Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 221518
Area Forecast Discussion
National Weather Service Salt Lake City UT
918 AM MDT MON AUG 22 2016
.SYNOPSIS...Moisture will continue to spread northward across
southern and eastern Utah today, then remain in place on Tuesday.
Meanwhile, an upper level disturbance will drift slowly across
the region, allowing drier air to spread over Utah on Wednesday.
.DISCUSSION...Morning water vapor and H5 analysis place a weak
trough axis extending from the 4-corners region west into SoCal,
with a subtle deformation axis extending as far north as central
Utah. Weak waves embedded within this axis exist with the most
notable for local weather concerns/potential over far northern
Arizona/Southwestern Utah attm. A pacific trough over extreme
southern BritCol continues to slowly track east southeast into the
northern Rockies region allowing a near westerly flow to impinge
on far northern Utah.
Deeper moisture continues to advect north this morning with
northern extent tied closely to the aforementioned deformation
axis over central Utah. This said, have noted a net increase in
PWAT areawide with values now exceeding .50 inches on the 12z KSLC
RAOB, whereas values remain near or just over 1.00 inch along the
UT/AZ border. BUFR profiles do support modest destabilization this
afternoon across the south where wetting storms remain forecast,
though timing of initiation may be delayed due to an extensive mid
level cloud deck in place beneath the axis. Any convection in the
north should remain high based and breezy with little rainfall,
and mostly confined south of the Great Salt lake and over the
terrain. Have made no updates to going forecast this morning.
As the pacific trough continues its track through the northern
rockies region tonight through tomorrow, flow aloft will trend
more cyclonic in nature with drier west to northwest trajectories
across the north, but added convergence across central/southern
Utah allowing more focused convection once again there. Though the
storms across the south will carry the potential of brief heavy
rainfall, do not foresee too much flash flood concern outside of a
rogue cell tracking through one of the more flashy drainages both
each afternoon. This drier flow aloft will continue to spread
south Wednesday shunting the deeper moisture largely south and
east of the area, with a notable cool down into the mid week
period. Will address the medium range in the afternoon package.
.AVIATION...VFR conditions are anticipated to prevail at KSLC
through the TAF period, though there is a 10 percent chance for an
isolated shower or thunderstorm in the vicinity of KSLC from 20Z-
24Z. A southeast wind should shift to the northwest toward 20Z,
though there is a 30 percent chance of the switch not taking place
.FIRE WEATHER...Deeper moisture will continue to spread into southern
Utah today aided by a weak disturbance along the Utah/Arizona
border. Scattered showers and thunderstorms will become increasingly
wet today across southern and portions of eastern Utah as a result.
Across northern Utah, this moisture will not nearly be as deep so
expect little more than isolated dry thunderstorms. A drier
northwesterly flow will begin to spread into the area tomorrow. This
will cause the airmass to dry north to south tomorrow through
Wednesday. Moisture looks to return Thursday afternoon and may
linger through the weekend.
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