Flash Flood Watch 2, NWS Las Vegas, NV

978 
WGUS65 KVEF 011729
FFAVEF

URGENT - IMMEDIATE BROADCAST REQUESTED
FLOOD WATCH
NATIONAL WEATHER SERVICE LAS VEGAS NV
1029 AM PDT MON AUG 1 2016

...FLASH FLOOD WATCH FOR MOHAVE...LINCOLN...AND NORTHEAST
CLARK COUNTIES THROUGH TONIGHT...

.A VERY MOIST AND UNSTABLE AIRMASS WILL PROVIDE FAVORABLE
CONDITIONS FOR THUNDERSTORMS WHICH MAY PRODUCE VERY HEAVY
RAINFALL AND FLASH FLOODING. THUNDERSTORMS EARLY THIS MORNING
HAVE PRODUCED SIGNIFICANT RAINFALL IN EXCESS OF 2 INCHES PER
HOUR... AND SIMILAR RAINFALL RATES ARE EXPECTED THIS AFTERNOON AND
OVERNIGHT. 

NVZ015-016-021-021200-
/O.EXA.KVEF.FF.A.0002.000000T0000Z-160802T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
LINCOLN COUNTY-NORTHEAST CLARK COUNTY-
LAKE MEAD NATIONAL RECREATION AREA-
1029 AM PDT MON AUG 1 2016

...FLASH FLOOD WATCH IN EFFECT THROUGH LATE TONIGHT...

THE NATIONAL WEATHER SERVICE IN LAS VEGAS HAS EXPANDED THE FLASH
FLOOD WATCH TO INCLUDE PORTIONS OF SOUTH CENTRAL NEVADA AND SOUTHERN
NEVADA...INCLUDING THE FOLLOWING AREAS...IN SOUTH CENTRAL
NEVADA...LINCOLN COUNTY. IN SOUTHERN NEVADA...LAKE MEAD NATIONAL
RECREATION AREA AND NORTHEAST CLARK COUNTY.

* THROUGH 5 AM TUESDAY.

* THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY ACROSS LINCOLN COUNTY
  AND WILL BE CAPABLE OF TORRENTIAL RAINFALL AND FLASH FLOODING. A
  CLUSTER OF STORMS IS EXPECTED TO MOVE ACROSS LINCOLN AND NORTHEAST
  CLARK COUNTY THIS EVENING AND OVERNIGHT.

* IMPACTS...RAPIDLY FLOWING WATER ALONG WITH MUD AND ROCKS COULD
  IMPACT AREA ROADWAYS AND LOW LYING AREAS. SOME ROADS MAY BECOME
  IMPASSABLE AND OR DAMAGED BY FLOODWATER. RAPID RISES IN LOCAL
  WASHES AND DRAINAGES ARE LIKELY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.

YOU SHOULD MONITOR LATER FORECASTS AND BE PREPARED TO TAKE ACTION
SHOULD FLASH FLOOD WARNINGS BE ISSUED.

&&

$$

AZZ001>003-036-021200-
/O.CON.KVEF.FF.A.0002.000000T0000Z-160802T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NORTHWEST PLATEAU-LAKE HAVASU AND FORT MOHAVE-NORTHWEST DESERTS-
LAKE MEAD NATIONAL RECREATION AREA-
1029 AM MST MON AUG 1 2016

...FLASH FLOOD WATCH REMAINS IN EFFECT THROUGH LATE TONIGHT...

THE FLASH FLOOD WATCH CONTINUES FOR

* MOHAVE COUNTY

* THROUGH 5 AM TUESDAY

* THUNDERSTORMS ARE EXPECTED TO DEVELOP TODAY ACROSS MOHAVE COUNTY
  AND WILL BE CAPABLE OF TORRENTIAL RAINFALL AND FLASH
  FLOODING...ESPECIALLY AS THEY ORGANIZE INTO LARGER CLUSTERS DURING
  THE EVENING AND OVERNIGHT HOURS.

* IMPACTS...RAPIDLY FLOWING WATER ALONG WITH MUD AND ROCKS COULD
  IMPACT AREA ROADWAYS AND LOW LYING AREAS. SOME ROADS MAY BECOME
  IMPASSABLE AND OR DAMAGED BY FLOODWATER. RAPID RISES IN LOCAL
  WASHES AND DRAINAGES ARE LIKELY.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A FLASH FLOOD WATCH MEANS THAT CONDITIONS MAY DEVELOP THAT LEAD
TO FLASH FLOODING. FLASH FLOODING IS A VERY DANGEROUS SITUATION.
MONITOR FORECASTS AND BE PREPARED TO TAKE ACTION SHOULD FLASH FLOOD
WARNINGS BE ISSUED.

&&

$$

WOLCOTT

089 
WGUS65 KVEF 021153
FFAVEF

FLOOD WATCH
NATIONAL WEATHER SERVICE LAS VEGAS NV
453 AM PDT TUE AUG 2 2016

...FLASH FLOOD WATCH FOR PORTIONS OF SOUTHEAST NEVADA AND NORTHWEST
ARIZONA WILL BE ALLOWED TO EXPIRE...

AZZ001>003-036-NVZ015-016-021-021300-
/O.EXP.KVEF.FF.A.0002.000000T0000Z-160802T1200Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
NORTHWEST PLATEAU-LAKE HAVASU AND FORT MOHAVE-NORTHWEST DESERTS-
LAKE MEAD NATIONAL RECREATION AREA-LINCOLN COUNTY-
NORTHEAST CLARK COUNTY-
453 AM PDT TUE AUG 2 2016 /453 AM MST TUE AUG 2 2016/

...FLASH FLOOD WATCH WILL EXPIRE AT 5 AM PDT /5 AM MST/ EARLY
THIS MORNING...

THE FLASH FLOOD WATCH FOR PORTIONS OF NORTHWEST ARIZONA AND
SOUTHEAST NEVADA WILL EXPIRE AT 5 AM PDT /5 AM MST/. THOUGH
SCATTERED SHOWERS AND STORMS CONTINUE IN FAR SOUTHERN MOHAVE
COUNTY...THE THREAT OF EXCESSIVE RAINFALL HAS ENDED ACROSS THE WATCH
AREA EARLY THIS MORNING. THUS THE FLASH FLOOD WATCH WILL BE ALLOWED
TO EXPIRE.

$$

CMS

Area Forecast Discussion
National Weather Service Las Vegas NV
942 PM PDT SUN JUL 31 2016

.SYNOPSIS...Scattered showers and thunderstorms are expected
through the upcoming week...especially over the eastern half of the
area through mid week then mainly Mohave County late in the week.
The western portions of the area will be increasingly dry as the
wears on. Temperatures will remain near or slightly below seasonal
normals.
&&

.UPDATE...Made some tweaks to the 11 pm - 5 am POP grids based on
accelerated outflow boundary pushing south through Lake Mead Natl
Recreation Area and Mohave County.
&&

.PREV UPDATE...628 PM PDT SUN JUL 31 2016
.UPDATE...Last few runs of the HRRR showing more consistency with
current storms over Lincoln County and southwest Utah shifting
southeast the rest of this evening and impacting northeast Clark and
northern Mohave County into the early morning hours of Monday. There
is the potential of development along outflows as far west as Las
Vegas and the Spring Mountains. Therefore increased POPs in the
aforementioned areas.
&&

.AVIATION...For McCarran...Afternoon round of thunderstorms has
dissipated and expect a southeast wind around 10 kts this evening.
Mormon Mesa and Peach Spring corridors most likely impacted by
thunderstorms into the early morning hours of Monday. Lower
confidence in the forecast between 06z-10z tonight. During that time
there is the potential for gusty outflow winds from the northeast
with a thunderstorms possibly developing. Forecast will be updated
as conditions develop and become more certain. Otherwise, skies are
expected to be partly to mostly cloudy with cloud bases generally
above 10kft.

For the rest of southern Nevada...northwest Arizona...and southeast
California...Strongest thunderstorms expected across
Lincoln, northeast Clark and northern Mohave County tonight.
Otherwise...south-southeast winds expected with gusts to 20 knots.
Sct clouds at or above 10k feet with convective turbulence near
thunderstorms.
&&

.PREV DISCUSSION...245 PM PDT SUN JUL 31 2016
.SHORT TERM...Through Wednesday night.

The 19Z (latest available) HRRR forecasts storms developing this
evening in Lincoln, NE Clark and northern Mohave counties and
essentially combining and moving south through Mohave County
overnight. Previous runs showed this to some extent but also had
storms moving into southern Mohave County this evening from
convection over central Arizona. If the storm track/intensity
forecast is correct for the activity moving north to south, much of
Lake Mead and points throughout Mohave County could see intense
rainfall. Will need to monitor future model runs to see if this
becomes a trend or just one of the various iterations of storm
formation and track visualized by the HRRR.

Tomorrow, forecasted moisture is down and instability is much weaker
although sufficient for more isolated to scattered thunderstorm
coverage from Lincoln County down through portions of Clark County
and in Mohave County. A few could form over the Sierra as well. The
forecast for Tuesday could be interesting...or much of the same
depending on the model. The GFS brings an easterly wave to southern
Mohave County Tuesday afternoon and this is supported by the ECMWF
which gens up a closed circulation over the Phoenix area within the
easterly wave. This is consistent with the previous nights model
solutions...only a little sooner. The NAM now reaches out to this
far in the forecast and does not show this feature...instilling some
doubt in overall forecast confidence. By Wednesday, the forecast
becomes even less distinct as the GFS lifts the wave up through
Mohave County while the ECMWF washes it out and the NAM has an
inverted feature over Mohave County. Bottom line is a low confidence
forecast and broad brushed pops for now as many things could change
between now and then. Temperatures through mid week are forecast to
be near or below normal but could end up being well below normal if
the easterly wave idea pans out.

.LONG TERM...Thursday through Saturday...

In order to blend with neighboring offices a little better, minor
changes were made to the POP forecast in the extended otherwise
little to no change to other parameters. The following is from the
previous discussion.

Biggest feature of interest will be an inverted trough lifting
northward into Arizona late Tuesday through Thursday. This feature
will drive some very rich moisture into Arizona along with
considerable cloud cover. Being that our forecast area is on the
west edge of this, it may enhance our potential by easing the cloud
cover limitations on destabilization that will be more problematic
further east.  The feature will bear watching for the potential of
flash flooding. Otherwise...continued thunderstorm activity through
the week with our eastern areas most favored. Temperatures through
the period will remain near seasonal normals. &&

.FIRE WEATHER...Scattered thunderstorms are possible through the
night with locally heavy rainfall, gusty winds, and lightning.
Most storms are expected to be wet. Temperatures will be near
seasonal normals and with the added monsoon moisture provide an
increase in both afternoon and morning humidity levels. Similar
conditions expected throughout the week.
&&

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

Update...Pierce
Discussion...Salmen

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