Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
439 FXUS65 KVEF 121915 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 1215 PM PDT Wed Jun 12 2024 .SYNOPSIS...Slight relief from the heat arrives tomorrow as a weak low pressure moves in from Southern California. Rain showers may develop over northwest Arizona tomorrow afternoon and evening as well. Afterwards, temperatures increase again through Saturday before a broad trough enters the region next week and a more substantial cooldown occurs. && .SHORT TERM...Tonight through Saturday. The Excessive Heat Warning for sections of San Bernardino, Mohave, southern Nye, and Clark Counties including Las Vegas is in effect until 9 PM PDT/MST this evening. Tomorrow, high pressure centered over the Four Corners will be pushed east as a weak upper level low off the Pacific Coast moves into the region. Lowering heights should help decrease temperatures by a few degrees compared to today and lower HeatRisk across the area to to Level 1 (Minor) or Level 2 (Moderate). That being said, highs will still be 5 to 10 degrees above normal for this time of year and will affect those sensitive to heat, especially without adequate hydration or access to cooling. High pressure builds once again on Friday and Saturday, causing a steady rise in temperatures at the surface. Level 3 (Major) HeatRisk returns to certain desert valleys including the Las Vegas Valley on Saturday. Plan ahead and be ready for the heat, especially if spending time outdoors. Current satellite imagery shows a lack of low level moisture associated with the low pressure system off the Pacific Coast. Greater moisture can be seen at the mid and upper levels. Forecast soundings over northwest Arizona on Thursday also display an inverted-V pattern, meaning high based showers and dry air near the surface. This implies that much of the precipitation should evaporate before reaching the ground, and that strong outflow winds may occur with any showers that form. The HREF continues to show a 30 to 50 percent chance of outflows 35 mph or greater. Outside of northwest Arizona, thunderstorms may develop over the Sierra crest where orographic lift and instability provide a favorable setup. Once the low exits the area on Friday, dry conditions are expected across the area through the remainder of the short term. .LONG TERM...Sunday through next Wednesday. Some clarity is starting to show itself in the long range forecast or next week as models try to resolve an upper level trough digging into the region early next week. Models have come into some consensus in the past 24 hours that a deepening trough will dig south into the Southwest US by Monday, though there continues to be uncertainty in exact strength and how far it will dig. Impactful precipitation is not anticipated as the general trajectory on all possible solutions is dry. While there is still a decent temperature spread noted on high temperature possibilities early next week-increasing confidence that Monday and Tuesday will be cooler than what we have been experiencing. There is a 50% chance the high temperature in Las Vegas doesn`t reach 100F Monday through Wednesday next week. Winds will be the other thing to watch. Exact wind impacts will depend on the depth of the incoming low, increasing winds are likely based on many of the long range model camps but how strong they will get will depend on how deep and how far south the trough can get. NBM 1D viewer probabilities for impactful winds gusts have increased to around 40% in areas that are prone to west or southwest winds like Barstow, CA. It`s worth noting- there continues to be some impactful wind gust members on ECMWF Ensemble meteograms. ECMWF EFI plots suggest Monday has the best potential for impactful winds with smatterings of highlighted areas for higher than normal winds. && .AVIATION...For Harry Reid...East to southeast winds early this afternoon are expected to become southerly by 00Z. Wind Speeds will increase to around 10 knots by 20Z, and occasional gusts to 20 knots will be possible through sunset. Winds fall to 8 knots or less overnight and tomorrow morning, but southeast-to-south winds are expected to redevelop again by Thursday afternoon. VFR conditions will prevail through Thursday. For the rest of southern Nevada, northwest Arizona and southeast California...Winds will follow typical diurnal directional trends at all area TAF sites through Thursday. Occasional gusts of 20-25 knots can be expected area-wide this afternoon and early evening, followed by light winds less than 10 knots overnight. Similar wind patterns and speeds are expected tomorrow. VFR conditions will prevail through the period, with only a FEW mid-high clouds along the Sierra expected. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ SHORT TERM...Meltzer LONG TERM...Nickerson AVIATION...Planz For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter