Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 240938
Area Forecast Discussion
National Weather Service Salt Lake City UT
338 AM MDT SUN JUL 24 2016
.SYNOPSIS...Strengthening high pressure aloft across the region
will generate very warm and generally dry conditions across Utah
throughout the upcoming week.
.SHORT TERM (UNTIL 06Z THURSDAY)...High pressure aloft across the
southern half of the CONUS will gradually strengthen over the
eastern Great Basin during the first half of the week. A warming
trend will ensue with daytime highs reaching into the triple
digits in many locations by the middle of the week.
With the center of the greatest heights near the four corners
region early in the week, lingering moisture over Arizona could
work back into southern Utah beginning late Monday. This modest
increase in moisture will likely produce some terrain-based
convection both Monday and Tuesday afternoons over the southern
and eastern mountains.
By midweek the center of the upper ridge will likely shift toward
the western Great Basin, leaving much of Utah under a dry, stable
and quite warm northwest flow aloft. Suspect by this time even the
terrain-based convection will end with hot temperatures expected
across the entire forecast area.
.LONG TERM (AFTER 06Z THURSDAY)...A dry northwest flow is expected
through Thursday and most of Friday as the ridge centers over
Nevada. By the weekend this ridge shifts east and a more moist
southwest flow develops. Normally a southwest flow would be dry but
some monsoonal moisture is expected to move around the base of the
ridge on Thursday and Friday into southern portions of California
and Nevada, so when the ridge exits the moisture will already be in
place. Early indications are that the onset of this moisture may be
shallow so that dry thunderstorms could be an issue this weekend.
Temperatures are expected to remain above normal through this period.
.FIRE WEATHER...Residual moisture over the southern mountains and
eastern areas will be enough to keep a minimal threat of
thunderstorms across those areas this afternoon. As the flow aloft
backs a little more southerly on Monday there will be a slight
uptick in the moisture across the spine of mountains from southwest
Utah to the Uintas and points farther east. With this increase of
moisture and some better instability we should see a little more
thunderstorm activity, but not much. Further increase of
thunderstorms is expected across this same area Tuesday as a weak
trough encounters this air mass and brings additional instability.
Western valleys are expected to remain dry with low RH values
through this period.
In the wake of the Tuesday weak trough passage the moisture over
southeastern Utah is expected to be displaced south and east by a
dry northwest flow through Thursday. Moisture will again increase as
early as Friday over the extreme southern mountains but more likely
for the weekend as the ridge shifts eastward and a southwesterly
flow develops. Concern here is that the moisture may not be that
deep so that high based thunderstorms are more prevalent than wet
.AVIATION...Light and variable winds at the SLC terminal are expected
to become northwest by 16Z with a slight chance of occurring
earlier. Northwest winds will prevail through about 03-04Z this
evening before shifting back to southeast. Only operational weather
concern today is smoke from nearby Antelope Island Fire reducing
visby to under P6SM but that is only a 5 percent chance.
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