Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Las Vegas Nevada
826 PM PDT Wednesday Sep 2 2015
Synopsis...gusty southwesterly flow will persist across the area
into the weekend. Cooling temperatures along with periods of high
clouds can be expected as a trough deepens over the Pacific
Update...satellite shows two areas of mainly higher level clouds
this evening. One extended from eastern Lincoln County south to
Mohave County and another extended from Pahrump south-southwest
toward Barstow and Yucca Valley. Both of these batches were moving
north. There appears to be some enhancement of the clouds off the
San Bernardino range which may result in the sky grids being a
little underdone but the worded forecast output currently has partly
cloudy which is still reasonable.
Otherwise, winds are starting to slowly decrease across the area.
The forecast looks on track overall and no changes will be made at
Aviation...for McCarran...winds will slowly decrease overnight and
favor a southerly direction generally above 8 kts. Winds appear to
favor a 170-220 degrees true direction component tomorrow with
speeds picking up between 17z and 20z. Gusts over 25 kts are
possible in the afternoon and early evening. Gusty south to
southwesterly winds will prevail for through Saturday along with
variable clouds at or above 25k feet.
For the rest of southern Nevada...northwest Arizona...and southeast
California...southerly winds with afternoon and evening gusts of 20-
30 kts are expected through Saturday. Variable amounts of clouds at or above
issued at 309 PM PDT Wednesday Sep 2 2015
Short term...through Friday.
Dry southwesterly flow will be the main weather into the weekend. A
shortwave trough rotating through the longwave trough in the
northwest US will yield periodic middle and high level clouds through
the period in addition to gust winds...especially in the afternoon.
Winds will kick up even further Thursday and Friday as the upper
level low digs into northern California...with the strongest winds
expected in the southern Great Basin.
Otherwise a dry forecast in store. While probability of precipitation were left in northern
Mohave County today...removed or reduced inherited probability of precipitation for Thursday
and Friday as models are not bringing any additional moisture as far
west...and lingering moisture should be scoured out with southwest
flow. Temperatures will be cooling to below normal over the weekend
with height falls in response to approaching low. Did not change
temperatures much...still on the cooler side of guidance.
Long term...Saturday through Wednesday.
The long term period begins with generally good agreement among
operation model guidance...as a vigorous upper level low will be in
the process of traversing across the Great Basin and Mojave Desert
Saturday through Sunday. This will yield breezy/gusty conditions
across portions of the area...with a slight chance of a shower or
thunderstorm across far eastern Mohave County Saturday prior to
moisture getting scoured out by drier westerly flow. Otherwise...dry
and mostly sunny conditions are expected.
Like 12z model guidance...00z solutions diverge after
Sunday...therefore overall forecast confidence remains low through
the end of the period. Neither operational model or their associated
ensemble members deviated much from their previous solutions this
evening...giving little to work with in resolving potential features
and resultant weather through middle-next week. Both the GFS and European model (ecmwf)
do show similarities in bringing some moisture back into at least
Mohave County early in the week...though large discrepancies in the
handling of a potential shortwave will keep the overall synoptic
pattern and any resultant weather in question at this time. This
time period will be monitored closely through the end of the week
for any resolution in model guidance.
Fire weather...critical fire weather conditions expected across Nye
and Esmeralda counties through Friday due to the collocation of dry
fuels...low minimum relative humidity values...and winds of 20-25
miles per hour with gusts of 35 to 40 miles per hour. A red flag warning is in effect
through Friday. Critical fire weather may develop across parts of
Inyo County through Thursday afternoon but the duration looks to
remain brief and below criteria. Gusty conditions also expected in
the Spring and Sheep Range but minimum relative humidity values will
stay above 15 percent...but bears watching Thursday and Friday as
drier air filters in.
Spotter information statement...spotters are encouraged to report
any significant weather conditions according to Standard operating
short term/fire weather...Steele
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