralized over central Nevada along US-50 corridor and extending across eastern and northeastern Nevada with strongest thunderstorm chances near the Wendover area. The greatest threat from thunderstorms tomorrow will be strong gusty outflow winds up to 45-60 mph with brief periods of heavy rainfall. From Monday-Wednesday, the high pressure over the four corners will begin to shift west back towards Arizona. This will limit the amount of subtropical moisture entering into Nevada and drier air begins to move in. There is still some pockets of ample moisture with PWATs up to 0.7-0.85 inches shifting towards northeastern Nevada with ample instability to produce additional thunderstorms in the afternoon. Rest of the week, calmer weather conditions take hold as monsoon flow gets cut off with models showing better agreement that the high pressure will be centralized over Arizona and a southwesterly flow moves over Nevada. Temperatures remain in the 90s today and into the next week with a gradual cooling trend thanks to increase in cloud cover, with temperatures expected to get even cooler dropping into the 80s by the end of the week. Winds will be light in the afternoons with some patches of breezy southwesterly winds in central Nevada and Humboldt county up to 15-20 mph, gusts 25-30 mph through Wednesday, however thunderstorms can produce strong gusty erratic outflow winds up to 45-60 mph. End of the week, winds will gradually become breezy thanks to a low pressure system over the northwest that will tighten weather gradients along with the high pressure over Arizona.

FORECAST CONFIDENCE & DEVIATIONS: High confidence for active thunderstorms this afternoon through mid-week due to subtropical moisture from an active monsoon pattern over the southwest. Moderate confidence of dry, calm weather conditions returning late week with some breezy afternoon winds. High confidence of cooling temperature trends thanks to increase in cloud coverage and cooler flow by the end of the week. Changes to PoP, Thunder, and Weather grids were made to better reflect thunderstorm activity over the weekend and into Monday.

AVIATION

Active thunderstorms continue across central and northern Nevada with VCTS conditions at all terminals this afternoon and evening. Probability for thunderstorms over the terminals remain low which will be left out of the TAFs for now, however it cannot be ruled out that an isolated cell may move over the terminals. Breezy southerly winds up to 10-15 kts with gusts up to 20-25 kts, however gusty erratic winds from thunderstorms possible with gusts up to 40-50 kts. VFR dominant conditions at all terminals, however MVFR or lower possible from passing thunderstorms.

FIRE WEATHER

Southerly monsoonal flow continues this afternoon, keeping the subtropical flow over Nevada. By tomorrow and into next week, the monsoon flow will begin to weaken as the high pressure over the four corners will shift west towards Arizona. There will still be ample moisture in the atmosphere that will keep chances for isolated to scattered showers and thunderstorms for central and northern Nevada. Greatest hazards from these storms will be strong gusty erratic outflow winds up to 40-50 mph, ground lightning, and brief periods of heavy rainfall. Over western Nevada, thunderstorms are expected to be mainly dry as moisture levels are not as deep with stable air hindering instability potential. Winds will generally be light from the south at 10-15 mph with gusts up to 20-25 mph. Temperatures will be on a cooling trend thanks to cloud coverage and cooling down into the 80s and 90s by the end of the week. Models are showing better agreement that the cooler temperatures will stay, however southwesterly winds begin to elevate in the afternoons with drier air.

LKN Watches/Warnings/Advisories

None.