Grace in Hind-sight. An ULL that made a TC.
Posted by JAC on 10/6/2009, 7:43 am
 Late on October 4th, the weather system in the far northeast Atlantic acquired sufficient tropical characteristics to be classified as a Tropical Storm, and Grace was named. The visible image from GOES-12 above shows the counterclockwise swirl of clouds. GOES-12 is over the Equator at 75 degrees W Longitude, and Tropical Storm Grace at the time of the image above was at 45 degrees North latitude and 16 degrees W Longitude; consequently, the view angle is very oblique. Indeed, the visible image shows a convective spiral band that lies beneath the cirrus shield that covers the system. Note that no overshooting tops penetrate the cirrus overcast over the tropical system. The system sits over sea surface temperatures near 70 degrees Fahrenheit and those temperatures are yielding insufficient CAPEs to produce overshooting tops. Grace developed underneath a decaying upper-level low. The low was able to draw north modestly high values of precipitable water, as shown in the MIMIC analysis. Grace is associated with the very small region of enhanced precipitable water that is at 40 N, 20 W at the start of the loop, then moving northeastward towards Ireland. A comparison of Terra MODIS visible and 11.0 m IR images (below) showed that Grace exhibited a fairly well-defined banded structure and some semblance of an eye at 11:40 UTC. The core became warm with a strong surface-circulation and hence was classified as a TC.       |
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- Re: Grace in Hind-sight. An ULL that made a TC. - BobbiStorm, 10/6/2009, 10:07 am
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