Scientific Forecaster Discussion
fxus65 kslc 190357
Area forecast discussion
National Weather Service Salt Lake City Utah
957 PM MDT Thu Jul 18 2019
Synopsis...dry and seasonally warm conditions will continue
across the state through Saturday. High pressure aloft will
strengthen across the region during the latter half of the
weekend. Hot temperatures and increasing moisture from the
south will spread across Utah early next week.
Short term (through 00z monday)...the near zonal flow of the past
couple of days will begin to back in response to the upper trough
moving into the Pacific northwest this evening. This trough will
continue east along the US/Canadian border on Friday, then exit
into the northern plains late Friday night.
A surface front associated with the trough will settle into
extreme northern Utah early Friday. Weak low-level cold advection
develop as the upper trough moves through western Montana will
nudge the surface boundary south across northern Utah Friday
afternoon and evening. With little or no dynamic and thermal
support for lift and no significant moisture to work with,
modestly lower temperatures will be the only notable change behind
the passing front.
The west-to-East Ridge axis across the southern half of the Continental U.S.
Will begin to amplify across the interior west this weekend. A
portion of the deep layer moisture currently over southern
Arizona will make a run on southeast Utah Friday night before
shearing off to the east by early Saturday.
Northward advection of the bulk of the deep layer moisture will
likely commence Sunday as the upper ridge expands north with the
center near The Four Corners region. The leading edge of this
next moisture surge should advance to near the Utah/Arizona border
by late Sunday. Looking at limited convective activity across the
south during the afternoon, with most of this activity high-based
and producing mostly gusty winds and minimal rainfall.
Previous long term (after 00z monday)...it's largely been a year
without a monsoon so far for much of Utah...outside of a period
of enhanced, mainly mid-level moisture earlier in July. Both the
GFS and gefs solutions indicate this will likely change by
Tuesday...while the eps and deterministic ec are more insistent on
the upper level ridge remaining centered over Utah. This makes
confidence in the monsoonal surge relatively low.
The gefs/GFS solution would bring a significant moisture surge into
southern Utah by Tuesday afternoon. Current forecast
shear/instability profiles would favor initiation on higher terrain
followed by adjacent valleys later in the afternoon/evening. Much of
the rest of the state would see enhanced mid to low level moisture
by Wednesday afternoon and evening.
Meanwhile, the ec and eps solutions would bring very hot
temperatures and relatively dry conditions through next weekend.
Forecast package continues to trend more toward the wetter/more
progressive GFS/gefs solution.
Aviation...dry and stable conditions across northern Utah will
maintain VFR conditions at the terminal through the current taf
period. Southeast winds overnight will turn to the south and
increase slightly Friday morning, then turn to the northwest
between 19z and 20z.
Fire weather...a zonal flow pattern in place will transition to
more of a ridge pattern in the next 24 hours as high pressure
builds in from the east. Deep mixing will continue through early
in the weekend before moisture begins to filter into the region
from the south. Confidence is not high that this moisture surge
will be broad or significant, which may result in isolated pockets
of convection and thunderstorm potential which may lead to dry
thunderstorm potential by Tuesday of next week.
Hot and dry conditions will continue for Friday and part of
Saturday, with relatively less wind each day. Areas of critical
conditions may persist each day but overall the spatial coverage
of concern is becoming less through early in the weekend.
For more information from noaa's National Weather Service visit...