Damaging Wind in Nevada, September 8, 2022

Area Forecast Discussion
National Weather Service Las Vegas NV
250 PM PDT Thu Sep 8 2022

.SYNOPSIS...Hurricane Kay will bring big changes through next
Wednesday. Flash Flood Watches have been issued for much of
southeastern California, as well as parts of southern Nevada and
northwest Arizona for Friday and Saturday. Moisture from Kay will
linger through early next week as the hurricane deteriorates and the
remnant circulation eventually moves over the region, keeping
chances of showers and thunderstorms in the forecast. There are some
signs of drying late in the week.
&&

.SHORT TERM...through Sunday night. Early afternoon satellite loop
was quite interesting, especially over San Bernardino County, where
lower clouds associated with isolated thunderstorms were moving
quickly west while cirrus associated with the outflow of Hurricane
Kay were tracking northeast. Surface obs showed temperatures several
degrees lower than 24 hours ago southeast of I-15 under the
hurricane outflow cirrus canopy, but only a couple of degrees lower
in the sunnier conditions farther northwest. Obviously, Hurricane
Kay remains the feature of interest. The track of the center has
wobbled a bit to the right, bringing it onshore near the Baja Spur,
and the overall forecast track hasn't changed much, showing a north
northwestward track to about 31N before turning west due to the
influence of high pressure over the southwestern states and
weakening quickly over cooler waters. More important for our
purposes will be the southerly flow east of the center, which will
push a surge of tropical moisture into the deserts Friday and
Saturday. There is still a lot of uncertainty in exactly where bands
of heavy rain may set up, and the Flood Watch was left unchanged.
Even with the uncertainty, one area that looks especially favorable
for heavy rain is the Highway 62 corridor, including the Morongo
Basin, which will be closest to Kay's center and will see a long
period of southeasterly to easterly upslope flow. Precipitable water
drops off substantially on Sunday, which should end the widespread
heavy rain threat for much of the region. However, depending on how
much rain falls Friday and Saturday, the flooding threat may not
end, as the remnants of Kay will still be lurking offshore and
providing modest forcing.

.LONG TERM...Monday through Thursday.

Less confidence in the longer range as many of the more sensible
weather details will be dependent on the eventual track of what
remains of Hurricane Kay. Expectation remains that flow aloft will
turn more southwesterly next week, while remains of Kay may be
absorbed into the large scale flow and lift into the Mojave Desert
and Great Basin. This may keep precipitation chances alive for at
least the first half of next week, with precip tending to favor the
Great Basin zones with time. After a few days of southwesterly flow
aloft, conditions should dry out more noticeably by late in the week.
Meanwhile, what can be said with more confidence is that much cooler
conditions can be expected thanks to the abundance of moisture and
broad troughing taking shape across the West. Looking ahead at
the long range GEFS/EC H5 means, a series of Pacific shortwaves
keep any ridge rebuilding over the four corners through the next
10-14 days...which may mean the end of the 2022 Monsoon.
&&

.AVIATION...For Harry Reid...East-southeasterly winds will persist
for the next few hours before shifting and becoming south-
southwesterly later this evening. Winds should remain light through
the overnight hours. Gusty southeasterly winds will pick up around
15/16Z Friday morning. These gustier winds will persist throughout
Friday morning and afternoon. Mid-level and high cloud cover will
continue to increase, but cloud bases are expected to remain above
10 kft. Showers and thunderstorms are expected to pop up late Friday
afternoon and evening, impacting the southeast, southwest, and
potentially northeast approach corridors. These showers and
thunderstorm are not expected to impact the KLAS terminal area until
after 06Z.

For the rest of southern Nevada, northwest Arizona and southeast
California...KVGT and KHND will follow similar trends to KLAS. KBIH
will remain light and variable before swinging to the east-northeast
later this afternoon. Outflow winds from convection in the Eastern
Sierra and White Mountains will have the potential to impact KBIH
later this afternoon/evening. However confidence in these winds
materializing and the timing of them is currently low, so there is
no mention of them in the TAF. KDAG will shift back to the west this
evening before becoming light and variable. Winds will pick up and
shift to the southeast tomorrow morning with 20-25 knot gusts
expected. Showers and thunderstorms are expected to impact the KDAG
area on Friday afternoon, with the potential for them to move into
the vicinity as early as 18Z. Winds at KEED and KIFP will have a
more southerly component throughout the TAF period, with the
exception of convective influence later this afternoon and evening.
Showers/thunderstorms and their associated outflow winds are
expected to impact KEED and KIFP between 02-04Z. Gusts will likely
be out of the east, however they could become variable as the storms
pass, with speeds around 25-35 knots. Once the convection clears out
around 04/05Z, winds will swing back to the southeast with sustained
speeds around 10-15 knots.
&&

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

SHORT TERM...Morgan
LONG TERM...Outler
AVIATION...Stessman

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