Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 200954
AFDSLC

Area Forecast Discussion
National Weather Service Salt Lake City UT
354 AM MDT Wed Mar 20 2019

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

&&

.SHORT TERM (THROUGH 00Z SUNDAY)...
Several disturbances will combine to our west today, with a
spring storm eventually evolving. On approach, a northeasterly
pressure gradient will combine with pressure falls to the west to
support continued enhanced canyon winds, primarily along the
Wasatch and outlying Dixie. The magnitude of these winds will most
likely remain below Wind Advisory criteria.

With height falls and upper level diffluence associated with the
approach of this system reaching Utah this afternoon and
continuing into Friday, 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 tonight. 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 heavy precipitation rates could drag down the snow level a
bit further.

Initially convection will be high-based this afternoon into the
early evening, providing the possibility of locally gusty
convective winds.

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
evening into tomorrow morning. This is coincident with anomalously
high precipitable water values ahead of the lead wave pin-
wheeling into the region.

Friday 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.

Friday 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 providing for the beginning of the next round of
precipitation, with support from a second advancing Atmospheric
River.

.LONG TERM (AFTER 00Z SUNDAY)...
Over the last few runs the GEFs has trended closer to the EPS
regarding amplification of the late weekend trough...trend towards
more amplification, subtly. Perusing the NEAFS anomaly potential,
nothing out of the ordinary is signaled with this trough, and
deterministic fields support this regarding dynamic potential.
This said, it`s getting late in March, modest moisture will be
present, and even weak forcing aided by diurnal convective
potential can lead to locally modest+ precip. Continue to carry
high end PoPs through Saturday night with the trough overhead, and
through much of Sunday even though the precip will be turning
more convective in nature as the upper low shifts downstream.

Globals continue to line up better regarding height rises/ridge
amplification as this trough translates downstream...beginning
Sunday night. This trend continues through early next week as a deep
pacific trough winds up off the Pac coast. Sensibly, dry and
tranquil conditions will dominate...notable warming trend Monday
through Wednesday prior to the troughs arrival. Temps 5-8 degrees
above normal likely by day 7 (Wed).

&&

.AVIATION...
Southeasterly winds are expected to prevail through the day at
the KSLC terminal. Moderate gusts are possible after 18z, but
speeds are expected to remain well below airport weather warning
criteria. Mid and upper sky cover will increase from the SW during
the latter half of the period, but VFR conditions will be
maintained.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...Winter Weather Advisory from 6 PM this evening to 6 AM MDT
     Friday for UTZ010-517-518.

     Winter Weather Advisory from midnight tonight to 6 PM MDT
     Thursday for UTZ012-013.

WY...None.
&&

$$

SHORT TERM...10
LONG TERM/AVIATION...Merrill

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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