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 continues today as mid-level moisture and increasing cloud cover continues its northward trajectory

DISCUSSION

(This evening through next Sunday)

WEATHER PATTERN OVERVIEW: This afternoon and evening is that last day for highest chances (20-50%) for isolated to scattered wet/dry thunderstorms over northern and central Nevada. Tuesday and Wednesday will still have chances for additional showers and thunderstorms, but at a lower chance (10-30%) and more across eastern Nevada as the high pressure to the south moves west towards Arizona, which will cut off the monsoon moisture flow. Thunderstorms today will start off as dry then transition to a mix of wet and dry across central and northeastern Nevada, with Humboldt County expecting it by the evening. Storm motions is a little elevated which can hinder some storms from forming, however increased amounts of moisture with PWATs at or above 0.8 and ample instability will see rapid development with some of the storms capable of producing heavy rainfall. Greatest threats from these storms are still gusty erratic outflow winds up to 45-55 mph, cloud to ground lightning strikes, and brief periods of heavy rainfall. Thursday through Sunday, models are showing better agreement for the weather pattern forming, with the upper level ridge moving west, shifting the southerly flow into a more northwesterly flow with drier air. What has also changed with the models is they are now showing the upper ridge being further south over the US/Mex border with an upper level trough to the northwest settling over the Pacific ocean. This will cause a longwave westerly flow over Nevada that will be dry, but with much cooler temperatures given the lower forecast heights. For Monday, the models start to become different with each other but not by much, with both showing a trough forming over the northwest and cresting into Nevada, however ECMWF is showing the trough to be weak and short lived, while GFS is showing the trough to be stronger with the chance for more moisture. Either outcome will still have much cooler temperatures for the day with a southwesterly flow present, yet is uncertain in regards to moisture. Temperatures still on track with a cooling trend with highs in the 90s the first half of the week and dropping into the 80s over the weekend. Winds will be breezy in the afternoons with speeds up to 10-15 mph, gusts 20-25 mph. These winds with drier air will cause some elevated fire weather concerns for Humboldt County as much of the monsoon activity has bypassed the area, leaving it drier than others.

AVIATION

VFR conditions will be the dominant flight category across all terminals over the next 24 hour period. Active monsoon pattern continues today with rapid developing thunderstorms near all terminals except for KTPH. Winds will generally be from the south/southwest, however gusty erratic winds up to 45-50 kts possible with passing storms with the chance some storms producing heavy rainfall. VCTS at all terminals (except for KTPH) with possibility some storms will move over the terminals. This may cause MVFR or lower conditions.

FIRE WEATHER

Monsoon activity ramping up today with this being the last day for 20-50% chance for isolated to scattered wet/dry thunderstorms across central and northern Nevada. Activity expected across all zones this afternoon and evening with elevated fire weather conditions over zone 437 today as storm activity will start out as mainly dry, however Red Flag was not issued as storms are expected to transition to a more mix of wet and dry by the evening. Greatest threat from these storms is gusty erratic winds up to 45-55 mph, cloud to ground lightning strikes, and brief periods of heavy rainfall.

Monsoon activity expected to continue Tuesday and Wednesday but with lower chances at 10-30% and across eastern Nevada as the high pressure pushing the moisture begins to move west towards Arizona, cutting off the moisture flow. Winds will be 10-15 mph from the south with gusts up to 20-25 mph, shifting to a more southwesterly flow by Thursday.

LKN Watches/Warnings/Advisories

None.