Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 241017
Area Forecast Discussion
National Weather Service Salt Lake City UT
417 AM MDT Mon Oct 24 2016
.SYNOPSIS...A moisture southwest flow over the Great Basin will
persist into Tuesday. A couple of weather disturbances embedded
within the southwest flow will generate widespread precipitation
across the region through early Tuesday. A gradual warming and
drying trend will begin midweek as high pressure aloft strengthens
across the Great Basin.
.SHORT TERM (Until 00z Friday)...Latest GOES PWAT imagery shows a
broad area .65 to .85 inch values across much of the Great Basin,
with amounts near 1.00 inch over extreme southwest Utah at this
Convective precipitation remains concentrated along the axis of
highest PWATs extending from southern California through far
northern Utah. Seeing some organization in radar returns across
northwest Utah in association with a weak vorticity maxima lifting
northeast through the region. At this point precip remains on the
light side as deep layer instability is lacking and temp/dew
point depressions are still fairly wide outside of far northern
A vorticity lobe rotating northeast across the Pacific Northwest
and western Great Basin later today will continue to pump moisture
across western/northern Utah and nudge somewhat cooler air aloft
into northern Utah this afternoon/evening. Deepening of the
moisture column along with increasing instability will likely
generate stronger convective precip and widespread rain across
much of the area late this afternoon through tonight. Isolated
thunderstorms could come into play late this afternoon and evening
as the entrance region of one jet max creates a broad area of
upper divergence across northern Utah. A second area of
thunderstorms could also form across the south as a second jet max
noses into northwest Arizona/southwest Utah by early this evening.
Light convective precip should linger across northern and eastern
Utah into Tuesday morning, then decrease fairly quickly as heights
begin to rise across the Great Basin in response to the deepening
of the upper trough over the eastern Pacific. The strong upper
ridge that eventually develops over the basin should bring dry
conditions and a warming trend to the forecast area through Thursday.
.LONG TERM (After 00z Friday)...The longwave pattern in place across
the western CONUS continues to amplify under a ridge of high
pressure. Latest global models are trending to further amplify this
ridge with a trough feature now forecast to remain slightly farther
west. In doing so, the short wave feature becomes a cut off low for
a shorter period of time, and looks to take a more northeasterly
path through the Intermountain West into late Friday. Tapping some
subtropical moisture under a deep southwesterly flow, precipitation
chances are not impressive with this faster and more northerly
track, and have trimmed PoPs back a bit.
Temperatures are affected very little across Utah and southwest
Wyoming with this next trough feature, 700hpa temps dip from +7C to
+4c, allowing temperatures to remain seasonable.
Round after round of short wave features rotating around a Low
center in the Gulf of Alaska seem to drop south through next
weekend. Long range models seem to hint at yet another northerly
tracking trough feature for next weekend.
.AVIATION...The SLC terminal will see southerly winds become gusty
around 12-13z, and remain elevated through the TAF period. Passing
showers could bring gusty erratic outflow winds between 14z and 17z.
CIGS will continue to lower through the day, between 12z and 00z, to
around 5000 ft.
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