Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 221048
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
448 AM MDT FRI JUL 22 2016

.SYNOPSIS...The upper level trough moving east across the northern
Rockies will push a dry cold front through northern Utah tonight.
Much drier air will follow the front and cover the region this
weekend. High pressure aloft will strengthen across the area early
next week.

&&

.SHORT TERM (UNTIL 06Z TUESDAY)...A weak vorticity lobe lifting
northeast across northern Utah spawned scattered high-based
showers and isolated thunderstorms earlier this evening. Much of
this convection has been on a downward trend since midnight...and
should end most areas as the vorticity lobe exits the area early
this morning.

The pattern over the western CONUS is in transition today, with
the upper trough along the PAcific Northwest coast tracking east
across the northern Rockies as the upper ridge gains a west-to-
east orientation across the southern CONUS.

The cold front associated with the northern Rockies trough will
work into northwest Utah later today, then settles into central
Utah by late tonight or early Saturday. Not anticipating any
organized convection along the front until it settles into
central Utah where it will first encounter moisture from the plume
across southern/eastern Utah. Convection that does develop along
the boundary will likely be weak as any dynamic support for deep
lift will be removed well to the north. Still looking at the best
chance of showers/storms to remain in the core of the moisture
plume across the southeast quadrant of the state.

Significantly drier air will spread across all but the four
corners region behind the exiting upper trough this weekend.
The GFS maintains dry conditions heading into early next week as
the upper ridge pins the bulk the moisture well to the south of
the elongated ridge axis.

The 00Z ECMWF does offer a slightly different solution where two
separate high centers form, one over the eastern Pacific and
another over the southern Rockies. This southern Rockies center
would allow some moisture to work back into southern/eastern Utah
early next week. Also, the weak trough along the west coast would
help pump moisture back into region. Have put some mention of
terrain-based convection in the forecast, though suspect the air
mass may still be too stable to support deep convection until
later in the week.

.LONG TERM (AFTER 06Z TUESDAY)...Axis of the mean ridge will
continue to remain south and west of the eastern Great Basin through
the extended period. With this said, flow aloft locally will remain
oriented from the west to northwest and very dry, with deeper
moisture pinned well south along the southern periphery of the high.
Of more note is the potential for an extended heat wave across the
area within a strongly subsident and dry airmass. Current guidance
suggest H7 temps hovering in the +17 to +20 range each day, likely
resulting in the longest/hottest stretch thus far this summer. Can
not rule out several days in a row of triple digit heat once again
across the more populous Wasatch Front, as well as most other lower
elevation valley/basin areas across the area.

&&

.AVIATION...Isolated showers across northern Utah this morning will
continue to allow for a 10 percent chance of gusty and erratic winds
at the KSLC terminal through 16z. Southerly winds will remain
dominant into this afternoon, but a shallow boundary will move
across the terminal this afternoon and is expected to switch winds
to the northwest between 19-21z while providing drier conditions for
the remainder of the day.

&&

.FIRE WEATHER...Advancement of a sharp upper trough tracking
through he PacNW and associated jet downstream will continue to
fire isolated to widely scattered showers across northern Utah this
morning. A shallow front coincident with this trough will aid to
spread significantly drier air into the north beginning this
afternoon, but moisture across central/eastern portions of the
district will maintain a threat for scattered storms this afternoon
into the evening before said drying trend takes form in those areas.
Wetting rain potential will remain modest over the east this
afternoon, but a very low probability exists across the north this
morning.

The southern high pressure will begin to retrograde west for the
weekend allowing a dry west phasing northwesterly flow aloft to
spread across the district. This pattern looks to remain persistent
through much if not all of next week, this promoting a very hot and
dry period.


&&

.SLC Watches/Warnings/Advisories...
UT...None.
WY...None.
&&

$$

Conger/Merrill

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