Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion 
National Weather Service Salt Lake City Utah
346 PM MDT Friday Jul 25 2014

Synopsis...a stalled front will remain across central Utah
through Friday maintaining moisture across the south and drier
air across the north. This moisture will slowly work its way
northward during the upcoming weekend and remain in place into
early next week.

&&

Discussion...afternoon analysis indicates a nearly stationary
front dividing the state from roughly Gandy to Utah County to the
Uinta Basin. South of this boundary...sufficient moisture remains
to allow for the development of convection. Storm motions are
fairly decent today but training of cells or collisions of outflow
boundaries/cell mergers could help to produce flash flooding in
the more flood prone areas of southern Utah including normally dry
washes...Slick Rock areas and small streams in steep terrain.
North of the boundary...dry and cooler conditions remain in place.

This boundary will further weaken overnight. The deepest moisture
will remain south of the weakened boundary again Saturday. An
upper level low diving south across the upper Midwest will help to
amplify the ridge across the western United States. This will help
to bring deeper moisture northward Sunday afternoon.

A disturbance moving north on the western periphery of the ridge
will help to increase the threat of convection Monday afternoon
into Tuesday. Have increased probability of precipitation to coincide with this increase
in lift across the area Monday afternoon into Tuesday afternoon.
Expect subsidence in the wake of this disturbance for many areas
Wednesday.

For the forecast beyond Wednesday...small differences between
models have a fairly large impact on the degree of moisture in the
area...and thus confidence in the forecast past Wednesday is
fairly low at this time given model to model variance.

&&

Aviation...VFR conditions are expected throughout the evening at
the slc terminal with some scattered clouds. Northwest winds are
expected to shift to the southeast between 03z and 05z.

&&

Fire weather...a stationary surface boundary remains draped across
central Utah this afternoon and delineates more stable and dry air
to the north and deeper moisture to the south. Western valleys have
been hitting red flag criteria this afternoon due to Bone dry
surface conditions and gusty southerly winds and a red flag warning
remains in effect through this evening.

Have noted scattered shower and thunderstorm developed today with
focus across central and eastern Utah...more isolated across
central Utah where a few dry thunderstorms are possible into this
evening. Decided to issue a Fire Weather Watch for zone 492 in
west central Utah for tomorrow afternoon/evening as areal coverage of
mostly dry thunderstorms is expected to increase slightly. This
threat could continue across zone 492 and possibly portions of 478
on Sunday but surface moisture should allow storms to trend more
wet by that time. Will continue to monitor this threat closely.

An upper level feature will track across western Utah Monday
spreading deep moisture to all areas...and allowing for a greater
wetting rain potential with storm activity at that time.

Winds after today will trend lighter as flow aloft decreases later
tomorrow into early next week. Outside of localized areas light
diurnally driven slope flows look to be the norm.

&&

Slc watches/warnings/advisories...
Utah...red flag warning until 9 PM MDT this evening for utz492-495.

Fire Weather Watch from Saturday afternoon through Saturday
evening for utz492.

Wyoming...none.
&&

$$

Kruse/Merrill/traphagan

For more information from National oceanic and atmospheric administration/S National Weather Service visit...
http://weather.Gov/saltlakecity (all lower case)

For frequently asked questions about the area forecast discussion
visit...
http://weather.Gov/saltlakecity/general/afd_faqs.Php (all lower case)

National Weather Service Glossary of Abbreviations