Area Forecast Discussion

KEY MESSAGES

* Hotter than normal temperatures will continue through next week.

* Moisture will increase this weekend leading to a slight chance of showers and thunderstorms over portions of eastern Nevada and western Arizona.

DISCUSSION

Through next Wednesday.

Above normal temperatures are expected through next week. Temperatures will climb as heights rise today then peak on Friday. Temperatures drop back somewhat from Friday as the anomalously high upper level heights wane and moisture is introduced to the atmosphere, but will remain about 5-10 degrees above normal. Major HeatRisk is possible in some portions of Death Valley, Las Vegas Valley, and the Colorado River Valley on Friday and Saturday, however it will be isolated in area as well as longevity. This is decently captured in probability for Major HeatRisk, for example: in Las Vegas probabilities for Major HeatRisk peaks on Friday around 50% then decreases into the weekend. This seems more representative of the risk as high temperatures won't climb much higher than what we have already seen this summer. Moisture is advertised to advect north this weekend which may limit heating in areas of Arizona and southern Nevada. With all these factors in mind, decided to not issue any heat products at this time. That said, widespread Moderate HeatRisk (level 2 of 4) is expected through the weekend across the region with the pockets of Major HeatRisk (level 3 of 4) previously mentioned. This type of heat can be hazardous to anyone who has prolonged outdoor plans, is sensitive to the heat, is not acclimated to the desert, or does not have access to cooling or water. Temperatures climb slightly next week as moisture wanes and the upper level ridge re-establishes itself over the region, and Major HeatRisk becomes more of a risk in desert valley locations Tuesday or Wednesday.

Overnight satellite showed a decently organized MCV with frequent lightning through the overnight hours over the Baja Peninsula. This feature will wane but be a source of increased moisture into the region. Models are in decent agreement that moisture will surge northward Friday and linger over far southern Nevada and western Arizona through the weekend. PWATs of 0.75" to 1.00" spread through Clark, eastern Lincoln, and Mohave counties by Saturday morning. There will be minimal synoptic forcing over the region which will limit precipitation chances, mainly focusing on the terrain. However will need to watch what the MCV remnant do as it could provide additional lift through the southern Colorado River Valley and increase precipitation chances. Showers and thunderstorms will be possible at times Saturday and Sunday in southern Clark, eastern Lincoln, and Mohave County. Low levels will have to saturate after being very dry, which will limit the heavy rain risk but could increase for sudden gusty winds with any precipitation. If enough lightning can occur, dry lightning could bring an increased fire risk. SPC shows a 10% chance for dry lightning in Lincoln and northern Mohave counties. Moisture will wane Monday into next week, and precipitation chances decreasing with it.

AVIATION...For Harry Reid

For the 12Z Forecast Package..A weak cold front moving through this morning will bring gusty north- northeast winds to Las Vegas Valley TAF sites with directional variability between 030 and 060 and gust speeds peaking between 20 and 25 kts. This winds will surface mainly after daybreak, but a shift in wind direction is likely before dawn. Winds will veer towards the southeast as the afternoon progresses... becoming southwesterly after sunset. No operationally significant cloud cover. Thursday's forecast high temperature is 104F, with best chances of 100F between 21Z and 04Z.

For the rest of southern Nevada, northwest Arizona and southeast California...For the 12Z Forecast Package...A weak cold front will bring gusty northeast winds to the Las Vegas Valley TAF sites and north winds to the Colorado River Valley TAF sites around sunrise with gust speeds peaking between 20 and 25 kts. KDAG will gust from the westthis evening to around 25 kts. No operationally significant cloud cover.

SPOTTER INFORMATION STATEMENT

Spotters are encouraged to report any significant weather or impacts according to standard operating procedures.