Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 300257

Area Forecast Discussion
National Weather Service Salt Lake City UT
857 PM MDT Mon May 29 2017

.SYNOPSIS...Strong high pressure aloft will move slowly east
across Utah through Wednesday. A weak Pacific trough will cross
northern Utah during the latter half of the week.


.DISCUSSION...The high amplitude ridge remains in place over the
western US nwd into wrn Canada this evening. The airmass has
warmed and this sent temps into the 80s in many valleys
including along the Wasatch Front. The warming airmass brought
sufficient instability for isolated high based convection to
develop over the mtns. Rain probably did not make it to the ground
in most spots but a few locations may have had a little. This
convection is dissipating at this time and expect it to be gone
within the next hour or two.

The 700 mb thermal ridge sits nw to se just south of our CWA this
eve. Convection was a little more widespread under this axis
today and is being a little more persistent lingering into the
eve. This axis shifts over swrn UT tomorrow aftn and then squarely
over the CWA on Wed. Expect a corresponding uptick in convective
coverage as a result each aftn. Swly flow also increases Wed and
expect cells to move off the terrain.

This convection will remain high based with a threat of brief
gusty outflow winds increasing as coverage increases.

Will update forecasts to remove the mention of evening pops as
soon as the convection dissipates.


.HYDROLOGY...The increasingly warm temperatures expected across
northern Utah through Wednesday will lead to an accelerated
snowmelt and increased flows on all rivers fed by this increased
runoff. The river of most concern is the Logan River above the
confluence with the Little Bear River. Already elevated flows are
forecast to reach flood stage around midnight Tuesday night and
stay above flood stage through at least the next week. A flood
warning is in effect for this river through Monday June 5, 2017.

The remaining high elevation snowpack still contains significant
water and will likely take a while to run off, even with warm
temperatures. Waterways fed by snowmelt runoff are expected to
remain elevated well into the month of June


.AVIATION...Winds at the KSLC terminal are expected to shift to
southeasterly around 04-05z. There is a 40 percent chance the
wind shift is later, around 05-06z.





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