Formation of a warm seclusion off the US East Coast

March 25th, 2013 |
GOES-13 0.63 µm visible channel image (click image to play animation)

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

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) revealed the formation of an eye-like signature that suggests the formation of a warm seclusion off the US East Coast on 25 March 2013.

AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 18:16 UTC (below) showed the early stages of the development of the cloud-free core of the warm seclusion. Strong convective squalls were developing along the occluded frontal zone in the eastern portion of the satellite scene.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with surface analysis and ocean buoy observations)

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with surface analysis and ocean buoy observations)

Severe thunderstorms produce hail and damaging winds across Florida

March 25th, 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)

AWIPS images of GOES-13 10.7 µm IR channel data (above; click image to play animation) showed a band of strong to severe thunderstorms that moved eastward across central Florida during the afternoon hours on 24 March 2013. These storms produced a few reports of hail up to 1.0 inch in diameter, as well as a number of damaging wind reports which included a gust to 75 knots or 86 mph at Orlando International Airport at 18:40 UTC or 2:40 PM local time (SPC storm reports).

1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR images with overlays of surface METAR reports and SPC storm reports (below) revealed that there was a cluster of overshooting tops with cloud-top IR brightness temperature values as cold as -67º C (darker red color enhancment) that appearaed to be associated with the reports of high wind gusts at the surface.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with overlays of surface reports and severe weather reports)

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images (with overlays of surface reports and severe weather reports)

A comparison of a 1-km resolution Suomi NPP VIIRS 11.45 µm IR image with the corresponding 4-km resolution GOES-13 10.7 µm IR image (below) demonstrated the advantage of higher spatial resolution for aiding in the identification of the location and magnitude of the coldest cloud-top IR brightness temperatures (-67º C with VIIRS, vs -60º C with GOES). In addition, the effect of parallax was evident on the GOES-13 IR image, with features being displaced to the northwest.

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR images

Suomi NPP VIIRS 11.45 µm IR and GOES-13 10.7 µm IR images

GOES-13 sounder Lifted Index (LI) and Total Precipitable Water (TPW) derived product images (below) indicated that moisture (TPW values as high as 45 mm or 1.78 inches) and instability (LI values as low as -10.4º C) were in place in the pre-convective environment across central Florida at 16:00 UTC or 12:00 PM local time.

GOES-13 sounder Lifted Index and Total Precipitable Water derived product images

GOES-13 sounder Lifted Index and Total Precipitable Water derived product images