Category Archives: Weather

Breaking weather news, updates, and long-range forecast discussion for the Charleston, SC metro area.

Derived Parameters in Unidata AWIPS on macOS

I have a really big post in the works about how I’m using Unidata’s fork of AWIPS II for weather stuff these days on my Macs. It has come a long way in a year, and I’m really digging it. (In fact, I have it up on a monitor at virtually all times at home these days as a situational awareness display.) In the meantime, I wanted to share an important finding on its own that may help a lot of struggling AWIPS users out there. Continue reading

AWIPS animation of visible satellite on Friday, December 16.

AWIPS animation of GOES-East visible imagery on December 16, 2016. Roll clouds are very evident in this imagery. Also note the hard edge of the cloud canopy of the cool air wedge in place around Lumber City, GA.

Yesterday’s skies were particularly awesome, with lots of roll clouds on display. Shea Gibson of WeatherFlow shared some photos from the ground as well as a great explainer on how the clouds ended up like they did over on Facebook.

The only thing more fun than armchair storm chasing with RadarScope or the Gibson Ridge suite is finding all the non-meteorological things on radar, such as this roost ring of birds that happens on cue at sunrise during the summers at Lake Moultrie.

Timelapse: One Storm Dies, Another’s Born

A severe-warned thunderstorm that produced quarter-size hail in Hanahan missed my part of West Ashley to the northeast this afternoon. However, this thunderstorm produced an outflow boundary which intersected with the seabreeze over the Charleston/Dorchester county line to generate new showers and thunderstorms. These thunderstorms pushed east and dropped a brief amount of rain and a little wind before moving on to the southeast.

Summer is the best.

I took some opportunities this past weekend to get my feet really wet with the GoPro’s time-lapse shooting capability. Here’s a couple hours of shots watching the skies ahead of a potent evening thunderstorm on Hilton Head Island.

Tornado debris signature on April 28, 2014 in SE Tennesee.

Tornado debris signature as seen by the Hytop, AL radar (KHTX) on the night of April 28, 2014. Clockwise from left: Base reflectivity, storm relative velocity, correlation coefficient, differential reflectivity (ZDR). Tornado debris signature is where the “debris ball” of high reflectivity (reds and pinks) colocate with the strong velocity couplet (reds and yellows next to greens in the velocity image), the drop in correlation coefficient (blue circle) and ZDR (gray areas).

Dan Satterfield: NWS Weather Radar Upgrade Proving Wildly Successful

Dual-polarization is a new thing, but I sure don’t know how I or anyone else confidently interpreted radar without it. There is little doubt that the confidence dual-pol products lend to warning forecasters and broadcast meteorologists conveying those critical messages saved a lot of lives on April 28. (Unfortunately, 36 people have died as a result of the outbreak, so there is still plenty of work to be done.)

GR2Analyst 2.0 is a really welcome upgrade

GR2Analyst 2.0 radar screenshot

GR2Analyst 2.0 (branded as #chswx Analyst) looking at the KGSP radar Saturday afternoon. (Alas, a quiet day in Charleston.)

A big upgrade to one of my go-to radar analysis tools, GR2Analyst 2.0, is now out, allowing for a uniform presentation between it, GRLevel3, and GREarth, all tools I use on a regular basis. Here’s what I particularly like about GR2Analyst 2.0 (and, in many cases, the 2.x series of GR products in general):

  • Easy movement between panel configurations. The GR radar viewers let you split the screen into 2 and 4 panels to assist in more rapid and accurate diagnosis of radar features, and you can assign up to 8 panel configurations to the number keys 1-8 for quickly flipping through them. For instance, I’ll be looking at radar when I see an area of what looks like rain moving into the area; I can hit the ‘4’ key which brings up a two-panel view of reflectivity and correlation coefficient (a dual-polarization product) which can pretty quickly tell me if I’m dealing with something meteorological or not. I also have presets saved with four-panel views of varying tilts of a storm’s reflectivity and velocity, a four-panel view for tornado debris detection, as well as a four-panel view which focuses on locating areas of damaging winds and large hail. I have similar presets in GRLevel3 especially surrounding hydrology (rainfall products do not currently exist in GR2Analyst because they are not base data).
  • Right-click to zoom. Previous versions of the GR products required enabling a separate zoom tool; now, just hold the right mouse button and drag and it zooms in on an area. This works really well on my Magic Mouse; on the trackpad, I more typically just flick upward to zoom in, though if I hold Control and drag, that will have the same effect.
  • A cleaner overall presentation. Being able to choose the widths of lines and add borders and highlights to many of them reduces the potential for confusion between state and county lines when using shades of gray to delineate them. I also appreciate that cities are outlined and not tied to a specific point and that warnings have similar borders and highlights now. One cool thing in the 2.x GR products is their ability to parse through tornado warning text and apply special highlights if the tornado is reported on the ground or the NWS employs “Tornado Emergency” wording.
  • A long-standing bug with Flash Flood Warnings has been fixed. In previous versions of GR2Analyst, if a flash flood warning is extended using a Flash Flood Statement, it did not know about it and would remove or fail to rebox the polygon despite the fact the warning would continue for at least part of the area. The 2.x series of GR products fixed this bug and I’m glad I’ll have consistent flash flood polygon display again across all my software packages.
  • I can maintain one set of color tables. At long last, my gigantic GR 1.x color table folder can either be purged or converted to GR 2.x-compatible color table files. Incompatible color tables were a big growing pain during the transition to the new products; I’m glad this transition is over for me. (People who use vanilla GRLevel2 will still need to maintain older color tables.)

The GR 2.x series also ships with the ability to acquire high-resolution background imagery from various sources (depending on zoom level). While beautiful, the Landsat imagery isn’t terribly compatible with a lot of my more advanced color tables designed to help subtle features stand out; I also find that in my Windows XP virtual machine the Landsat background, when combined with the METAR placefile from AllisonHouse, causes a big drag on performance. I’m not sure if I’m going to keep the background enabled in Analyst as a result. Otherwise, though, performance is great in the VM — really surprisingly good considering it is running against a Core 2 Duo.

All in all, the new GR2Analyst will make it that much easier to do what I do over on @chswx, and that is pretty outstanding. (A free upgrade because I bought the dual-polarization addon for 1.x helps, too.)

More flooding in downtown Charleston today

I feel like a broken record on the weather side these days mentioning storms every day. This year has just been utterly ridiculous for rainfall (33″ as of today) and for the second time in two weeks downtown Charleston flooded again after thunderstorms packing 1-3″/hr rain rates trained over Charleston, one after the other, right at time of high tide, which also coincided with the evening rush. Makes for an awesome night!

The National Weather Service has a Facebook gallery; also check out Holy City Sinner’s photo gallery.

I’m ready for a drier pattern…

Link

Return of the #chswx blog!

An issue with nginx rewrite rules would not let my image uploads be great, but that’s all settled now. I’m looking to transition away from so much reliance on Twitter and switch to more of a live blog format during events (though weather Tweets won’t go away). The P2 theme lets me create a fully integrated environment to receive storm reports on a thread, which is awfully nice. Keep this page bookmarked as I’m going to try out a few cool things there. (Eventually, the whole chswx.us site will run on WordPress — stay tuned.)