Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 250446

Area Forecast Discussion
National Weather Service Salt Lake City UT
1046 PM MDT Wed May 24 2017

.SYNOPSIS...A cold front will sag south across northern Utah
later tonight, then stall over central Utah Thursday. The next
upper trough will move across the area Friday maintaining
unsettled conditions into the first half of the holiday weekend.


.SHORT TERM (Rest of tonight through Thursday)...The afternoon and
early evening convection has weakened considerably the past
hour with lingering light showers and a few thunderstorms all that
left late this evening. Inverted-V soundings from late this
afternoon brought very strong microburst winds with many of the
convective elements earlier this evening. The air mass across the
north has changed over fairly quickly to a more moist profile as
evidenced by heavy rain from the mid-evening convection across far
northern Utah/southwest Wyoming.

The anticipated cold front is becoming much better defined as
convection is lining up and filling in across northern Nevada,
extreme northwest Utah and eastern Idaho. This front will move
south into a still quite moist air mass later tonight. Good
dynamic lift from the next vorticity lobe rotating around the
northern Rockies upper low, a tight low-level thermal gradient and
favorable moisture should maintain convection as the front sweep
south overnight.

The frontal boundary will likely weaken as it heading into central
Utah Thursday. The moisture profile will still be quite
favorable, but with the vorticity lobe lifting off to the
northeast and separating from the low level thermal boundary would
think that convection will weaken during the morning through
early afternoon hours. The next vorticity lobe will catch up with
the remnant of the low level baroclinic zone and possibly fire up
additional convection across central and southern Utah beginning
late in the afternoon.

.PREVIOUS SHORT TERM (Thursday night through 12z Saturday)...
The northern Rockies trough will continue to spin up Thursday
night through Friday, with another short wave lobe dropping into
the area from the northwest Friday. Baroclinicity will once again
tighten over the area, and coupled with modest upper forcing and
diurnal trends do expect scattered convection to develop across
the northern half of the area once again. Made minimal changes to
PoPs as forecast trends remain on track.

.LONG TERM (After 12z Saturday)...A mid level ridge is forecast to
be the dominant weather feature through the majority of the forecast
period. Initially this ridge will remain centered west of the
forecast area along the west coast, as the last in a series of
shortwave troughs exits the forecast area during the day Saturday.
After this time, as the ridge axis slowly builds eastward, expect a
warming trend through the latter half of the weekend into the middle
part of next week. Lingering moisture will provide a small chance of
afternoon and evening convection primarily along the terrain east of
I-15. The long range models diverge a bit during the
Wednesday/Thursday timeframe, with the GFS breaking down the
ridge, while the EC holds onto a stronger ridging solution over
the Great Basin. As such have held off on making any significant
changes to the latter portion of the forecast period.


.AVIATION...Earlier strong convection has exited the area, with
linger showers at the terminal overnight into early Thursday. An
outflow boundary from earlier storms will sweep south along the
Wasatch Front, crossing the terminal and increasing north winds
before midnight.

A cold front extending across northern Nevada through extreme
northwest Utah will move south across northern Utah overnight.
Convection will fire up along this boundary with increasing
showers and thunderstorms later tonight. Suspect that the bulk of
the heavier showers and isolated thunderstorms will remain north
and west of the terminal through early Thursday. Any impact from
these showers and storms will likely be with the magnitude and
direction of winds at the terminal.





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