Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
407 PM MDT Wednesday may 27 2015
Synopsis...an upper low moving out of the Pacific northwest will
impact much of Utah through Thursday. High pressure will
strengthen across the region late in the week through the upcoming
weekend resulting in a warming and drying trend.
Short term (through 06z sunday)...an upper low pressure system is
spinning over Idaho this afternoon...with the southern portions of
the trough impacting Utah and southwest Wyoming. This trough has
helped initiate thunderstorms across the northern two thirds of
the forecast area...with some of these storms becoming
severe. Large hail has been reported...as well as a couple funnel
cloud reports near the Uinta Basin. Effective bulk shear is not
all that impressive...generally 20-25 knots...but some of the
stronger cells have been in areas with small analyzed pockets of
30-40 knots of shear.
Good instability will likely persist into the evening
hours...with some stronger cells likely to move into Tooele and
Box Elder counties from Nevada. Lowered probability of precipitation a bit between 06z and
12z Thursday...as most models have showers calming down during the
overnight hours...but showers will likely increase again Thursday
morning across northern Utah as the low drops into the area.
Severe storms could be possible again Thursday afternoon as the
trough axis passes through the County Warning Area...though showers may end
earlier than usual with the trough moving to the east shortly
after 00z Friday.
The trough finally exits the region through the day Friday...with
a shortwave ridge building over the Great Basin. This will begin a
warming and drying trend heading into the weekend...with
temperatures rising above seasonal normals by Saturday afternoon.
Long term (after 06z sunday)...
Significant warming and drying trend continues during the second
half of the weekend into early next week with the ridge centering
overhead Sunday. Storm coverage will continue to thin out and become
relegated to the mountains.
Southerly winds become gusty late Sunday afternoon through early
next week as the ridge shifts east of The Rockies. By midweek the
next closed low traverses the northern rockies...increasing
shower/thunderstorm coverage across the north. Expecting
temperatures to cool to or just below normal with the passage of a
cool front by midweek.
Aviation...northerly winds are expected to prevail at the
slc terminal through about 03z then shift to southeasterly. Showers
will be increasing in coverage in the area through the rest of this
afternoon and into this evening. VFR conditions will prevail but
ceilings could dip to or below 6000 feet with passing showers and gusty
erratic winds are also possible. Showers could become more frequent
after about 05-06z with prevailing ceilings at or below 6000 feet and brief MVFR
possible in heavier rain.
Fire weather...the rest of today and tomorrow will be warm and
fairly dry across the south...while the north remains cool and
moist. The best chance for a wetting rain is also across the north.
Showers and storms increase in coverage through the remainder of
this afternoon. It should remain active across the north this
evening...then again tomorrow as well. The strongest activity will
bring a chance for cloud to ground lightning...gusty/erratic
winds...and small hail.
The pattern shifts Friday through the weekend as a ridge builds in.
Expect very warm conditions and a drying trend across all of Utah.
The chance for afternoon showers and thunderstorms will thin each
day and be relegated to the mountains for the most part. Southerly
winds will become gusty Sunday...increasing through
Tuesday...increasing the likelihood of seeing critical meteorological
fire weather conditions into early next week.
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)