Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
411 PM MDT Sat Oct 25 2014
Synopsis...a cold front approaching Utah will generate strong
southerly winds through this evening. The front will cross the state
late tonight through Sunday ushering in a colder airmass.
Short term (through 00z wednesday)...south winds have picked up
this afternoon ahead of the approaching trough over the West Coast.
The most notable winds are currently gusting into the 35-45mph range
over the western valleys of Utah. These winds will continue through
late this evening. With excellent mixing provided by said
winds...temperatures have soared well above normal once again across
the entire area...with the Salt Lake Airport already reaching a new
record maximum for the day.
Big change in temperatures will come as the upstream trough pushes a
cold front into the area. This front is expected to cross northern
Utah late tonight and push through central and southern Utah
tomorrow. Expect maximum temperatures tomorrow to plummet close to 20
degrees from todays values across northern Utah...with a 5 to 10
degree drop across the south.
A few showers will be associated with the frontal passage across the
north tonight. However...models have continued to trend less
enthusiastic regarding measurable precipitation along the
boundary...and this does not seem unreasonable given the shallow
nature of the initial front and the lack of moisture both in place
and upstream. Have trended downward on overnight probability of precipitation as a result.
Upper support will be a bit better during the day tomorrow as colder
air spreads into the area. However...with the trough losing
amplitude as it crosses the Great Basin...most of this support will
just graze northern Utah. Best chance of precipitation will remain
across the northern mountains and along the Idaho border...but
models have trended weaker with this as well. As it looks
now...storm total precipitation should be relatively light.
However...with the cold airmass...snow levels are still expected to
lower to around 6500-7000ft during the day tomorrow and bottom out
near 5500-6500ft towards the tail end of the storm tomorrow night.
Temperatures aloft are set to reach a minimum tomorrow night...but
clouds in place should keep lows at the surface above freezing across
many of the valley areas. Expect afternoon maxes on Monday to fall a
few more degrees from sundays values as stable airmass underneath a
building ridge will trap some of the cold air in place. A weak
disturbance Monday evening looks to bring some clouds to the
area...and depending on how quickly skies clear out behind this
wave...the coldest valley temperatures could occur Monday night with
a potential for a hard freeze in some of the normally colder
Long term (after 00z wednesday)...global models continue to trend
towards an amplifying pattern beginning middle week of next week...with
interior ridging across the intermountain region as the next Pacific
trough carves south along the Pacific coast. With jet well north of
the area bulk of Pacific moisture and short wave energy riding the
mean storm track will remain across southern Idaho as its southern
most point Wednesday...with trends to shift further north through the end
of the week. Building heights locally combined with increasing
southwesterly flow aloft will allow for both subsident warming and
warm air advection allowing temperatures to climb well above seasonal norms once again.
Dry and likely mostly clear conditions will be the norm.
Aforementioned Pacific trough should turn inland late next
weekend...but confidence in timing remains minimal at best.
Maintained climatology probability of precipitation for Saturday as such...though forecast could
easily remain warm/dry to start off next weekend.
Aviation...southerly surface winds will continue to remain very
gusty at the kslc terminal with gusts in excess of 30 miles per hour lasting
through 00z at least. A few gusts may exceed 40 miles per hour.
A cold front will pass through the terminal between 09-11z tomorrow
morning switching winds to the northwest. A 40 percent chance exists
for ceilings at or below 6000 feet above ground level thereafter through the morning hours.
Utah...Wind Advisory until midnight MDT tonight for utz003-005-015-016.
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http://weather.Gov/saltlakecity (all lower case)
For frequently asked questions about the area forecast discussion
http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)