Home > News Archive
> Lander High Wind Event - 2/16/2003
February 16, 2003 -
Lander High Wind Event
On the evening of Sunday, February 16th a strong
pacific cold front pushed through Lander around 6 PM MST. A
narrow line of rain showers along the front was followed by west winds
at 20 to 30 mph and a 4 millibar rise in surface pressure. The
associated upper level circulation crossed over
the Continental Divide just to the north of the Wind River Mountains
(approximately over Togwotee Pass) afterwards around 9 PM MST.
Water vapor satellite imagery showed rapid
drying on the east side of the Wind River Range behind this circulation
at 930 PM MST. This signature is an indication that much drier air from the stratosphere was being pulled downward by strong
upper level winds near the boundary between the stratosphere and
troposphere, or the tropopause. This phenomena occurs as these
straight-line upper level winds cross perpendicular to a large mountain
range causing the winds to be initially pushed up (into the
stratosphere) and then pulled back down on the east side of the mountain
range in a wave-like pattern. Occasionally, these winds will
push down all the way to the surface resulting in sudden strong gusts of
wind. Note in the observations
from 9 PM to 10 PM (2100 to 2200 MST) that the pressures fell suddenly
(4 millibars) and the airmass dried out rapidly with the dewpoint
bottoming out at 11 degrees F. A maximum wind gust of
77 mph occurred around 10:05 PM MST or 22:05.
|
D
a
t
e |
Time
(mst) |
Wind
(mph) |
Vis.
(mi.) |
Weather |
Sky Cond. |
Temperature (ºF) |
Pressure |
| Air |
Dwpt |
6 hour |
altimeter
(in) |
sea level
(mb) |
| 16 |
23:53 |
N 17 G 28 |
10.00 |
Fair |
CLR |
35 |
11 |
|
|
29.79 |
1011.1 |
| 16 |
22:53 |
W 48 G 68 |
6.00 |
Light Rain and Windy |
CLR |
34 |
14 |
41 |
33 |
29.67 |
1007.2 |
| 16 |
22:37 |
W 53 G 66 |
4.00 |
Light Rain and Windy |
CLR |
34 |
16 |
|
|
29.67 |
NA |
| 16 |
22:28 |
W 56 G 70 |
2.50 |
Light Rain and Windy |
CLR |
34 |
18 |
|
|
29.67 |
NA |
| 16 |
22:19 |
W 48 G 64 |
3.00 |
Light Rain and Windy |
CLR |
34 |
18 |
|
|
29.68 |
NA |
| 16 |
22:12
|
W 43 G 77 |
1.75 |
Light
Rain Squalls and Windy |
CLR |
34 |
18 |
|
|
29.68 |
NA |
| 16 |
22:04 |
W 44 G 70 |
6.00 |
Light Rain Squalls and Windy |
CLR |
34 |
14 |
|
|
29.67 |
NA |
| 16 |
21:53 |
W 43 G 60 |
10.00 |
Windy |
CLR |
34 |
11 |
|
|
29.71 |
1008.7 |
| 16 |
20:53 |
W 13 |
10.00 |
Fair |
CLR |
34 |
13 |
|
|
29.81 |
1012.3 |
| 16 |
19:53 |
W 18 G 25 |
10.00 |
Fair |
CLR |
36 |
12 |
|
|
29.80 |
1011.7 |
| 16 |
18:53 |
NW 17 G 22 |
10.00 |
Partly Cloudy |
FEW055 SCT120 |
38 |
20 |
|
|
29.78 |
1010.8 |
| 16 |
18:17 |
W 31 G 38 |
10.00 |
Breezy |
SCT022 SCT043 |
39 |
25 |
|
|
29.71 |
NA |
| 16 |
17:53 |
SW 21 |
4.00 |
Light Rain |
BKN020 BKN041 |
37 |
32 |
|
|
29.71 |
1008.4 |
|
Top
The water
vapor image above (taken at 930 PM MST on February 16, 2003) shows
moisture content at approximately 30,000 feet above sea level.
Light colors indicate higher levels of moisture, and darker colors show
drier air. The ( L )
over north central Wyoming is the center of an upper level circulation
or low pressure center after it crossed the Continental Divide.
The blue arrow shows darker coloration
indicating very dry air east of the Wind River Mountains over Lander.
This localized area of very dry air indicates that the dry, heavier air
from the stratosphere is being pulled down into the lower levels of the
atmosphere. The yellow arrow shows
the position of the main jet stream where the strongest upper level
winds are occurring. (Click on image to enlarge)
Top |
|
RSS Feeds