Severe Thunderstorm Warning 65, NWS Las Vegas, NV

590 
WWUS55 KVEF 040618
SVSVEF

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
1118 PM PDT WED AUG 3 2016

AZC015-NVC003-040630-
/O.CON.KVEF.SV.W.0065.000000T0000Z-160804T0630Z/
MOHAVE AZ-CLARK NV-
1118 PM PDT WED AUG 3 2016

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 1130 PM
PDT/1130 PM MST/ FOR SOUTHWESTERN MOHAVE AND SOUTH CENTRAL CLARK
COUNTIES...

OUTFLOW WINDS FROM THUNDERSTORMS TO THE NORTH CONTINUED TO BLAST
SOUTH ACROSS LAKE MOHAVE AND WILL PERSIST THROUGH 1130 PM.

LOCATIONS IMPACTED INCLUDE...
COTTONWOOD COVE AND COTTONWOOD COVE CAMPGROUND. 

PRECAUTIONARY/PREPAREDNESS ACTIONS...

STRONG WIND GUSTS AND HIGH WAVES CAN BE EXPECTED! IF ON OR NEAR LAKE
MOHAVE...HEAD TO SAFE HARBOR IMMEDIATELY OR STAY CLOSE TO SHORE
UNTIL THE STORM PASSES.

&&

LAT...LON 3523 11453 3523 11465 3554 11473 3553 11457
TIME...MOT...LOC 0616Z 237DEG 121KT 3597 11388 

$$

Area Forecast Discussion
National Weather Service Las Vegas NV
958 PM PDT WED AUG 3 2016

.SYNOPSIS...Deeper monsoon moisture will bring an increasing threat
of flash flooding to parts of the area through Thursday. Conditions
will begin to dry out on Friday, and the area will likely be storm
free by Sunday. Temperatures will be near to slightly below normal
for the next seven days.
&&

.UPDATE...
Storms moving through northeast Clark and northwest Mohave Counties
at this time are propagating southward into a 25-30 kt 850-mb jet
oriented mainly along the Colorado River. According to mesoanalysis,
storms are moving into slightly lower instability and increased CIN,
which may lead to a general weakening trend overnight. Nevertheless,
high rainfall rates have been observed with these storms this
evening in a moist (PWs 1.25-1.50 inches -- near-record territory)
atmosphere. Additionally, gusts 40-50 mph have been observed with
the leading outflow. Still seeing occasional development in San
Bernardino and central/southern Mohave County as well, with
mesoanalysis suggesting somewhat higher instability in these areas.
As such, increased PoPs in Clark, eastern San Bernardino, and Mohave
Counties based on these trends through the overnight hours.

High-resolution guidance has not performed particularly well with
the convective evolution of the storms in Clark/Mohave Counties,
especially the farther west propagation. Additionally, the
redevelopment of convection in southwest Utah overnight (as
suggested by "some" HRRR simulations) seems questionable given the
stabilizing effects of previous convection. But with the elongated
vorticity maximum in the midlevels still present from southeast
Nevada across far northern Arizona and southern Utah, cannot rule
this out completely. As such, increased PoPs a bit through the
morning hours as well.

Expecting another fairly active day tomorrow. Flash flood watch
looks good for now.

Will send out another update if conditions change dramatically in
the next couple hours.

.AVIATION...For McCarran...Gusty northeast winds from an outflow
boundary will remain through 07z with gusts over 40 kts before
decreasing with winds remaining northeast around 10-15 kts through
08z. After 08z winds will gradually shift back to the south to
southwest winds speeds around 10 kts. Thunderstorms will again be in
the forecast through Thursday with gusty outflow winds
possible...especially in the late afternoon and evening.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Scattered thunderstorms with gusty winds to 45 kts will
continue through early morning over for mainly Mohave, Clark, and
far eastern San Bernardino Counties. Storms will gradually diminish
late tonight with winds also decreasing. Thunderstorms will again be
in the forecast through Thursday with gusty outflow winds
possible...especially in the late afternoon and evening.
&&

.PREV DISCUSSION...
216 PM PDT WED AUG 3 2016

.SHORT TERM...through Saturday morning.

The primary weather concern over the next couple of days is the
potential for flash flooding. Lincoln, Clark, Mohave and eastern San
Bernardino counties all are prime areas for scattered thunderstorms
that will be capable of producing very heavy rain (2-4 inch per hour
rain rates). High resolution time lagged ensemble output pinpoints
northern Mohave with the best potential for substantial rain amounts
but given that precipitable water values are through the roof over
the southeastern third of the CWA, stronger storms anywhere in this
deeper moisture could create flooding problems real quick. The 12Z
Vegas sounding had a > 200 percent of normal PWAT value of 1.5
inches which is a record for the date. Forecast soundings show
little change for Thursday so it looks like another active day
convection wise similar to today beginning with terrain driven
storms transitioning to outflow based development. A Flash Flood
Watch is in effect through 5 AM Friday for areas that are forecast
to have the highest potential for flash flooding.

Some drying takes place on Friday however the moisture hangs tough
across much of the eastern CWA and a chance of storms continue. A
trough sweeping into the west coast Saturday pushes drier air
further east and thunderstorm chances are forecast to come to an end
for all but far NE Mohave County. No changes were made to the
Saturday forecast or to the long term.

.LONG TERM...Sunday through Tuesday.
Picking up Sunday morning, troughing along the West Coast will bring
dry southwest flow to our CWA, resulting in mostly sunny skies,
seasonably hot temperatures, and lower humidity. This pattern holds
through Tuesday. There is one feature of note on Monday as the ECMWF
brings a tropical wave/cyclone near the tip of the Baja Peninsula,
which would suggest a return of deeper moisture to our area on
Wednesday. The GFS is more bearish with this wave and does not show
any moisture surge. There is plenty of time to watch this, and it is
worth noting that a similar pattern last Thursday brought the
current episode of deeper moisture and thunderstorms.
&&

.FIRE WEATHER...Monsoonal moisture will continue to stream into the
area through Thursday...with chances of storms in southern Nevada,
eastern San Bernardino, and Mohave counties. Very heavy rainfall,
frequent lightning, and gusty winds are possible with these storms.
Conditions will begin to dry out from west to east on Friday, with a
return to seasonably hot and rain-free conditions by Sunday.
Conditions may approach critical fire thresholds this weekend,
especially in the southern Great Basin, where stronger winds are
forecast.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
significant weather according to standard operating procedures.
Spotter activation may be necessary in Lincoln, Clark, Mohave and
San Bernardino counties through tomorrow.
&&

Update:  Shafer
Aviation:  Gorelow
Short Term/Fire Weather...Salmen
Long Term: Morgan

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

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE LAS VEGAS NV
738 PM PDT WED AUG 3 2016

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

0729 PM     FLASH FLOOD      3 NNW NEEDLES           34.89N 114.65W
08/03/2016                   SAN BERNARDINO     CA   LAW ENFORCEMENT

            HIGHWAY PATROL REPORTS ROADWAY FLOODING AT
            DAVID DRIVE AND RIVER DRIVE. APPROXIMATELY
            10 VEHICLES STUCK IN WATER. .

&&

NWS LAS VEGAS NV
IRIS SYSTEM