High pressure pushed temperatures well above normal across the Mojave Desert. Death Valley National Park reached Excessive Heat Warning criteria.
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The episode as NWS VEF wrote it up.
High pressure pushed temperatures well above normal across the Mojave Desert. Death Valley National Park reached Excessive Heat Warning criteria.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Las Vegas, NV wrote its last area forecast discussion before the first event at May 8, 7:55 AM PST, 4 hours 5 minutes earlier.
Area Forecast Discussion National Weather Service Las Vegas NV 855 AM PDT Fri May 8 2020 .SYNOPSIS...Dry and unseasonably warm weather will continue through Saturday. There will be a slight chance of thunderstorms Sunday as southerly wind flow ushers in moisture. Little to no rain is expected with these storms, but there is some concern for wildland fire starts due to lightning. Temperatures then fall back to near normal Tuesday and Wednesday, but low humidity and breezy to windy conditions may result in continued elevated wildland fire concerns. && .UPDATE... High pressure will build in today and tomorrow leading to temperatures rising across the area. Excessive Heat Warning for Death Valley still looks good as high temps top out between 108-113 both afternoons at Furnace Creek. Breezy winds down the Colorado River Valley will increase this afternoon out of the north with speeds around 15 knots gusting 20-25 knots. This will lead to some wave action between 1 to 1.5 feet across Lake Mohave. Forecast looks mostly on track and only minor tweaks were made to winds and temps. && .DISCUSSION...Very little change to previous forecast reasoning. High temps in Death Valley today and tomorrow are forecast to be 109 and 112, with Heat Risk a solid 3 in the lower elevations of the park, so the Excessive Heat Warning still looks good. Las Vegas high temp underachieved by a couple of degrees yesterday, so evening shift tweaked today's forecast down a bit, which looks reasonable. Still watching the potential for dry lightning over the weekend. By Saturday afternoon, models suggest neutrally stable or very weakly unstable conditions southeast of I-15, and just enough moisture to produce cumulus clouds, with thunderstorm development very unlikely but not impossible. Models are trending slightly more bullish on instability Saturday night, and previous shifts introduced small PoPs to parts of Clark and Mohave counties Sunday morning, which looks like the correct trend. Model thunderstorm probabilities have trended downward a bit on Sunday, but still exceed 10 percent east of a line from Caliente to Overton to Laughlin and top out near 25 percent in the Arizona Strip. Confidence in timing and placement of dry thunderstorms is not high enough to justify upgrading the Fire Weather Watch to a Red Flag Warning, so will let it ride for now. A pattern change is on the way for the first half of next week as a deep Pacific low (an offshoot of the big low currently spinning in the Gulf of Alaska) nears the Pacific Northwest coast Monday, breaking the heat wave, flushing out any lingering moisture, and bringing increasing southwest winds and lower humidity. These conditions will cause fire weather concerns, and if winds pick up just a bit more than forecast, Red Flag Warnings could be needed Monday or Tuesday. && .FIRE WEATHER...Hot and dry conditions over the last few weeks have cured lower elevations fuels in many areas of the lower Great Basin and Mojave Desert. This creates some concern over the weekend as moisture over northern Mexico gets pulled up into the Southwest, bringing with it a chance for low precipitation (dry) thunderstorms and associated lightning. On Saturday, thunderstorm formation over the lower Colorado River Valley and extreme southern Mohave County remains highly uncertain due to differences in timing of the moisture arrival among computer models. This will need to be watched closely. On Sunday, however, things appear more certain for dry thunderstorm formation. Due to this plus fuel moisture conditions, the Fire Weather Watch remains in effect for Mohave County and the Spring Mountains and Sheep Range in Clark County. Will hold off for issuing over Lincoln County for now, as fuel conditions are more marginal in that area and the northern extent of the thunderstorms is uncertain. && .AVIATION...For McCarran...East-northeast winds around 10kts will persist for a couple more hours before veering south and dropping below 8kts for the rest of the morning. Once winds drop off, expecting typical wind patterns through Saturday morning generally remain at or below 8kts. SCT-BKN high clouds are expected through the TAF period. For the rest of southern Nevada, northwest Arizona and southeast California...Gusty north winds are expected down the Colorado River Valley this morning, though speeds will be slightly lower than yeserday's winds. After midday, the strongest winds will be over and gusts should drop off at EED/IFP, and light winds are expected for this evening through Saturday morning. Elsewhere, light diurnal wind patterns are expected today. The only wind concern will be if a quick push of southwest or west winds will make it into BIH this afternoon. If breezy winds did push into BIH, they would likely pick up 23-03Z with gusts 15-20kts possible. Typical west winds 10-15kts expected tonight at DAG, otherwise light winds will prevail overnight. Occasional high clouds are expected at times through Saturday morning. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && Discussion/Fire Weather...Morgan Aviation...Nickerson Update...Guillet For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter
The national radar mosaic for the moment the first event began.
1 excessive heat. Local standard time, as filed.
Death Valley National Park reached Excessive Heat Warning criteria.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2020Every state in 2020This day in weather historyWarnings in California, May 2020
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 892296.