Flash Flood Warning 117, NWS Las Vegas, NV

Area Forecast Discussion
National Weather Service Las Vegas NV
1215 PM PDT Mon Aug 8 2022

.SYNOPSIS...With moisture in place, monsoon activity is forecast to
ramp up through the week. Scattered thunderstorms will be possible
today, with increasing coverage tomorrow through Thursday. Flash
flooding will be the primary concern with these storms. Cooler
temperatures are expected throughout the week.
&&

.SHORT TERM...Today and Tuesday.

An uptick in convection is expected on Tuesday compared to the past
few days as moisture increases across the region. Also watching the
potential for an MCV to form and move into the area late
tonight/Tuesday morning, which would provide not just additional
moisture but a forcing mechanism as well. Hi-res models and HREF
probabilities for over 40dbz reflectivities all show at least
scattered thunderstorms Tuesday afternoon in northern Inyo County,
southern Nevada, eastern San Bernardino, and Mohave County...with
lesser convection in much of southern Inyo County into west-central
San Bernardino County. PWATs of 1 inch or greater will be in place
across the region per ensemble probabilities, with heavy rain and
flash flooding possible with any storms. HREF PMMs for 3hr QPF for 1
inch highlights Clark and Mohave Counties, as well as portions of
eastern San Bernardino County, which is also where the axis of
highest instability should set up Tuesday afternoon. This is also
the area highlighted by a slight risk in the day 2 excessive
rainfall outlook, which is reasonable given the environment and
overall set up. There is also a signal for heavy rain through this
area in the 1hr rainfall amounts, though there is differences in
where that may occur with anywhere through Clark, Lincoln, and
Mohave counties potentially being impacted. Will need to watch how
the potential MCV and how that develops- if there is an increase
signal for a piece of energy to move into the region Tuesday
morning, higher flash flood impacts are possible in parts of the
region.

.LONG TERM...Wednesday through Sunday.

An active monsoon pattern is expected to continue through the
remainder of the week and over the weekend with a favorable
monsoonal flow keeping moist conditions in place across our region
through the period. On Wednesday, an area of low pressure along the
Oregon and northern California coast and high pressure over the
Intermountain Region continues to direct deeper moisture northward
into our area. Ensemble mean forecasts widespread anomalous PWATs
across our area through much of the long term period. The moisture
will keep thunderstorms in the forecast each day along with below
normal temperatures through the period. The Climate Prediction
Center's 8-14 day forecast graphics show probabilities of above
normal precipitation and below normal temperatures continuing
through the 3rd week of August.
&&

.AVIATION...For Harry Reid...Monsoon moisture will return to
southern Nevada today through Wednesday. Thunderstorms will likely
develop over the higher terrain early this afternoon, with the best
chance of seeing storms in the Las Vegas Valley between 21-00z.
Gusty outflow winds up to 30 kts are possible near any storm and
CIGS could potentially lower to around 8k feet. Additional
thunderstorm activity is expected Tuesday with storms being more
widespread during the afternoon and early evening.

For the rest of southern Nevada, northwest Arizona and southeast
California...Monsoon moisture increasing across the region today
will lead to isolated to scattered thunderstorms primarily over the
mountains with cloud bases of 12-15 kft MSL Storm movement will be
toward the west-northwest. There is a possibility of thunderstorms
impacting TAF sites in the Las Vegas Valley, DAG and BIH. Prevailing
winds will be light and variable this morning then increasing to 10-
20 knots this afternoon and TAF sites could see gusty outflows from
distant thunderstorms this afternoon into this evening. Additional
thunderstorms are expected Tuesday across most areas.
&&

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

SHORT TERM/LONG TERM...Nickerson
AVIATION...Gorelow

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

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