Area Forecast Discussion
Issued by NWS Las Vegas, NV
Issued by NWS Las Vegas, NV
791 FXUS65 KVEF 251722 AFDVEF Area Forecast Discussion National Weather Service Las Vegas NV 1022 AM PDT Tue Jun 25 2024 .SYNOPSIS....Moisture will spread northward today, resulting in scattered showers and thunderstorms through Clark, Lincoln, Inyo, Mohave and San Bernardino counties. By midweek, low pressure will push the moisture eastward, decreasing precipitation chances but increasing winds Thursday and Friday. After a brief dip in temperatures late-week, temperatures will climb again through the weekend into early next week. && .UPDATE...Expecting isolated convection across the forecast area this afternoon, with CAPE values ranging from 500 to 1000 J/kg and PWATs approaching 200% of normal. Best rain makers will form in Mohave and southeastern Lincoln counties as moisture continues to make its way into the low-levels of the atmosphere. Yesterday, storms in eastern Mohave County observed around 1 inch of rainfall. Storms in the higher terrain with little movement could produce similar rain amounts in northeastern Arizona this afternoon. Low- level moisture dwindles further north and west in the forecast area. Thunderstorms are expected once again in Inyo County today, though these are likely to have frequent lightning and strong gusty winds - rather than high rain rates. As mentioned in the previous discussion, storms will favor the higher terrain with the absence of synoptic forcing. No changes were made to the forecast this morning as it looks to be in good shape. && .PREVIOUS DISCUSSION...146 AM PDT Tue Jun 25 2024/ .DISCUSSION...Through the Weekend. Anomalous moisture will continue to push north today. By this afternoon, PWATs will be over 200% of normal across the region, with the axis of highest moisture pooling over San Bernardino, Clark, and Mohave counties where probabilities for over 1.00 inch PWATs is very high (90%+). With moisture spreading further north than yesterday, expecting scattered showers and thunderstorms further north as well, including in the Springs and Sheep Range as well as in Lincoln County. Mohave County will continue to have the highest risk for convection this afternoon as this is where HREF is painting 50%-70% probabilities for surface CAPE over 500 J/Kg and the highest moisture will be available. Also expecting another round of showers and thunderstorms in the White Mountains and Sierra this afternoon that will be fairly similar to what developed yesterday. Precipitation should favor the terrain as there is a lack of a significant forcing trigger and instability remains meager and elevated. Some models hint at an outflow pushing in from central Arizona which could trigger more thunderstorms cover in the valleys in eastern Mohave County this afternoon around 3pm-7pm. The best chance for heavy rain and flash flooding will be in Mohave County, but given the scattered and unorganized nature of the convection this afternoon- the threat should remain isolated. The main threat today will be gusty outflow winds over 40 MPH. The highest risk for this will be in Inyo through the southern Great Basin where downdraft CAPE will be highest and the low levels will remain the driest. Precipitation will diminish after sunset, though isolated showers and thunderstorms could linger through the first part of the night in Lincoln County. On Wednesday, the axis of anomalous moisture will shift east as an incoming shortwave from the Pacific Northwest shoves it out and replaces it with drier air. Afternoon shower and thunderstorm chances will favor Lincoln and Mohave counties as areas further west dry out somewhat. Similar threats are expected Wednesday with isolated flash flooding possible but the main concerns will be lightning and gusty winds. For Thursday and Friday, the upper level trough will continue to dig into the region and knock most of the moisture out and replace it with drier air and cyclonic flow aloft. There is a low chance for isolated showers and thunderstorms in far eastern Mohave County where limited moisture could kick something off on Thursday- however any impacts would be minor to none. By Friday, the area will be dry. As the trough moves in and brings drier conditions, it will also bring breezy southwest winds. The probability for impactful wind gusts over 40 MPH is low (less than 30%) across the region, however with drier air and breezy winds, fire danger will increase. Forecast wind gusts of 20-35 mph on Thursday should yield at least elevated fire danger, particularly in the lower elevations where fuels have cured and afternoon RH values are expected to be around 8-12%. As we head into the weekend, the southern US ridge begins to extend westward into the Desert Southwest. As a result, winds weaken while temperatures rise again. There is some uncertainty in how warm temperatures will be this weekend as models are struggling to resolve how quickly the ridge builds back in and if it will have to fight with another shortwave moving through the Pacific Northwest. However, even with the large temperature spread noted on long range ensembles, based on the monthly temperature data thus far and the latest model guidance, Las Vegas will be hard- pressed to NOT experience its hottest June on record. A little number crunching shows that even if the 5th percentile of high/low temperatures from the NBM verify these last 7 days, we`ll still set the record. At this point, its not a matter of "if" but "by how much" we break the warmest June record. && .AVIATION...Setup looks very similar to past several days. The current southerly wind will continue and eventually weaken by 16Z this morning. From 16Z through about 22Z, the wind direction will probably fluctuate between 130-180 degrees, before shifting more out of 170-210 degrees after 22Z with gusts up to 20 knots this afternoon. Also there is a low, but not zero, chance that a thunderstorm outflow from the south or east may affect the terminal around/or after 03Z this evening. If that does not occur, typical south to southwest winds are expected overnight. For the rest of southern Nevada, northwest Arizona and southeast California...Thunderstorm chances are expected from Inyo and Esmeralda counties eastward through Lincoln County and then south to Mohave County and the mountains of Clark County. The Bishop terminal has the highest probability of being affected by thunderstorms today. The main concerns with storms will be erratic gusty winds, brief heavy rain, along with lower ceilings below 8000 feet occasionally obstructing the terrain. Away from storms, southerly winds gusting 15 to 25 knots are expected. && .SPOTTER INFORMATION STATEMENT...Spotters are encouraged to report any significant weather or impacts according to standard operating procedures. && $$ UPDATE...Soulat DISCUSSION...Nickerson AVIATION...Pierce For more forecast information...see us on our webpage: https://weather.gov/lasvegas or follow us on Facebook and Twitter