Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
1030 am MST Sat Jan 31 2015
Synopsis...an upper low will move south out of the area this
evening. A moist west northwest flow will develop across the
northern Great Basin Monday and continue into Wednesday.
Discussion...the upper low center over southern Nevada that had been
sending moisture and precipitation into the County Warning Area is weakening and
becoming absorbed into the primary upper circulation centered over
the central Gulf of California.
Upstream the short wave ridge entering northern Utah from the north at
this time is heading southward and the associated strong drying and
subsidence is bringing clearing skies. This will continue to push
southward today and reach the southern Utah border by the end of the day.
Precipitation has come to an end across about the northern 1/3 of the County Warning Area and
should be ending across central Utah by noon or so. This should
allow US to cancel winter weather highlights from the central mountains
northward. The remaining deformation zone across southern Utah should also
dissipate and shift southward by late today but will leave existing
highlight in effect and allow it to expire this afternoon.
A fairly tight northerly surface gradient develops across the County Warning Area
this afternoon and persists across central and southern Utah tonight. This
could bring enough mixing to these areas to sufficiently dry lower
levels and preclude much fog development tonight.
The upstream ridge just off the coast today crosses the County Warning Area on sun
and flattens rapidly Sun night as a weak wave passes mainly to our
north. This wave does push some moisture into far northern Utah.
This pattern of an increasingly moist west-northwesterly flow over northern Utah
continues through Tuesday night with a continued chance of valley rain
and mountain snow from about slc north. The last wave in this series is
a bit deeper and passes on Wednesday bringing an end to this precipitation
threat Wednesday night.
Updated earlier to make some minor adjustments to probability of precipitation and sky
cover over the north. Will likely update again around midday to
cancel a portion of the Snow Advisory.
Aviation...temporary ceilings near 7000 feet above ground level at the slc
terminal will continue through about 19z. Otherwise...north to
northwesterly winds will continue at the terminal through the day.
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http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)