Flash Flood Warning 57, NWS Las Vegas, NV

773 
WGUS75 KVEF 022309
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
409 PM MST TUE AUG 2 2016

AZC015-030100-
/O.CON.KVEF.FF.W.0057.000000T0000Z-160803T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MOHAVE AZ-
409 PM MST TUE AUG 2 2016

...THE FLASH FLOOD WARNING REMAINS IN EFFECT UNTIL 600 PM MST FOR
SOUTH CENTRAL MOHAVE COUNTY...

AT 406 PM MST...DOPPLER RADAR AND AUTOMATED RAIN GAUGES INDICATED
THUNDERSTORMS PRODUCING HEAVY RAIN OVER SOUTHEAST MOHAVE
COUNTY...ALONG AND NEAR U.S. HIGHWAY 93 SOUTH OF INTERSTATE 40.
FLASH FLOODING IS LIKELY IN THE AREA.

SOME LOCATIONS THAT WILL EXPERIENCE FLOODING INCLUDE...
WIKIEUP...
ALAMO LAKE AND BURRO CREEK CAMPGROUND. THIS INCLUDES U.S. HIGHWAY 93
BETWEEN INTERSTATE 40 AND THE MOHAVE COUNTY LINE.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TURN AROUND...DON'T DROWN WHEN ENCOUNTERING FLOODED ROADS. MOST FLOOD
DEATHS OCCUR IN VEHICLES.

&&

LAT...LON 3424 11374 3503 11375 3510 11333 3432 11333
      3429 11336 3431 11354 3423 11360 3421 11370

$$

WOLCOTT

415 
WGUS75 KVEF 030056
FFSVEF

FLASH FLOOD STATEMENT
NATIONAL WEATHER SERVICE LAS VEGAS NV
556 PM MST TUE AUG 2 2016

AZC015-030103-
/O.EXP.KVEF.FF.W.0057.000000T0000Z-160803T0100Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
MOHAVE AZ-
556 PM MST TUE AUG 2 2016

...THE FLASH FLOOD WARNING FOR SOUTH CENTRAL MOHAVE COUNTY WILL
EXPIRE AT 600 PM MST...

THE HEAVY RAIN HAS ENDED OVER THE AREA BETWEEN WIKIEUP AND THE BILL
WILLIAMS RIVER. FLOODING IS NO LONGER EXPECTED TO POSE A THREAT AND
THE FLASH FLOOD WARNING WILL BE ALLOWED TO EXPIRE AT 6 PM MST.


LAT...LON 3424 11374 3503 11375 3510 11333 3432 11333
      3429 11336 3431 11354 3423 11360 3421 11370

$$

Area Forecast Discussion
National Weather Service Las Vegas NV
923 AM PDT TUE AUG 2 2016

.SYNOPSIS...Scattered thunderstorms remain in the forecast for the
rest of the week as monsoonal moisture continues to stream into the
area. Locally heavy rainfall may occur with some of these storms,
especially in Mohave County. A drying trend is forecast for the
weekend into early next week. Temperatures should be near to
slightly below normal for the next seven days.

&&

.UPDATE...Overnight convection ended over the area by 8 am and most
areas should not see anything develop until late this morning or
this afternoon. I lowered sky cover and pops in most areas for the
morning hours. Latest models indicate sufficient moisture and
instability for thunderstorms late today and early this evening over
Esmeralda and northern Inyo Counties and a bit farther west in
Lincoln County so I added mention of thunderstorms in those areas.
&&

.PREV DISCUSSION...
321 AM PDT TUE AUG 2 2016

.DISCUSSION...Through Monday.

Storms are currently propagating southward through Mohave County
with area gauges suggesting the strongest cores are producing nearly
one inch of rainfall as they pass through. The HRRR has done a
reasonably good job simulating this convective evolution overnight,
whereas its depiction of a similar band of convection developing in
the southern Great Basin moving southward into Clark County has not
materialized. Ongoing convection is strongly tied to an elongated
band of midlevel vorticity stretching from SW Utah to SE California.
Operational models suggest this elongated vorticity will pivot to a
more zonal orientation in the next 24 hours while remaining
primarily centered over Mohave and San Bernardino Counties.
Meanwhile, the moisture content of the atmosphere continues to
increase, with 2-inch PWs now nudging their way into southern parts
of the area. Combined with antecedent instability, scattered
convection in eastern parts of the area is a pretty good bet in the
next 24 hours.

However, high-resolution output for today is not particularly
aggressive in developing more organized convection. Instead,
convective initiation will likely commence in the higher terrain of
Clark, San Bernardino, and Mohave Counties again by early afternoon
with outflows being key to developing convection in the adjacent
deserts/valleys. Additionally, high-resolution model output is quite
variable in depicting potentially more active regions/corridors of
convection. A subset of these simulations suggests the potential for
a loosely organized cluster of storms moving into Mohave County from
adjacent southern Utah/north-central AZ, but these depictions are
quite variable run to run. As a result, though Mohave County again
looks like the region at highest risk, the lack of a more consistent
signal of more widespread potentially heavy convective precipitation
does not justify extending the flash flood watch at this time.
Nevertheless, this does not preclude the possibility of flash
flooding there or elsewhere, and subsequent shifts may issue a new
watch if a more consistent signal emerges.

As the week rolls on, the monsoonal moisture gets a shove
northwestward as an upper-level trough moves into the central
Pacific Coast by 00Z Friday. This increases the chances of storms
farther westward into southeast Nevada and southeast California
Wednesday and Thursday. Guidance is trending a little lower with
PoPs on Wednesday and a little higher with PoPs on Thursday, which
makes sense given the increasing influence of the approaching trough
on Thursday as well as some indication of a smaller perturbation
within the southwest flow moving across the area on Thursday (as
seen on the 00Z/06Z NAM). Fine-tuned the PoPs a tad to depict this
trend and to decrease chances a bit more in southwest parts of the
area. Also reduced PoPs a tad overall as I suspect convection will
be a bit more scattered with only some "loose" organization expected
given improved but still somewhat limited upper-level support.

Temperature forecast through Friday is tricky with cloud
cover/variability a big factor in what occurs. Given the low
confidence in the expected convective coverage/evolution the next
few days, was too hesitant to change much from the previous
forecast. Bottom line is temps near or slightly below normal, with a
higher-than-average chance of being "loud wrong".

Models have continued to trend drier for the weekend, with chances
of storms greatly reduced outside of Lincoln and Mohave Counties on
Friday and barely present at all for Mohave County by Saturday. Have
removed PoPs beyond Saturday with this forecast package. Operational
models keep a longwave trough in the West for much of next week,
which is not favorable for precipitation in our area but will at
least inhibit a more substantial warmup. Kept temps near or below
climatology Saturday onward given the expected pattern.
&&

.AVIATION...For McCarran...Another day with chances of storms, at
least in the nearby higher terrain and in the flight corridors. Wind
forecast is tricky with poor model agreement and verification.
Current thinking is that a general east flow should transpire
through much of the day before transitioning to SE or S by late
afternoon. Speeds should generally be 7-12 kts. Outflows may affect
the terminal, especially late this afternoon/evening, with gusts
and erratic directions likely should this happen.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Isolated to scattered storms will develop again today,
especially over the higher terrain of Clark, San Bernardino, and
Mohave Counties. Outflows generated by this convection may affect
area terminals. Otherwise, primarily south winds are expected today
with potential gusts to 20 kts in the Colorado River Valley.
Light/diurnal winds expected this evening/tonight.
&&

.FIRE WEATHER...Scattered thunderstorms are possible today in
Clark, eastern San Bernardino, and Mohave Counties, especially in
the higher terrain. Some storms may produce very heavy rainfall,
frequent cloud-to-ground lightning, and gusty winds. Moisture will
increase considerably Wednesday and Thursday as a disturbance moves
through the area. This will result in increased thunderstorm
activity and widespread cloud cover. Temperatures will hover near to
slightly below normal, with elevated humidity values through the
period.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
significant weather according to standard operating procedures.
Spotter activation may be necessary in Mohave County this
afternoon and tonight.
&&

UPDATE...Harrison
PREV DISCUSSION...Shafer

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