High pressure over the Desert Southwest brought four days of excessive heat.
Every event with a place to put it; 5 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS VEF wrote it up.
High pressure over the Desert Southwest brought four days of excessive heat.
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 Sep 6, 9:26 AM PST, 1 hour 34 minutes earlier.
Area Forecast Discussion
National Weather Service Las Vegas NV
1026 AM PDT Mon Sep 6 2021
.SYNOPSIS...Dry weather and seasonably warm temperatures expected to
continue through midweek. Chances of monsoonal moisture returning
have diminished as the ridge of high pressure continues to build
over the Desert Southwest.
&&
.UPDATE...Not a lot to update this morning. Expect another warm
day under mostly clear skies as a strong high pressure system
builds overhead, warming temperatures this afternoon to above
seasonal normal. Currently, KLAS is +3 degrees from 24 hrs ago.
Forecast soundings this morning indicate that the forecast high
will be 107, which is also what NBM says for today. For context,
the normal high temperature for KLAS for September 6th is 99
degrees. An Excessive Heat Warning will go into effective this
morning as a result of abnormally warm temperatures with little
overnight relief across the lower elevations of the Mojave Desert.
&&
.PREV DISCUSSION... /issued at 242 AM PDT Mon Sep 6 2021/
.DISCUSSION...Today through next Sunday.
The forecast through midweek has changed quite drastically in the
last 24 hours. Originally, the area of high pressure bringing us
unseasonably warm temperatures was going to continue to grow over
the Great Basin through the holiday weekend before weakening and
retreating east due to an incoming Pacific Northwest trough. This
trough would shift the upper level flow from the south, allowing
moisture to funnel up the Colorado River Valley from northern
Mexico. Additionally, there was a glimpse of moisture flux from a
tropical system approaching the Baja at the same time, which would
bring widespread precipitation chances to the Desert Southwest, and
drop temperatures.
However, updated ensemble forecasts indicate that the area of high
pressure will actually continue to intensify over the Desert
Southwest, essentially winning in the fight between Pacific NW
Trough and Desert Ridge. This dominating ridge of high pressure will
extend up the western United States through the first half of the
work week, which would raise heights enough to prevent a strong,
digging trough... thus preventing an upper level shift from the
south. The center of the high pressure will remain too far west over
the course of the week to facilitate moisture transport indicative
of monsoon season. What does this mean? Less chance of rain; hotter
temperatures.
Forecast high temperatures on Wednesday have increased quite a bit
due to the lack of moisture, so the Excessive Heat Warning has been
extended another day for the entire warned area. There was
consideration of added the Owens Valley to a warning as well as our
northern zones to a Heat Advisory; however, I decided to hold off
due to HeatRisk values failing to reach criteria... let me explain.
Though Bishop, CA is forecast to tie or break record high
temperatures in the afternoon, the evening will cool off
substantially. For context, the high in Bishop on Sunday was 100F
with a morning low of 50F, so a diurnal range of 50 degrees. Though
record high temperatures are possible in the Owens Valley, warm
temperatures will not be maintained through a 24 hour period like
the remainder of the warned zones where records are possible for
both afternoon highs and warm morning lows. Warm morning lows are
often the reason for heat-related illness in populations
experiencing homelessness, as the body is unable to adequately cool
off at night. Northern zones were not included in Heat Advisories
for similar reasons. Records and forecast temperatures through
Wednesday are highlighted below in the CLIMATE section.
Guidance has trended considerably drier in the longer range period
as a result. Forecast precipitation chances are now obsolete on
Wednesday, and have been reduced by 2/3rds on Thursday from the
forecast 24 hours ago. There will still be a modest increase in
precipitable water for the latter half of the week, thanks to a
tropical system in the mouth of the Gulf of California and a more
favorable southerly flow regime, but the quantity of moisture will
be limited. PoPs for Thursday and Friday look to favor the higher
terrain and northwest Arizona at this time. With the decrease in
moisture, warmer temperatures are likely to continue, with afternoon
highs averaging 3-5 degrees above normal through the weekend.
&&
.CLIMATE...Numerous locations have the potential to tie or break
record high and warm low temperatures through Wednesday.
The table below shows the record high temperature, the year the record
was last set, and the forecast temperature for all of our climate sites.
MAX HIGH MONDAY, SEPT 6 TUESDAY, SEPT 7 WEDNESDAY, SEPT 8
Record(Yr)/Fcst Record(Yr)/Fcst Record (Yr)/Fcst
Las Vegas 114(2020)/107 108(1977)/108 110(1979)/107
Bishop 104(2020)/101 102(2020)/103 100(1979)/103
Needles 120(2020)/108 117(2020)/112 115(2018)/110
Barstow-Daggett 116(2020)/107 109(2020)/108 108(2018)/109
Kingman 110(2020)/100 107(2020)/101 105(1915)/101
Desert Rock 109(2020)/102 102(1979)/104 102(2018)/105
Death Valley 123(2020)/118 121(1932)/119 120(2018)/120
The table below shows the record warm low temperature, the year the record
was last set, and the forecast temperature for all of our climate sites.
WARM LOW MONDAY, SEPT 6 TUESDAY, SEPT 7 WEDNESDAY, SEPT 8
Record(Yr)/Fcst Record(Yr)/Fcst Record (Yr)/Fcst
Las Vegas 84(2020)/81 84(2020)/82 81(2018)/83
Bishop 61(1950)/52 63(2020)/55 63(2020)/55
Needles 88(2019)/82 88(2012)/83 87(1986)/84
Barstow-Daggett 83(2020)/76 82(2020)/77 78(1974)/78
Kingman 77(1917)/71 72(1949)/71 84(1914)/72
Desert Rock 78(1989)/70 74(2020)/72 75(2012)/73
Death Valley 96(2013)/87 98(1913)/89 92(1979)/91
&&
.AVIATION...For McCarran...Another day with wind speeds generally
staying 6 knots or less, though an easterly direction will be
possible in the afternoon hours. A more definitive southwest
direction overnight with speeds 6-10 kts possible. No operationally
significant cloud cover.
For the rest of southern Nevada, northwest Arizona and southeast
California...Wind speeds generally less 10 knots favoring typical
diurnal trends can be expected across the Mojave Desert and southern
Great Basin through tonight. No operationally significant cloud
cover expected.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
UPDATE...Peters
DISCUSSION...Varian/Outler
CLIMATE...Varian
AVIATION...Pierce
For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and TwitterThe national radar mosaic for the moment the first event began.
6 excessive heat. Local standard time, as filed.
Excessive Heat Warning criteria were reached four days in a row.
Excessive Heat Warning criteria were reached four days in a row.
Excessive Heat Warning criteria were reached three days in a row.
Excessive Heat Warning criteria were reached four days in a row. Seven people died of heat related causes.
Excessive Heat Warning criteria were reached four days in a row.
Excessive Heat Warning criteria were reached three days in a row.
As the offices recorded each death: direct deaths were caused by the weather itself, indirect ones by something it set in motion.
| Event | Date | Age | Sex | Where | Kind |
|---|---|---|---|---|---|
| Excessive Heat, Las Vegas Valley | 2021-09-06 | 61 | Male | Unknown | Direct |
| Excessive Heat, Las Vegas Valley | 2021-09-09 | 76 | Male | Camping | Direct |
| Excessive Heat, Las Vegas Valley | 2021-09-09 | 57 | Male | Outside/Open Areas | Direct |
| Excessive Heat, Las Vegas Valley | 2021-09-08 | 43 | Male | Outside/Open Areas | Direct |
| Excessive Heat, Las Vegas Valley | 2021-09-08 | 52 | Male | Outside/Open Areas | Indirect |
| Excessive Heat, Las Vegas Valley | 2021-09-10 | 67 | Male | Permanent Home | Indirect |
| Excessive Heat, Las Vegas Valley | 2021-09-08 | 79 | Male | Permanent Structure | Direct |
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2021Every state in 2021This day in weather historyWarnings in Nevada, September 2021
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: 984968, 984969, 984970, 984971, 984972, 984973.