Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 232145
Area Forecast Discussion
National Weather Service Salt Lake City UT
345 PM MDT TUE AUG 23 2016
.SYNOPSIS...Moisture will remain in place across southern and
eastern Utah today as an upper level disturbance drifts slowly
across the Utah/Arizona border. A northwest flow will usher in
drier air on Wednesday. Moisture will make a quick return
Thursday and remain in place through the end of the week.
.SHORT TERM (Until 12Z Friday)...Drier and somewhat cooler air is
sliding southward across northern areas of the CWA this afternoon.
This drier northwest flow will push across central and southern
Utah overnight leaving only enough moisture for terrain induced
convection to develop over the southern mountains Wednesday. The
main threat for showers and thunderstorms this evening will be
across southwest and south central Utah where PWs are over 0.90 of
an inch and a 300mb vorticity max is forecast to create some lift.
The trough over the Northern Rockies elongates southwest into the
western Great Basin Thursday and this will allow moisture to seep
northward across the CWA for an increase chance of showers and
thunderstorms Thursday over southern and central Utah.
.LONG TERM (After 12z Friday)...The positively tilted upper trough
continues to push across the region through the day Friday, aiding
the development of showers and thunderstorms across most of the CWA
(except for far northern Utah, where a drier airmass remains in
place). Weak west-northwesterly flow behind this trough on Saturday
should help push this dry air further south, with convective
activity Saturday limited to either the southern half or southern
third of Utah. Temperatures remain relatively cool for Friday-
Saturday, as 700mb temperatures hover around 10C.
After the trough exits the region, a ridge is expected to build over
the Intermountain West late Saturday through Monday, producing a
general drying and warming trend. Temperatures will gradually warm
up to above seasonal averages by the beginning of next week, with
very little thunderstorm activity expected through the first half of
.AVIATION...Modest northwesterly surface winds currently in place at
the KSLC terminal will continue into this evening before returning
to a southeasterly drainage wind between 03-04z. VFR conditions will
be maintained under increasingly clear skies through the valid TAF
.FIRE WEATHER...Another cold front is moving across northern Utah
this afternoon bringing in somewhat drier air across the region
along with gusty winds. The Wasatch Mountains (zone 479) is
currently seeing RFW conditions and should continue to have low RH
and gusty winds through early this evening. Therefore, current RFW
remains in effect through 9pm.
Moisture continues to prevail across central and southern Utah
although drying is beginning to take place across west central
Utah this afternoon. Scattered showers and wet thunderstorms are
expected over the southern mountains and adjacent valleys into
this evening. PW values are near an inch over Dixie and with a 300
mb vorticity max headed across southwest Utah this evening have
boosted pops some to high chance.
In the wake of this vorticity max (disturbance) a drier northwest
flow is expected to push across the fire district Wednesday. Other
than isolated mountain thunderstorms over the southern mountains
Wednesday it should be a more quiet day.
Another shortwave dropping southward in the main trough over the
northern Rockies will move southward and cause the trough to dig
southwest into the western Great Basin Thursday into Saturday which
will turn the flow southwesterly across Utah opening the door for
moisture to seep northward across at least southern and central
Utah and into southern portions of northern Utah. Drier conditions
will follow for Sunday into next week as the flow turns more
UT...Red Flag Warning until 9 PM MDT this evening for UTZ479.
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