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Office: LKN

FXUS65 KLKN 151011
AFDLKN

Area Forecast Discussion
National Weather Service Elko NV
211 AM PST Fri Dec 15 2017

.SYNOPSIS...Increasing clouds later today, with light snow
showers tonight across mainly northern and east-central NV. A few
flurries linger over eastern NV into Saturday afternoon, then
cool and dry Saturday night into next week. Another storm system
will impact the region next Wednesday with a little more snow.

&&

.SHORT TERM...Today through Sunday. Some cirrus clouds are moving
into northwestern NV early this morning, which will drift
southeastward today. Look for clouds to both thicken and lower
later today as the ridge breaks down with the approaching cold
front. Light snow will begin to move into northwestern Humboldt
County shortly before sunset this afternoon, and gradually drift
southeast across NV this evening and overnight. Latest guidance
has slightly increased the QPF amounts associated with the cold
front. At this time most valley locations across northern NV look
to see a quarter to a half inch of snow tonight, with central NV
valleys locations seeing a trace to a quarter inch of snow. Most
mountain areas should see 1-3 inches of snow with this weak
system. The trough axis exits southeast Saturday afternoon leaving
a cold northerly flow aloft across the region. Expect below
normal temperatures across the region Saturday night and Sunday
afternoon.


.LONG TERM...Northwest flow will be in place at the start of the
long term period and a little energy and moisture will be moving
through this flow Sunday night through Monday night. Most of the
moisture stays to our north but a few showers may occur in very
northeastern Nevada during this period.

The flow will turn more westerly on Tuesday as the next cold
front approaches. Models remain in pretty good sync with this
front. One difference compared to 24 hours ago is that the
models are bringing the system through a bit earlier, beginning
earlier in the morning Wednesday in northwest Nevada and then
moving it across the state on Wednesday, along with a period of
light snow. This looks to be a cold system from the start and some
valleys still looking like they may get an inch or two with this
fast moving system. Some stronger west winds possible staying
ahead of the front on Wednesday, mainly in higher elevations,
though looking sub advisory at this time.


After some leftover snow showers on Wednesday night, a cold
northerly flow will set up for Thursday. Near normal temperatures
at the start of the long term will warm a little above normal by
Tuesday in the westerly flow only to drop back down near normal
with the frontal passage.

&&

.AVIATION...A cold front will approach the region from the
northwest later Friday bringing a band of thicker high and mid-
level cloudiness along with the chance of a few brief snow showers
to KWMC, KEKO, and KELY later Friday night into early Saturday
morning. MVFR CIGS and VIS likely with these showers and possible
very temporary IFR conditions.

&&

.LKN WATCHES/WARNINGS/ADVISORIES...None.

&&

$$

96/90/90



Office: VEF FXUS65 KVEF 150518 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 917 PM PST Thu Dec 14 2017 .SYNOPSIS....Gusty conditions will dwindle this evening with mostly clear skies and lighter winds Friday. Another cold front will move through Saturday bringing wind, clouds, cooler temperatures and even the possibility of brief showers over parts of southern Nevada. && .UPDATE...There is a slight possibility that the dry streak for Las Vegas could be interrupted as early as Saturday. The 00Z GFS, 21Z SREF and even the 12Z ECMWF solution indicate the potential for brief showers over the southern Nevada mountains on Saturday and at least a few sprinkles in the Las Vegas Valley cannot be completely ruled out. A fast moving trough is forecast to dive across southern Nevada and surrounding states Saturday morning through the afternoon before moving across Arizona Saturday night. There are some differences in details among the models, but sufficient moisture, instability and dynamic forcing will be in play to introduce the possibility of some showers over Clark County along with Lincoln. The Pop/WX grids were updated to reflect this trend. -Adair && .PREV DISCUSSION... 224 PM PST Thu Dec 14 2017 .SHORT TERM...Today through Sunday. Gusty north winds will continue through much of the afternoon today before brief shortwave ridging takes over tomorrow. The Wind Advisory and Red Flag Warning for the Colorado River Valley remain in effect until 6PM PST today. Slightly cooler temperatures will filter in tomorrow before the second system moves through on Saturday. Mostly clear conditions can be expected through much of Friday before a thick batch of high clouds will move over the area Friday night which may help in keeping low temperatures warmer on Saturday morning. The mid-range models are now in fairly good agreement on the evolution of the second system briefing splitting across the region this weekend before eventually reforming into an elongated shortwave across the Midwest. Some slight chances for light snow are possible mainly across the Lincoln County panhandle early Saturday morning. The main impact with this system will be gusty north winds Saturday into Sunday in the wake of the surface cold front, with Wind Advisory potential. Though, models have been deviating from run to run and the exact details with this system are still uncertain. The windiest location likely will be, yet again, down the Colorado River Valley. Much cooler temperatures will filter in behind the associated cold front on Saturday, dropping temps to near normal and snow levels to 2000-6000 ft. Partly cloudy skies move through with the frontal passage Saturday with mostly clear skies behind it for Sunday. .LONG TERM...Monday through Thursday. Things will calm and warm Monday and Tuesday as ridging tries to build back in. However, that ridging will build a bit further west over the eastern Pacific instead of the western US. This will keep the door open for additional, deeper waves to ride down the eastern edge of the ridge. Confidence is low in the details right now, but the first of those waves may approach the region next Wednesday, increasing southwesterly flow (and winds) across the area. This system appears to be relatively dry, but could squeeze out a little precipitation over the Sierra/southern Great Basin late next week. Depending on the track and depth of the systems late next week, they could usher in the coldest air of the season, as well as periods of strong winds, and perhaps even some precipitation (again, for the moment things continue to look mostly dry). && .AVIATION...For McCarran...Expect lighter winds on Friday before another front brings gusty northerly winds back to the terminal on Saturday. For the rest of southern Nevada, northwest Arizona and southeast California...The strongest winds will continue to be down the Colorado River Valley with winds stay up overnight around 15 to 20kts. Other than a few high clouds, skies will remain mostly clear tonight. Friday will have lighter winds though some enhancement down the Colorado River Valley is expected with gusts to around 25kts. High clouds will overspread the area by Friday afternoon ahead of the next system moving in from the northwest. && .FIRE WEATHER...North winds will linger through the weekend as yet another frontal system moves across the region Saturday and fire danger will likely be enhanced again down the Colorado River Valley. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM/FIRE...Kryston AVIATION...Wolf LONG TERM...Wolcott For more forecast information...see us on our webpage: http://weather.gov/lasvegas or follow us on Facebook and Twitter
Office: REV FXUS65 KREV 142217 AFDREV Area Forecast Discussion National Weather Service Reno NV 217 PM PST Thu Dec 14 2017 .SYNOPSIS... Temperature inversions and reduced air quality in urban valleys continue through Friday afternoon, with a weak system Friday night increasing surface winds and bringing improved air quality for the weekend. Inversions are likely to strengthen again early next week before a cold front moves through for the middle of next week and breaks the inversions. && .SHORT TERM... Beefed up winds in Sierra Saturday into Sunday morning, otherwise little change to the short term forecast. Temperature inversions continue today and are expected to weaken Friday night and Saturday as a fast-moving shortwave moves through northeast California and western Nevada. Better mixing and increasing northerly low level winds should be enough to allow for increasing air quality going into the weekend. This system has very little moisture associated with it and is forecast to begin shearing/splitting as it moves through central California. The best precipitation chances in early morning simulations are in far northwest and north-central Nevada behind the cold front; however, some late morning simulations indicate a narrow precipitation band moving down to between Pyramid Lake and I-80 in far western Nevada. Dry air ahead of the cold front will help snow levels drop quickly to valley floors, but with the lack of moisture (less than 0.10" of precipitation in most simulations), little (less than 1/2") to no snow accumulation is expected for most areas. Still, be alert if traveling early Saturday as even light snow showers overnight could bring a thin layer of patchy ice as temperatures fall to near or below freezing Saturday morning. One other item of note will be strengthening easterly winds over Sierra ridges for the weekend as high pressure rebuilds into the Great Basin. The depth of the colder air intrusion and strength of winds aloft should be sufficient to bring increased winds on Lake Tahoe by Saturday afternoon, likely lasting into Sunday morning. The winds are likely to cause issues for small craft on the lake, especially for mid-lake and western shores where waves will be highest. -Zach/Snyder .LONG TERM...Monday onward... High pressure returns for early next week resulting in poor mixing and ventilation again for Monday and Tuesday. Haze may once again form mainly near population centers as well. Simulations continue to show a strong cold front moving southward through the area Wednesday with some much colder air spreading into the Sierra and western Nevada. Low chances for showers remain for Wednesday along this front. The storm doesn't have a significant moisture tap, but it will require monitoring since it will be so cold. The very cold nature of the storm may result in snow even down to valley floors. The air behind this front will be some of the coldest we have seen so far and it could linger into the weekend right ahead of Christmas. Hohmann/Edan && .AVIATION... Mainly VFR with light winds (less than 8-10 kts) for valleys through Friday morning. Valley inversions will remain strong through Friday, resulting in slantwise visibility concerns for lower valleys, especially in the Reno/Sparks, Carson City, and Minden areas. Increased northerly winds Friday night and Saturday may allow some of the haze to clear out, at least for a day or two. -Edan/Hohmann && .REV Watches/Warnings/Advisories... NV...None. CA...None. && $$ For more information from the National Weather Service visit... http://weather.gov/reno