Author: Zac

Surface Weather Mobile

Surface Weather Mobile provides surface weather observations of temperature, dewpoint, pressure, wind, visibility and ceiling across the United States from automated weather observing systems (AWOS/ASOS).

With Surface Weather Mobile you can examine the current temperature, dewpoint, pressure, wind, visibility and ceiling across the United States.

Soundings Mobile 1.3 Update!

A new Soundings Mobile update is out which will improve the reliability of observed sounding data. The data is now being provided by AllisonHouse, so many thanks to them!

With Soundings Mobile you can view atmospheric temperature and dewpoint profiles from select stations across the United States. If you’re interested in wind shear then there is a hodograph just for you! Wondering if the atmosphere is stable or not? Utilize the parcel displays to help judge instability!

WeatherWall Mobile 1.7 Released

WeatherWall Mobile 1.7 is now live in the App Store! This version comes complete with SPC Day 1 risks, severe thunderstorm & tornado warnings, color coded radars (blue for supports Dual-Pol, white for non Dual-Pol).

Additionally there are two new products, hydrometeor classification and azimuthal shear. Hydrometeor classification is useful for determining what types of hydrometeors (rain drops, large rain drops, hail) are present in the storm at the altitude of the radar beam, not the surface.

Azimuthal shear is useful for determining if there is rotation in a storm. Red areas indicate cyclonic rotation while blue areas indicate anti-cyclonic rotation. Compare base velocity and azimuthal shear for a tornado case:

Finally, a purely cosmetic change, the app features a new icon:

Grab the update now! As always, it is available in the app store.

Tornadic Debris Signature

The upgraded dual-pol 88Ds are very useful for determining if there is a tornado currently on the ground. Debris (vegetation and dirt) lofted into the atmosphere by the tornado creates tell tale drops in correlation coefficient. Watch the animated image below as the intense area of detected debris (dark blues initially) spreads out over time.

Version 1.1 of Soundings Mobile

A new update to Soundings Mobile has been released into the app store! This version features forecast sounding support from the NAM/GFS/RUC!

The iPhone version should be out in the very near future as well!

Soundings Mobile!

Soundings Mobile, our latest app, has been released into the app store! With Soundings Mobile you can view atmospheric temperature and dewpoint profiles from select stations across the United States. If you’re interested in wind shear then there is a hodograph just for you! Wondering if the atmosphere is stable or not? Utilize the parcel displays to help judge instability! Currently Soundings Mobile is iPad only but expect iPhone & iPod Touch support to be coming in early January.

Soundings Mobile isn’t the only project we’ve been working on! An update to our popular EF Scale app is now also available in the app store! This update adds the capability to easily share on Twitter and Facebook. A few minor bugs related to displaying of pictures were also corrected.

And finally how about a glimpse towards the future? Work has not stopped on WeatherWall Mobile either. Take a peak below at what the future my hold for that app!

WeatherWall Mobile Update 1.1

The much anticipated update to WeatherWall Mobile is now live in the App Store! This update brings many more dual-polarization radars into the app with the total now standing at 11 across the United States. Performance has been improved across all devices! A black map background option has been added as requested! Topography is now color shaded for a more realistic representation! Radar scan time can now be displayed absolutely or relatively! Plus many other additional features!

New products:
High Res VIL
Storm Total Accumulation

Feature Additions:
Map can now have a black or gray background.
Topography is now colored instead of monochromatic.
Radar reflectivity can now be used to contour, grayscale or mask other products.
Time displayed can either be relative to product or absolute time.
The radar range ring can now be turned on or off.
Find my location no longer adjusts zoom level.
Displayed cities no longer overlap, major and more populated cities are shown first.

Differential Reflectivity in Summertime Showers

With the newly upgraded dual-polarization weather radars it is possible to glean information about the distributions of water and ice inside of storms. This is very advantageous when trying to determine if a storm might be producing hail or just rain. Here is an example from the Vance AFB, OK radar of a few light summer time showers.

You can see in the reflectivity, located in the top panel, that one of the storms has reflectivity values of over 50 dBZ. In fact, looking at the contours on the bottom panel it is easy to see that there is a small region of >55 dBZ reflectivity. Now normally with reflectivity values >50 dBZ you might start to worry hail with the storm. However, in this case you can use the differential reflectivity (also called ZDR), located in the bottom panel, to distinguish between large rain drops and hail.

This brings us to a side discussion of what exactly is differential reflectivity? Well differential reflectivity is the log of the ratio of horizontal reflectivity to vertical reflectivity. The dual-pol upgrade to the radars modifies them so that they can transmit energy that is oriented both vertically and horizontally. This transmitted energy bounces off the cloud drops, rain drops, hail, etc located inside of a storm and returns to the radar. The radar is then able to measure how much if the returned energy is oriented vertically and horizontally, we refer to these values as the vertical reflectivity and horizontal reflectivity. The horizontal reflectivity is what we all know and love as the standard “radar reflectivity” product. Now the amount of energy returned to the radar that is oriented vertically depends the height of the rain, hail, etc. Likewise the amount of horizontal energy returned depends on the width of the rain, hail, etc.

So given this, if we have high differential reflectivity it means the rain, hail, etc is much wider than it is tall. This occurs when you have large rain drops, which given that they are falling end up elongated and wider than they are tall. If you have small rain drops they depend to be able to hold their spherical shape better which means the differential reflectivity is close to 0. What happens in the case of hail? Well hail tends to tumble as it is falling, which means that to a radar it will appear to be spherical thus giving you a differential reflectivity value close to 0.

Going back to the example figure above you can see an area of high reflectivity with correspondingly high differential reflectivity. This means that the most likely hydrometeor is a large elongated rain drop. In the example figure there is also a region of low differential reflectivity and correspondingly low reflectivity which can be associated with small spherical rain drops. If hail was present anywhere it would appear as a region of high reflectivity collocated with low differential reflectivity.

This is just one example of what you can do with the dual-polarization products!

WSR-88D Dual-Polarization Update Schedule

One of the unique capabilities of WeatherWall Mobile is the ability to view the dual-polarization products from the newly upgraded WSR-88Ds (Weather Surveillance Radar). So of course this begs the question of when will the updates be coming to a radar near you? Well here is the list of radars that have already been upgraded:

Radar Site Upgrade Completion Date
Vance AFB, OK (KVNX) March 4th, 2011
Phoenix, AZ (KIWA) June 5th, 2011
Morehead City, NC (KMHX) June 26th, 2011
Wichita, KS (KICT) July 17th, 2011
Pittsburgh, PA (KPBZ) July 17th, 2011

You might think this a random order for the radars to be upgraded in but it turns out to make a lot of sense. The radars that have been upgraded first are ones where a lot of research has been done on quality control and precipitation estimation. This plays a key role as the driving force behind the upgrades has largely been claims of improvement to rain estimates. The Phoenix area has been the focus of initial precipitation estimation work as the power provider in that region, the Salt River Project, has been very forward thinking in sponsoring hydrology related research.

Likewise, the Tar River in North Carolina is subject to one of the National Severe Storms Laboratory’s main hydrometeorology projects, CI-FLOW. This project is focused on total water levels from combined river flooding and storm surge during a hurricane. The forcing mechanism behind some of the models is radar rainfall estimates and so it makes sense to prioritize the dual-pol upgrade of the Morehead City, NC weather radar.

As the NWS gets more familiar with the dual-pol upgrade process the upgrading of radars will accelerate. Currently they are being upgraded 1 or 2 at a time but this should accelerate to 3 or more at a time through the end of this year and into next year as all of the radars are eventually updated. Here is the upgrade schedule for the rest of 2011:

Radar Site Upgrade Start Date Expected Completion Date
Spokane, WA (KOTX) September 12th, 2011 September 25th, 2011
Seattle, WA (KATX) September 26th, 2011 October 9th, 2011
Pendleton, OR (KPDT) September 26th, 2011 October 9th, 2011
Portland, OR (KRTX) October 10th, 2011 October 23rd, 2011
Chicago, IL (KLOT) October 17th, 2011 October 30th, 2011
Billings, MT (KBLX) October 24th, 2011 November 6th, 2011
Riverton, WY (KRIW) November 7th, 2011 November 20th, 2011
Cleveland, OH (KCLE) November 28th, 2011 December 11th, 2011
Goodland, KS (KGLD) November 28th, 2011 December 11th, 2011
Grand Rapids, MI (KGRR) November 28th, 2011 December 11th, 2011
Atlanta, GA (KFFC) December 5th, 2011 December 18th, 2011
Memphis, TN (KNOA) December 5th, 2011 December 18th, 2011