Turbulence Probability and moisture with a strong jet

November 30th, 2021 |
GOES-17 Air Mass RGB, 2001 UTC on 30 November, along with Derived Motion Wind plots from 250-350 mb (red) , 350-450 mb (yellow), and 450-600 mb (green) (Click to enlarge)

The GOES-17 Air Mass RGB, above, shows a distinct jet in the northwestern quadrant of the image. Derived Motion winds are as strong as 170 knots between 250-350 mb (they’re almost as strong from 350-450 mb!) In contrast, winds from 450-600 mb are closer to 70 knots just to the northwest of that upper-level jet. As you might expect, Turbulence Probability fields have a maximum along that very strong jet, as shown below. High Probabilities of turbulence also exist northeast of Hawaii (in the lower left corner of the image), and near the upper-level low at 33 N, 134 W. Turbulence Probablities are derived from GOES-17 infrared data and from GFS estimates of upper level stability. (Training on this product is available here under ‘Machine-Learning for Turbulence Detection by Satellite’).

GOES-17 Air Mass RGB and Turbulence Probability fields, 2001 UTC on 30 November 2021 (Click to enlarge)

In addition to their availability in AWIPS, as shown above (via an LDM feed from CIMSS), Turbulence Probabilities are also available on line at https://cimss.ssec.wisc.edu/turbulence. Values from 2000 UTC are shown below in the GOES-17 ‘Gulf of Alaska’ and ‘Vancouver’ domains.

Probabilty of Moderate or Greater (MOG) turbulence over the Gulf of Alaska, and over regions just to the south of the Gulf of Alaska, 2000 UTC on 29 November 2021 (Click to enlarge)

Turbulence probability fields from 2120 UTC, below, show that most of the Pilot Reports of turbulence align with the axis of higher probabilities. But not all of them: Severe turbulence (denoted in red) is noted near Oahu in a region of small (but not zero!) probability.

The strong jet obvious in the Air Mass RGB is associated with strong transport of moisture towards the Pacific Northwest. MIMIC Total Precipitable Water (TPW) fields, below, show abundant moisture traveling across most of the Pacific. OSPO’s TPW Percent of Normal fields show values exceeding 200% in this moist airstream (image from 1500 UTC on 30 November).

MIMIC Total Precipitable Water (TPW) fields at 0600 UTC on 30 November 2021 (Click to enlarge)

Tropical Storm Nyatoh in the Philippine Sea

November 30th, 2021 |

A tropical depression in the Philippine Sea has developed into Tropical Storm ‘Nyatoh’. The system is currently moving northwestward. Once it enters the Philippine Area of Responsibility (PAR), it will likely exit the area within 24 hours. Forecasters have predicted the storm will strengthen quickly, but its track will not pass over the Philippine islands.  A Tropical Cyclone Advisory has already been issued by the NWS office in Guam.

The Himawari-8 satellite houses the Advanced Himawari Imager (AHI) that provides full disk geostationary data at a high temporal resolution, similar to the GOES-16/17 ABI. AHI’s domain is perfect for monitoring storms such as Nyatoh.

A composite of AHI true color and infrared imagery is shown, with the SSEC IR rain rate superimposed on top. Imagery is shown from 11-29-2021 at 22UTC to 11-30-2021 at 18UTC using RealEarth, a free data visualization web tool.
Tropical storm Nyatoh is currently moving northwestward but may change to move northeastward by December 2.