textproduct: Salt Lake City

KEY MESSAGES

- Another round of cold temperatures tonight result in freezing concerns across portions of northern UT with freeze warnings currently in effect.

- Record-breaking warmth re-develops tomorrow afternoon through Wednesday.

- High-based showers and thunderstorms look to develop across southern UT Monday afternoon.

- An active pattern develops Wednesday with widespread precipitation possible into the weekend.

DISCUSSION

Another round of freezing overnight temperatures, hopefully the last, looks to develop across portions of northern UT tonight. High pressure overhead with clear skies will set up one more instance of favorable radiational cooling this evening with chances of reaching less than 32F ranging from 40-70% across eastern Box Elder county, extreme southern Tooele Valley, Rush Valley, Utah County (lower chances along the I-15 corridor), and the San Rafael Swell. As such, a freeze warning is in effect for these areas through tomorrow morning. Be sure to protect young / recently planted crops!

Some whiplash may occur tomorrow as afternoon temperatures look to warm quite markedly across the forecast area bringing temperatures roughly 5-10F above average to the majority of the forecast area as transient ridging builds in. Despite the pattern breaking down throughout the forecast period and becoming more active as a result, a warm airmass will still remain over the region keeping afternoon high temperatures 5-10F above average each day through at least Wednesday.

On Monday, a weak shortwave within the southern stream will progress east across southern CA / Baja into the Desert Southwest. Ample mid- upper level moisture advection is expected to occur throughout the morning to afternoon hours, increasing cloud cover across southern UT initially with some upper level clouds potentially developing up to N UT / SW WY. In the afternoon, modest forcing will arrive spurring convective development across southern UT and higher terrain of central UT. Highest PoPs will generally be confined to higher elevation locations as orographics and higher RH will allow rain to reach the ground, though dry thunderstorms appear probable across primarily southern UT in the afternoon hours. While a more robust severe threat is not expected at this time given SBCAPE values ranging from 100-200J/kg and deep layer shear ranging from 20- 30kts at best, inverted-v thermodynamic profiles are evident with unstable lapse rates (700-500mb LR's >8C/km), suggesting a few instances of strong gusts are probable.

Following the passage of the shortwave, a transient upper ridge begins to build over the area and will slide east by Wednesday afternoon. Some mid-level moisture is expected to remain in place Tuesday afternoon yielding terrain driven showers into late Wednesday morning / early afternoon. Most lower elevation locations will remain dry through Wednesday afternoon.

Late Wednesday into early Thursday morning, mid-level moisture returns to the region within a southwesterly diffluence regime ahead of a closed upper low spinning off the CA coastline. Ensemble cluster guidance continues to show a complex solution where various members continue to disagree on where the upper level low will progress over time. The split remains 50/50, similar to the prior forecast cycle as the upper level low that dives down from the Gulf of Alaska continues to muddy the waters with forecast confidence. Cutoff lows are typically difficult to forecast at this range, and the potential phasing of the cutoff low and Gulf of Alaska trough, or lack thereof, does not help guidance resolve a solution any easier. Regardless, measurable precipitation remains expected across the majority of the forecast area as we approach the end of the work week.

REST OF UTAH AND SOUTHWEST WYOMING

VFR conditions will prevail across all terminals through the TAF period along with light, diurnally driven winds.

SLC WATCHES/WARNINGS/ADVISORIES

UT...Freeze Warning until 9 AM MDT Sunday for UTZ102-103-106-121.

WY...None.