Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
822 PM PST Thursday Jan 29 2015
Synopsis...rain chances will increase tonight and continue through
Friday night...then end from north to south on Saturday as the storm
slowly moves away to the southeast. Dry weather is likely for the
first few days of February with above normal temperatures.
Update...light rain is now being reported across portions of San
Bernardino and Mohave counties this evening including Twentynine
Palms and Kingman. Expect rain to continue to slowly increase in
coverage through Friday morning from southeast to northwest as a
broad upper level low shifts draws moisture into the region. At this
time it looks like rain may be a factor during the morning rush hour
in Las Vegas with rain starting in the 5am-8am time frame. Made some
tweaks to pop/qpf/sky grids into Friday based on the latest
observations and short term guidance. Will continue to monitor and
further updates may be necessary.
207 PM PST Thursday Jan 29 2015
Short term...through Saturday night...forecast is still on track
with minimal changes from previous shifts. Precipitation chances will
increase over Mohave County and the Colorado River area overnight
and then spread across most of the County Warning Area Friday and Friday night as
low pressure moves from the Baja California into Southern California and
deepens. High pressure then noses in from the northwest...pushing
the moisture back southeast and ending rain chances from northwest
to southeast on Saturday. Skies should clear in most areas Saturday
night...leading to the possibility of fog Sunday morning in areas
which receive significant rain Friday. The main negative factor for
fog development will be north winds which are expected to increase
as the storm pulls away to the southeast.
Long term...Sunday through Thursday...high pressure will be the
dominant feature during the extended period. There will be a weak
disturbance that will briefly weaken the ridge Monday...but any
impactful weather will remain over Utah. Otherwise...mainly light
winds...occasional high clouds and temperatures a few degrees above
normal will be the main story.
Aviation...for McCarran...ceiling height will drop between midnight
and sunrise...with rain chances increasing rapidly around sunrise.
It appears that the best chance of the lowest ceiling and visibility
will be Friday afternoon into Friday night...with ceilings possibly
under 2000 feet and visibility possibly two miles or less in rain
and fog. Improving ceilings and visibilities are expected on
Saturday...but north to northeast winds could cause runway
configuration issues. There is an outside chance of fog Sunday
morning...but if the wind stays up it will prevent fog formation.
Much better conditions are expected from Sunday Onward.
For the rest of southern Nevada...northwest Arizona...and southeast
California...clouds will lower and thicken beginning tonight...with
rain chances increasing over Mohave County tonight and spreading
across the entire area on Friday. Low ceilings...poor
visibility...and mountain obscurations will all be issues on Friday.
Rain chances will end from north to south Saturday and Saturday
night. Fog will be possible Sunday morning in areas which receive
significant rain on Friday. Otherwise...much better conditions are
expected from Sunday Onward.
Spotter information statement...spotter activation is not expected
at this time. Spotters are encouraged to report any significant rain
or snow...especially on Friday.
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