Area Forecast Discussion
Issued by NWS Las Vegas, NV

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FXUS65 KVEF 250412
AFDVEF

Area Forecast Discussion
National Weather Service Las Vegas NV
820 PM PST Fri Nov 24 2017

.SYNOPSIS...Record warmth will continue into the weekend before a
weather pattern change brings an increase in wind and cooler
temperatures to the region late Sunday into Monday. The system will
bring a chance of rain and high elevation snow to the Sierra and
Southern Great Basin. Cooler conditions will settle in for the
week.
&&

.UPDATE...Tranquil and mild conditions continue this evening with
only substancial cloud cover streaming well to the north of our
forecast region.  Another mild late November night is in store
tonight, with near record temperatures likely again tomorrow and
Sunday. A change is in the offing though, with renewed winds and
cooler temperatures expected by Monday.  The current forecast is in
good shape and no updates are planned this evening.

-Outler-

&&

.SHORT TERM...through Monday night.

High clouds will thin and dissipate overnight with mostly sunny
conditions on Saturday. Winds are expected to remain light and
variable with temperatures warming again to around 15 degrees above
normal Saturday. Sunday we will begin to see the weather pattern
changes we have been talking about as high pressure moves off to the
east and deep layer southwest flow develops over our area. Stronger
winds are forecast to develop but will likely be confined to the
Sierra and northwestern portions of the CWA including Inyo,
Esmeralda and central Nye counties. Precipitation chances should
hold off in the Sierra until later in the day. Most areas will see
one more day of this well above normal warmth before the effects of
an incoming Pacific low are felt late Sunday into Monday.

The aforementioned low will rapidly approach California Sunday and
Sunday night...reaching the California coast by daybreak Monday.
This is potent, progressive low which models take directly over
southern Nevada Monday afternoon/evening. 12Z Model forecasts keep
precipitation mainly over the Sierra and Southern Great Basin
although Vegas could see some sprinkles as the front moves through
in the afternoon. Most of the area will see breezy to windy
conditions develop Monday as a cold front enters the northwest
portion of the CWA and presses southward during the day. Locally
strong winds are possible in some areas and wind hazard products
highlighting the potential are possible as well. The other aspect of
the system will be cooler temperatures. After a prolonged period of
well above normal conditions across the region, Mondays temperatures
are expected to be 10-15 degrees cooler than Sunday.

For now, it looks like the dry streak for Las Vegas will continue
however, models have been trending slower and stronger with the low.

.LONG TERM...Tuesday through Friday. By Tuesday morning, models
agree that the aforementioned storm system will be exiting to the
east, although there are some differences in speed. This will bring
an end to precip chances areawide and also kick up northerly winds,
with the strongest speeds down the Colorado River Valley.
Temperatures will still be a few degrees above normal, although the
breezy winds and the big drop from record highs around Thanksgiving
will make it feel cooler. The next shortwave trough zips into the
Pacific Northwest Tuesday afternoon, and the models start to diverge
rapidly with whether or not to deepen it or even split it with one
piece diving southwest to form a cutoff low off the CA Coast. This
causes significant differences with surface high pressure building
into the Great Basin Wednesday, leading to a highly uncertain wind
forecast, again mainly for the Colorado River Valley. At this time,
suffice it to say that there is potential for a prolonged period of
strong north winds down the river valley Wednesday through Friday,
although confidence is very low. The models differences also lead to
very uncertain temperature forecasts, so made only minimal changes
to the previous forecast. Dry weather looks likely through the
period. If the cutoff low forms, it could help pull moisture into
our area, although that is most likely to occur after Friday.
&&

.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.

               SAT 11/25  SUN 11/26
Las Vegas, NV  76 (1970)  75 (1997)
Bishop, CA     78 (1954)  76 (1954)
Barstow, CA    81 (1959)  81 (1977)
Needles, CA    83 (1949)  85 (1913)
Kingman, AZ    83 (1921)  84 (1924)
&&

.AVIATION...For McCarran...Light winds following typical diurnal
patterns are expected through Saturday with SCT-BKN clouds AOA 20Kft.

For the rest of southern Nevada, northwest Arizona and southeast
California...Generally light winds through Saturday morning with SCT-
BKN clouds AOA 20Kft.
&&

.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report
any significant weather or impacts according to standard operating
procedures.
&&

$$

Short term...Salmen
Long term/Aviation...Morgan

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