Scientific Forecaster Discussion
fxus65 kslc 221703
Area forecast discussion
National Weather Service Salt Lake City Utah
1103 am MDT Fri Jun 22 2018
Synopsis...an upper level trough will graze far northern and
eastern portions of the area late Saturday and Saturday night. The
attendant cold front will bring a modest cool down to the area
for Sunday. High pressure aloft will return to the area to begin
the work week.
Discussion...morning water vapor and 500 mb analysis depict building
heights and increasingly stable conditions in wake of the short
wave that grazed the area overnight. Nearly cloud free across the
whole area, not much to note sensibly this morning outside of near
seasonal temps and locally breezy northwesterly winds. The latter
poses local fire weather concerns as described below in the fire
No updates made or planned. Previous discussion follows...
Previous discussion...a new shortwave advancing towards the
britcol/Pacific northwest coast this morning will move inland
later today. From there this feature will turn to the southeast
and strengthen in response to upstream ridging near 130w. The
trajectory of this feature will take the core of the trough across
the northern rockies/northern Great Basin. The southwest extent
of this trough will graze far northern Utah/southwest Wyoming
Saturday night, then exit the area early Sunday.
Fairly strong low-level cold advection along with the dynamic
and thermal support from the trough should overcome the mostly dry
air mass and generate some light precip across far northern and
northeast Utah along with southwest Wyoming. Precip is unlikely
farther south as the mid-level dynamic support and colder air are
too far removed to the north to support sufficient lift for
precip. Temperatures in the wake of this mid-level feature will
likely come in at readings below late June norms across the entire
forecast area Sunday afternoon and night.
A pretty quiet extended period looks to be on tap for next work
week, with high pressure generally dominating over the Desert
Southwest. The ridge builds directly over Utah on Monday, leading
to a significant warming trend compared to Sunday. A trough passes
north of the forecast area on Tuesday, with very little impact
expected across the County Warning Area. A little additional mid- level moisture
could move into the area in the westerly flow, potentially
allowing for isolated mountain-based convection Tuesday afternoon,
but otherwise hot and dry weather dominates.
After the bulk of the trough exits the west, ridging amplifies over
The Four Corners, with continued hot and dry conditions expected for
Wednesday. Southwesterly flow will likely increase Thursday and/or
Friday ahead of the next trough moving into the Pacific northwest,
but agreement starts to break down in the global models by the end
of the week, especially with regards to the north/south track of
Aviation...VFR conditions with northerly winds are expected to
persist through the day at the slc terminal. The winds should shift
to become calm to southeasterly late in the evening between 2-3z and
continue through the night.
Fire weather...a cold front has moved through most of Utah
overnight, leading to a cooler day today, but with a persistent very
dry airmass. In portions of eastern Utah, these low relative
humidity values will combine with gusty northwest winds to create
critical fire weather conditions today.
A warming trend is expected Saturday with increasing southwesterly
winds, ahead of yet another cold front. With the dry airmass still
in place, another day of critical winds and relative humidity values are expected
across southern and eastern Utah on Saturday. The front is expected
to move through northern Utah on Saturday afternoon, then the rest
of the state Saturday evening/night, with windy northwesterlies
expected behind the front. Widely scattered showers and
thunderstorms are also possible across northeast Utah on Saturday
After a cooler day behind the front Sunday, high pressure will
return for the beginning of next work week, with more hot and dry
weather on tap.
Utah...red flag warning from noon to 11 PM MDT Saturday for utz493>498.
Red flag warning until 11 PM MDT Saturday for utz482-484-488-489.
previous discussion/fire weather...Conger/schoening
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