Heavy rain in Florida

October 26th, 2017 |

Aided in part by precipitation associated with Hurricane Irma, some areas of Florida have received record rainfall during the June-October 2017 period:

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

GOES-16 Visible (0.64 µm, left), Near-Infrared

GOES-16 Visible (0.64 µm, left), Near-Infrared “Vegetation” (0.86 µm, center) and Near-Infrared “Snow/Ice” (1.61 µm, right) images [click to play animation]

A comparison of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (above) showed that water was a strong absorber of radiation at 0.86 µm and 1.61 µm wavelengths — therefore wet ground, rivers, lakes and the oceans appeared dark in those images. This makes those two GOES-16 ABI spectral bands useful for identifying areas of flooding.

Two areas in Florida are noteworthy on the images: the St. Johns River in the northeast part of the state (where Moderate Flooding had been occurring), and parts of South Florida (which had just received an additional 1-5 inches of rain on  the previous day).

A closer look at those 2 areas using Terra MODIS Visible (0.65 µm) and Near-Infrared “:Snow/Ice” (1.61 µm) images are shown below.

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing central and northeastern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice" (1.61 µm) images, showing southern Florida [click to enlarge]

Terra MODIS Visible (0.65 µm) and Near-Infrared :Snow/Ice” (1.61 µm) images, showing southern Florida [click to enlarge]

In stark contrast to the periods of heavy rain, a strong cold front brought clear skies and very dry air over Florida, as seen in MIMIC Total Precipitble Water product (below).

MIMIC Total Precipitable Water product [click to enlarge]

MIMIC Total Precipitable Water product [click to enlarge]

This dry air evoked enthusiasm in least one South Florida resident:


Santa Ana winds in Southern California

October 24th, 2017 |

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

GOES-16 Land Surface Temperature product, with hourly surface reports plotted in white [click to enlarge]

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

The GOES-16 Land Surface Temperature product (above, courtesy of Jordan Gerth, CIMSS) revealed a dramatic increase in the land surface temperature (or surface “skin temperature”) following the onset of easterly/northeasterly Santa Ana winds in Southern California’s Ventura County during the overnight and early morning hours of 24 October 2017. Between 06-14 UTC (11 PM-7 AM local time), the surface air temperature increased from 66-91ºF at Oxnard (KOXR), 75-90ºF at Point Mugu (KNTD) and 77-91ºF at Camarillo (KCMA). Surface wind gusts of 32 mph were recorded at Camarillo during this period, although 64 mph was reported at South Mountain (elevation 2350 feet)..

A warming trend in that same area was also evident in the MODIS Land Surface Temperature product (below), during the time between the Terra (0539 UTC) and Aqua (0951 UTC) overpasses — LST values ranged from the low 60s F (lighter shades of yellow) to the upper 80s and low 90s F (darker shades of red) in the higher elevations.

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

Terra and Aqua MODIS Land Surface Temperature product [click to enlarge]

A similar warming signature was seen over Ventura County on GOES-16 Shortwave Infrared (3.9 µm) images (below) — although an even more pronounced Santa Ana wind warming signal was evident farther to the southeast over Orange County (where winds gusted as high as 69 mph); note how the warmer orange-enhanced infrared brightness temperatures surged southwestward toward the coast.

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

A number of record high temperatures resulted from this Santa Ana wind event:


Record high temperatures in the San Diego, California

Record high temperatures in the San Diego, California area

In fact, the highest temperature in the Lower 48 states that day was 108ºF at Miramar Naval Air Station and San Luis Obispo, California.

National Temperature extremes

National Temperature extremes

Super Typhoon Lan in the West Pacific

October 21st, 2017 |

Advanced Dvorak Technique (ADT) plot for Typhoon Lan [click to enlarge]

Advanced Dvorak Technique (ADT) plot for Typhoon Lan [click to enlarge]

A plot of the Advanced Dvorak Technique for Typhoon Lan (above) showed that the tropical cyclone underwent a period of rapid intensification during the 00-12 UTC period on 20 October 2017.

A 24-hour animation of Himawari-8 rapid-scan (2.5 minute interval) Infrared Window (10.4 µm) images (below) revealed the development of a very large eye during the 20 October/06 UTC to 21 October/06 UTC period.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1700 UTC or 2:00 AM kocal time (below; courtesy of William Straka, CIMSS/SSEC) provided a good visualization of the “stadium effect” — an eye that was more narrow at the surface, with a larger diameter at higher altitudes. A packet of mesospheric airglow waves (reference) was also evident on the Day/Night Band image, propagating south-southeastward away from the eye.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (10.4 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (10.4 µm) images [click to enlarge]

A 2-panel comparison of Himawari-8 Visible (0.64 µm) and Infrared Window (11.45 µm) images (below) showed the eye of Lan after it attained Super Typhoon status at 18 UTC on 20 October. Mesovortices could  be seen within the eye on the rapid-scan images.

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images [click to play MP4 animation]

Himawari-8 Visible (0.64 µm, left) and Infrared Window (10.4 µm, right) images [click to play MP4 animation]

A large amount of moisture was associated with this tropical cyclone, as depicted by hourly images of the MIMIC Total Precipitable Water product (below) — note the large area with TPW values of 70 mm or greater (light violet color enhancement).

MIMIC Total Precipitable Water product [click to play animation]

MIMIC Total Precipitable Water product [click to play animation]

A TPW value of 72.5 mm (2.87 inches) was derived from the Minamidaitojima, Japan rawinsonde data at 12 UTC on 21 October (below). Minamidaitojima is the largest island in the Daito Islands group southeast of Okinawa, Japan  — this station was just to the northeast of Lan around 12 UTC.

Rawinsonde data from Minamidaitojima, Japan [click to enlarge]

Rawinsonde data from Minamidaitojima, Japan [click to enlarge]

GOES-16 and Fog Detection

October 18th, 2017 |

GOES-16 Brightness Temperature Difference (10.3 µm – 3.9 µm) “Fog Product” from 0202 – 0357 UTC on 18 October 2017 (Click to animate)

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

Stratus and Fog formed over the valleys of Kentucky (and in surrounding states) early on 18 October 2017 (It was there on 17 October as well). When was the fog first obvious from Satellite imagery? It very much depends on the spatial resolution of the Satellite viewing the scene. The Brightness Temperature Difference field (10.3 µm – 3.9 µm) from GOES-16, shown above, can be used to identify regions of stratus clouds that are made up of water droplets. Carefully examine the animation; the time when fog is definitively present over valleys of eastern Kentucky (around 84º W Longitude) is around 0327 UTC.

GOES-16 has 2-km resolution (at the sub-satellite point — 89.5º W Longitude during GOES-16 Check-out); this is superior to GOES-13’s nominal 4-km resolution at the subpoint (75º West Longitude). The GOES-13 Brightness Temperature Difference Field (10.7 µm – 3.9 µm) at 0330 UTC shows no distinct indication of Fog/Stratus over eastern Kentucky. A series of animations of the GOES-13 Brightness Temperature Difference field, from 0215-0345 UTC, from 0415-0500, from 0545-0700 and from 0700-0815 suggest GOES-13 identified the region of fog about 4 hours after GOES-16, at 0730 UTC.

The GOES-13 vs. GOES-16 toggle below, from 0700 UTC on 18 October 2017, shows how the resolution improvement with GOES-16 facilitates earlier detection of fog and stratus as it develops overnight.

Toggle between 0700 UTC 18 October 2017 Brightness Temperature Differences from GOES-13 (10.7 µm – 3.9 µm) and GOES-16 (10.3 µm – 3.9 µm) (Click to enlarge)