183 FXUS65 KVEF 101104 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 404 AM PDT Mon Jul 10 2023 .SYNOPSIS...Seasonably warm and breezy conditions will continue across the region through Monday resulting in elevated fire danger across portions of southern Nevada and northwest Arizona. High pressure builds and intensifies over the area this week bringing another round of above-normal temperatures. Dangerously hot conditions spread across the region late this week through the upcoming weekend and warnings have already been issued to highlight this upcoming event. && .SHORT TERM...Today through Thursday. The upper level pattern responsible for our breezy afternoons and critical fire conditions will persist through today and gradually level off through the mid-week as we transition into the well anticipated heat wave this upcoming weekend. Confidence continues to increase for broad ridging to set up over the Desert Southwest over the course of the week, amplifying significantly by the latter half of the week. Until then, temperatures gradually increase across the region, adding more high heat days for parts of Arizona and southern Nevada, and increasing the risks for heat related illness each day. Should any impacts occur, they will likely occur first in the extreme southern parts of the CWA, including the CRV and Death Valley, then that concern spreads north to much of the region heading into Friday. There is a very low end chance for isolated storms for far eastern Mohave County Tuesday as PWATs temporarily ramp up to over 1". This short lived surge of moisture will scour out quickly by Wednesday however. Any storms that develop will likely occur east of the eastern Mohave county border, but a non-zero chance for outflow gusts could spread westward. Then all eyes shift to the hot dry setup coming next weekend. .LONG TERM...Friday through next Monday. An anomalous ridge of high pressure will set up over the Desert Southwest late-week into next weekend. The center of the ridge will begin over northern Mexico, but will slowly meander northwestward, putting the center of the 600+dm 500mb high pressure directly over southern Nevada Sunday and Monday. Temperatures will increase to well-above-average next weekend, with conditions steadily worsening each day. [Friday] "Moderate" HeatRisk paints majority of the forecast area, with pockets of "Major" HeatRisk in our desert valleys including Las Vegas, Pahrump, Death Valley, Kingman, and the Colorado River Valley. This is when our heat concerns shift from conditional (mainly those most vulnerable) to the majority of the population that are exposed. [Saturday] "Major" HeatRisk expands to cover almost all of southern Nevada, southeastern California, and northwestern Arizona below 4000 feet in elevation thus meaning all of our population centers in the region being at significant risk for heat impacts. "Moderate" HeatRisk persists for higher elevations of the southern Great Basin. [Sunday] "Major" HeatRisk expands to include all elevations below 6000 feet, with "Extreme" HeatRisk (the highest level) presenting across southern Inyo, southern Nye, Clark, and southern San Bernardino counties. Higher elevations including the Spring Mountains and Sheep Range of Clark County increase to "Moderate" HeatRisk. For reference, high temperatures at KLAS may approach all time record levels. [What Does This Mean?] Temperatures this weekend and into early next week will be very dangerous, and not just for some. We are not only going to encounter temperatures over 10 degrees above mid- July averages, but we are doing so with relatively minimal time given to acclimate to the 110+s given our abnormally cool June. Tourists and those sensitive to the heat are strongly discouraged to recreate or work outside this weekend. [So Head to the Mountains?] The City of Mount Charleston and surrounding trails will be under "Moderate" HeatRisk still. This level of heat affects most individuals sensitive to heat, but especially those without access to air-conditioning and/or adequate hydration. If you're hiking, you are in this category. Other factors to consider: relative humidity values on Mount Charleston could range 10-15% higher than relative humidity values in Las Vegas, which will contribute to a higher "feels like" temperature. Additionally, these hot temperatures could exacerbate altitude sickness symptoms. Because of all of these reasons and our high confidence in the setup for this heat this weekend, we have opted to issue our heat headlines much earlier than typical to emphasize both the high confidence and the high risk that are expected. Heat is the number one weather related killer, and our number one goal is to prevent that from happening. We will continue to update and fine tune the details as we approach this upcoming weekend, but we highly appreciate all efforts to legitimize the risks expected. && .AVIATION...For Harry Reid...Light southwest winds around 5 knots continue through sunrise. Later in the morning, east-southeast breezes are expected to develop, with speeds of 6-10 knots. This should last a few hours before winds shift to the south-southwest. There remains some uncertainty on the exact timing of the shift, with model guidance showing a range of times between 17z and 22z. Think the shift will most likely occur between 18z-20z, similar to yesterday. Gusts of 20-25 knots are expected. Wind speeds and gust taper off in the evening, leaving light southwest breezes to continue overnight. Clear skies. For the rest of southern Nevada, northwest Arizona and southeast California...VFR conditions through the TAF period as clear skies persist. Light winds this morning with breezy south-southwest winds developing this afternoon. Gusts of 20-25 knots likely. Wind gusts expected to cease around sunset, except KDAG where gusts will continue until 06z-08z. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...TB3 LONG TERM...Varian/TB3 AVIATION...Woods For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter