Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
925 FXUS65 KSLC 261002 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 402 AM MDT Wed Jun 26 2024 .SYNOPSIS...Increasing moisture will bring a round of showers and thunderstorms to much of Utah and southwest Wyoming this afternoon and evening, with heavy rain and gusty winds the main threats. Eastern Utah will see additional convective activity on Thursday with drier air moving into western Utah. Dry and increasingly hot conditions will develop over the weekend. && .SHORT TERM (Through 12Z/6AM Friday)...High pressure has shifted east of the area this morning, putting Utah and southwest Wyoming under a southerly flow aloft. This will allow deeper moisture over southern Utah to spread northward across the entire CWA. By the afternoon, anticipating PWs in the 0.8 to 1.0 inch range across much of the area, and higher over southern Utah. Seeing some showers and a few thunderstorms persisting overnight over western Utah due to a weak boundary over west central Utah and some shortwave energy moving across northwest Utah. This convection is expected to dissipate by mid-morning, resulting in a lull. However, will see a good amount of convective development across much of the area this afternoon owing to the increase in moisture. Heavy rain will be the greatest threat over southern Utah, and thus conditions are favorable for flash flooding once again. However, the presence of shortwave energy ejecting from a Pacific Northwest trough will put a bit greater instability over northern Utah. Despite limited shear, storms that develop will be capable of producing gusty winds and hail. The previously mentioned Pacific Northwest trough is expected to graze northern Utah beginning Thursday, shifting the flow aloft to a west to northwest direction that will bring a gradual drying trend. Thus, enough moisture and instability will remain around for another round of afternoon and early evening convection, though it will be more focused over eastern portions of the forecast area. Additionally, the trough will bring a cold front through, bringing maxes back to within 5F of seasonal normals. .LONG TERM (After 12Z/6AM Friday)...Much drier and cooler air will move into the region behind a departing trough. This cooler air will help bring temperatures back closer to normal for Friday. The cooler air will be fleeting, however, as shortwave ridging builds back in over the weekend with a return to above normal temperatures (upper 90s for most valleys with mid 100s across southern Utah). A PNW trough starts to approach by Sunday with southwest flow increasing. This will result in increasing southerly surface winds Saturday-Monday with winds particularly strong on Sunday with widespread gusts 30-40 mph. This will increase the fire weather risk, but guidance has started to introduce a little more moisture compared to previous runs, so RH values are now forecast to stay >10% Sunday afternoon as opposed to single digits that were being forecast in previous runs. As the trough approaches on Monday there will be a slight chance (<20% chance) for some afternoon high based thunderstorms developing. Anything that is able to develop will be capable of producing microbursts given the dry sub cloud layer. A frontal passage associated with the trough will scour out the higher moisture content as drier and cooler air advect into the region. This will bring the temperatures down closer to normal for early next week. Winds aloft will remain elevated as the jet stream stays positioned across the area with a resultant westerly flow. These elevated winds will mix down during the afternoon so expect breezy conditions to continue through most of next week with low relative humidities that will pose a fire weather risk. && .AVIATION...KSLC...VFR conditions will persist for the KSLC terminal through the period. Some light showers moving in from the southwest could bring some mid level clouds and breezy variable winds in the morning. These will transition to afternoon convection that will pose a threat for gusty and erratic winds, lightning, and heavy rain. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail across the airspace. Light rain showers across western Utah will gradually transition east and dissipate. A brief lull in activity will give way to scattered afternoon convection across most of the region. These storms will pose a risk for gusty outflow winds, lightning, and heavy rain. && .FIRE WEATHER...Moisture that has been concentrated over southern Utah will spread northward across the entire state, bringing the threat of afternoon and evening showers and thunderstorms areawide. Some storms could be strong with the potential to produce gusty outflow winds as well as some hail. Locally heavy rainfall will also be possible with storms, particularly over southern Utah. A trough moving in from the Pacific Northwest will bring a drying trend beginning Thursday. However, showers and thunderstorms will continue to be a threat over eastern Utah. The drying trend will continue Friday through the weekend, bringing a threat of critical fire weather conditions due to gusty winds and low relative humidity to southwest Utah on Friday and across the entire state by Sunday. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ SHORT TERM/FIRE WEATHER...Traphagan LONG TERM/AVIATION...Mahan For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity