Mesoscale vortex over western Lake Ontario

November 21st, 2011 |
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)

1-km resolution GOES-13 0.63 µm visible channel images (above; click image to play animation) revealed a mesoscale vortex (or “mesolow”) propagating slowly westward across the western end of Lake Ontario on 21 November 2011. The GOES-13 satellite had been placed into Rapid Scan Operations (RSO) mode, providing images as frequently as every 5-10 minutes. With high pressure located to the north over western Quebec, the surface winds were generally light from the east across the region — and with a stable air mass in place, no precipitation was reported at any of the observing stations as the mesolow approached the coast and moved inland.

The structure of the mesoscale vortex could also be seen using 250-meter resolution Terra and Aqua MODIS true color images from the SSEC MODIS Today site (below).

Terra and Aqua MODIS true color images

Terra and Aqua MODIS true color images

In addition, the mesolow could also be seen on a true color image from one of the early overpasses of the VIIRS instrument on the NPP satellite (below).

NPP VIIRS true color image

NPP VIIRS true color image

Thanks to David Zaff and Robert Hamilton of the NWS Buffalo forecast office for bringing this feature to our attention!

Hurricane Kenneth

November 20th, 2011 |
GOES-11 0.65 µm visible channel images + ship reports

GOES-11 0.65 µm visible channel images + ship reports

According to the National Hurricane Center, on 20 November 2011 Tropical Storm Kenneth became the latest-forming named tropical storm in the eastern North Pacific basin since Hurricane Winnie formed on 04 December 1983. GOES-11 0.65 µm visible channel images from the CIMSS Tropical Cyclones site (above) showed a well-defined circulation, with a ship report of tropical storm force winds north of the storm center.

The corresponding GOES-11 10.7 µm IR images (below) showed a trend of increasing convection withing the northern semicircle of the storm.

GOES-11 10.7 µm IR images + ship reports

GOES-11 10.7 µm IR images + ship reports

AWIPS images of the MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) indicated that TPW values associated with Tropical Storm Kenneth were in the 50-60 mm range (darker orange colors), as rich moisture was sill in place along the Inter-Tropical Convergence Zone (ITCZ) / Monsoon Trough.

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

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

======== 21 November Update ========

GOES-15 0.63 µm visible images (click image to play animation)

GOES-15 0.63 µm visible images (click image to play animation)

Kenneth was upgraded to a Hurricane on 21 November. GOES-15 0.63 µm visible channel images (above; click image to play animation) showed a ragged eye forming as curved convective bands wrapped around the center of the tropical cyclone. Kenneth was able to intensify in part because it was in an environment that possessed uncharacteristically low values of deep layer wind shear (below).

GOES-11 10.7 µm IR image + deep layer wind shear

GOES-11 10.7 µm IR image + deep layer wind shear

======== 22 November Update ========

GOES-15 0.63 µm visible channel images (click image to play animation)

GOES-15 0.63 µm visible channel images (click image to play animation)

Hurricane Kenneth strengthened to a Category 4 storm on 22 November, becoming the most intense major hurricane to form so late in the season in the satellite era. GOES-15 0.63 µm visible channel images (above; click image to play animation) showed the well-defined eye of Kenneth.

Snow cover increasing across the north-central US

November 20th, 2011 |
MODIS 0.65 µm visible channel image + MODIS Red/Green/Blue (RGB) false color image

MODIS 0.65 µm visible channel image + MODIS Red/Green/Blue (RGB) false color image

A comparison of an AWIPS image of 1-km resolution MODIS 0.65 µm visible channel data with the corresponding MODIS false color Red/Green/Blue (RGB) image created using the 2.1 µm “snow/ice channel” (above) showed that snow cover was beginning to increase in areal extent across parts of the north-central US on 20 November 2011. This example also demonstrates the utility of RGB imagery for helping to discriminate between snow cover (which shows up as shades of red on the RGB image) and supercooled water droplet clouds (which show up as varying shades of white). Snow depths at the time included 11 inches at Mount Rushmore, South Dakota, 10 inches at Rice, Minnesota and 5 inches at Minot, North Dakota.

MODIS false color RGB images created using data from consecutive overpasses of the Terra (17:22 UTC) and Aqua (19:03 UTC) satellites (below) also show the movement of the low cloud features during that period.

MODIS false color Red/Green/Blue (RGB) images

MODIS false color Red/Green/Blue (RGB) images

As pointed out in the NWS Minneapolis Area Forecast Discussion, the swath of fresh snow cover would have an impact on daily high and low temperatures at locations where the snow was deepest. An AWIPS image of the 1-km resolution MODIS Land Surface Temperature (LST) product (below) revealed that LST values were in the 0º F to +10º F range (cyan to blue color enhancement) over the areas with snow cover, in contrast to LST values in the 30s F (green color enhancement) over adjacent areas with bare ground.

MODIS Land Surface Temperature product

MODIS Land Surface Temperature product

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS.

Record-setting early winter season cold in Alaska

November 19th, 2011 |
MODIS 11.0 µm IR image + METAR surface reports

MODIS 11.0 µm IR image + METAR surface reports

Much of interior Alaska experienced record-setting early winter season cold temperatures during the middle of November 2011:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
304 AM AKST SAT NOV 19 2011

…THE RECORDS CONTINUE TO FALL AT FAIRBANKS…

THE EARLY WINTER NOVEMBER COLD SNAP CONTINUES TO RE-WRITE THE RECORD BOOKS AT FAIRBANKS. THE CURRENT COLD SNAP WILL GO DOWN IN THE RECORD BOOKS AS ONE OF THE MOST SEVERE EARLY SEASON COLD SNAPS AT FAIRBANKS.

THE HIGH TEMPERATURE YESTERDAY AT THE FAIRBANKS INTERNATIONAL AIRPORT WAS 21 BELOW. THIS BREAKS THE PREVIOUS RECORD LOW MAXIMUM TEMPERATURE OF 19 BELOW WHICH WAS ESTABLISHED IN 1969. THE LOW TEMPERATURE YESTERDAY OF 36 BELOW BREAKS THE PREVIOUS RECORD LOW FOR THE DATE OF 33 BELOW ALSO SET IN 1969.

AT 213 AM THIS MORNING…THE TEMPERATURE AT THE AIRPORT DROPPED TO 36 BELOW. THIS BREAKS THE OLD RECORD LOW FOR NOVEMBER 19TH OF 33 BELOW IN 1969.

TODAY (SATURDAY) MARKS THE 5TH CONSECUTIVE DAY WITH A LOW TEMPERATURE OF 30 BELOW OR COLDER AT THE AIRPORT. THIS TIES WITH 1956…1969 AND 1989 FOR THE MOST CONSECUTIVE DAYS WITH A
TEMPERATURE OF 30 BELOW OR COLDER SO EARLY IN THE WINTER SEASON.

THE LOW TEMPERATURE HAS NOW BEEN 35 BELOW OR COLDER EACH OF THE LAST 5 DAYS. THIS HAS NEVER HAPPENED BEFORE SO EARLY IN THE WINTER SEASON AT FAIRBANKS. THE OLD RECORD WAS ONLY 2 DAYS…AND WAS LAST RECORDED IN 1989.

THE HIGH TEMPERATURE HAS NOW BEEN 20 BELOW OR COLDER EACH OF THE LAST 3 DAYS. THIS TIES WITH 1989 FOR THE MOST CONSECUTIVE DAYS WITH A HIGH TEMPERATURE OF 20 BELOW OR COLDER SO EARLY IN THE WINTER SEASON.

The coldest surface air temperature reported during the period was -54º F (-48º C) at Manley Hot Springs on 17 November. AWIPS images of MODIS 11.0 µm IR data (above) and POES AVHRR 12.0 µm IR data (below) showed thermal signatures of some the coldest air draining into river valleys and other low-lying areas (darker blue color enhancement).

POES AVHRR 12.0 µm IR image + METAR surface reports

POES AVHRR 12.0 µm IR image + METAR surface reports

======== 20 November Update ========

POES AVHRR 0.86 µm visible channel images

POES AVHRR 0.86 µm visible channel images

20 November marked the sixth consecutive day with a daily minimum temperature at Fairbanks International Airport of -35º F (-37º C) or colder — such a long cold streak had never been recorded before so early in the season. While western Alaska was not as cold as the interior, the air was cold enough to promote the rapid formation of sea ice off the west coast. A sequence of three 1-km resolution POES AVHRR 0.86 µm visible channel images (above) showed the extent of the sea ice on 20 November.

A comparison of 1-km resolution MODIS 0.64 µm visible channel and 11.0 µm IR channel images (below) showed that the sea ice exhibited much colder IR brightness temperatures (-10º to -15º C, orange color enhancement) than the adjacent ice-free waters.

MODIS 0.64 µm visible channel image + MODIS 11.0 µm IR image

MODIS 0.64 µm visible channel image + MODIS 11.0 µm IR image

An AWIPS image of the 1-km resolution POES AVHRR Sea Surface Temperature (SST) product (below) indicated that the waters just beyond the ice edge had SST values in the upper 20s to low 30s F, which would be conducive to a further expansion of the ice field away from the coast.

POES AVHRR Sea Surface Temperature product

POES AVHRR Sea Surface Temperature product