509 FXUS65 KSLC 132105 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 305 PM MDT Sun Apr 13 2025 .SYNOPSIS...High pressure will bring a warming trend to start the work week, followed by a cooler and unsettled pattern for the latter portion of the week. && .SHORT TERM (Through 12Z/6AM Tuesday)...The Pacific Northwest trough that grazed northern Utah yesterday is now centered over North Dakota. The low that was off the Pacific coast last night has split, with the larger portion having ejected westward and the weaker portion putting diffuse shortwave energy over central Utah. Earlier cloud cover from a deformation axis between the Pacific and Pacific Northwest based features has all but diminished, with the shortwave providing enough instability for some cumulus over portions of eastern Utah but little else. Behind yesterday`s cold front, now weakening over far southern Utah, temperatures are noticeably cooler. Highs are running near seasonal normals over northern portions of the area and up to 5F above climo over southern Utah. With the weakening of the Pacific feature, high pressure will be allowed to build in earnest over the Great Basin to start the work week, allowing temperatures to steadily warm. Highs on Monday will average 5F above seasonal normals over northern Utah and southwest Wyoming and around 10F above normal over southern Utah as skies remain mostly clear with light winds. .LONG TERM (After 12Z/6AM Tuesday)...There is high confidence in a change from ridging in the western U.S. to a more active pattern with precipitation. For Tuesday and Wednesday, southwest Wyoming and Utah will have a low amplitude ridge in place. A closed low will be to the southwest, while a trough will be digging south from western Canada. Temperatures will be around 10-15F warmer than normal each day. Mostly dry conditions will last through Tuesday, but as the aforementioned systems approach, there will be isolated to scattered showers Wednesday. There is lower confidence in details from Thursday through the end of the week. The expectation is that the closed low to the southwest will lift northeast, while a longwave trough will dig southward out of Canada and into the area Thursday. Details with how these systems phase, or if they do, have a big influence the forecast. Ensemble data brings around an 80% probability that the systems phase near southwest Wyoming and Utah, while around 20% of members either keep the low to the southwest or have the longwave trough grazing the area. Within the phasing scenario, which would be the better one for more precipitation locally, there are differences in where that takes place. Around 40% of members phase the systems near the California, Nevada, and Arizona border, while around 40% of members phase them more north and east, closer to the southern Nevada and Utah border. A further southwest phasing would bring less cooling to southwest Wyoming and Utah, but mountain snow would be likely with either rough location those systems phase. The less likely scenario would bring minimal precipitation, with cooler, but less cool conditions than if the longwave trough tracks into the area. && .AVIATION...KSLC...VFR conditions will prevail through the TAF period. Cloud cover will continue dissipating resulting in clear skies for the duration of the period. Gusty north-northwesterlies around 20kts will develop at the terminal soon, dissipating by 02Z. .REST OF UTAH AND SOUTHWEST WYOMING...VFR conditions will prevail across all sites through the TAF period. Gusty winds across our northern sites will continue sporadically out of the north- northwest, subsiding later this evening. Southern sites will also be quite gusty out of the north with KCDC, KBCE, and KSGU subsiding around 02-04z. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...None. WY...None. && $$ SHORT TERM...Traphagan LONG TERM...Wilson AVIATION...Worster For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity