Area Forecast Discussion
Issued by NWS Salt Lake City, UT
Issued by NWS Salt Lake City, UT
510 FXUS65 KSLC 101044 AFDSLC Area Forecast Discussion National Weather Service Salt Lake City UT 444 AM MDT Fri May 10 2024 .SYNOPSIS...A low pressure system spinning across Nevada will maintain easterly winds across northern Utah through midday, as well as fuel showers and thunderstorms across the region. This low will move east along the Utah Arizona border Saturday, bringing another round of showers and thunderstorms. Temperatures across the region will trend warmer through the weekend into early next week. && .SHORT TERM (Through 12Z/6AM Sunday)...An elongated mean upper low stretches across central Utah westward into central Nevada early this morning. Along the northern periphery of this circulation, easterly flow has become established across northern Utah/southwest Wyoming, as well as a zone of low level cold advection over areas north of I-80 and east of I-15. This continues to drive downslope winds along the northern Wasatch Front early this morning, where peak winds peaked at 66 mph this far in Farmington. Away from this area, wind have remained muted along the eastern Cache Valley and Box Elder county. The setup remains favorable for winds to continue through at least mid morning, and will leave going headlines as is. The upper circulation is forecast to become consolidated around a circulation across Nevada and drift south through the day today, with a mid level deformation axis extending downstream from southwest to northern Utah. A combination of daytime heating, cold air aloft, and weak forcing associated with this deformation axis will support showers and a few thunderstorms along the terrain this afternoon and early evening, with perhaps more widespread coverage this evening across southwest Utah in closer proximity to the upper low. As this low begins to eject east and slowly traverses the Utah/Arizona border region Saturday, cold air aloft coupled with a wave rotating around the back side of the low will support another round of showers and thunderstorms along the terrain. These storms will spread south with time, moving down drainage across the Grand Staircase region. Given this, have included possible in the Flash Flood Potential outlook mainly for small, fast responding basins. Despite the upper low spinning across the region, temperatures will trend 2-5 degrees warmer both today and again Saturday as the airmass gradually modifies. .LONG TERM (After 12Z/6AM Sunday)...Our main weather story coming up next week will center around warming temperatures! Temperatures will be back to their seasonal normals for the middle of May and even a few degrees above normal. High pressure is expected to be the dominant weather pattern building in from the west by Sunday but it is worth a mention here that while the high is dominant, there remains an exiting low to our east. There may be enough moisture left over to initiate shower/thunderstorm development in eastern Utah Sunday afternoon, a trend particularly favored by the SREF model. If you`re headed out on a boat, or really doing anything recreational, on Sunday, in the Wasatch Back (Strawberry / Jordanelle) or western Uintas it would be good to keep yourself weather aware of the potential for thunderstorms. Our high pressure area begins to shift slightly southward Monday as a shortwave traverses through Idaho. This wave may skirt across the state border and bring an increased chance for rain and thunderstorms during the afternoon. Similar to yesterday, the wave isn`t too impressively strong and confidence of widespread impacts is very low. But it is something to keep watching. We`re not any closer to getting a consensus on the forecast come mid- week. Deterministic GFS and ECMWF runs indicate a fairly potent trough incoming across the Intermountain West and interacting with a cut-off low to our southwest. A cold front passage may accompany said trough with further questions as to what becomes of this trough later in the week. The deterministic GFS incorporates more abundant amounts of moisture associated with the low/trough compared to the deterministic ECMWF and ensemble members in no way show a consensus. There are several members of the GEFS that indicate 0.1 to 0.3 inches of rainfall in the SLC metro with this wave but this again is the forecast model with the higher range of possible QPF amounts. Comparatively, a few members of the ECMWF ensemble indicate a few hundreds of an inch of rainfall but the majority forecast no rain. Surely we`ll get a better model consensus in the coming days. && .AVIATION...KSLC...VFR conditions are forecast today while high based clouds continue. Occasional breezy conditions are possible from the east and southeast through the afternoon. .REST OF UTAH AND SOUTHWEST WYOMING...Breezy easterly winds are forecast across OGD/LGU and EVW this morning with occasional breezes possible through this afternoon. Mid and high based clouds are forecast at these terminals through the afternoon with P6SM allowing for VFR conditions. From HCR southward, isolated shower and thunderstorm development will be possible during the afternoon hours and potentially could impact terminals. Lightning, gusty outflow winds and lowered visibilities are possible. && .FIRE WEATHER...A low pressure system centered over southern Nevada will maintain easterly flow across northern Utah through much of the day today. The result will be a favorable setup for gusty easterly winds through midday, with winds becoming locally strong at times along the eastern benches of the Wasatch Front north of I-80, as well as the Cache Valley. These winds will peak this morning then trend downward through the day. Moisture associated with this low will fuel showers and thunderstorms this afternoon and again Saturday. These storms will initially develop over the higher terrain midday, then spread into the adjacent valleys by mid to late afternoon. The greatest concentration of showers and thunderstorms will come late this afternoon and evening across southwest Utah. This moisture will also keep daytime RH elevated today and again Saturday with excellent overnight recovery. Despite the low overhead, the airmass will gradually warm through Saturday, followed by a more robust warming trend Sunday into Monday. By Monday afternoon temperatures across the region will run nearly 10 degrees above normal. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...Wind Advisory until 10 AM MDT this morning for UTZ103-105-107. High Wind Warning until noon MDT today for UTZ104. WY...None. && $$ Seaman/NDeSmet For more information from NOAA`s National Weather Service visit... http://weather.gov/saltlakecity