These turrets can develop when there is some strong lifting mechanism around the20,000-foott level, such as an approaching strong mid- and upper-level trough
Wintertime upper-level maps often fall into one of three basic patterns for the United States, with an upper-level trough
in the west, in the center or the east.
5 (20 May) Strong upper-level trough
and jet over Upsondes: 18 New Mexico and Oklahoma.
The occurrence of western Iran heavy rain is related to existence STJ in based on upper-level trough
which is propagated to Western Iran located above surface cyclone with extending pressure trough to western Iran and North Arabia Saudi .
We're under the influence of an upper-level trough
pattern, and that's keeping the onshore flow and precipitation right here," said Metcalf.
After one of the warmest autumns on record in the Mojave Desert, a drastic shift in the upper air pattern took place in mid-December 2008 as a deep, upper-level trough
established itself across the western United States.
The presence of this upper-level trough
has caused a large portion of otherwise northwesterly moving hurricanes to swing away to the north before reaching the U.
The reduced static stability also leads to an increased Rossby penetration depth, which promotes vertical connections between the upper- and lower-level perturbations (DeMaria 1996), and leads to enhancement of both the developing secondary circulation and the vertical motions resulting from quasigeostrophic forcing for ascent downshear of the upper-level trough
(Kelly and Mock 1982).
As an upper-level trough
swings through, the coldest upper air moves overhead and destabilizes the atmosphere," said Charles Dalton, a meteorologist serving with the National Weather Service in Portland.
The upper-level trough
located to the south of Sandy also contributed to the westward track of Sandy (e.
For example, a convective outlook discussion from the Storm Prediction Center may mention an upper-level trough
becoming negatively-tilted with time, which might cue you to go check out that 500-mb chart.
The rule of thumb for upper-level lift is that it is most often found downstream from upper-level troughs