GOES-16 Visible Imagery, above, shows convection (imagery at 1-minute intervals) surrounding Tropical Storm Nate, just onshore in northeastern Nicaragua.

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

The Tropical Depression (#16) in the western Caribbean Sea has strengthened to become a minimal Tropical Storm, acquiring the name Nate. The animation from GOES-16, above, shows disorganized convection over the entire basin, stretching into the Pacific Ocean south of central America. (The sheared remains of Pacific Tropical Storm Ramon are also present south of Mexico). The animation below, from 0000-1300 UTC on 5 October 2017, shows the mid-level Water Vapor Infrared Imagery (6.95 µm) from GOES-16. Convection develops over the center of Nate, over Nicaragua, at the end of the animation.

Microwave Imagery, below, from SSMI/S at around 1000 UTC on 5 October, (from this site) suggests that Nate is centered very near the coast of Nicaragua. Nate is forecast to move north into the Gulf of Mexico; its path through the northwest Caribbean suggests strengthening is possible if Nate remains far enough from land. Very warm water is present in the northwest Caribbean; that warmth extends to great depth as shown by this plot of Oceanic Heat Content; that warmth extends into the central Gulf of Mexico.

Nate formed at a time when the Moon was Full. Thus, Suomi NPP Day Night Band Visible Imagery showed excellent illumination. The image below is from 0627 UTC on 5 October.

Total Precipitable Water in advance of Nate is plentiful, as shown in the loop below (from this site). There is dry air over the continental United States, however, associated with a strong High Pressure System. Easterly winds south of that system are apparent in Scatterometer winds from early in the morning on 5 October.

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The YouTube link, above, shows the GOES-16 “Clean Window” (10.3 µm) Infrared Imagery over the Atlantic, showing the evolution of Hurricanes Franklin through Maria, from 7 August through 1 October. (The original mp4 video (250 Meg) is available.)

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

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* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

The Accumulated Cyclone Energy (ACE) for September 2017 set a new record for any month over the North Atlantic basin:

Since it was released on a Sunday morning, many missed the monthly summary from NHC confirming Sept 2017 as the most active month on record pic.twitter.com/7T3svWUmQ4

— Eric Blake ? (@EricBlake12) October 2, 2017

Two significant contributors to this record ACE value were long-lived and very intense Hurricane Irma and Hurricane Maria.

Hurricane Irma – Ace: 66.6 – Duration: 13 Days

One noteworthy statistic of Hurricane Irma: during its 3 days and 3 hours as a Category 5 hurricane (above), the storm had an intensity of 160 knots or 185 mph for 37 consecutive hours — which set a new world record. GOES-16 “Clean” Infrared Window (10.3 µm) images during this period of 185 mph intensity (below) showed a well-defined eye, with cold cloud-top infrared infrared brightness temperatures (occasionally -80ºC or colder, denoted by the violet color enhancement) within the adjacent eyewall region.

Hurricane Maria – Ace: 44.6 – Duration: 14 Days

One noteworthy aspect of Hurricane Maria was its intensification to a Category 5 storm on 18 September (above) — just before making landfall on the island of Dominica — and less than 48 hours before making landfall over southeastern Puerto Rico as a high-end Category 4 storm. GOES-16 Infrared Window (10.3 µm) images at 1-minute (pre-landfall) and 30-second (post-landfall) time intervals (below) showed that while the eye of Maria quickly eroded as the tropical cyclone moved northwestward across the island and interacted with its rugged terrain, deep convection of the eyewall region persisted over much of Puerto Rico during the transect. Note that the last hourly surface observations from Roosevelt Roads (TJNR) and San Juan (TJSJ) were from 04 UTC and 09 UTC, respectively — after which times power and communications to weather equipment (such as the San Juan radar) were lost.

Hurricane Jose – Ace: 42.2 – Duration: 17 Days

Although not as intense as Irma or Maria, the long duration of Hurricane Jose allowed it to achieve an ACE value nearly as high.

Individual storm montage images are available here on the CIMSS Tropical Cyclones site.

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GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing

A modest early-season storm has produced a snowfall over north-central Montana and southern Alberta. This image (source) shows total precipitation, with a minimum axis over northern Montana that has an echo in the Visible Imagery above: Whereas most of the snow cover is bright, a region west of Cut Bank MT shows a greyer view, suggestive of less snow on the ground.

GOES-16 includes a channel that senses reflected solar radiation at 1.61 µm and this is a wavelength at which snow strongly absorbs radiation. Thus, snow-covered grounds (and cirrus clouds) appear dark in the 1.61 µm Channel, but very bright in the Visible (0.64 µm). Clouds made up of water droplets are bright in both channels during the day. A Toggle between just the Visible and the Snow/Ice Channel is shown below to highlight regions of snow where clouds are not present over northern Montana and southern Alberta. Note that snow can be inferred in these regions using only the Visible Imagery because rivers — still ice-free in early October — stand out very well in the Visible.  Snow is also apparent in the Mountains of northeastern Wyoming:  Bright in the visible, Dark in the Snow/Ice channel.

Note that the localized minimum in precipitation, that shows up somewhat dark in the visible, is comparatively bright in the Snow/Ice Channel.  In addition, the 3.9 µm Infrared Imagery at the same time shows a region of relative warmth:  above freezing surrounded to the north and south by sub-freezing brightness temperatures.  All three channels — the visible, snow/ice and shortwave IR suggest a relative minimum in snow from Cut Bank westward to the Rocky Mountains.

GOES-16 Baseline Products include a Land Surface Temperature Product that is shown below from 2247 UTC. Temperature warmer than Freezing are diagnosed in/around Cutbank and to th west, with subfreezing temperatures to the north and south. Previous to that time, the Cloud Mask diagnosed clouds over the snowcover and the Land Surface Temperature did not produce a value. This toggle shows the Cloud Mask at 2227 and 2237 UTC — clear skies (black) expand over the snow cover in those ten minutes.

================= Added 4 October 2017 ====================The snow on the ground and clear skies allowed for cold temperatures. The Land Surface Temperature Baseline Product from 1047 UTC, below, shows isolated sub-zero values between Cut Bank and Havre. The morning low in Havre, which had a record snowfall from this storm, was 8.

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