Setting Records

I woke up this morning to signs of rain overnight. Windows had droplets, smell of wet ground, and also the subtle smell of the GSL gases. When I checked yesterday morning, the October 2025 monthly total precipitation was already within the top five wettest Octobers on record, so obviously I wanted to check on where SLC ranked this morning after potentially more rain overnight. As of yesterday's and last night's rainfall (0.83"), Salt Lake City has broken the October monthly record for total precipitation (4.31"). This is a fairly large number for only being halfway through the month. With more liquid on the way today through tomorrow and whatever the remainder of the month bring, I am interested in where SLC will end the month at. 

So how much more precip are we going to get with unsettled weather forecasted the next couple of days? 

Wednesday 10/15/2025

An occluded Pacific system/low located over Nevada will translate north and east through Utah today (Wednesday). Utah sits downstream of the low, with deep and relatively moist southwesterly flow across the state. 

GOES East True Color imagery on 10/15/2025 with 500mb analysis overlaid

The Pacific air mass associated with the system has been highly modified and the stronger baroclinic characteristics of the storm have been somewhat muted. However, a cooler air mass still remains under the center of the low, with an attendant cold front now located over central and southwestern Utah. As the low progresses E-NE through Utah on Wednesday, this cold front will move across the Wasatch front late morning into the afternoon. Cooler air along with precipitation will fill into the state as the cold front moves over. Rainfall will generally be light to moderate for areas, with a few opportunities for heavier showers if clouds part and the sun is able to destabilize things a bit. 

Thursday 

The trough axis (center of the trough) looks to pass over northern Utah sometime overnight Wednesday into Thursday morning. By this point, the main moisture field with be exiting the state but trailing wrap-around moisture and energy will filter in from the W-NW. Cooler mid to upper-level temperatures combined with surface heating will aid in some cold-core shower/thunderstorm development through the day. Most precipitation will be light and scattered. 

ECMWF 00Z 10/15 four-panel forecast for 10/16/2025 @ 12Z: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness;700 mb gph, RH, temp, and winds; 300 mb gph and winds; 500 mb gph, vorticity, and winds

Mid to upper-level winds look to shift NW on Thursday, bringing more favorable conditions for some scattered upslope showers in the mountains. However,  Thursday morning 700 mb temperature drop to -4 to -5C under the core of the low, so the snow line will likely be somewhere near 6500-7000' early Thursday morning before rising to around 7000-7500' by the afternoon. 

ECWMF 00Z 10/15/2025 forecasted 10/16 12Z 700mb temperature

Another few inches of snow for the higher elevations across most of the state. Hard to say exactly how much the Cottonwoods will get due to the fairly disorganized nature and unfavorable conditions for much of the storm. However, most guidance puts down about 3-6" of snow for locations > 8000'.

ECMWF 00Z 10/15/2025 forecasted total precipitation (in) 10/15-10/17/2025 00Z

All said and done SLC is forecasted to get anywhere between 0.5-1" of additional rainfall between Wednesday and Thursday, with the highest accumulations expected along an arc spanning the west to north to east perimeter of the SLV. Much of the central SLV may get shadowed due to the flow direction associated with the storm.  

Beyond 

ECMWF 00Z 10/15 four-panel forecast for 10/19/2025 @ 06Z: (Top left to bottom right) MSLP/precip and 1000-500 mb thickness;700 mb gph, RH, temp, and winds; 300 mb gph and winds; 500 mb gph, vorticity, and winds

Conditions dry out by Friday, but cooler air remains in place across the state, with highs in the upper 50s for the northern valleys. Temperatures moderate each day going into the weekend as a ridge builds over the Great Basin. Next storm looks to impact the state early next week. However, there's plenty of uncertainty about the track and strength, and models have been trending drier and warmer with this storm. So far, I have been enjoying the relative storminess intermixed with periods of nice fall weather. Still hasn't got too cold yet..

KSLC observed and forecasted temperature (F) 10/15-10/22/2025