Area forecast discussion
National Weather Service Salt Lake City Utah
949 PM MDT Thursday may 23 2013
Synopsis...a cold front will surge south across Utah tonight
through early Friday. A return to southerly winds will bring a
warming trend back for the weekend.
&&
Discussion...a secondary surge of low-level cold air has served
to boost northerly winds across northwest Utah this evening. The
latest 00z NAM shows a decent cold advection push into central
Utah later tonight. This colder air will catch up with the current
frontal boundary stalled over central Utah...and then accelerate
this feature south through the remainder of the state by early
Friday.
Strong southerly winds over central/southern Utah south of the
front have been trending downward during the evening. Suspect
these winds will remain elevated ahead of the front...but peak
winds will remain below advisory criteria through the balance of
the night. Winds may briefly increase out of the north behind the
front later tonight...though a prolonged strong wind event is not
anticipated.
Some concern that temperatures will dip below freezing in some of the
higher northern valleys...and a few central valleys by late tonight
or early Friday morning. The northerly surface pressure gradient
relaxes rapidly late tonight as the center of the surface high
settles into southeast Idaho and far northern Utah. Substantially
lower dew points just upstream over southwest Idaho could trickle
into northwest Utah late tonight. These lower dew points...light
winds and mostly clear skies could bring temperatures down into the middle
to upper 20s in some of the normally colder valleys of the far
north. Can not rule out a few reading in the upper 20s in the
central and west-central valleys late tonight...though sufficient
winds should keep readings near or above freezing in most of the
prone areas.
The mean pattern of a trough to the west and a strong ridge across
the central Continental U.S. Will allow temperatures to bounce back across much of
southern and eastern Utah this weekend. Still looking at a
situation where shortwaves ejecting out of the mean trough
position will generate shallow cool advection for the north...
keeping temperatures somewhat in check over the weekend. Little in the
way of moisture will find its way into the state until Sunday
night. As such will keep any mention of convection out of the
short term forecast.
Update issued earlier to lower temperatures and remove wind headlines.
&&
Aviation...northwest winds have increased at the kslc terminal as
a second dry cold front has moved through the area. These winds
should taper off after 05z...though a general north winds should
persist through much of the night. VFR conditions under mostly
clear skies are expected through the overnight hours.
&&
Fire weather...the dry cold front over central Utah will surge
east and south again later tonight. Local gusty northwest winds
will trail the front...along with cool temperatures and a still
dry air mass. The strong and dry southwest winds ahead of the
front will continue to decrease this evening...but will remain
gusty ahead of the advancing cold front. Generally cool and quite
stable conditions will cover the northern and central fire
districts Friday.
Locally gusty south winds will redevelop Friday across the south
and east but are not expected to be as strong as today. The south
winds will redevelop across most districts both afternoons this
weekend...with the airmass staying quite dry. Even though winds
and low relative humidity meet criteria...no fire weather highlights are planned
through Saturday. Sunday could be a different story if fuels reach
critical levels.
The next Pacific system will start to affect the area Sunday with
a threat of evening high based showers and thunderstorms over the
far north. This threat will increase through middle week with an
increasing chance of wetting rain from the storms after Monday.
&&
Slc watches/warnings/advisories...
Utah...none.
Wyoming...none.
&&
$$
Conger
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