Post by ironman2323 on Sept 3, 2013 23:32:37 GMT
Very interesting stuff was observed today in New London County Connecticut. The NWS New York NY received multiple reports of large hail in the county. Many were of quarter size in New London, Groton, and Montville, but in Ledyard hail up to 1.75 inches was observed.
Dual polarization data from KOKX gives us some excellent insight to whats going on inside this storm to help with warning operations and also verifying reports and whats happening at the ground.
For those not familiar with Dual Polarization, head to these links.
www.wdtb.noaa.gov/courses/dualpol/outreach/
www.wdtb.noaa.gov/courses/dualpol/trainingaid/ <<<has nice modules when you click a variable which give great info and charts for what the values mean!
The variables in the image below are Reflectivity (Z, top left), Differential Reflectivity (ZDR, top right), Correlation Coefficient (CC, bottom left), and Specific Differential Phase (KDP, bottom right). I will summarize what you are seeing with the variables below.
ZDR is the ratio of the horizontal reflectivity to the vertical reflectivity. The ZDR is generally high with the reds and yellows in the region with the highest Z. This is an indication of large rain drops or giant drops with some ice or hail mixed in. But under the red square you will see some very low ZDR in the greys and blues. This is an indication of large hail. When you have ZDR this low, it means the horizontal and vertical pulses are almost the same (not exactly the same) which with hail being more spherical, you will see a lower ZDR.
CC is the measure of how similarly the horizontal and vertical returned powers behave among all pulses within a volume scan. The dark reds and purples are indicating a near "1" correlation or a horizontal and vertical returned power that are nearly the same. This means similar sized rain drops or similar hydrometeors. However, the yellows and oranges and are lower, between .8 and .9, which means the sizes and shapes are not all the same. This is a great indicator of large hail mixed in with rain...different size and shapes of hydrometeors.
KDP is more difficult to understand so I will not explain the complete science here. I will let you learn about it from the link above. However it is generally a measure of the liquid water content. The brighter the colors the heavier the rain. In the image, you seen some greens which is very heavy rain occurring but just next to it are much lower values. When you have a lower KDP like this and a high Z, it suggests the contribution to Z is likely from hail and not from liquid. There could be hail in the higher KDP, but it is likely melting.
I hope you enjoyed this post. Here are two pictures tweeted from Meteorologist Ryan Hanrahan from NBC Connecticut. These came from the region under this hail core.
Dual polarization data from KOKX gives us some excellent insight to whats going on inside this storm to help with warning operations and also verifying reports and whats happening at the ground.
For those not familiar with Dual Polarization, head to these links.
www.wdtb.noaa.gov/courses/dualpol/outreach/
www.wdtb.noaa.gov/courses/dualpol/trainingaid/ <<<has nice modules when you click a variable which give great info and charts for what the values mean!
The variables in the image below are Reflectivity (Z, top left), Differential Reflectivity (ZDR, top right), Correlation Coefficient (CC, bottom left), and Specific Differential Phase (KDP, bottom right). I will summarize what you are seeing with the variables below.
ZDR is the ratio of the horizontal reflectivity to the vertical reflectivity. The ZDR is generally high with the reds and yellows in the region with the highest Z. This is an indication of large rain drops or giant drops with some ice or hail mixed in. But under the red square you will see some very low ZDR in the greys and blues. This is an indication of large hail. When you have ZDR this low, it means the horizontal and vertical pulses are almost the same (not exactly the same) which with hail being more spherical, you will see a lower ZDR.
CC is the measure of how similarly the horizontal and vertical returned powers behave among all pulses within a volume scan. The dark reds and purples are indicating a near "1" correlation or a horizontal and vertical returned power that are nearly the same. This means similar sized rain drops or similar hydrometeors. However, the yellows and oranges and are lower, between .8 and .9, which means the sizes and shapes are not all the same. This is a great indicator of large hail mixed in with rain...different size and shapes of hydrometeors.
KDP is more difficult to understand so I will not explain the complete science here. I will let you learn about it from the link above. However it is generally a measure of the liquid water content. The brighter the colors the heavier the rain. In the image, you seen some greens which is very heavy rain occurring but just next to it are much lower values. When you have a lower KDP like this and a high Z, it suggests the contribution to Z is likely from hail and not from liquid. There could be hail in the higher KDP, but it is likely melting.
I hope you enjoyed this post. Here are two pictures tweeted from Meteorologist Ryan Hanrahan from NBC Connecticut. These came from the region under this hail core.
