Excessive Heat in California, July 7 to 13, 2021

Area Forecast Discussion
National Weather Service Las Vegas NV
955 AM PDT Wed Jul 7 2021

.SYNOPSIS...Temperatures will continue climbing well above normal
today leading to a period of excessive heat which will take hold of
the region into early next week. Southeast flow Thursday and Friday
will bring a brief period of increasing moisture, mainly to
northwest Arizona and the lower Colorado River Valley, though
excessively hot conditions will continue.
&&

.UPDATE...The Excessive Heat Warning is now in effect for the
entire region through Monday (with Heat Advisories for the higher
elevations of southern NV). We are running about 2-3 degrees
warmer than those observed yesterday. So another warm and dry day
is in store. No forecast changes were needed this morning.
-Peters &&

.PREV DISCUSSION... /issued at 239 AM PDT Wed Jul 7 2021/

.SHORT TERM...Today through Friday.

The main story will be the Excessive Heat Warning going into effect
for the entire region today and continuing through at least Monday.
Temperatures this afternoon will likely break the record of 106 in
Bishop and be within 2-3 degrees of record values for Las Vegas and
Death Valley (see climate section below).

The center of of the high pressure responsible for the heat will
slowly move from near southern Nevada toward the Four Corners
Thursday and Friday. This will place our region in southeast flow
aloft which will allow mid level moisture from Arizona and New
Mexico to move our way. In addition, there are indications from
various models that moisture from the surface to 850 mb will push up
from the Gulf of California Thursday into the Colorado River Valley
past Lake Havasu to Laughlin-Bullhead City and nearby areas of
eastern San Bernardino and southern Mohave counties. The latest NBM
dewpoint grids also have values of 55-60F over these areas. Though
confidence is low in a significant gulf surge event making it up
into southern Nevada, it is worth keeping an eye on. The increasing
moisture won't provide any appreciable heat relief since humidity
will increase. The latest NBM PoP grids keep values below 10 percent
and no mention of thunderstorms is warranted for now. However, there
is a 20 percent chance of thunderstorms over the mountains between
eastern Mohave county and Flagstaff Thursday and Friday and any
storms would move to the west or northwest.

.LONG TERM...Saturday through Tuesday.

High pressure is forecast to intensify over the weekend with the
high centered directly over the forecast area. NBM temperatures have
inched up over the weekend with Saturday continuing to stand out as
the hottest day although very little change in temperature is
forecast for Sunday. The latest NBM probability of seeing 115
degrees in Las Vegas sits at 74 percent on Saturday and 65 percent
on Sunday. Probabilities for tying the all time record of 117
degrees in Las Vegas on Sat/Sun is now 43 and 34 percent
respectively. Looking up in the Spring Mountains at roughly 7000
feet, high temperatures are forecast around 90 degrees both days but
probabilities are very high that temperatures could reach the mid
90s which would mean some of the hottest conditions on record. So,
any way you cut it, it's going to be dangerously hot this weekend.
Excessive Heat Warnings and Heat Advisories are out and everyone is
encouraged to plan accordingly and take the necessary precautions to
stay safe.

High pressure remains over the area into early next week although
the intensity is forecast to wane by Tuesday. Very hot conditions
linger into Monday, as does the extreme heat headlines, even with
temperatures forecast to decrease a few degrees. This very slight
cooling is not expected to provide any relief and instead, just adds
another day to the duration of this heat event. A more substantial
drop in temperatures is forecast for Tuesday but will still be above
the seasonal averages.
&&

.CLIMATE...Listed below are a few climate locations showing both the
record high maximum and high minimum temperature for each location
and the year the record was last set for next Wednesday, Thursday
and Friday.

LOCATION            WED-JULY 7        THU-JULY 8        FRI-JULY 9
(HIGH MAX)          Record(year)      Record(year)      Record(year)

Las Vegas NV          116(2017)        113(2017)         113(2012)
Bishop CA             106(2017)        106(2017)         107(2002)
Barstow CA            116(1989)        113(2017)         113(2002)
Needles CA            122(2017)        120(2017)         119(1961)
Kingman AZ            112(2017)        108(2017)         108(1985)
Desert Rock NV        111(2017)        109(2018)         112(2002)
Death Valley CA       127(2017)        128(1913)         129(1913)

LOCATION             WED-JULY 7        THU-JULY 8        FRI-JULY 9
(HIGH MIN)           Record(year)      Record(year)      Record(year)

Las Vegas NV           93(2018)          92(2017)         92(2017)
Bishop CA              72(2014)          70(1991)         72(1975)
Barstow CA             80(2018)          83(1989)         85(2017)
Needles CA             95(1942)          95(2018)         93(1985)
Kingman AZ             80(1917)          84(2017)         82(2017)
Desert Rock NV         82(1981)          79(1996)         86(1985)

&&

.AVIATION...For McCarran...Typical diurnal winds are expected
through most of the TAF period, with generally east winds and
southwest breezes overnight with speeds 8KT or less. A brief period
of southeast winds is possible around 00Z with speeds around 8-10KT
possible. There is also a low chance for west winds at 10-15KT to
push into the terminal about 03Z-06Z before speeds drop back and
winds veer to southwest again after 06Z.

Extreme temperatures are expected through the weekend, with
temperatures reaching  100 degrees each morning between by 10AM and
falling below in the 10-11 PM time frame. High temperatures each day
will reach over 110 degrees. Otherwise, occasional clouds around
15kft are expected, especially this afternoon and again Thursday
morning.

For the rest of southern Nevada, northwest Arizona, and southeast
California...Another day with breezy southeast winds at BIH is
expected, with gusts this afternoon 20-25KT likely. A brief push of
west to southwest winds is possible at BIH around 00Z, but low
confidence for this to occur at this time. DAG should also see their
typical west push starting at 00Z, with speeds around 15KT and low
chance for gusts to 25KT at times. Otherwise, light diurnal wind
trends are expected through Thursday morning. Clouds are possible at
times at around 15kft.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.

&&

SHORT TERM...Adair
LONG TERM...Salmen
CLIMATE...Peters
AVIATION...Nickerson

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