Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Las Vegas Nevada
208 PM PST Thu Nov 23 2017
record challenging temperatures continue into the weekend. The
next weather pattern change will come early next week as a storm
system passes across the region bringing increased winds, cooler
temperatures, and chances or rain and snow to the southern Sierra.
Short term...today through Sunday.
Unyielding ridge will weaken slightly through tomorrow as a
shortwave trough passes to the north. This will have little impact
on the weather as temps continue to push to daily record values
and high clouds continue to spill over the ridge. High pressure
builds back northward on Saturday, slowly shifting eastward going
into Sunday as the next storm system begins its approach to the
West Coast. Locally, this will lead to breezy, southerly winds
across the southern Great Basin each afternoon and continued warm
temps. Ridgetop winds across the southern Sierra will increase
Saturday night through early Monday as this system pushes closer.
Winds across the Spring Mountains will follow suit a bit later
increasing Sunday night into early Monday. Confidence is low in
these winds making it down to the lower elevations overnight
Sunday into Monday but will continue to monitor as wind advisories
may be needed. Rain and snow chances will increase across the
southern Sierra late in the day on Sunday and into Sunday night.
Any accumulations will be minimal and limited to the higher elevations.
Long term...Monday through Thursday.
Models continue to agree on the existence of a trough swinging
through the region Monday and Monday night, but not much else, so
confidence in the details is below average and minimal changes
were made to the previous forecast. The GFS remains shallower and
faster and the European model (ecmwf) remains deeper and slower, similar to
previous runs. The upshot will be a period of breezy southwest
winds over much of the desert either Monday if the faster solution
pans out or Monday night if the slower solution does, followed by
a period of strong north winds down the Colorado River valley and
temperatures falling down to a few degrees above late November
normals. There is good agreement on high pressure passing by
Tuesday and Wednesday, suggesting dry weather and temperatures
rising at the higher elevations but perhaps not so much in the
valleys. For Thursday, there are some indications of low pressure
approaching from the Pacific, but little or no agreement on any
details. Will hold off on introducing anything for now and see if
future runs come into better agreement.
Climate...temperatures will be in record territory over the next
couple of days threatening records that have stood strong for decades
in many instances. Below is a table featuring a few locations around
the region and their current records and year set.
Thursday 11/23 Friday 11/24 Sat 11/25 sun 11/26
Las Vegas, Nevada 76 (1995) 81 (1949) 76 (1970) 75 (1997)
Bishop, California 78 (1959) 80 (1949) 78 (1954) 76 (1954)
Barstow, California 82 (1949) 85 (1949) 81 (1959) 81 (1977)
Needles, California 82 (1995) 84 (1949) 83 (1949) 85 (1913)
Kingman, Arizona 82 (1915) 84 (1921) 83 (1921) 84 (1924)
Aviation...for McCarran...light winds following typical diurnal
patterns are expected through Friday with sct- bkn clouds aoa 20
For the rest of southern Nevada, northwest Arizona and southeast
California...generally light winds through Friday with sct-bkn
clouds aoa 20 kft.
Spotter information statement...spotters are encouraged to report
any significant weather or impacts according to Standard operating