083 
FXUS65 KSLC 210926
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
326 AM MDT Thu Mar 21 2019

.SYNOPSIS...
A pacific storm system will bring low elevation rain and mountain
snow across much of Utah through Friday. After brief ridging late
Friday into Saturday, another pacific storm system will bring 
widespread precipitation across the state for the upcoming weekend.

&&

.SHORT TERM (THROUGH 00Z MONDAY)...
With height falls and upper level diffluence associated with the 
approach of the storm system persisting over Utah today into
tomorrow morning, precipitation chances increase significantly, 
especially for southern and central Utah. There is sufficient 
instability and lapse rates to mention the threat of thunder 
during this period.

Snow levels look to remain above 6kft for the areas with the bulk
of the precipitation. Southern and central mountains may see 
locally significant accumulations aided by south-southeast 
orographic enhancement. Most valleys look to remain rain or a 
rain/snow mix. Best bet for valley snow accumulations will be 
north of Hanksville into Price and across the western Uinta Basin.
The thermal profile is marginal to support snow for Price, though
heavier precipitation rates could drag down the snow level a bit 
further.

Expanded the Winter Weather Advisory northward to include the
southern Wasatch and the western Uinta mountains. While the ending
time was set to match the ongoing mountain advisory, its
conceivable that an extension in time into the mid afternoon
Friday may be needed before the affects of the storm system
sufficiently abate.

Given the convective nature of precipitation, LCL lowering to near
850mb, and warm cloud depth increasing to 3-4kft, locally heavy
rainfall will be possible across southern valleys, especially this 
morning. This is coincident with anomalously high precipitable 
water values ahead of the lead wave pin-wheeling into the region.

Tomorrow is a transition day with the trough making its way to 
our northeast, encouraging building heights and warming aloft from
southwest to northeast during the afternoon and evening.

Tomorrow night into Saturday morning should largely be quiet 
across the region under a ridge, however warm advection ahead of 
the next quick-moving storm system may sustain showery activity 
across portions of the north. Diffluence aloft increases Saturday 
afternoon into Sunday providing for the next round of 
precipitation, with support from a second advancing Atmospheric 
River. Snow levels initially look to be rather high around 6500
feet, but may fall closer to 5000 feet Sunday.

.LONG TERM (AFTER 00Z MONDAY)...
Sunday's trough will be quickly pulling away from the region to 
start the long term forecast period. A period of shortwave ridging
should bring milder temperatures to the state before another cold
trough crosses the region. Much of the ensemble guidance favors a
longwave trough crossing the western United States Wednesday into
Thursday...potentially remaining in place into the weekend. 

For now the general details indicate a loosely organized trough will 
approach the coast Tuesday...with several waves rotating around the 
trough. This...colocated with a jet maxima impinging on the central 
Sierras. Global guidance indicates this system has the potential to 
be fairly cold for late March, with 700mb temperatures between -7 
and -9C post frontal. For now...cooled Thursday well below 
temperatures earlier in the week...and if the trend 
continues...these temperatures will need to be cooled further. While 
there is a chance of snow to valley floors...confidence is not high 
this will occur. 

&&

.AVIATION...
Southerly winds will continue at the SLC terminal. Expect a 
period of light rain and lowered ceilings...near 5000-6000 feet 
AGL between 12-18Z. Ceilings should then lift until later Thursday
evening.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory until 6 AM MDT Friday for UTZ008>010-517-
     518.

     Winter Weather Advisory until 6 PM MDT this evening for UTZ012-
     013.

WY...None.
&&

$$

SHORT TERM...10
LONG TERM/AVIATION...Kruse

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