Scientific Forecaster Discussion
fxus65 kslc 261321 aaa
Area forecast discussion...updated
National Weather Service Salt Lake City Utah
721 am MDT Fri may 26 2017
Update...updated aviation section.
Synopsis...an upper trough will move across the area today. A
cool northerly flow will follow for Saturday. A warming trend
starts Sunday and continues into mid week.
Short term (thru 18z sunday)...a cool upper low is centered
over swrn Idaho early this morning with a southwesterly flow over Utah.
A cold front across the County Warning Area has been retreating north as a warm
front overnight and has made it to near slc.
The upper low tracks east across srn Idaho today and into wrn Wyoming
tonight. Increasing upper support ahead of this low has been
generating elevated convection across nrn Utah over the last few
hours. Expect this to persist today as the low tracks east.
Coverage should be mainly scattered with the most numerous storms
this morning east of the Wasatch and north of about I-80.
Surface based development should maintain numerous coverage in
these areas this aftn as well as in the uintas.
The cold front pushes back south thru the County Warning Area today as the upper
low tracks east with a band of convection along it. This could
last into the eve across the south before it dissipates. A cooler
northerly flow is forecast for the County Warning Area on Sat in the wake of the
low. Models continue to generate some terrain based convection Sat
aftn along the mtn spine with a few cells over the east.
Long term (after 18z sunday)...high pressure is expected to move
back over the area beginning Sunday. With a bit of residual
moisture in place (particularly in the GFS solution) there is the
possibility of a few showers/storms over the higher terrain of
northern Utah Sunday and Monday. However, the vast majority of the
forecast area should remain dry with steadily warming
temperatures. Maxes should be in excess of 5f above seasonal norms
by Memorial Day, climbing further for Tuesday and Wednesday.
Latest GFS continues to indicate a weakening of the ridge that
allows moisture to be drawn northward into the forecast area. By
Tuesday it indicates pws in the 0.5 to 0.7 inch range moving into
southern Utah before gradually spreading northward Tuesday into
Wednesday. It then brings a weakening trough across the forecast
area Thursday into Friday, adding to the instability. Meanwhile,
the ec is still showing a much drier solution, with the ridge
remaining strong through Tuesday before weakening Tuesday
night/Wednesday as a grazing trough moves by. Ec has been more
consistent to this point, so have leaned toward the drier
solution, but have kept in some isolated pops to account for the
Aviation...the slc terminal will see VFR conditions through the
day with any cigs remaining above 6000 feet above ground level. Winds will remain
northwesterly through the day as well. There is a 30 percent
chance that showers in the vicinity of the terminal will result in
periods of gusty and/or erratic winds.
Fire weather...the cold front that pushed south across Utah
yesterday is retreating north early this morning and will head
back south again today as a weather system crosses the north. Warm
windy and dry conditions are expected again today south of the
front with the strongest winds over the southeast. Showers and
thunderstorms will increase across the north today then shift
south tonight with the cold front and gradually dissipate.
Isolated thunderstorms are possible again Saturday afternoon
mainly over the mountains and east. A warming trend begins Sunday
and continues into mid week. Expect isolated afternoon terrain
based thunderstorms each day Sunday through Tuesday with storms
possibly becoming more numerous Wednesday.
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