no es bueno

[lolife]

Looked like it was gonna clear up tonight. Drove out under clear sky. Satellite looked good. Got one image done and the clouds moved in. When back in and checked the satellite and it looked perfectly clear still. Yet overhead was clouds. Thick clouds.

no comprende.

[Starforce2]

Did you check the infrared image? Visual satellite images only work when it's sunny, or at least most of them do - like Weatherbug.

[kibatme]

Looked like it was gonna clear up tonight. Drove out under clear sky. Satellite looked good. Got one image done and the clouds moved in. When back in and checked the satellite and it looked perfectly clear still. Yet overhead was clouds. Thick clouds.

no comprende.

Same thing happened here in Bloomington. It did come on fast here at my place -- low, not-so-thick clouds (Moon visible through them) moving rapidly from east-to-west.

I wonder if it wasn't a 'localized' effect, as opposed to a 'weather system', resulting from all the moisture in and on the ground? Maybe too small to show on satellite? Or perhaps the interval between sateliite images is large enough that the image was just out of date?

[lolife]

did u check infared? satalite only works when it's sunny, or atleast most of them do, like weatherbug.

Yes, it was infrared I was looking at...

[RussD]

Ok, time to put my meteorology degree to work...

This is not uncommon, low level clouds often do not show up well on IR satellite images.

The images require that the cloud tops are of different temperature than the ground in order to show up at all. Last night the tops of those low lying clouds were very close in temperature to the ground so they did not show up very well in the IR satellite pictures. I took a look at the weather service balloon sounding data from last night which showed the cloud top temperature to be at about 59 degrees F.

The ground temp early in the evening was just about 60 degrees. Which is why the clouds did not show up very well at all on the IR imagery.

It looks like those low level clouds were caused by the high pressure system that was just off to our NE. The air to our NE was significantly cooler and the air over us...just after sunset that dome of high pressure oozed our way cooling the moist air at the periphery creating a slowly westward marching cloud bank. Interestingly you can see this cloud "ring" that evenually formed all around the high pressure system in this satellite picture by this morning...

http://www.mnastro.org/forums/album_page.php?pic_id=121


Russ

[lolife]

Ok, time to put my meteorology degree to work...
Russ

Thanks, Russ, that's what I was thinking must be happening. The air temp was about 58 degrees so the clouds were indistinguishable from the ground. It cost me a night, dab nabit.

I always ignore the visible (non-infrared) stuff but perhaps if I had looked at that I would have seen something fishy prior to sunset.

Cheers,
Michael

[RussD]

Cost me a night too, but my commute was just 10 feet. Still, just as I was gearing up for the night those clouds rolled in.

I have made the habit of looking at the visual loop and the infrared loop just to make sure I am not missing something. Usually it works. But not always.

Russ

[mlfj4901]

Greetings,

So you have a meterology degree eh russ?

Does that make you similar to a weather man?

If it does perhaps every night you could predict/forcast a cloudy night with bad seeing.

Seriously though, thanks for the explanation on those fast moving clouds. Thankfully I only walked about the same 10 feet you did before packing my scope back up and walking back inside with my head hanging low.


-matt