Area Forecast Discussion
Issued by NWS Salt Lake City, UT
FXUS65 KSLC 242136
Area Forecast Discussion
National Weather Service Salt Lake City UT
336 PM MDT WED AUG 24 2016
.SYNOPSIS...A relatively dry northwesterly flow will remain over
northern and central Utah through this evening. Moisture over
southern Utah will return northward tomorrow and Friday. Drier air
will return for the weekend and early next week.
.SHORT TERM (Through 06Z Sunday)...Drier air has moved into
northern and central Utah this afternoon in northwest flow behind
a cold front. Satellite derived PWs indicate values of 0.3 to 0.4
inch over northern Utah and southwest Wyoming with values of 0.7
to 0.8 inch elsewhere. Widely scattered showers and thunderstorms
have developed in the more moist airmass, most concentrated over
southeast Utah. Convection will diminish this evening and
overnight with the loss of daytime heating.
Southerly flow is expected to return to the forecast area early
tomorrow ahead of an approaching weak disturbance, allowing
moisture to spread back northward. The wave will track across the
area through Friday, keeping the moisture in place. Maxes will
remain a few degrees below climo in the cooler airmass behind the
front over northern Utah Thursday, with a slow warming trend as
the weekend approaches. Cloud cover will likely keep southern Utah
temperatures a bit below climo as well.
Behind the exiting disturbance, weak high pressure is expected to
return over the weekend. The flow aloft is progged to become more
west/northwesterly at this time, allowing drier air to move back
in from the north. As a result, coverage of showers and
thunderstorms is expected to decrease once again.
.LONG TERM (After 06Z Sunday)...The global models are in really good
agreement through Monday night but then the EC weakens the ridge
overhead by bringing in the Pacific Northwest trough across the
Great Basin a little faster than the GFS. As a result, the 700mb
temperatures are just a couple of degrees cooler then the GFS. The
EC ensemble, however, is closer to the GFS operational forecast so
have leaned toward the GFS. Consequently, have nudged maximum
temperatures upwards a couple of degrees for Tuesday and Wednesday.
Also pushed min temperatures up several degrees over northwest Utah,
especially along the Wasatch Front, where the surface gradient and
winds aloft should keep temps rather mild.
Dry conditions are expected from Sunday through midday Wednesday
under a dry southwest flow aloft. However, as the trough from the
Pacific Northwest moves a little closer by Wednesday the flow
becomes a little more southerly and some moisture is imported into
the region. Have kept the low POPs over the southern mountains as
well as expanded POPs westward to the Pine Valley Mountains for
.AVIATION...Gusty northwest winds are expected at the SLC terminal
through about 01-02Z before relaxing and becoming more northerly.
Winds should shift to the southeast about 04-05Z. VFR conditions
will persist through the TAF period.
.FIRE WEATHER...A cooler and drier northwest flow is over northern
Utah behind a cold front. Moisture and instability remain over
southern Utah, however, where some showers and thunderstorms will
continue into the early evening before weakening. The flow over
the area will turn more southwesterly tomorrow and Friday as a
weak disturbance moves over the area. This will spread moisture
into central Utah as well as parts of northern Utah. The district
will begin to dry from the north again on Saturday with high
pressure moving back in, with the drier and warmer airmass
persisting into the early part of the upcoming week.
SHORT TERM/FIRE WEATHER...Traphagan
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