Two oddities on the recent IWX NEXRAD
First, there is the large WNW-ESE cigar shape that seems to shoot from South Bend over to Fort Wayne and then drop due south into northern Wabash and Huntington counties. There was no weather, and the area once developed moves southward at about 15mph.
Second, is the smaller thinner linear feature (which becomes slightly bowed) heading out of near Racine WI southeastward across Lake Michigan, winding up a bit north of Michigan City IN (on the southeast "corner" of the lake). This features moves at about 27mph.
Curious … anyone have an explanation for either of these?
UPDATE 2010-01-20 08:33:14
This is the reply I got when I emailed the NWS Northern Indiana WFO (where the IWX nexrad is located):
Hi Tony,
Excellent question! We have been discussing this for nearly a half hour. Our leading thought is that what you see coming across Lake Michigan may be chaff, which is used in military training for pilots. It can get caught up in the mid level flow and travel downstream with the wind. Our radar is able to see this because chaff reflects energy just as precipitation does. What is most curious is looking at our radar images on AWIPS, the southward sinking boundary over us actually looks like it splits and diverges. This may be a function of the chaff somehow "seeding and feeding" the lower stratus clouds that were in place and we are seeing some type of dissipation. We are going to check with a group of radar experts who may be able to look at it and offer their opinions. Anytime we get an inversion in the atmosphere, we can see strange things as the radar beam gets bent and ducted back toward the surface. I will let you know if we hear anything different.
Sam
awc 2010-01-19 20:47:58
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