Flooding in Nevada, March 17, 2023

Area Forecast Discussion
National Weather Service Las Vegas NV
116 AM PDT Fri Mar 17 2023

.SYNOPSIS...A weak system will bring some light showers to
far northern Mohave County this morning. Otherwise, gusty north
winds up to 30 mph possible in the lower Colorado River Valley
today and Saturday. Region staying cool with highs about 8 to 12
degrees below normal. The next storm next week will bring chances
for additional rain and heavy mountain snow Tuesday and Wednesday.
&&

.SHORT TERM...Through Saturday night.

Have seen a few light showers develop over far northern Mohave
County over the past 2-3 hours. Also, satellite shows more
concentrated areas of clouds across southwest Inyo and San
Bernardino Counties currently. All this is associated with a weak
trough moving over the area. HREF output indicates those light
showers over far northern Mohave County will probably continue
through 10 am MST before dissipating. Trough will slide east tonight
and be replaced by weak ridging Saturday. Otherwise, gusty north
winds up to 30 mph will mostly be confined to the lower CRV today
and Saturday. Region staying cool with highs running about 8-12
degrees below normal.

.LONG TERM....Sunday through Thursday.

The brief reprieve from wet weather comes to an end on Sunday as the
active pattern resumes. A weak shortwaves moves through Sunday
night, bringing light precipitation chances to the high terrain.
However, this shortwave is just the appetizer for the main trough
Monday night through Wednesday. Both GFS and Euro ensembles depict a
plume of anomalous moisture (3+ sigma) making landfall in northern
Baja California and far southern California. While the core of the
atmospheric river is forecast to pass to our south, moisture and
synoptic forcing will be sufficient to bring widespread
precipitation chances to our area. PoPs peak Tuesday afternoon, with
the latest NBM giving the entire CWA a 50+% probability of
precipitation. QPF amounts will be highest in the high terrain such
as the Sierra, White, and Spring Mountains, along with the eastern
halves of Lincoln and Mohave Counties. Rainfall totals in the lower
deserts will be less, ranging from a couple hundreths to a couple
tenths. Snow levels are expected to be lower with this system,
starting around 6-7kft, and dropping to 3500-4500 by Wednesday
afternoon. This places light snow in some of our northern valleys,
including parts of Lincoln, Nye, Esmeralda, and Inyo. These forecast
snow levels also result in impactful snow amounts in the Sierra,
White, and Spring Mountains, as well as the higher terrain of
Lincoln County. Latest NBM guidance shows quite a bit of spread in
snow accumulations at Aspendell, with the 25th percentile at 5
inches and the 75th percentile at 28 inches. The large spread is
largely attributable to model QPF discrepancies, as Aspendell lies
on the northern fringe of the moisture plume. Farther east at
Pioche, the 25th and 75th percentiles of NBM snow accumulation are
2" and 7", respectively.

Not only will this system bring widespread rain, but a reinforcing
shot of below-normal temperatures and gusty southwest winds.
Temperatures on Wednesday are forecast to be 10-20 degrees cooler
than their seasonal norms. We may not even reach 60 here in Las
Vegas, with the NBM giving a 65% chance of falling short. For
reference, our normal LOW temperature for that date is 52. Combined
with the gusty winds, it won't feel like mid-March out there. Winds
are expected to be strongest on Tuesday, with minor wind impacts
possible. Guidance is already picking up on the likelihood of minor
wind impacts, with ensemble mean peak gusts of 35+ mph at Barstow
and Las Vegas. The one potential caveat to the forecast winds will
be the coverage and intensity of precipitation, as heavier
precipitation tends to limit wind speeds. This system finally exits
the area Wednesday night, leaving cool and calmer conditions in its
wake.
&&

.HYDROLOGY...Minor flooding from higher than normal stream flows are
forecast to continue within the Meadow Valley Wash through the
weekend. Next weeks storm system will likely bring an increase in
those stream flows. This will only act to exacerbate the ongoing
flooding in the county.
&&

.AVIATION...For Harry Reid...Winds will remain light, 10 knots or
less, and will follow typical diurnal directional trends. FEW low
clouds will clear out of the area by mid-morning, with FEW to SCT
high clouds moving in during the afternoon.

 For the rest of southern Nevada, northwest Arizona and southeast
California...With the exception of the two Colorado River Valley TAF
sites, winds at the remaining TAF sites will remain light (10 knots
or less) and will follow typical diurnal directional trends with
periods of light and variable winds as they transition. KEED and
KIFP will favor a more northerly direction through the afternoon and
into the evening. Sustained winds at KEED will increase to 10-15
knots around 18Z and will continue into the evening. 20-25 knot
northerly wind gusts will pick up at KIFP around 17Z and will also
persist into the evening hours.
&&

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

SHORT TERM/HYDRO...Pierce
LONG TERM...Woods
AVIATION...Stessman

For more forecast information...see us on our webpage:
https://weather.gov/lasvegas or follow us on Facebook and Twitter

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
935 PM PDT THU MAR 16 2023

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0730 PM     FLASH FLOOD      1 SSE TOPOCK            34.75N 114.48W
03/15/2023                   MOHAVE             AZ   PUBLIC

            PHOTOS SHOWED FLOOD DEBRIS, STUCK VEHICLE,
            AND ERODED ROADWAY ON OATMAN HIGHWAY AT WARM
            SPRINGS WASH.

&&

MW