Anyone who looked at radar animation of this past weekend's nor'easter would have quickly noticed an intense precipitation band that stretched from Long Island northward into Connecticut. This band, at times, had dBZ values that were higher than 55 dBZ, and predominantly produced snow. (There are some reports that in southern Connecticut sleet or maybe small hail were also reported.) Beneath this band snowfall accumulations were upwards of 6" per hour!

For those who did not witness this band in person, I have put together an animated gif depicting the evolution of this band. The animation begins near 23 UTC on 08 Feburary 2013 and ends 06 UTC on 09 Feburary 2013. The four panels are:

• Upper Left: Lowest Tilt Base Reflectivity
• Upper Right: Lowest Tilt Correlation Coefficient
• Lower Left: Lowest Tilt Base Velocity
• Lower Right: Lowest Tilt ZDR

You may recognize the background. It's the black and white version of the GRx Population Backgrounds, which were announced in this post.

For a larger image animation, click on the image above to get the full resolution. Warning, it's about a 22MB animation!

Tonight I created a couple of Gibson Ridge Radar Viewer backgrounds that display the 2010 population data on a 5km grid. You can see a color and black and white version below. Since the background images are actually displaying interesting data, I’ve also provided a colorbar for both of these images. The color curve is logarithmic.

and

You can see what they look like in GR by looking at this and this. If you would like to download these background images, you can get the color version here and the black and white version here.

To install, you will need to:

1. Start GR
2. Click on “GIS” in the menu across the top
3. Click on “Setting” in the resulting drop-down menu
4. Click on “Backgrounds…” in the resulting drop-down menu
5. Select the file you downloaded. (You will need to unzip the zip file if you haven’t already.)
6. Enter the longitude and latitude values for the various corners. These are:
   • Left Lon: -125.
   • Right Lon: -63.
   • Bottom Lat: 22.5
   • Top Lat: 50.
7. Select “OK”

If you like these, please let me know!

For the final post (at least for now) in this sequence of estimating the climatological probability of an occurrence of some sort of severe weather phenomena, I turn my attention to day 1 severe weather outlooks from the Storm Prediction Center.

I used a similar method as with the previous graphics, however, because the severe weather outlooks are larger in size than severe weather reports, I used a smaller spatial smoother. (In fact, you can do the analysis without using a spatial smoother, but the probability edges are jagged.) The spatial smoother is 80km, and affects the resulting probability magnitudes by less than 1% for slight risks.

For more animations, check out the original post, the “non-significant” severe first post in this series, or the "significant severe" second post! As with the previous graphics, the raw images should become available on the Storm Prediction Center’s website in the coming weeks.

Because the image quality is a bit degraded in the animations, the color scales for each animation are listed below.

I’ve now uploaded the animations of estimates climatological probabilities of F/EF-1 or greater tornadoes, Hail 1″ or greater, and significant severe weather. The probabilities are estimated from the 30 year period of 1982-2011. Probability animations exist for tornadoes, hail, wind, and any severe. For more information check out the original post or the post on the “non-significant” severe! The raw images should become available on the Storm Prediction Center’s website in the coming weeks.

Because the image quality is a bit degraded in the animations, the color scales for each animation are listed below.

I’ve cleaned up and finally uploaded the animations of estimates climatological probabilities of severe weather. The probabilities are estimated from the 30 year period of 1982-2011. Probability animations exist for tornadoes, hail, wind, and any severe. For more information check out the original post! The raw images should become available on the Storm Prediction Center’s website in the coming weeks.

Because the image quality is a bit degraded in the animations, the color scales for each animation are listed below.