914 FXUS65 KVEF 141209 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 509 AM PDT Mon Apr 14 2025 .SYNOPSIS...Today through midweek, expect similar temperatures as Sunday. Late-week, a dynamic weather system moves into the region, which will increase chances of precipitation, gusty winds, and will cool off temperatures substantially. && .SHORT TERM...Today and Tuesday. Through the day today, an upper-level low in the southeastern Pacific will continue to strengthen. As it does so, a shortwave will ride counter-clockwise around it, pushing into the Desert Southwest this evening. Moisture content associated with this shortwave is modest, with forecast PWATs between 100 and 140% of normal (normal PWAT this time of year is around 0.30"). Coupled with sub-optimal PWATs for measurable precipitation, forecast HRRR soundings show a pronounced inverted-V signature, indicating very dry low-levels. As such, not expecting widespread measurable precipitation, but this evening between about 7pm and 12am, a swath of sprinkles will push northward through the forecast area. Cannot rule out the occasional bolt of lightning, which would result in locally higher rain rates as well as erratic, gusty winds from its direction, but overall, not expecting impacts aside from a ruined car wash. Otherwise, heights over the region will remain elevated across the Desert Southwest through mid-week, so temperatures will continue to range 7 to 10 degrees above seasonal normals, with widespread "Minor" Heat Risk. .LONG TERM...Wednesday through Sunday. A notable pattern change arrives mid/late week as two systems phase together over our area. On Wednesday, ensemble guidance is in fairly good agreement with a shortwave moving south out of western Canada and a cutoff low moving onshore near Point Conception. As anomalous low-level moisture pools between the two systems, scattered showers and isolated storms are expected to develop across the Great Basin and Sierra on Wednesday. On Thursday and Friday, guidance merges the systems together, forming a single, closed low over the Great Basin and Mojave Desert. With lingering low-level moisture and cold air aloft, precipitation chances continue and spread southward across most of the area. Latest NBM has PoPs ranging anywhere from 30-50%, with the higher probabilities across the southern Great Basin. Thunderstorms will certainly be possible (10-30% chances) with this activity as well. The cold air aloft will also foster lower snow levels, particularly if the low moves directly overhead. This should result in late-season snow accumulations to the Sierra and Spring Mountains, where there is a ~50% chance of 4"+. Outside of the precipitation potential, the other main features of the late-week systems are the gusty winds and cooler temperatures. Winds are expected to be strongest on Wednesday and Thursday as the systems approach and begin to phase. Best chances (40-60%) of wind impacts are across western San Bernardino County, while the rest of the area ranges from 10-30%. As guidance moves the low overhead on Friday, winds weaken. This is also when temperatures will be their coldest. Forecast highs across the area go from 75-90 degrees on Wednesday to 55-75 degrees on Friday, some 10-15 degrees below-normal. Over the weekend, ensemble guidance has the low advancing eastward, pushing out of our area. As a result, precipitation chances wane while temperatures moderate toward seasonal values. && .AVIATION...For Harry Reid...For the 12Z Forecast Package...Light and variable winds early this morning will settle out of the northeast by 16Z, increasing to around 10KT, with continued high clouds streaming over the region. This afternoon, winds will become light and variable until early evening, when a southerly wind shift is expected with winds again increasing to around 10KT with intermittent higher gusts to 15-20KT possible. However, low to moderate confidence in the occurrence of gusts as well as precise timing precludes inclusion in the current TAF. These winds will be coincident with an increase in midlevel clouds as ceilings lower to around 15kft. After 06Z, winds again become light as ceilings gradually improve, with winds settling out of the southeast after daybreak. The only other concern late evening and overnight will be potential for virga in the vicinity of the terminal, which could produce brief degradations in ceilings as well as gusty winds, though the potential for this looks to be very low at this time. For the rest of southern Nevada, northwest Arizona and southeast California...For the 12Z Forecast Package...At KVGT and KHND, northeasterly winds around 5-8KT are expected through this afternoon, gradually shifting to the south- southeast through early evening. After 02-03Z, winds will increase to around 10KT, before becoming light and variable after 08-09Z. At KBIH will see traditional diurnal wind patterns, with northwesterly winds shifting to the south- southeast during the afternoon. Up- valley gusts to around 17KT are expected before winds become light and variable after sunset. Winds at KDAG will also follow diurnal patterns through early afternoon, when winds shift to the east- southeast and become gusty, with gusts to 20-25KT expected. After sunset, winds return to the west with gusts expected to diminish and sustained speeds gradually fall below 10KT by 10Z. For Lower Colorado River Valley terminals, KEED and KIFP will both see intermittently gusty north winds this morning, with gusts to 18-20KT expected. Gusts will briefly diminish as winds become light and variable for a few hours after 18Z, then increasing out of the south- southeast through early evening, remaining southeasterly thereafter. An increase in mid and high level clouds is expected, with ceilings between 10-15kft expected this afternoon into late evening before gradually improving. KVGT, KHND, KEED, and KIFP could see virga and potential erratic and gusty winds during the evening, though confidence is low at this time. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...Soulat LONG TERM...Woods AVIATION...Phillipson For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter