Severe thunderstorms in Arizona

August 2nd, 2018 |
Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

Visible images from GOES-15 (0.63 µm, left), GOES-17 (0.64 µm, center) and GOES-16 (0.64 µm, right), with SPC storm reports plotted in red [click to play animation | MP4]

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

GOES-15 (GOES-West), GOES-17 and GOES-16 (GOES-East) Visible images (above) showed the development of thunderstorms which produced hail and damaging winds (SPC storm reports) in the Phoenix, Arizona area on 02 August 2018. The images are displayed in the native projection of each satellite (no re-mapping). Due to a Full Disk scan, GOES-15 mages were only available every 30 minutes at the beginning of this particular time period; images from GOES-17 were every 5 minutes; a GOES-16 Mesoscale Domain Sector provided images at 1-minute intervals.

The strong thunderstorm winds also produced significant blowing dust — winds gusted to 47 knots (54 mph) and visibility was reduced to 1/2 mile at Phoenix KPHX (below). Winds gusted to 53 knots (61 mph) and visibility fell to 1/4 mile at Chandler KCHD.

Time series of surface observations for Phoenix, Arizona [click to enlarge]

Time series of surface observations for Phoenix, Arizona [click to enlarge]



Southwest US monsoon convection: GOES-15 vs GOES-16

July 12th, 2018 |

GOES-15 Visible (0.63 µm, left) and GOES-16 Visible (0.64 µm, right) images [click to play MP4 animation]

GOES-15 Visible (0.63 µm, left) and GOES-16 “Red” Visible (0.64 µm, right) images [click to play MP4 animation]

GOES-15 (GOES-West) Visible (0.63 µm) and GOES-16 (GOES-East) “Red” Visible (0.64 µm) images — displayed in the native projection of each satellite, and centered on Las Vegas, Nevada — are shown above, depicting the development of deep convection across parts of the Desert Southwest on 12 July 2018. While the GOES-15 satellite was in Rapid Scan Operations mode (providing 2 extra images nearly every hour, at :11 and :41), a GOES-16 Mesoscale Sector was providing images at 1-minute intervals. Numerous flash flood watches, warnings and advisories were issued by NWS Las Vegas during the course of the day as some of the storms produced heavy rainfall (with as much as 0.75 inch at Cal Nev Ari and 0.61 inch at Needles, California KEED).

Note that the GOES-15 Visible images do not appear as bright as those from GOES-16 — prior to the GOES-R Series of satellites, the performance of visible detectors degraded over time, leading to imagery that appeared more dim as the Imager instrument aged. Visible detectors on the new ABI instrument benefit from on-orbit calibration to remedy this type of degradation.

The corresponding GOES-15 Infrared Window (10.7 µm) and GOES-16 “Clean” Infrared Window (10.3 µm) images (below) revealed cloud-top infrared brightness temperatures around -70ºC (black enhancement) associated with some the stronger thunderstorms; this was the tropopause temperature at an altitude of 16.7 km / 48,300 feet on 00 UTC Las Vegas rawinsonde data. The improvement in spatial resolution from 4 km (at satellite sub-point) with GOES-15 to 2 km with GOES-16 is very apparent — even though the satellite viewing angle is about 10 degrees higher for GOES-16 than it is for GOES-15.

GOES-15 Infrared Window (10.7 µm, left) and GOES-16 "Clean" Infrared Window (10.3 µm, right) images [click to play MP4 animation]

GOES-15 Infrared Window (10.7 µm, left) and GOES-16 “Clean” Infrared Window (10.3 µm, right) images [click to play MP4 animation]

Higher spatial resolution Infrared Window images from Terra/Aqua MODIS and Suomi NPP VIIRS (below) revealed a cloud-top infrared brightness temperature as cold as -79ºC in far northwestern Arizona on the 2017 UTC VIIRS image.

Infrared Window images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

Infrared Window images from Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) [click to enlarge]

In addition to heavy rainfall, some thunderstorm winds created areas of blowing sand:

The GOES-16 Total Precipitable Water derived product (below) showed that rich moisture was present across the Desert Southwest, fueling the development of the widespread convection. TPW values in the 1.0 to 2.0 inch range were seen over southeastern California, southwestern Arizona and far southern Nevada.

GOES-16 Total Precipitable Water derived product [click to play MP4 animation]

GOES-16 Total Precipitable Water derived product [click to play MP4 animation]

A 4-km resolution Terra/Aqua MODIS Total Precipitable Water product (below) indicated values in the 40-55 mm or 1.6-2.2 inch range.

Terra/Aqua MODIS Total Precipitable Water product [click to enlarge]

Terra/Aqua MODIS Total Precipitable Water product [click to enlarge]

Fires in Saskatchewan

May 15th, 2018 |

GOES-16 ABI Band 1 (“Blue Visible”, 0.47 µm, top), Band 2 (“Red Visible”, 0.64 µm, middle) and Band 7 (“Shortwave Infrared”, 3.9 µm, bottom) from 1345 to 2230 UTC on 15 May 2018 (Click to animate);  Note that the yellow enhancement in the shortwave infrared starts at 305 K.

Fires that developed over the plains of Saskatchewan, near Meadow Lake in west-central Saskatchewan, and near Prince Albert in central Saskatchewan, showed up well in Visible and Infrared imagery, shown above.  A wind shift that occurred as the fires burned changed the direction of the smoke plume.  Prince Albert had visibilities that dropped to 3 statute miles.  Meadow Lake had visibilities down to 4 statute miles.

True-Color imagery (Source: (Link), imagery provided by Paul Ford, ECC Canada), also shows the distinct smoke plumes from the fires.

True-Color imagery over Saskatchewan, 1730-2000 UTC

The Dual-Pol S-band radar at Radisson captured the plume north of Prince Albert at 1900 UTC (See below; click here for the satellite imagery at that time).  Very small Cross-Correlation coefficients are apparent in the smoke plume. The radar at 2010 UTC (link) suggests 3 separate fires, which agrees with the satellite imagery. (Click here for 2015 UTC Satellite Imagery).

Cross-Correlation Scan from the dual pol, S-band at Radisson, Saskatchewan, 1900 UTC on 15 May 2018 (Click to enlarge)

Many Thanks to Paul Ford, ECC Canada, for the radar imagery, and for alerting us to this event. Saskatchewan fires can be tracked at this website. Most of Saskatchewan is currently under a fire ban.


========== ADDED ============
AWIPS imagery of this fire were collected. Click here to see the towns of the region. Full-disk imagery is available from GOES-16 at 15-minute increments. The 3.9 µm imagery is shown from 1200 to 2345 UTC, followed by the Fire RGB Imagery. The Fire RGB image combines the 3.9 µm (Red), 2.2 µm (Green) and 1.6 µm (Blue) imagery. The wavelength of the radiation emitted by the fire decreases as the temperature of the fire increases; a relatively cool fire will emit mostly 3.9 µm energy and will be red in the RGB. A very hot fire will emit all three wavelengths and will appear whiter in the RGB.

GOES-16 ABI Band 7 (“Shortwave Infrared”, 3.9 µm) from 1200 to 2345 UTC on 15 May 2018 (Click to enlarge)

GOES-16 ABI Fire RGB, combining 3.9 µm, 2.2 µm and 1.6 µm imagery, from 1200 to 2345 UTC on 15 May 2018 (Click to enlarge)

The imagery below is zoomed in on the region of the three fires.  (Map).  The 3.9 µm is shown first, then the Fire RGB.

GOES-16 ABI Band 7 (“Shortwave Infrared”, 3.9 µm) from 1200 to 2345 UTC on 15 May 2018 (Click to enlarge)

GOES-16 ABI Fire RGB, combining 3.9 µm, 2.2 µm and 1.6 µm imagery, from 1200 to 2345 UTC on 15 May 2018 (Click to enlarge)

 

The RGB — like many — gives an excellent qualitative estimate of the fire.  Quantitative estimates are available that more define the fire more comprehensively. The 1845 UTC Fire RGB suggests a very hot fire (the 3.9 µm imagery at 1845 UTC suggests the same thing). What do the Baseline fire products show? The Fire Temperature, Fire Power, and Fire Area products for 1845 UTC are shown below.  (Animations are here:  Fire Temperature, Fire Power, Fire Area)   Hotter fire pixels are apparent at 1745 and 2015 UTC.    Click for toggles of Band 7 (3.9 µm), Fire RGB and Baseline Fire Temperature at 1745 UTC, 1845 UTC, and 2015 UTC.  These products might facilitate resource allocation in a way that single channels or RGB combinations cannot.

GOES-16 Baseline Fire Temperature Product 1845 UTC on 15 May 2018 (Click to enlarge)

GOES-16 Fire Power Baseline Product, 1845 UTC on 15 May 2018 (Click to enlarge)

GOES-16 ABI Fire Area Baseline Product at 1845 UTC on 15 May 2018 (Click to enlarge)

Fires and blowing dust across the Upper Midwest and southern Manitoba

April 29th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images, with surface station identifiers plotted in cyan [click to play MP4 animation]

The combination of strong winds and low relative humidity prompted the SPC to forecast elevated to critical fire weather potential across parts of the Upper Midwest on 29 April 2018. A Mesoscale Domain Sector was positioned over the region, providing data at 1-minute intervals — and “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) revealed the smoke plumes and thermal anomalies or “hot spots” (black to yellow to red pixels) associated with some of these larger fires. The most prominent fires were located in southeastern Manitoba later in the day (including the largest fire EA015, which was listed as Out of Control).

On the Visible images, also note the hazy signature of blowing dust that developed from the northern Red River Valley of North Dakota and Minnesota into southern Manitoba — with winds gusting in excess of 50 knots, the surface visibility dropped to 3 miles at Grafton ND (KGAF) and Winnipeg International Airport (located just northwest of station CXWN in southern Manitoba).

Time series of surface observation data at Grafton, North Dakota [click to enlarge]

Time series of surface observation data at Grafton, North Dakota [click to enlarge]

Time series plot of surface weather data at Winnipeg, Manitoba [click to enlarge]

Time series plot of surface observation data at Winnipeg, Manitoba [click to enlarge]