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Office: LKN

FXUS65 KLKN 160814
AFDLKN

Area Forecast Discussion
National Weather Service Elko NV
114 AM PDT Tue Aug 16 2022

.SYNOPSIS...High pressure continues to provide warm temperatures,
light winds, and a moisture push from the south. Afternoon showers
and thunderstorms are forecasted across central Nevada Tuesday
and Wednesday afternoon, before another disturbance makes its way
in later Wednesday.

&&

.SHORT TERM...Tuesday through Wednesday.

High pressure continues around the area providing light winds,
warm temperatures in the 80s and 90s, while also transporting
moisture north. However, precipitable water values are low enough
where isolated to scattered showers and isolated thunderstorms are
possible across central Nevada, but more probable over western
Nye an SW Lander counties for Tuesday. Further north there may be
enough moisture around to cause cumulus buildups, with a low
probability of am isolated light shower as well. Things will
quite down later Tuesday evening. Lows will be in the 50s and 60s.


Wednesday, conditions start off partly cloudy, before isolated to
scattered showers and isolated thunderstorms are forecasted to
develop across central Nevada. With a continuation in moisture
being transported north, coverage of weather may extend north of
US-50 in the afternoon before an embedded shortwave trough makes
its way onshore from the CA coast. This low pressure will help in
providing isolated to scattered showers further north heading into
the evening. Instability and moisture may remain into the
overnight to provide isolated to scattered showers and
thunderstorms across central Nevada.  Highs are forecasted in the
90s to low 100s with lows in the upper 50s to mid 60s.

.LONG TERM...Wednesday night through next Monday

Summertime upper ridge will continue to drive monsoonal flow
throughout the long term forecast, delivering daily shower and
thunderstorm chances for the Silver State. The upper ridge will
amplify midweek with a large ridge axis trending NW to SE reaching
from the Texas Gulf coast into southern British Columbia. At the
same time models agree in developing a upper level trough off the
California coast, This will once again place the Great basin in a
favorable flow pattern for monsoon moisture to be lifted into the
area as the tandem flow around the ridge and trough will act as a
focusing funnel. Another feature to watch will be a inverted
tropical wave transiting Northern Mexico as this system will also
act to pump moisture northward into the desert southwest. By
Friday the upper trough off CA will push inland over NV/ID and the
tropical wave amplifies slightly over the Gulf of California.
This is when things get interesting, at least for this current
model run. The GFS is hinting with the ECMWF to a lesser extent,
at the two troughs interacting to form a large area of lower
heights that will extend from Eastern Oregon thorough the Great
Basin and into Arizona. If this occurs it will act as a focus for
showers and thunderstorms providing extra lift and organization
into the weekend, as the new week starts large scale pattern will
be fractured as the troughs separate again and the upper ride
weakens and splinters as well leading to a complex flow regime
with height maximums over the inter-mountain west and southern
California and height minimums over Colorado and Baja California
however enough moisture remains over NV for storms and showers to
continue for NV. As for temperatures the signal remains for
stability with highs averaging in the mid 80s to mid 90s, and
overnight lows dropping into the 50s and 60s.

&&

.AVIATION...Thunderstorm chances driven by monsoon moisture,
modest mid level instability, and diurnal heating continue for
Tuesday afternoon and evening at KTPH. Precipitation chances will
see a sharp north to south gradient as drier air has been
filtering in from the north which will leave the remaining
stations dry. However, depending the strength of the moisture push
north, showers may make a run on KWMC in the evening, though
confidence is not high at this time and therefore were not
included in the package.


&&

.FIRE WEATHER...Tuesday isolated showers and thunderstorms are
possible across 424, 427, and 426, and light winds being
forecasted. RH's will be lower in the 10-15 range across the
northern portions of the state, however no thunderstorms are
expected in these areas. Wednesday, similar condtions are expected
with slight recovery in RHs across the above mentioned zones.


&&

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

$$

91/98/98/91



Office: VEF FXUS65 KVEF 160445 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 945 PM PDT Mon Aug 15 2022 .SYNOPSIS...Afternoon thunderstorm chances to persist through the week, bringing the potential for heavy rain and flash flooding. Temperatures remain below-normal due to monsoon moisture and rain chances. && .UPDATE...A relatively narrow line of thunderstorms propagated toward the south-southwest from the Sheep Range into the Spring Mountains between 8 and 9 PM PDT this evening and just brushed the far northwest and west fringes of the Las Vegas Valley. Radar estimates and gage reports indicate 1.0-1.5 inches of rainfall in an hour from lower Kyle Canyon Road into Red Rock Canyon. There is still a possibility of a more direct impact on the metro area before midnight as additional cells were developing over Highway 93 near Coyote Springs and moving southward. Storms could also progress into northeast San Bernardino County and impact I-15 between Baker and Mountain Pass through midnight. Not much was going on elsewhere within the forecast area and the Flash Flood Watch will be allowed to expire at 10 PM MST for Mohave County. -Adair && .PREV DISCUSSION... 1137 AM PDT Mon Aug 15 2022 .SHORT TERM...Today and Tuesday. Morning satellite imagery depicts an MCV positioned over central Mohave County, collocated with abundant cloud cover that stretches up into northeastern Utah. These clouds are expected to erode this afternoon, allowing Mohave and eastern Clark Counties to destabilized, albeit a bit delayed and less than typical. This may temper afternoon storm activity across the county, but with deep moisture and the MCV present, heavy rain and flash flooding remain likely with any storms. As such, a flash flood watch remains in effect for Mohave County through tonight. Elsewhere, where skies are clearer, scattered storms are expected to develop along the higher terrain. Morning CAMs show activity spreading farther west than yesterday, possibly into Death Valley and the Sierra. Given the more isolated coverage outside of Mohave County, the flash flood watches for these areas were allowed to expire, though flash flooding will remain possible with any storm. Think we'll have keep an eye out for a potential northeast event this evening, as the MCV over Mohave County places the I-15 corridor between Vegas and St. George under northeasterly flow. We almost got one last night, and the setup looks more favorable today. Hi- res guidance doesn't seem too keen on this idea, perhaps due to the cloud cover currently in the area. However, these clouds should erode this afternoon and Lincoln County is already clear, so storms should develop and propagate south-southwest. Whether they make it into the Las Vegas Valley remains uncertain, but the potential is there. Heavy rain, flash flooding, and strong winds would be possible should this scenario occur. Tomorrow, activity continues to spread west, with scattered thunderstorms possible across the entire CWA. Latest HREF suggests the greatest coverage will be southeast of I-15, but shows scattered development out into Inyo and Esmeralda Counties. While these areas have gotten a much needed break, they remain very vulnerable to flash flooding and their thunderstorm potential will need to be monitored closely. Otherwise, tomorrow looks to be more of the same, with afternoon thunderstorms and below-normal temperatures. .LONG TERM...Wednesday through the weekend. Synoptic-scale south-southeast flow is expected to persist through the week, keeping moisture and storm chances around. Not seeing much in the way of larger-scale forcing mechanisms in ensemble guidance, so mesoscale features will be key. This means that pinpointing areas of greatest activity is likely going to be a day-by-day process. Nonetheless, heavy rain and flash flooding will continue to be the main hazards. As we head into the weekend, things become a little more interesting as the remnants of a Gulf of Mexico tropical system slide under the ridge and into southern Arizona. Guidance generally keeps this system south and east of our area, but this hinges on the timing of a westerly shortwave and the strength of the ridge. Changes in these details will likely alter the trajectory of tropical remnants/inverted trough. Should the system impact our area, it will bring the potential for widespread heavy rainfall; however, uncertainty remains high at this moment. What is more certain is the continuation of below-normal temperatures with the persistent moisture and rain chances. && .AVIATION...For Harry Reid...Another opportunity for gusty outflow winds this evening due to monsoonal thunderstorms in the vicinity of the LV valley. Quieter conditions after midnight with FEW-SCT clouds around 12-15k feet along with light winds. Similar conditions expected Tuesday with Isolated afternoon thunderstorms and generally easterly winds outside of any thunderstorm influences. For the rest of southern Nevada, northwest Arizona and southeast California...Lesser overall coverage of monsoonal thunderstorms expected across the region today, with the exception of Mohave County where thunderstorm coverage is expected to be more scattered. However, any storms that develop will likely produce outflows and if so, the terminals with the best potential for impacts would be KIFP/KEED as well as KVGT/KHND. Otherwise, generally light winds expected across the region today. Similar conditions are expected Tuesday with scattered afternoon thunderstorms, mainly over the eastern half of the area. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ DISCUSSION...Woods AVIATION...Gorelow For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter
Office: REV FXUS65 KREV 160926 AFDREV Area Forecast Discussion National Weather Service Reno NV 226 AM PDT Tue Aug 16 2022 .SYNOPSIS... A monsoon moisture surge will bring increasing chances for showers and thunderstorms today through Thursday, with the potential for flash flooding, new fire starts, and strong outflow winds. This weekend looks drier with seasonable temperatures. && .DISCUSSION... We're seeing the push of monsoonal moisture moving north northwest on water vapor satellite imagery early this morning; and there is a sharp gradient in surface dewpoints in the observations near and southeast of US-95 and those to the northwest. With deepening SSE flow, we'll continue to see increasing PWATs across the region today, with deeper moisture arriving Wednesday into Thursday as PWAT anomalies push the 150-200% of normal range. Thunderstorm chances today expand near and south of I-80, highest for the eastern Sierra and Mineral/southern Churchill counties (25- 50% chance for a storm at any given location). A few cells may continue north into the Tahoe Basin and north of I-80 along the Sierra Front, per HREF CAMs (10-15% chance). A hybrid of wet and dry thunderstorms are likely along the northern periphery of the moisture, and with DCAPE values exceeding 1000 J/kg due to a hot/dry surface layer, strong outflow winds are likely. This could kick up areas of dust, especially across the west central Nevada basin and range. An anti-cyclonically curved jet will push into the region late Tuesday through Wednesday. This will enhance chances for continued showers and embedded thunderstorms through the night. Lingering cloud cover Wednesday morning may cap deeper convection for a period, however, with the added forcing from the jet along with deep moisture and plenty of surface heating, we'll certainly see storms develop. Wednesday afternoon and evening will bring the greatest risk for heavy raining thunderstorms, bringing an increased threat for flash flooding over burn scars and other flood prone terrain. The one exception will be in northeast California and far northern Nevada where the lower levels of the atmosphere remain rather dry and storm motions begin to increase in the afternoon ahead of an approaching wave. This negatively tilted shortwave lifts through northeast California late Wednesday into Thursday morning keeping chances for nocturnal showers and thunderstorms. The area to watch at this point is northeast CA and far northern Washoe County. Elevated instability is present per model soundings and faster storm motions will result due to the shortwave and associated jet. In addition, the deeper moisture begins to push eastward along the leading edge of the wave. This brings increased chances for nocturnal dry thunderstorms and a Fire Weather Watch is in effect. Please see the fire section below for additional details. Storms will be overall wetter on Thursday with better organization due to increased shear. This could tip the scale toward severe storm chances, but also faster storm motions may limit flood risks outside of areas where storms train. One item to watch is an intrusion of drier air into the mid and upper levels behind the shortwave. This may limit storm development along the Sierra Front with the main activity in the northern Sierra and then across areas near and east of US-95. Conditions begin to dry out for Friday into the weekend, especially Sunday onward as another trough pushes into the PacNW, with drier southwest flow becoming established. Residual moisture could produce isolated thunderstorms Friday and Saturday, mainly near and south of US-50 (15% chance). The southwesterly flow will also bring the return of afternoon zephyr breezes and typical gusts of 20-30 mph from approximately 2 pm through 9 pm over the weekend. -Dawn && .AVIATION... Thunderstorm chances march northward today and especially into Wednesday and Thursday. Terminals have a 15-30% chance to have a storm in the vicinity today, increasing to 25-50% for Wednesday- Thursday. Nocturnal showers and thunderstorms are possible both tonight and again Wednesday night as well. The main aviation threats will be strong and gusty outflow winds in excess of 45 kts, especially along the northern periphery of the moisture, which could bring areas of blowing dust. Localized heavy rain is also on the table, bringing lowering CIGS/VIS and potential terrain obscuration. Smoke from the Red Fire should largely be contained to areas west of the Sierra crest due to the south southeast flow aloft. Density altitude may be a concern midday today with temperatures about 5 degrees above normal. -Dawn && .FIRE WEATHER... *** FIRE WEATHER WATCH remains in place Wednesday and Wednesday night for potential dry lightning across NE California and far NW Nevada. *** * Monsoon moisture will filter back across the eastern Sierra and western Nevada this week which will provide increasing chances for thunderstorms. A few thunderstorms capable of isolated dry lightning strikes will be possible this afternoon across the Sierra and western Nevada along the northern periphery of the moisture push. * However, the main threat appears to be Wednesday afternoon-night across northeast California and far northwest Nevada. These areas will sit at the fringe of the incoming moisture surge which will allow for continued dry low-levels and enough mid-level moisture to trigger fast moving storms. Areas northward of the Tahoe Basin extending into E.Sierra/E.Plumas/Lassen/E.Modoc and far northern Washoe counties will see the best potential for new starts from lightning. * An upper trough moving into the region may maintain thunderstorms through the overnight hours on Wednesday. As such, a Fire Weather Watch will remain in place for these areas for Wednesday afternoon through late Wednesday night due to the threat of dry lightning and potential strong and gusty outflows up to 50 mph. * Farther south across the Tahoe Basin and western Nevada, enough moisture will filter into the region where storms are likely to be wetter overall. Of course, isolated dry strikes are always possible outside of storm cores. By Thursday, storms are expected to transition to predominantly wetter storms; however, storms could be better organized with the potential for strong to severe storms possible, including a threat of hail and localized flash flooding particularly across area burn scars. Fuentes/Dawn && .REV Watches/Warnings/Advisories... NV...Fire Weather Watch from Wednesday afternoon through late Wednesday night NVZ458. CA...Fire Weather Watch from Wednesday afternoon through late Wednesday night CAZ270-271-278. && $$ For more information from the National Weather Service visit... http://weather.gov/reno