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Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
067 FXUS65 KVEF 191910 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 1210 PM PDT Fri Jul 19 2024 .SYNOPSIS...Isolated to scattered thunderstorms expected again this afternoon, with best chances in southern Nevada, the southern slopes of the Sierra Nevada, and northwestern Arizona. Impacts will include locally heavy rain, strong gusty winds, and small hail. Chances of isolated thunderstorms return each day through the weekend before increasing next week. Meanwhile, above average temperatures resulted in an Excessive Heat Warning through the weekend, with temperatures remaining elevated through the forecast period. && .DISCUSSION...Today through next Friday. Moisture caught beneath an upper-level area of high pressure over the region will return isolated shower and thunderstorm activity to our forecast area each day through the weekend. Today will have the most coverage over the next few days, with thunderstorm activity expected along the southern Sierra crest, across southern Nevada, and across northwestern Arizona. Ample moisture in Arizona could result in locally heavy rain rates and flash flooding, whereas dry low levels in southern Nevada could result in gusty outflow winds over 40 mph. Storms will favor the higher terrain as it relies on heat-driven instability and orographic lift. Meanwhile, the center of the aforementioned high pressure will remain over southern Nevada through the weekend, which will result in both afternoon high temperatures and overnight low temperatures ranging 8 to 10 degrees above seasonal averages. As such, an Excessive Heat Warning is in effect for our southern zones today including southern San Bernardino County, southern Mohave County, and the Colorado River Valley... expanding to include southern Nevada and portions of southeastern California Saturday... and lasting through Sunday. Temperatures will remain elevated through the forecast period with pockets of "Major" HeatRisk in desert valleys. Will continue to assess temperatures coupled with acclimation through the weekend to see if additional heat-related headlines are warranted next week. As mentioned in the previous forecast discussion, the monsoonal high will shift slightly northwest next week, which will allow for enhanced moisture advection up the Colorado River Valley once again. As such, afternoon precipitation chances range from 20% to 40% across southern Nevada and southeastern California (with upward of 60% chance around northwestern Arizona) each day through the week. Continued the methodology from the previous shift of taking precipitation chances down somewhat in the desert valleys, as NBM climatology is likely artificially inflating chances in these areas. Shortwave troughing originating from the Pacific Northwest will squash our high pressure somewhat, which may provide some relief to well-above-average temperatures. && .AVIATION...For Harry Reid...Another round of showers and thunderstorms expected around the Las Vegas Valley today, with nearby storms picking up around 19Z and lasting through 03Z. Strong, gusty winds possible from their direction with speeds to 30 kts. Outside of thunderstorm activity, winds will favor the south- southeast around 10 kts. Thunderstorms return Saturday afternoon with similar timing, but with less coverage than today. Less than 10 percent chance of a thunderstorm over the terminal on Saturday. Ceilings will drop to aoa 12kft with thunderstorm activity. For the rest of southern Nevada, northwest Arizona and southeast California...Thunderstorms in the vicinity of KLAS, KVGT, KHND, KBIH, and KIFP expected to cause erratic, gusty winds at terminals from the storm`s direction. Best timing of convection will be between 19Z and 03Z with gust potential to 30 kts. Ceilings will drop to 10-12 kft with thunderstorm activity. Winds will return to diurnal trends overnight before thunderstorm chances return to the region Saturday afternoon with similar timing, but less coverage. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION/AVIATION...Soulat For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter