411 FXUS65 KVEF 072011 AFDVEFArea Forecast Discussion National Weather Service Las Vegas NV 111 PM PDT Tue Oct 7 2025
.KEY MESSAGES...
* Dry conditions and a warming trend will continue today and Wednesday as high pressure builds across the region.
* Increasing confidence for showers and thunderstorms Thursday through Saturday as moisture from Hurricane Priscilla moves into the Desert Southwest.
* Pockets of very heavy rainfall and localized flooding are possible across parts of Northwest Arizona and Colorado River Valley late Thursday through Saturday.
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.DISCUSSION...through early next week.
Mostly clear skies dominate the region this afternoon as high pressure builds across the Southwest. Northerly breezes persist along the Colorado River Valley thanks to a 1022mb high across the Eastern Great Basin setting up a north to south pressure gradient across the region, which funnels down the Colorado River Valley, but generally light winds exist elsewhere. Meanwhile, temperatures remain seasonable today, before climbing a few degrees above normal for Wednesday under continued sunshine and rising heights.
Changes remain are in store Thursday onward as increasing moisture from Hurricane Priscilla is advected northward ahead of a deepening trough off the West Coast. Increasing cloud cover will spread northward Thursday morning and by Thursday afternoon, precipitable water anomalies of 250-300% of normal or greater will encompass most of the Mojave Desert and southern Great Basin. This deep subtropical moisture will remain in place through Saturday morning before gradually drying out from west to east through Sunday as the trough axis sweeps through.
This highly anomalous moisture advection interacting with the approaching trough and favorable jet dynamics will result in several periods of shower and thunderstorm activity late in the week. Forecast guidance seems to be hinting at an axis of precipitation developing on the western edge of the deeper moisture collocated with the right entrance region of an upper level jet by Thursday evening. This precipitation axis sets up roughly along the I-15 corridor, with additional pockets of precipitation developing across Northwest Arizona and the Colorado River Valley into Friday. What remains somewhat uncertain is how much of the precipitation late this week will be stratiform versus convective, but given the near record precipitatable water values that will be in play, along with synoptic enhancement from the approaching trough, heavier downpours could certainly pose a flood risk. Stay tuned to the forecast as we further hone in on the details and areas of greatest risk for locally heavier rainfall and flash flooding.
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.AVIATION...For Harry Reid...For the 18Z Forecast Package...Light northeast winds will persist into the early evening before turning southwest around sunset. While wind speeds will generally remain below 8 knots, a few gusts to around 15 knots will be possible through 00Z. Light and variable winds will continue overnight before turning southeast tomorrow afternoon. VFR conditions will prevail through tomorrow afternoon under mainly clear skies.
For the rest of southern Nevada, northwest Arizona and southeast California...For the 18Z Forecast Package...Most areas will experience winds of less than 8 knots through today, with the exception of the Colorado River Valley, where north winds gusting to around 20 knots are likely into the early afternoon before diminishing. All areas will see light winds overnight, followed by increasing southeast winds by tomorrow afternoon. VFR conditions will prevail through tomorrow afternoon under mainly clear skies.
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.SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures.
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DISCUSSION...Outler AVIATION...Planz
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NWS VEF Office Area Forecast Discussion