844 
FXUS65 KSLC 042205
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
405 PM MDT Sun Apr 4 2021

.SYNOPSIS...
Warm, dry and breezy conditions will develop Monday ahead of a 
storm system that will move through the area late Monday into 
Tuesday. High pressure will return for the middle of the upcoming 
week with slightly above average temperatures.

&&

.SHORT TERM AND FIRE WEATHER (Through 12Z Wednesday)...
This afternoon, the ridge over the southwest is flattening with 
the thermal ridge axis shifting east of the forecast area ahead of
the next approaching storm system seen moving into the Pacific 
Northwest. Skies have cleared this afternoon behind a weak 
disturbance that brought some mid and high level cloud cover 
across the state this morning. The ample solar isolation and 
exceptionally dry antecedent conditions are helping to create 
some breezy and dry conditions with near critical to critical fire
weather conditions across portions of the forecast area, 
including the Uinta Basin, where a Red Flag Warning is in effect.

On Monday, the next storm system will continue to approach the
region and will be in place near southwest Idaho and north central
Idaho by late Monday afternoon, with the surface cold front just
moving into northern Utah late in the afternoon. Ahead of this
storm system southwesterly to westerly winds will accelerate,
especially by early in western Utah and late afternoon in eastern
Utah, as 25-35 knots overspread the region from west to east. The
dry conditions and steep low level lapse rates with daytime
heating will allow for efficient momentum transfer to the 
surface. Humidity ahead of the front will drop into the single 
digits and low teen. Critical fuel conditions are in place for 
portions of southwest and eastern Utah, and Red Flag Warnings are 
in place for all such zones on Monday.

The cold front will continue to push across Utah Monday night,
bringing in a cooler airmass. The upper-level vort max is expected
to track east-southeastward across northern Utah Monday night.
Showers and some isolated rumbles of thunder are expected across
northern Utah ahead of this mid-level vort max moving through,
with orographic northwesterly flow showers lingering over the
northern Utah mountains into mid Tuesday morning. Temperatures do
get cold enough for some lake enhancement potential Tuesday
morning (lake sfc to H7 difference of 23C). However the flow will
quickly be turning from northwesterly to westerly as the low track
to the east, with drier air and subsidence quickly working in
behind the low Tuesday morning. Thus do not expect "lake effect"
per se, but rather some possible enhancement of already present
synoptic showers southeast and east of the lake. Some mountain
snow accumulations are looking more likely for the northern
mountains Monday night into Tuesday morning, which could result in
minor travel disruptions over mountain routes Tuesday morning.

Critical fire weather conditions are expected to linger in the
post-frontal breezy downslope flow across Castle County, the 
Swell and Henry Mountains zones through Tuesday. Some uncertainty 
remains father north with how low RH values will drop behind the 
front for the Tavaputs Plateau and Uinta Basin, which will be 
closer to the track of the low and its associated moisture. Thus a
Fire Weather Watch remains in effect for those zones on Tuesday, 
as winds will otherwise be supportive behind the front.

.LONG TERM (After 12Z Wednesday)...
A near zonal flow aloft is expected to remain the dominant 
pattern across the eastern Great Basin region for the latter half 
of the week. A fraction of globals do support the potential of a 
weak/dry cold frontal passage across the north Thursday night, but
enough spread remains in ensemble members regarding the amplitude
of its parent short wave to limit confidence of occurrence attm. 
Even with this, would only see temps buck back a few degrees 
across the north, and sensibly, a minimal shift only. In large, 
continuing to forecast some 5-10+ degrees above normal through the
end of the work week, with at best isolated diurnally terrain 
based showers in the north post front Friday. 

Transitioning into the weekend, globals continue to resolve a deeper 
trough translating across the northern Rockies region Saturday into 
Sunday, but evolution and amplitude of this remains a lower 
confidence forecast. Do see signals in enough of the ensemble 
members to lean towards at least a cool down, and chance for precip 
focused in the north however.

&&

.AVIATION...
VFR conditions are expected at KSLC through the valid TAF period.
Winds will transition to the southeast around 03Z. Mostly clear 
conditions will continue into Monday. Winds will transition to the
northwest around 18Z and be gusty at times. Scattered rain 
showers are possible after 00Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Red Flag Warning from noon Monday to 10 PM MDT Tuesday for 
     UTZ489-494.

     Red Flag Warning until 10 PM MDT Monday for UTZ482.

     Fire Weather Watch from Monday evening through Tuesday evening 
     for UTZ482>484.

     Red Flag Warning from noon to 10 PM MDT Monday for UTZ483-484-
     495.

WY...None.
&&

$$

SHORT TERM...Church
LONG TERM...Merrill
AVIATION...Wilson

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visit...
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