Area forecast discussion
National Weather Service Las Vegas Nevada
901 PM PDT Monday may 20 2013
Synopsis...a weak ridge of high pressure will result in lighter
winds tonight but a storm dropping into the Pacific northwest by
Tuesday will bring persistent breezy conditions to the region from
middle week into the Holiday weekend. Above normal temperatures are
expected through Wednesday then cooling to a few degrees below
normal on Thursday.
&&
Update...satellite shows an area of high clouds over the eastern
Pacific with leading edge of high clouds approaching the southern
Sierra Nevada this evening. GFS time height shows most concentrated
area of high level moisture passing across the area Tuesday. A
closed upper low will develop over the Pacific northwest
Tuesday...then remain nearly stationary through Thursday. This will
lead to a period of persistent breezy to windy south-southwest winds
for the southern Great Basin and Mojave Desert. A Fire Weather Watch
has already been issued for parts of Mohave County Wednesday with
the potential of a Wind Advisory being needed for the western Mojave
Desert of San Bernardino County as well Wednesday. No update
necessary this evening.
&&
Aviation...for McCarran...southerly wind at 8 kts or less tonight.
Light and variable winds Tuesday morning will give way to
south/southwest winds 12-16 kts with gusts to 25 kts Tuesday
afternoon. Skies will remain mostly clear through this evening with
high clouds becoming broken-overcast around 25 kft later tonight through
Tuesday.
For the rest of southern Nevada...northwest Arizona...and southeast
California...typical downslope/downvalley winds tonight.
South/southwest winds will pick up Tuesday afternoon to 10-20 kts
with gusts 25-30 kts. Mostly clear skies this evening with high
clouds becoming broken-overcast around 25 kft later tonight through Tuesday.
&&
Previous discussion...
254 PM PDT Monday may 20 2013
Short term...shortwave ridging will be over the area tonight with
winds becoming light. Deepening southwest flow develops over the
region Tuesday ahead of a strong area of low pressure that drops
south along the Canadian coastline and into the Pacific northwest.
The low is forecast to remain over the Pacific northwest with shortwave
energy rotating around its base and inland. Winds are expected to be
generally breezy middle to late week but could become enhanced at times
as shortwave energy passes north of the area. Timing of shortwaves
will be key in determining when the strongest wind periods will
be...which currently looks like Wednesday and Thursday afternoons. A
Fire Weather Watch was issued this afternoon in anticipation of
stronger winds over Mohave County Wednesday afternoon.
No precipitation is forecast at this time but a deeper/sharper
shortwave trough could result in more moisture getting further south
and producing showers across the north. Not expected at this time
but not out of the question. Temperatures will be above normal
Tuesday...falling to a few degrees below normal by Thursday.
Long term...Friday through Sunday...models generally in good
agreement with the overall pattern and have not really changed much
from what previous shifts have been looking at. Basically looking at
an upper low persisting over the Pacific northwest with a dry
southwest flow over our forecast area Friday through Sunday. Weak
shortwaves moving through the southwest flow will kick up winds at
times but overall breezy conditions are expected each afternoon.
Temperatures will be pretty close to or just below normal.
&&
Fire weather...a favorable weather pattern is setting up for an
extended period of southwest winds and dry conditions across the
area. Increased winds will first begin in the western Mojave Desert
on Tuesday and then spread area wide Wednesday and Thursday.
Southwest winds of 15 to 25 miles per hour are expected with potential gusts of
35 to 40 miles per hour. A Fire Weather Watch has been issued for the late
Wednesday morning into early Wednesday evening time period.
&&
Vef watches/warnings/advisories...
Nevada...none.
Arizona...Fire Weather Watch from Wednesday morning through Wednesday
evening for azz102.
California...none.
&&
$$
Update...Pierce
previous discussion...Salmen/Harrison
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