Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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596
FXUS65 KSLC 150936
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
336 AM MDT Tue Aug 15 2017

.SYNOPSIS...A cold front will stall across central Utah today. A
second system will cross the area Wednesday afternoon through
Thursday.

&&

.SHORT TERM (THROUGH 12Z THURSDAY)...
Water Vapor Satellite shows a wave lifting northeast over eastern
Idaho as the trough axis enters northwest Utah. The trough remains
baggy across the Southwest CONUS. 400mb-200mb MDCARS wind
observations place a 90kt-125kt northerly jet from the British
Columbia coast to about Reno. GOES/SLC 00Z RAOB/HRRR indicate that
precipitable water values vary from 0.25"-0.45" southern Utah,
0.75"-1.00" across the north.

Maximum period of height falls currently underway, as the
aforementioned Polar Jet dives toward southern California. This
has resulted in the lead wave pivoting out of the area thinning
out earlier showers and storms.

Convective re-development possible along the central Utah boundary
and northeast Utah terrain through evening. The passage of the
mid-level trough will lead to height rises and benign weather
overnight and into early Wednesday.

The next embedded disturbance may allow isolated convection to
once again re-develop Thursday in similar areas.

Enjoy the cooler weather while it lasts!

.LONG TERM (AFTER 12Z THURSDAY)...
Weak ridging is expected to build over the forecast area Thursday
and Friday. A bit of lingering moisture and instability will be
in place, allowing for a bit of afternoon and evening convection
over the higher terrain. However, the overall trend will be toward
drying and warming, with maxes pushing near to a few degrees
above seasonal normals through the first part of the weekend.

The ridge is then expected to flatten on Saturday as a trough moves
across Canada over the top of it. In the GFS, the resultant zonal
flow draws in moisture and shortwave from an ill-defined trough
along the California coast, while the EC initially keeps things
drier. By Sunday both models shift the flow to a more southerly
direction, bringing more moisture northward through day seven. In
the EC, however, this is primarily confined to southeast Utah as
much of the state stays tapped into drier air in the vicinity of the
low. Have gone with a compromise between the wetter GFS and the
drier EC as both have been consistent in their respective camps, but
confidence is a bit lower in the extended than usual.

&&

.AVIATION...
The SLC terminal will see VFR conditions throughout the
day with some scattered clouds. Northerly winds are expected to
become light southeasterly or light and variable for a time
beginning between 12Z and 14Z before returning to the northwest by
18Z. However, there is a 30 percent of northerly winds persisting
through the morning.

&&

.FIRE WEATHER...
ERC values are below the 50th percentile across southern, south
central and eastern Utah. Values are higher, varying from 50th
through 79th percentile across north central and northern Utah.

The stalling cold front which is currently laying across south
central Utah as of this writing should weaken throughout the day.
Cooler and more moist, especially northern and central Utah.
Tomorrow begins a warming and drying trend into the upcoming
weekend.

Isolated to scattered showers and thunderstorms today primarily
across central and northeast Utah, with lower coverage expected
tomorrow. Convection late week will be rather isolated and
primarily along the mountains.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...None.
WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Rogowski
LONG TERM/AVIATION...Traphagan

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php



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