Development of an intense winter storm off the US East Coast

February 8th, 2013 |
POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images

POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images

A winter storm began to intensify just off the East Coast of the US on 08 February 2013. A sequence of 1-km resolution POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images (above) revealed the formation of gravity waves in the lower-tropospheric cloud field within the southwest quadrant of the area of low pressure (corresponding IR images).

GOES-13 4-km resolution 6.5 µm water vapor channel images (below; click image to play animation) showed a very well-defined dry slot and the development of a distinct comma head. Strong northwesterly winds were also causing mountain waves to the lee of the Appalachians.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

The MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) showed TPW values as high as 48 mm or 1.9 inches being drawn northward into the intensifying low.

MIMIC Total Precipitable Water product (click image to play animation)

MIMIC Total Precipitable Water product (click image to play animation)

Similarly, the Blended Total Precipitable Water product (below; click image to play animation) also showed high values of TPW (up to 36 mm or 1.4 inches) off the Virginia/North Carolina coast as the low was intensifying.

Blended Total Precipitable Water product (click image to play animation)

Blended Total Precipitable Water product (click image to play animation)

These TPW values were in excess of 200% of normal for this region and this time of year (below; click image to play animation).

Percent of Normal TPW product (click image to play animation)

Percent of Normal TPW product (click image to play animation)

A MODIS 11.0 µm IR image at 03:04 UTC on 09 February (10:04 PM local time on 08 February) revealed a distinct hook-shaped pattern to the cloud features near the storm center as it continued to intensify (below). Peak wind gusts at this time were 58 knots at Nantucket and 54 knots at Boston.

MODIS 11.0 µm IR image with overlays of surface/buoy resports and surface analysis

MODIS 11.0 µm IR image with overlays of surface/buoy resports and surface analysis

===== 09 February Update =====

MODIS 0.65 µm visible image with surface/buoy reports and surface analysis

MODIS 0.65 µm visible image with surface/buoy reports and surface analysis

As the storm was nearing peak intensity on the morning of 09 February 2013, the formation of a tight circulation around its center was becoming evident in 1-km resolution visible channel images with overlays of surface data from MODIS at 15:06 UTC (above) and VIIRS at 17:01 UTC (below).

Suomi NPP VIIRS 0.64 µm visible image with surface/buoy reports

Suomi NPP VIIRS 0.64 µm visible image with surface/buoy reports

A 250-meter resolution MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; displayed using Google Earth) showed the locations of maximum snowfall totals for select states (which included 40.0 inches at Hamden, Connecticut), as well as some of the maximum wind gusts (which included 83 mph at Cuttyhunk, Massachusetts).

MODIS true-color Red/Green/Blue (RGB) image with maximum storm total snowfall amounts and peak wind gusts

MODIS true-color Red/Green/Blue (RGB) image with maximum storm total snowfall amounts and peak wind gusts

GOES-13 Water Vapor imagery, displayed in a 2-day loop below, captures many interesting aspects of this potent storm.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

Auroral Display over very cold Canada

February 7th, 2013 |
Suomi/NPP VIIRS Day/Night Visible Band and 3.74 µm infrared channel images (click image to play animation)

Suomi/NPP VIIRS Day/Night Visible Band and 3.74 µm infrared channel images (click image to play animation)

The Day/Night band on Suomi/NPP once again detected an extensive display of Aurora Borealis over northern Canada, as shown in the image toggle above. The Day/Night Band shows bright illumination over the northern halves of Quebec, Ontario and Manitoba. At the same time, near-infrared imagery at 3.74 µm shows very cold air, strongly suggestive of clear skies. The High Pressure responsible for the clear skies will influence the large snowstorm predicted to hit the Northeast United States on February 8th and 9th.

A magnified version of the imagery above, shown below, focuses on the area of Ontario between Lake Superior and James Bay. Highway 11, part of the TransCanada Highway, shows up as an thin strand of light. Airports near this Highway confirm the numbing cold depicted in the 3.74 µm imagery. There are a few relatively warm pixels near Kapuskasing (CYYU), however. Brightness temperatures are at -33 and -34 C rather than -38 to -40 C in the regions that are dark in the Day/Night band. Even a town of 9000 can have a thermal signature detectable from satellite.

Suomi/NPP VIIRS Day/Night Visible Band and 3.74 µm infrared channel images (click image to play animation)

Suomi/NPP VIIRS Day/Night Visible Band and 3.74 µm infrared channel images (click image to play animation)

Sea ice motion in the Canadian Maritimes

February 5th, 2013 |
GOES-13 0.63 µm visible channel images (click image to play animation)

GOES-13 0.63 µm visible channel images (click image to play animation)

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed that the effect of strong winds in the wake of an unusually intense storm off the coast of Labrador could be seen in the motion of sea ice in the waters of the Canadian Maritimes on 05 February 2013.

A comparison of AWIPS images of MODIS 0.65 µm visible channel data and the corresponding false-color Red/Green/Blue (RGB) composite at 15:28 UTC (below) demonstrated the value of using RB images for cloud vs snow discrimination (snow and ice appear as darker shades of red in the RGB image). Surface reports plotted on the images showed that 2 sites were reporting wind gusts of 50 knots or higher at that time.

MODIS 0.65 µm visible channel + False-color Red/Green/Blue (RGB) images

MODIS 0.65 µm visible channel + False-color Red/Green/Blue (RGB) images

Mesoscale snowfall band across Missouri and Illinois

February 3rd, 2013 |
GOES-13 10.7 µm IR channel images (click image to play animation)

GOES-13 10.7 µm IR channel images (click image to play animation)

From the Area Forecast Discussion issued by the National Weather Service forecast office in St. Louis, Missouri:

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ST LOUIS MO
340 AM CST SUN FEB 3 2013

.SHORT TERM…
ISSUED AT 330 AM CST SUN FEB 3 2013
(TODAY THROUGH TUESDAY)

THANKS TO A COMPACT AND POTENT NW FLOW VORT MAX…SOME RATHER IMPRESSIVE LOW LEVEL FORCING AND A POCKET OF STEEP MID LEVEL LAPSE RATES…A NICE BAND OF 2-4 INCHES OF SNOW FELL LAST NIGHT WITH THE HIGHEST AMOUNTS CENTERED RIGHT THROUGH THE ST LOUIS METRO. KUDOS TO THE SAT AFTERNOON RUNS OF THE HRRR WHICH WAS THE SOLE MODEL THAT COMPLETELY NAILED THE SNOWFALL FORECAST.

A sequence of 4-km resolution GOES-13 10.7 µm IR channel images (above; click image to play animation) showed the disturbance as it was moving southeastward through the region during the night-time (pre-dawn) hours on 03 February 2013. Some of the cloud elements appeared to be convective in nature, with cloud top IR brightness temperatures as cold as -40 C (yellow color enhancement).

A comparison of a 4-km resolution GOES-13 10.7 µm IR image with a 1-km resolution MODIS 11.0 µm IR image (below) demonstrated the advantage of improved spatial resolution for depicting the location and edges of the individual cloud elements with polar-orbiting satellite imagery. Despite the times shown on the image labels, the actual times that the 2 satellites were scanning this area were fairly close — the northwestward displacement of the cloud features on the GOES-13  IR image is due to parallax.

MODIS 11.0 µm IR channel and GOES-13 10.7 µm IR channel images

MODIS 11.0 µm IR channel and GOES-13 10.7 µm IR channel images

On the following afternoon, a comparison of a 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel image with the corresponding False-color Red/Green/Blue (RGB) image at 18:51 UTC or 12:51 PM local time (below) showed the northwest-to-southeast oriented swath of snowfall — snow on the ground appeared as the darker shades of red in the RGB image. The highest snowfall amount reported was 5.0 inches (NWS St. Louis event summary).

Suomi NPP VIIRS 0.64 µm visible channel and False-color Red/Green/Blue (RGB) images

Suomi NPP VIIRS 0.64 µm visible channel and False-color Red/Green/Blue (RGB) images

 

A closer view using 250-meter resolution MODIS true-color and false-color RGB images from the SSEC MODIS Today site (below) showed the snow cover at 19:03 UTC or 1:03 PM local time. In this particular false-color RGB, snow cover appears as shades of cyan.

MODIS true-color and false-color Red/Green/Blue (RGB) images

MODIS true-color and false-color Red/Green/Blue (RGB) images