Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
445 am MDT Sat Oct 25 2014
Synopsis...a cold front approaching Utah will generate strong
southerly winds today. The front will cross the state Sunday
through Sunday night ushering in a colder airmass.
Short term (through 00z wednesday)...early morning water vapor
imagery and objective analysis depicts a robust shortwave trough
approaching the Pacific coast near 130w...while downstream a deep
layer southwesterly flow extends across the Great Basin/Colorado
plateau region. As this trough moves inland today...a tightening
southerly gradient coupled with strengthening flow aloft will
yield very windy conditions across the western valleys by
afternoon...with gusts approaching 50 miles per hour. Expanded the going Wind
Advisory into zone 3...as the Tooele Valley and portions of the sl
valley tend to gust strongly in these flow regimes.
Meanwhile a very mild airmass resides across the forecast
area...with 700mb temperatures currently near 10c per rap analysis. With
strengthening southerly flow deep mixing is once again
anticipated...and although the airmass is forecast to cool a bit
by afternoon...near record temperatures are once again expected at
The Pacific trough is forecast to lift northeast through the
Pacific northwest and northern Great Basin this afternoon through
tonight. The associated surface front is expected to cross
northern Utah overnight...bringing a chance for showers to
northern Utah. In the wake of this boundary there may be a lull in
precipitation along and south of I-80 until the upper trough axis
swings through the area late Sunday afternoon/Sunday
evening...with snow levels falling below 7 kft during this time.
Any snow accumulation is expected to remain minor.
Rising heights in the wake of this wave will bring and end to
precipitation Sunday night. A cool airmass will linger across the
region Monday...and if skies remain mostly clear Monday night
outlying areas of northern Utah may experience a hard freeze Tuesday
Long term (after 00z wednesday)...both the 00z ec and 00z GFS have
continued the trend of shifting the jet further north...bringing the
associated zone of warm air advection north of the County Warning Area into central
Idaho. This shift will likely keep precipitation north of the border
late Tuesday into Wednesday. There is a slight chance of a few showers
right along the Idaho/Utah border Wednesday as the ridge over the
eastern Pacific begins to amplify in response to the approaching low
moving across the Gulf of Alaska.
This ridge will build into the area Wednesday through at least Friday.
Both the 00z GFS and the 00z ec continue to develop a fairly robust
trough off the Pacific coast Friday into Saturday. There is a large
model spread with the evolution of this system as it pushes into the
California coast. Started introducing near climatology probability of precipitation Saturday in
response to the higher than average chance of a trough impacting the
area in some form.
Aviation...southerly winds will become gusty at the slc terminal
between 12-15z this morning and remain strong through the day. Wind
gusts in excess of 40 kts are possible this afternoon and evening.
Utah...Wind Advisory from noon today to midnight MDT tonight for utz003-
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