Mesoscale vortices in Oregon and Idaho

December 7th, 2018 |

* GOES-17 images shown here are preliminary and non-operational *

As noted by NWS Boise, a pair of mesoscale vortices were apparent over far southeastern Oregon and far southwestern Idaho on 07 December 2018. A comparison of GOES-17 and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (below) showed that even with the larger GOES-16 viewing angle (or satellite zenith angle), the features could still be seen rather well.

GOES-17 and GOES-16

GOES-17 and GOES-16 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Topography in feet [click to enlarge]

Topography in feet [click to enlarge]

A look at the local topography (above) indicated that the low altitude quasi-stationary Oregon vortex was located within the Owyhee River valley, just northeast of the Rome airport KREO. With high pressure centered over the Idaho/Montana border (surface analyses), the low-level southerly/southeasterly flow seen in a plot of 12 UTC rawinsonde data from Boise, Idaho (below) was being channeled between the higher terrain surrounding the valley; interactions with that terrain likely caused the Oregon vortex to form. The Idaho vortex was moving toward the northeast — Boise rawindsonde data showed southwest winds at 727 hPa or an altitude of 2700 feet. The 2 vortices wre quite small, having a diameter of only

12 UTC rawinsonde data from Boise, Idaho [click to enlarge]

12 UTC rawinsonde data from Boise, Idaho [click to enlarge]

The pair of vortices likely formed just before or right around sunrise, since there was no signature seen in earlier nighttime MODIS or VIIRS “Fog/stratus” infrared Brightness Temperature Difference (BTD) images {below).

MODIS and VIIRS

MODIS and VIIRS “Fog/stratus” infrared BTD images [click to enlarge]

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