Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Salt Lake City Utah
956 PM MDT Thursday Sep 18 2014
Synopsis...an upper trough will slowly advance into the western
Great Basin through tonight then form a closed low off the Southern
California coast by late Friday. This closed low will cross the area
over the weekend.
Discussion...large-scale pattern shows splitting storm system
extending from off the Bay area coast and into the northern rockies.
A line of occasionally strong thunderstorms developed across
northwest Utah today ahead of the trough...but splitting nature of
the system has minimized the eastward propagation of the line.
Storms are now mostly elevated and not as strong as before...as cold
air has settled in at the low levels. Storms are finally starting to
make some eastward progress now...and all models are showing this
progression into the Wasatch front and mountains towards midnight.
Have updated the forecast to lower pop/sky for many areas...but did
keep some higher probability of precipitation across northern portions due to this model
Storms will continue into tomorrow before gradually tapering off
through the day as the northern branch of the split exits the area
and the southern branch low cuts off over the West Coast. This low
will eject inland over the weekend...with moisture beginning to
spread into southwest Utah Saturday afternoon. Widespread moisture
looks to return for Sunday as this low lifts across the area.
Aviation...northwest winds will prevail through late tonight before
turning back to the south after around 08-10z. There is 30 percent
chance that a thunderstorm will impact the terminal between 0500 UTC
and 0900 UTC. However...there is a greater likelihood that gusty
erratic winds from nearby convection will impact the terminal.
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