Hurricane Joaquin

September 30th, 2015 |

DMSP-18 SSMIS Microwave (85 GHz) and GOES-13 Infrared (10.7 µm) images [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) and GOES-13 Infrared (10.7 µm) images [click to enlarge]

Joaquin reached Category 1 hurricane intensity on the morning of 30 September 2015 (NHC advisories). An eye structure was becoming apparent on a 1259 UTC Microwave (85 GHz) image from the SSMIS instrument on the DMSP-18 satellite (above).

The GOES-13 (GOES-East) satellite was placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-7 minutes. Visible (0.63 µm) images (below; also available as an MP4 movie file) showed a number of convective bursts during the day, with a few overshooting tops.

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images (below; also available as an MP4 movie file) showed that cloud-top IR brightness temperatures associated with these convective bursts were in the -80º to -90º C range (violet colors). An organized eye structure was beginning to appear on the IR images at the end of the day.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

===== 01 October Update =====

The ASCAT Scatterometer on board METOP-A sampled the eastern half of Joaquin shortly after 0230 UTC on 1 October, as shown below. Hurricane-force winds were observed 20-30 miles away from the storm center; tropical storm-force winds extended about twice as far out.

GOES-13 Infrared (10.7 µm) images and METOP-A ASCAT Scatterometer winds, 0230 UTC on 1 October; the NHC Forecast track for Joaquin is indicated [click to enlarge]

GOES-13 Infrared (10.7 µm) images and METOP-A ASCAT Scatterometer winds, 0230 UTC on 1 October; the NHC Forecast track for Joaquin is indicated [click to enlarge]

Joaquin intensified into a Category 4 hurricane late in the day on 01 October (ADT intensity plot) as the storm slowly moved of the warm sea surface temperature and high ocean heat content waters in the vicinity of the Bahamas. Joaquin became the first Category 4 hurricane to move though the Bahamas in October since 1866 (Capitol Weather Gang blog).  A fairly persistent but rather ragged-appearing eye was seen on GOES-13 Infrared (10.7 µm) images (below; also available as an MP4 movie file). Once again, the well-defined eye structure was more evident on DMSP SSMIS microwave imagery.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images (below; also available as an MP4 movie file) showed a continuation of the development of convective bursts with overshooting tops in the eyewall region of the hurricane.

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

Tropical Storm Joaquin off the East Coast of the United States

September 29th, 2015 |
Suomi NPP VIIRS 11.45 µm Infrared and Day/Night Band 0.70 µm Visible images [click to enlarge]

Suomi NPP VIIRS 11.45 µm Infrared and Day/Night Band 0.70 µm Visible images [click to enlarge]

Tropical Storm Joaquin over the Tropical Atlantic is forecast to move northward off the East Coast of the United States during the week of 28 September to 3 October. The toggle above shows Suomi NPP VIIRS 11.45 µm Infrared imagery and Day/Night Band 0.70 µm visible imagery (illuminated by a near-Full moon) at 0642 UTC or 1:42 am local time on 29 September. The presence of northerly deep-layer wind shear (image below from the CIMSS Tropical Cyclones site; animation of GOES-13 IR images) causes the strongest convection to be displaced to the south of the surface circulation, and a small cloud swirl (the low-level circulation center of Joaquin: magnified image) is apparent in the night-time visible imagery near 26.7º N, 70.3º W, northwest of the strongest convection.

850-200 hPa Wind Shear Analysis, 1500 UTC 29 September 2015 [click to enlarge]

850-200 hPa Wind Shear Analysis, 1500 UTC 29 September 2015 [click to enlarge]

Analyses of Total Precipitable Water, below, from Morphed Microwave Data, show the storm forming in an environment rich in moisture. Note also the generous moisture amounts in the northeastern Gulf of Mexico. Joaquin is forecast to move northward off the East Coast of the United States. As it moves, the storm will draw with it abundant moisture.

Total Precipitable Water, 1500 UTC 26 September - 1400 UTC 29 September 2015 [click to enlarge]

Total Precipitable Water, 1500 UTC 26 September – 1400 UTC 29 September 2015 [click to enlarge]

GOES-13 Water Vapor Infrared (6.5 µm) Imagery [click to Play Animation]

GOES-13 Water Vapor Infrared (6.5 µm) Imagery [click to Play Animation]

A week-long animation of GOES-13 Water Vapor imagery, above, shows Joaquin developing over the tropical Atlantic in a region that was initially a large upper-level low pressure system.

GOES-13 Storm-Centered Infrared Window Channel (10.7 µm) Imagery [click to Play Animation]

GOES-13 Storm-Centered Infrared Window Channel (10.7 µm) Imagery [click to Play Animation]

The animation above shows GOES-13 10.7 µm Infrared imagery centered on the latitude/longitude point for each of the 6-hour-interval advisories issued by the National Hurricane Center during Joaquin’s first two days (click here for an animation without a map). The slow increase in organization, symmetry and high cold cloud tops is apparent. Note also that outflow to the north is occurring at the end of the animation, suggestive of a relaxation in northerly wind shear.

For the latest information on Joaquin, consult the National Hurricane Center and the CIMSS Tropical Cyclones site.

Strong storm along the East Coast

September 25th, 2015 |
GOES-13 Infrared Water Vapor (6.5 µm) images [click to play animation]

GOES-13 Infrared Water Vapor (6.5 µm) Imagery [click to play animation]

A slowly-moving storm was migrating northeastward along the East Coast of the United States on 25 September 2015. The GOES-13 water vapor animation, above, shows the evolution of this system between 22 and 25 September 2015. The center of circulation in the water vapor imagery has wobbled around the state of Georgia for the past three days as a strong jet along the United States-Canada border has has maintained a series of surface High Pressure systems northeast of the storm, effectively blocking the Low Pressure’s exit from the southeast US.

Moisture available to this storm is depicted in the animation of MIMIC Total Precipitable Water, below. Moisture that moves southwestward towards the southeast US along the Gulf Stream is being joined by moisture moving northward from the tropical Atlantic Ocean.

MIMIC Total Precipitable Water for the 72 hours ending 1400 UTC 25 September [click to enlarge]

MIMIC Total Precipitable Water for the 72 hours ending 1400 UTC 25 September [click to enlarge]

This system has generated flooding rains over South Carolina. The GOES-13 Visible animation from 24 September 2015, below, shows persistent inflow off the Atlantic Ocean. Click here for a media report; Columbia SC reported 2.84″ of rain on 24 September, a record for the date.

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) Imagery [click to play animation]

The thunderstorms associated with this system also caused a brief EF-2 tornado near Johns Island in Charleston County, SC (SPC Storm Reports). An animation of auto-detected Overshooting Tops, below, captures an overshooting top sequence persisting near Charleston at about the time of the tornado (0445 UTC). The toggle between Terra MODIS (0315 UTC) and Suomi NPP VIIRS (0618 UTC) 11 µm infrared data shows the general northwestward motion of the thunderstorm that produced the tornado (GOES-13 Infrared animation). The coldest cloud-top IR brightness temperature from MODIS was -75º C, with -76º C detected by VIIRS.

Autodetected Overshooting Top from GOES-13 Infrared (10.7 µm) imagery, 0315-0545 UTC [click to enlarge]

Autodetected Overshooting Top from GOES-13 Infrared (10.7 µm) imagery, 0315-0545 UTC [click to enlarge]

Terra MODIS 11.0 µm and Suomi/NPP VIIRS 11.45 µm infrared imagery [click to enlarge]

Terra MODIS 11.0 µm and Suomi/NPP VIIRS 11.45 µm infrared imagery [click to enlarge]

The pressure gradient between the storm over the southeast US and the High Pressure over the Canadian Maritimes had caused long-fetch onshore winds over much of the mid-Atlantic coast. This (and a Full “Super” Moon on Sunday) presages a weekend of coastal flooding. The animation of ASCAT (from METOP-B) winds below, shows 20-25 knot winds over a large region of the Atlantic Ocean between the Gulf Stream and North America. That long fetch will help generate large waves. The surface circulation off the coast of Georgia is also apparent in the 0220 UTC image.

METOP-B ASCAT Scatterometer Winds, 0000-1500 UTC over the western Atlantic [click to enlarge]

METOP-B ASCAT Scatterometer Winds, 0000-1500 UTC over the western Atlantic [click to enlarge]

Semi-Truck/School Bus Collision in Fog in Southeast North Dakota

September 25th, 2015 |
GOES-13 Visible (0.63 µm) imagery and surface observations of visibility; Richland County is outlined [click to play animation]

GOES-13 Visible (0.63 µm) imagery and surface observations of visibility; Richland County is outlined [click to play animation]

Three Semi-Truck/Trailers collided with a school bus in fog in Richland County North Dakota just before 9 AM CDT (1400 UTC) on 25 September 2015. The GOES-13 Visible animation, above, shows an eroding fog bank over southeastern North Dakota. Richland County is outlined in the imagery. The school bus was traveling on Highway 46, which hugs the northern border of Richland County; the accident was about 3 miles west of Interstate 29 (Press Report 1 ; Press Report 2).

Suomi NPP VIIRS "fog/stratus product" IR brightness temperature difference images [click to enlarge]

Suomi NPP VIIRS “fog/stratus product” IR brightness temperature difference images [click to enlarge]

During the preceding nighttime hours, Suomi NPP VIIRS “fog/stratus product” IR brightness temperature difference images at 0756 UTC (2:56 am CDT) and 0937 UTC (4:37 am CDT), above, showed an increasing signal of fog/stratus – yellow to red color  enhancement – over the region during that time period (when surface visibilities also began to rapidly decrease at Wahpeton KBWP, the county seat of Richland County).

GOES-R IFR Probability fields, 1300-1515 UTC on 25 September 2015 [click to play animation]

GOES-R IFR Probability fields, 1300-1515 UTC on 25 September 2015 [click to play animation]

GOES-R IFR Probability fields, above, around the time of the accident, showed a high probability of IFR Conditions over southeast North Dakota. High values were present over the area before sunrise (Sunrise in Fargo on 25 September is at 1318 UTC). Values at 1400 UTC show largest values over northern and western Richland County. The Low IFR Probabilty field for 1400 UTC, below, immediately after the time of the crash, shows a maximum across northern Richland County where the accident occurred.

GOES-R Low IFR Probability field, 1400 UTC on 25 September 2015 [click to enlarge]

GOES-R Low IFR Probability field, 1400 UTC on 25 September 2015 [click to enlarge]