1-day observed precipitation for 25 and 26 January 2012

Maps of the 1-day total precipitation for 25 January and 26 January 2012 (above) showed that much of Texas and Oklahoma received several inches of rainfall during that 48 hour period.

AWIPS images of the MODIS 0.65 µm visible channel and the corresponding  MODIS Land Surface Temperature (LST) product (below) revealed a large swath of rain-cooled ground across much of that region. LST values where heavy rain fell were in the 60s F (yellow to light orange color enhancement), in contrast to LST values in the 70s and 80s F (darker orange to red color enhancement) to the north and the to the south of the rain-cooled areas.

MODIS 0.65 µm visible chanel image + MODIS Land Surface Temperature product

View only this post Read Less

Aqua MODIS: 11.0 µm IR images (grayscale, and color-enhanced) + "Fog/stratus product"

A comparison of AWIPS images of 1-km resolution Aqua MODIS 11.0 µm “IR Window” channel data (both grayscale, and color-enhanced) and the corresponding MODIS “Fog/stratus product” (above) showed some areas of fog and/or stratus cloud over the eastern half of Hudson Bay, Canada on 26 January 2012. On the fog/stratus product, low clouds and/or fog appear as the yellow-to-red enhanced features, while cirrus cloud features appear darker black.

The primary feature of interest here is the very thin – almost “translucent” – patch of fog/stratus located in the upper center portion of the image, to the west of Akulivik (station identifier CYKO) and Povungnituq (station identifier CYPX). The exact edges of this feature were difficult to identify in either the grayscale or the color-enhanced IR images — but the conventional “Fog/stratus product” (simply the difference in IR brightness temperature between the 11.0 µm and 3.7 µm channel data) allowed unambiguous identification of the edges.

About 45 minutes earlier, a similar comparison using McIDAS images of of 375-meter resolution Suomi NPP VIIRS 11.450 µm IR data (both grayscale, and color-enhanced) and the corresponding VIIRS “Fog/stratus product” (below) showed much more detail associated with this particular thin fog/stratus feature. The higher spatial resolution allowed many more of the  ice leads to be seen — even some of the larger ones that were located below the thin fog/stratus feature.

Suomi NPP VIIRS: 11.450 µm IR (grayscale, and color-enhanced) + "Fog/stratus product"

View only this post Read Less

Suomi NPP VIIRS visible and IR images of the eye of Tropical Cyclone Funso

On 24 January 2012 NASA renamed the recently-launched NPP satellite (formerly known as the NPOES Preparatory Project)  the Suomi National Polar-orbiting Partnership (or Suomi NPP) in honor of Dr. Verner Suomi, recognized as “the father of satellite meteorology” (see: NASA News | University of Wisconsin News). A comparison of Suomi NPP 375-meter resolution VIIRS 0.640 µm visible channel and 11.450 µm IR channel images (above) showed the eye of Category 4 Tropical Cyclone Funso, which was located in the Mozambique Channel between Africa and Madagascar at 11:02 UTC on 24 January (track of Tropical Cyclone Funso).

On 25 January 2012, another Suomi NPP 375-meter resolution VIIRS 11.450 µm IR image (below) displayed very cold cloud top IR brightness temperatures (as low as -77º C) associated with a large thunderstom complex over Texas — this storm produced hail up to 1.25 inches in diameter (SPC storm reports) and heavy rainfall of up to 9.29 inches at Uhland (NWS Austin/San Antonio Texas Public Information Statement).

Suomi NPP VIIRS 11.450 µm IR image

The corresponding 4-km resolution GOES-13 (GOES-East) 10.7 µm IR image (below) showed much less structure to the cloud top temperature field, with the coldest IR brightness temperature being -70º C.

GOES-13 10.7 µm IR image

View only this post Read Less

POES AVHRR 12.0 µm IR images + surface reports

Unusually cold conditions were seen across the North Slope region of Alaska during the 22 January – 24 January 2012 period. A sequence of AWIPS images of 1-km resolution POES AVHRR 12.0 µm IR channel data (above) showed the expansion of a large area of surface IR brightness temperatures of -50 C and colder (violet to white color enhancement) across the interior portions of the North Slope. Nuiqsut (station identifier PAQT) was as cold as -62 F (-52 C) on 24 January, and Barrow (station identifier PABR) reached a low temperature of -45 F (-43 C) on 23 January (the record low temperature for the date was -47 F, and the normal low for the date is -20 F).

Another feature of interest over the Arctic Ocean was the appearance of a number of what resembled “warm cracks”  in the sea ice, where IR brightness temperatures were -30 C or warmer (yellow color enhancement) — significant amounts of thermal energy from the warmer waters below were able to “bleed up” through weaknesses and thinner areas of the sea ice, showing up as warm anomalies on the IR imagery.

A Public Information Statement was issued by the National Weather Service forecast office at Fairbanks:

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE FAIRBANKS AK
700 PM AKST TUE JAN 24 2012

…SEVERE COLD CONTINUES OVER THE NORTH SLOPE OF ALASKA…

A VERY COLD AIR MASS CONTINUES OVER THE NORTH SLOPE…COMBINED
WITH WINDS IN SOME AREAS. HERE ARE SOME LOW TEMPERATURES RECORDED SO FAR TODAY ACROSS THE NORTH SLOPE OF ALASKA.

NUIQSUT……………..62 BELOW
UMIAT……………….59 BELOW
INIGOK………………54 BELOW
ALPINE………………53 BELOW
ATQASUK……………..48 BELOW
DEADHORSE……………47 BELOW
WAINRIGHT……………44 BELOW
KAKTOVIK…………….40 BELOW
BARROW………………39 BELOW

TEMPERATURES OVER THE NORTH SLOPE WILL REMAIN IN THE 40S AND 50S BELOW WITH POCKETS NEAR 60 BELOW FOR THE NEXT FEW DAYS…AND POTENTIALLY INTO THE WEEKEND.

$$

JM

View only this post Read Less