Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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106
FXUS65 KSLC 191632
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
1032 AM MDT Wed Jul 19 2017

.SYNOPSIS...Monsoonal moisture spreading into the forecast area
through tomorrow will increase shower and thunderstorm activity
and bring a potential for heavy rain. Drier air will spread back
into the area from the northwest Friday into Saturday.

&&

.DISCUSSION...Deep moisture is in place over the forecast area
this morning, with widespread PWs in excess of 1.0 inch across
central and southern Utah spreading into northern Utah this
afternoon. Precipitation late this morning is focused along a
shortwave near the NV/AZ border, which is well defined on
satellite imagery. This shortwave will lift northward today across
western Utah, reaching the central part of the state this
afternoon.

Best instability and thus best coverage of convection will
be in association with this shortwave though thick cloud cover may
delay convective initiation. However, given the very moist
airmass, at least scattered coverage is expected for the entire
southern half of the state. Any of these storms will be capable of
producing heavy rain, resulting in an elevated threat of flash
flooding. A flash flood watch remains in effect through this
evening. On the leading edge of the moisture over northern Utah,
storms may be on the drier side and capable of producing gusty and
erratic winds.

The monsoonal moisture will remain in place over much of the
forecast area through tomorrow, though some drier air is progged
to creep into northwest Utah as early as tomorrow afternoon.
With PWs remaining in excess of 1.0 inch across southern and
eastern Utah, the threat for heavy rain will remain. By Friday,
the ridge is expected to flatten as a trough moves over the top of
the ridge. This will shift the flow aloft to a more westerly
direction, allowing drier air to move in through the weekend.

Updated the forecast earlier to adjust POPs and cloud cover for
today. No additional updates planned.

&&

.AVIATION...Southerly winds at the SLC terminal are expected to
shift to the northwest between 19Z and 21Z, but there is a 20
percent chance that prevailing southerly winds will last later
than expected. There is a 30 percent chance that showers in the
vicinity of the terminal will result in periods of gusty and/or
erratic winds this afternoon into this evening.

&&

.FIRE WEATHER...Monsoonal moisture over southern Utah will spread
northward across much of the fire district this afternoon.
Widespread showers and wet thunderstorms will develop over central
and southern Utah today. Locations over northwest and far northern
Utah will be on the northern fringe of this moisture and could see
storms on the dry side that have the potential to produce gusty
outflow winds. The moisture will remain in place across much of
the area Thursday except for a bit of drying across far northwest
Utah during the afternoon. The increased moisture will lead to
cooler temperatures and much higher humidities for much of the
fire district.

More robust drying from the northwest will take place Friday and
Saturday, limiting the bulk of showers and thunderstorms to
southern through east-central Utah. Latest models indicate some
moisture will return to northern Utah for the early part of next
week.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flash Flood Watch through this evening for UTZ010-012>016-
     019>021-517-518.

     Red Flag Warning until 10 PM MDT this evening for UTZ478.

WY...None.
&&

$$

Traphagan

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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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