High Plains Drifter


disclaimer:  "The meteorological views/forecast thinking expressed are those solely of the author of this blog
and do not necessarily represent those of official National Weather Service forecast products,
therefore read and enjoy at your own risk and edification!"

July 19, 2008

Chase Acct: July 19, 2008 (Northwest KS)

Filed under: Chase Accounts,Storm Chasing — Mike U @ 1:11 am

I started this chase at 1:30 am.  Yes.  Since my sleeping schedule wasmessed up, I was pretty much up for good by that time.  With a fullmoon out, I decided to do some moonlit landscape photos at MonumentRocks north of Scott City.  By the time I got there around 4am, though,the moon was getting very low in the sky.  I experimented a bit with"flashlight illumination" of the Monument Rocks formation.  Overall, itwasn’t much of a success, as it’s difficult to spread even amounts ofillumination on such a large subject.  None of the images turned outall that great to my liking.  Sunrise was a little bit better, though,and I got some decent images in the sunrise light. 

 

 

 

Fast-forwarding to later in the day… 

This was kind of a gamble chase — gambling that there could possibly be anything of interest to photograph in terms of storm structure given the crappy summertime flow regime.  It was a gamble that I think paid off, because even though the storms I chased were barely severe, I managed to photograph some interesting storm structure — not necessarily updraft structure per-se, but beautiful, tall, contrasted rain-shafts, impressive rain-foots, and even some small/weak gustnadoes at the leading edge of outflow boundaries.  There was a brief moment of excitement north of Colby when two storms were converging on each other, ultimately forming a decent but brief rotating area when the storms converged.  At this point, a very nice looking and rather low-to-the-ground wall cloud formed — actually one of the better looking wall clouds I’ve seen all year!  It didn’t last long, though, and evolved into an outflow dominant shelf cloud.  I photographed probably 6 or 7 different storms over the span of about 3 or 4 hours from northwest of McCook to Atwood to southeast of Colby.  I witnessed and reported through SpotterNetwork 3/4" or larger diameter hail on two separate occasions – the largest hail witnessed being a piece just barely larger than a quarter just west of Atwood on the back edge of a storm.  I also saw a bunch of small, short-lived gustnadoes along an outflow boundary southeast of Colby.  I got one CG lightning image from the Lightning Trigger and that was it for the entire day from a lightning standpoint.  I got back home just after midnight — thus concluding my nearly 24-hour chase day!  I slept for 13 hours after that :)   Below are a few images from the chase:

 

 

 

 

 

July 17, 2008

Chase Forecast — July 17, 2008

Filed under: Chase Forecasts/Outlooks,Storm Chasing — Mike U @ 12:42 am

I will be chasing today, Thursday, July 17th.  It is my two days off between midnight and day shifts which start Saturday.  Obviously, with it being summer, the wind shear setup is less than ideal for long-lived supercell thunderstorms, but the thing today has going for it is a lot of moisture.  As I type, much of western Kansas is soaking in 65-67 degree dewpoints, with a 66 dewpoint at Imperial, NE.  Coincidentally enough, Imperial, NE is my target.  All the models generate quite a bit of convective precipitation, so I am giving today about a 60-75% chance of observing and photographing a severe thunderstorm of some sort in the target area of Southwest Nebraska and adjacent far Northeast Colorado.  Since I am fresh off midnight shifts, my sleeping pattern is F*d up.  My day has essentially begun at 1:30am.  I plan to do some moonlit landscape photography at the Monument Rocks north of Scott City before heading north toward the chase target.  I’ll probably get there late morning which will allow me to grab a midday power-nap of sorts before storms start developing.  

UTM Update — July 17, 2008

Filed under: UTM Updates — Mike U @ 12:31 am

Over the past week and a half or so, I have been adding a number of chase image albums dating back to Late May.  I have them updated through Day 5 of my late-June chase vacation.   Here is a list of the new storm photography albums.  These are all accessed through Under The Meso Collections (except May 21,22,23 — I forgot to include those for some reason, I’ll get those linked soon):

July 7, 2008

Nikon D3 & Night Sky Photography

Filed under: Photography — Mike U @ 11:56 pm

A test of super-ultra long exposure with Nikon D3.  After work on Sunday night, July 6th, I decided to drive south to my favorite nearby photography location — Big Basin Prairie Preserve.  I wanted to give the Nikon D3 + 14-24mm f/2.8 lens combination a try in some really low light conditions — the night sky.  I really was curious to try a super-ultra long exposure (greater than 30 minutes) to see how the sensor noise was leaving the shutter open for so long.  Digital imaging sensors will accumulate "hot" pixels the longer the shutter is left open.  As technology has improved in digital imaging sensors, the duration one can leave the shutter open without introduction of noise has greatly improved over the years.  I remember my very first digital camera was a point and shoot Nikon Coolpix 950.  You couldn’t take 8 second exposures without introducing all sorts of horrible "hot" pixels dotting your image.  When I then got my first digital SLR (Nikon D70) one of the first things I noticed was the absence of hot pixels at 8 to 30 seconds!  They were absolutely clean of noise at low ISO.  That being said, image sensor noise ("hot" pixels) started showing up at super long exposures of 5 to 10 minutes.  Also, this thing called "amp glow" also started showing up in the form of a pink blotchy area at the corner of a frame due to the sensor heating up.  Internal camera digital noise reduction can eliminate much of this by a simple technique called frame subtraction (whereby taking another black-frame exposure of the same time length and subtracting that from the original image).  The only kind of photography really needing this kind of long exposure is star trail photography, which require 30 minutes to 3 hours worth of exposure time, depending on how much trailing you are interested in for your shot.  

Along comes the D3.  I was really curious how long I could keep the shutter open on this camera before the hot pixels and/or "amp glow" became too much of a problem.  On the old D70 I had, the amp glow started really becoming a problem at about 8 to 10 minutes exposure time.  Below are two versions of the same image from the D3 I shot last night with a shutter speed of 3,650 seconds (1hr, 0min, 50sec).  The first is the processed version adjusting the exposure compensation, levels/curves, noise reduction in Adobe Lightroom:

 

In the 2nd image, which is unprocessed, you can barely pick out the slight purple-ish hue at the very bottom of the frame.  You really have to look closely, but it’s there.   This is a ONE HOUR exposure, and you have to squint to find the amp glow.  I think Nikon finally got it right with the D3 and hot pixel/amp glow digital sensor issues for exposures longer than 10 minutes.  Some of the star trails, though, have some holes in them, as if it wasn’t exposing properly for a bit during the one hour.  I can’t entirely explain what was going on there.

But here is what really excited me…

Milky Way looking south.  Nikon D3, 14-24mm f/2.8 lens @ 14mm.  Exposure 99s @ f/2.8, ISO 1250 

 

I couldn’t believe the detail I was able to capture here.  Of course, the artificial lighting on the horizon was a bit of a pain, but given this shot, I am excited to get out on another clear, moonless night absent of any horizon lights to shoot the Milky Way again.  A full album of images from last night (just 7 images), is available. 

Mike U 

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