Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 290845
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
245 AM MDT Mon May 29 2017

.SYNOPSIS...High pressure will slowly build across the region
through the remainder of the holiday weekend, resulting in a
warming trend extending into the middle of the week.

&&

.SHORT TERM (THROUGH 12Z WEDNESDAY)...
Water vapor loop shows a ridge over the Interior West with a
disturbance lifting toward northern California. AMDAR 400mb-200mb
wind observations reveal split flow over the west, with the polar
jet well into Canada and the Subtropical jet near the Mexican
border. GOES/HRRR/00Z KSLC RAOB indicate precipitable water values
range from 0.15"-0.25" mountains to 0.30"-0.50" valleys.

Warming and drying into midweek as a ridge builds in. SREF
indicates modest destabilization across northeast Utah mountains
today and most mountains tomorrow to continue to advertise
isolated convection each afternoon/evening. With light flow kept
adjacent valleys without mention.

The ridge axis centers overhead tomorrow, which will allow 700mb
flow to become southerly, increasing mid level moisture and thus
instability. Simulated Reflectivity from Convective Allowing
Models indicates convection should remain moderately weak any
mainly over the mountains through the short term period.

.LONG TERM (AFTER 12Z WEDNESDAY)...
A summer-like pattern has set up for the long term portion of the
forecast, with mean ridging in place for portions of the period.
Wednesday will begin with a ridge over the Rockies with a
weakening shortwave trough approaching from the west. Deep
southwest flow will keep the area relatively dry with 700mb
temperatures near 12-13C. Given the anticipated well mixed
boundary layer, 700mb temperatures near 13C would yield highs near
90F. Nearly all of the available guidance, bias corrected or not,
forecast the Wasatch Front to reach 90F or higher. Increased
current MaxT grid to 90F for these locations. Looking back at
climatology, June 8th is the mean for the first 90F at Salt Lake
City Airport, so a bit early but not by much.

While convective development is possible Wednesday afternoon, given
how dry the airmass is, expected convection to be limited to the
higher terrain. A few dry microbursts out of virga may be possible,
especially across the west deserts and Wasatch Front by later in the
afternoon. Given the low chance of any measurable precipitation from
these virga related microbursts, reduced pops in most valley
locations.

The previously mentioned shortwave trough will slowly...very
slowly... move westward into Thursday. There may be a window early
Thursday afternoon for an enhanced threat of virga/microburst winds
depending on the timing of the exit of the shortwave from Utah.

Another weak wave will cross the area Thursday, with the potential
for a weak boundary to cross northern Utah Thursday evening into
Thursday night. Ridging is expected to develop behind this wave,
bringing a period of dry weather through the remainder of the
weekend.

&&

.AVIATION...
High pressure will yield little weather concerns for the SLC
terminal. Winds are expected to shift to the northwest between
18-19Z.

&&

.FIRE WEATHER...
Good clearing today will rise to Excellent tomorrow and Wednesday
with increasing transport winds and mixing.

A ridge will give way to a splitting trough later this week.
Isolated to perhaps widely scattered showers and thunderstorms can
be expected, primarily in the mountains and during the afternoon
and evening hours. In addition to lightning, there is a threat of
gusty/erratic winds near any showers.

A warming/drying trend peaks Wednesday, then slightly backtracks
at the end of the work week. Poor overnight RH recovery is
expected across southern Utah through Wednesday. Light winds for
the most part, though southerly winds increase Wednesday ahead of
the trough, though they will not be strong.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Flood Watch from Tuesday morning through Saturday evening for
     UTZ001-007.

WY...None.
&&

$$

SHORT TERM/FIRE WEATHER...Rogowski
LONG TERM/AVIATION...Kruse

For more information from NOAA`s National Weather Service visit...
http://weather.gov/saltlakecity

For frequently asked questions about the Area Forecast Discussion
visit...
http://weather.gov/saltlakecity/general/afd_faqs.php


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