Strong and nearly stationary high pressure aloft led to a week long heat wave which set many record high temperatures in the Mojave Desert.
Every event with a place to put it; 6 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.
Strong and nearly stationary high pressure aloft led to a week long heat wave which set many record high temperatures in the Mojave Desert.
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 Aug 14, 8:33 AM PST, 2 hours 27 minutes earlier.
Area Forecast Discussion
National Weather Service Las Vegas NV
933 AM PDT Fri Aug 14 2020
.SYNOPSIS...Excessive heat will take hold of the region over the
weekend and continue through most of next week under a strong ridge
of high pressure setting up over the western states. Isolated
afternoon thunderstorms will be possible over the southern Sierra,
central Nevada and northwest Arizona at times due to limited
moisture circulating within the area of high pressure.
&&
.UPDATE...More of the same is expected today for the Sierra as well
as higher elevations of San Bernardino County with regard to light
rain chances and the potential for a dry lightning strike this
afternoon. Increased this afternoon's precipitation chances in the
corresponding areas. No other changes to the forecast were made this
morning.
Primary concern today will be the ongoing, persistent,
prolonged heatwave that we are about to endure. The Excessive Heat
Warning for the bulk of our forecast area (southern Nevada,
southeastern California and northwestern Arizona) as well as the
Heat Advisory for the mountains kicks off this morning at 11am and
is currently queued to go through Wednesday night. These heat
headlines look to be in good shape.
&&
.PREVIOUS DISCUSSION...310 AM PDT Fri Aug 14 2020/
.SHORT TERM...Today through Saturday.
Today kicks off what looks to be the longest heat wave we have
experienced this summer as high pressure expands and amplifies from
the Desert Southwest all the way up into western Canada by Saturday
afternoon. A combination of heat and smoke will be the primary
weather concerns as we head into the weekend due to southwest flow
carrying smoke from wildfires near Los Angeles across southeast
California into parts of southern Nevada. Haze and smoke from the
HRRR smoke forecast were used to indicate the areas which should be
most impacted today through Saturday morning...which includes most
of San Bernardino County along with central and southern Clark
counties. Isolated afternoon thunderstorms will be possible
primarily over the southern Sierra and White Mountains today and
Saturday while the rest of the region should see fairly dry and
stable conditions. High temps will be within a degree or two
of record values at some sites, including Las Vegas, beginning
today and records will likely start to be broken by Saturday.
&&
.LONG TERM...Sunday through Thursday.
Not much to say except, HOT, HOT, HOT next week as ensembles
continue to advertise an anomalously strong ridge parked over the
area. GEFS indicates an area of H5 heights in excess of 597 dm
Sunday-Wednesday. GEFS indicates only a slight decrease in heights
Thursday into next weekend as the high center slowly weakens and
migrates eastward. Previous shift extended the the Excessive Heat
Warning/Heat Advisory through Wednesday. That looks warranted based
on expansive area of high to very high HeatRisk.
As far as any precipitation. If the GEFS and ECMWF ensemble guidance
pans out don't see any significant infiltration of low level
moisture into the region. Without that injection of low level
moisture instability/CAPE under this strong of a ridge will remain
limited. This keeps the primary threat of afternoon and evening
thunderstorms confined to the higher areas of the southern Great
Basin, southern Sierra and northwest Arizona. The storms would
produce more wind and lightning than rain so new fire starts is a
concern.
&&
.CLIMATE...
DAILY RECORD HIGH MAXIMUM TEMPERATURES
TDY 8/14 SAT 8/15 SUN 8/16 MON 8/17
Las Vegas, NV 111 (2016)* 111 (2002)* 113 (1939)* 111 (1939)*
Bishop, CA 106 (2002) 105 (2002)* 106 (1994)* 106 (2015)*
Barstow, CA 112 (2002)* 112 (2002)* 114 (1994)* 111 (2015)*
Needles, CA 117 (2012)* 118 (2019)* 118 (2015)* 117 (1892)*
Kingman, AZ 109 (1933) 106 (1933)* 110 (1933)* 106 (2001)*
Death Valley 124 (2002) 124 (2002)* 125 (1994)* 124 (2001)*
DAILY RECORD HIGH MINIMUM TEMPERATURES
TDY 8/14 SAT 8/15 SUN 8/16 MON 8/17
Las Vegas, NV 86 (2007)* 86 (2016)* 88 (2008)* 89 (2015)*
Bishop, CA 67 (2015) 65 (1958) 67 (1992) 65 (1992)*
Barstow, CA 81 (1983)* 83 (1996)* 81 (1994)* 82 (2012)*
Needles, CA 93 (1996)* 92 (1962)* 93 (1892)* 94 (1903)
Kingman, AZ 79 (1996) 78 (1972)* 77 (1917)* 81 (1903)*
Death Valley 100 (1924) 97 (2008)* 98 (2008)* 99 (2013)*
*-Current forecast may be close to current record values.
&&
.AVIATION...For McCarran...Light and variable winds this morning
will favor the easterly direction through around 21z. West southwest
winds will take over at that point with speeds increasing to around
10 knots gusting 15-20 knots at times through this evening.
Southwest winds at speeds of 8 knots or less are expected overnight
into Saturday morning. SCT mid and high cloud cover will linger
around through mid morning before lifting northward, leaving clear
skies outside of a few cumulus that develop over the higher
elevations this afternoon.
For the rest of southern Nevada, northwest Arizona and southeast
California...Light winds this morning will lead into another
afternoon of west to southwest winds at 9-13 knots. A few spots
could see gusts of 15-20 knots this afternoon. Precipitation should
be limited to the Sierra which could enhance west to northwest flow
at KBIH later this afternoon into this evening. Lingering mid/high
cloud cover will lift northward by late morning leaving clear skies
outside of some cumulus developing over the higher elevations this
afternoon.
&&
.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&
UPDATE...Varian
SHORT TERM...Adair
LONG TERM...Pierce
AVIATION...Guillet
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.
7 excessive heat. Local standard time, as filed.
Excessive Heat Warning criteria were reached for seven straight days.
Excessive Heat Warning criteria were reached for seven straight days.
Excessive Heat Warning criteria were reached for eight straight days.
Excessive Heat Warning criteria were reached for eight straight days.
Excessive Heat Warning criteria were reached for eight straight days.
Excessive Heat Warning criteria were reached for eight straight days.
Excessive Heat Warning criteria were reached for seven straight days.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Nevada in 2020Every state in 2020This day in weather historyWarnings in Nevada, August 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: 911539, 911540, 911541, 911542, 911543, 911544, 911545.