Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
323 am MDT Monday Jul 6 2015
Synopsis...high pressure will remain centered over the southern
rockies through much of this week. Abundant moisture along with
weak weather disturbances moving through the region will generate
showers and thunderstorms through midweek. A broad upper low
will move through the eastern Great Basin late in the week.
Short term (through 12z thursday)...
water vapor loop shows the ridge axis weakening over The Four
Corners...with a wave over the northern Nevada border ahead of a
closed low off the California coast. Amdar 400-250mb wind
observations show a 100-140kt cyclonic jet over the northern
rockies and into south central Canada. GOES/GPS/rap/00z slc radiosonde observation
indicate the precipitable water value ranges between 0.45"
northeast mountains...to 0.90"-1.30" across most valleys.
Isolated convection still going south of I-70 as a weak wave has
snuck into the ridge axis. Plenty of instability today and tomorrow
and given the combination of weak waves and terrain circulations
should have little issues developing isolated to scattered
convection each day.
Wednesday is a transition day as the upstream closed low makes its
way into central California. Increasing dry southwesterly flow will
limit convection across the south and provide the opportunity for
the development of gusty winds across a few southwestern valleys.
Further north and east where convection does form...it will be
transitioning to higher based activity.
Long term (after 12z thursday)...
a Pacific storm system is prognosticated to move onshore over the
California coast during the day Thursday. The approach of the
system will move some drier air into western Utah. Global models
have come into better agreement with the track of this
system...sweeping it across Utah Thursday night/Friday as it
weakens. The passing system will provide a focus for a bit of
overnight convection during that time...with showers lingering
over northern Utah into Friday afternoon. Have raised probability of precipitation a
bit...primarily for Thursday night...with these current trends.
Drier air is expected to move back in beginning Friday night as
the trough exits and high pressure centered over the plains builds
back into the forecast area. This would result in dry and stable
conditions for the upcoming weekend.
Aviation...the slc terminal will see VFR conditions throughout the
day. Light southeast winds are expected to shift to the northwest
between 17z and 19z.
Fire weather...isolated to scattered showers and thunderstorms will
be the rule through tomorrow. New lightning starts are the primary
concern...with some storms providing an opportunity for a wetting
rain. The convective coverage will keep temperatures down and
humidity up a bit.
An abrupt pattern shift is currently advertised during the middle of
the week. A dry and gusty southwesterly flow develops trending
humidity lower...beginning Wednesday afternoon across the far
southwest valleys. Convection will still be around...though wetting
rain becomes less of a possibility as activity becomes higher
Short term/fire weather...rogowski
For more information from National oceanic and atmospheric administration/S National Weather Service visit...
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)