Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 201003
Area Forecast Discussion
National Weather Service Salt Lake City UT
403 AM MDT SAT AUG 20 2016
.SYNOPSIS...High pressure will move into the forecast area today,
resulting in a drying trend. Moisture will spread back into much
of the forecast area Sunday into Monday.
.SHORT TERM (Through 00Z Tuesday)...A mid level high is centered
over nrn CA early this morning with a broad trof over the central
CONUS. We are under a dry nwly flow between these features. Cooler
air spread south thru WY overnight and some of this low level
cooling spilled wwd over the mtns and into the Wasatch Front. The
easterly surface gradient peaked several hours ago and is already
relaxing and canyon winds were not much more than the normal
nighttime breezes. However temps look to be a tad cooler across
the north today.
With the drier nwly flow in place, the only threat of convection
today would be isolated weak cells over the srn mtns possibly
drifting south off the terrain late aftn.
On Sunday the moisture that stayed in place to our south over AZ
starts to spread back north into the CWA with an increasing chance
of convection over the south. This trend continues Mon with a threat
of convection pretty much over the whole CWA by Mon aftn.
Precipitable water values rise into the .75 to 1.00 inch range
across the south and isolated pockets of heavy rain are possible.
.LONG TERM (After 06Z Tuesday)...A tale of two troughs will
impact the region into midweek. A Pacific trough moving through
the south Monday night hosts an embedded shortwave feature,
promoting precipitation potential to persist into Tuesday.
Meanwhile a more substantial northern trough will ooze a 700mb
baroclinic zone into the northern CWA on Tuesday, shunting
moisture throughout the region progressively north to south by
midweek. Global models differ a bit on timing and extent of
cooling, with an average 700 mb temperature drop of 5 degree C
across the northern half of the CWA by Wednesday,bringing
afternoon highs a few degrees below norms for this area.
A pursuant zonal flow will allow a series of shortwaves to slide
through the south, keeping convective potential alive primarily
over the high terrain of Utah`s lower tier into the end of the
work week.Temperatures by this time should rebound to seasonal
norms in the north, while remaining a few degrees below norms in
the south due largely to persistent cloud cover.
.AVIATION...Light winds should become primarily southeast at the KSLC
terminal by 11z. Winds are expected to switch to the northwest
between 17z and 18z, with a slight chance that the switch occurs as
early as 16Z. VFR conditions will prevail through the TAF period.
.FIRE WEATHER...A dry northwest flow is over the district today
and any buildups will be limited to the southern mountains and
will be quite isolated. These could drift south off the mountains
late afternoon and early eve. Moisture will start to move back
into southern Utah Sunday with an increasing chance of afternoon
and evening thunderstorms over the southern mountains and isolated
storms northward into the Uintas. The moisture will spread north
on Monday with scattered showers and thunderstorms over the
southern half of the district and all the mountains...and more
isolated coverage over the northern valleys. Rh will come up
Monday as well. A system passing to the north will start to dry
the far north on Tuesday while scattered showers and thunderstorms
continue over the remainder of the area. This drying spreads
across most of the district on Wednesday.
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