Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
200 am PDT Sat Apr 25 2015
Synopsis...cool and unsettled weather is expected today as a strong
trough moves through the area. Showers and thunderstorms can be
expected across the southern Great Basin and Mohave County with
scattered to isolated shower and thunderstorms possible elsewhere.
Very strong winds are anticipated across the western Mojave Desert
creating areas of blowing dust and haze. Improving conditions are
expected Sunday with a warming trend commencing during the workweek.
Short term...through Saturday night.
Vigorous shortwave currently moving through northern California
will be the main player in our weather today bringing areas of high
winds and shower potential. Showers will be on the increase during
the day across the southern Great Basin and especially Lincoln
County where a wetting rain is likely. Some thunderstorm activity
is expected as well as marginal instability will be in place in
combination with strong frontogentic forcing.
Meanwhile across the western Mojave Desert...strong winds will
continue to blow early Saturday before intensifying by mid-morning.
Wind gusts exceeding 60 miles per hour are likely across much of the western
deserts by Saturday afternoon with localized gusts to 70 miles per hour
possible. This magnitude of wind can cause structural damage and
make for dangerous driving and flying conditions in the area due to
strong cross winds and areas of blowing dust. Windy conditions will
extend east across most of San Bernardino County...southern Clark
County...and Mohave County but will be less severe than across the
far western desert.
By late in the afternoon a strong cold front will push south across
the region...some showers and isolated thunderstorms will be
possible as this moves through even across the desert valleys. Best
chance for showers in the Las Vegas Valley will be in the 5pm to
10pm time frame as the cold front pushes through the area.
By late Saturday evening the trough will shift eastward into Arizona
with precipitation becoming limited to Mohave County. Winds across
the western Mojave will gradually ease but gusty conditions may
linger into the early morning hours.
Long term...Sunday morning through Friday.
At the start of the long term period, our deep trough that is
providing the shower chances and windy conditions will be just east
of the Nevada-Utah border and continue to push east. Any showers
would be over extreme eastern Lincoln County and eastern Mohave
County early in the day before dry conditions set in. Expect gusty
north winds of 20-30 miles per hour across much of the area, with higher wind
speeds likely along the Colorado River valley. Will keep an eye on
the potential for a wind headline for the river zones. Breezy north
winds will linger into Monday, yet lighter than Sunday. Strongest
gusts will remain along the Colorado River valley. Sunday afternoon
temperatures will continue to run below normal for this time of
year, then trend near normal for Monday.
Winds will be weaker and trend toward typical diurnal directions
Tuesday and Wednesday as high pressure fully takes control.
Temperatures will also trend much warmer through the week, with
afternoon highs climbing roughly 10 degrees above normal for the
latter half of the week. There remains some difference in strength
and timing, but models continue to indicate a low pressure system
moving through the Pacific northwest /perhaps northern California/
late Thursday through Friday. Some breezy southwest winds are
possible Thursday afternoon and again Friday. Breezy conditions may
last into the weekend, as some weak troughing lingers across the
Great Basin. For now, it appears any moisture with this trough is
extremely limited and should stay north of the forecast area.
Aviation...for McCarran...gusty south winds expected again today
with sustained winds of 15-25kts expected after 15z with gusts as
high as 35 kts. Scattered-broken clouds expected much of the day with a cold
front expected to move through in the late afternoon between 00z-04z
resulting in a wind shift to northwesterly winds of 15 to 20kts
before gradually easing Saturday night. Showers possible at the
airfield between 23z and 04z with ceilings around 8k expected.
Improvement in sky conditions expected after 4z.
For the rest of southern Nevada...northwest Arizona...and southeast
California...unsettled weather expected across the region today with
strong and gusty west-southwest winds expected across the Mojave
Desert eastward into northwest Arizona. Winds of 20 to 30 kts with
gusts to 40 expected with even stronger winds in the kdag area and
far western Mojave Desert where gusts will exceed 50kts. Areas of
blowing dust likely with dangerous Crosswinds on north-south
oriented runways. Further north widespread showers and thunderstorms
likely across the southern Great Basin mainly north of klas through
00z. Showers expand across northwest Arizona and far southern Nevada
after 00z as a cold front moves through and winds shift to the
Spotter information statement...spotters should report according to
Standard operating procedures.
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