*POSH -Probability of Severe Hail. Severe hail is defined as hail over three-quarter inch in diameter.
*TVS -A TVS (Tornado Vortex Signature) is a Doppler radar alarm resulting from at least 45-knot outbound adjacent to at least 45-knot inbound radial velocity.
A TVS on radar does not necessarily mean a tornado is occurring. To be a tornado the circulation must be on the ground.
The radar is not able to tell if the "tornado signature" is on the ground.
*ETVS -A ETVS (Elevated Tornado Vortex Signature) is a circulation that does not extend all the way to the lowest tilt on radar, but is strong among the other tilts.
*3DC Shear -Some weak inner-cloud rotation has been detected.
*Meso -Mesocyclone -A storm-scale region of rotation, typically around 2-6 miles in diameter and often found in the right rear flank of a supercell
(or often on the eastern, or front, flank of an HP storm). The circulation of a mesocyclone covers an area much larger than the tornado that may develop within it.
Properly used, mesocyclone is a radar term; it is defined as a rotation signature appearing on Doppler radar that meets specific criteria for magnitude,
vertical depth, and duration. Therefore, a mesocyclone should not be considered a visually-observable phenomenon
(although visual evidence of rotation, such as curved inflow bands, may imply the presence of a mesocyclone).
*Storm Track -This is a visual aid to help show predicted speed and direction of storm cell paths over the next hour.
Storm tracks consist of white lines with Xs at the 15 minute marks. Shorter lines are slower storms; longer are faster.
*DBZ -"dBZ" stands for decibels of Z, Z being the reflectivity factor. The higher the reflectivity factor, the heavier the rainfall.
Reflectivities in the range between 5 dBZ and 75 dBZ are detected when the radar is in precipitation mode.
Reflectivities in the range between -28 dBZ and +28 dBZ are detected when the radar is in clear air mode.
*Severe Thunderstorm -A severe thunderstorm is a thunderstorm which produces hail 3/4 inch,
and/or damaging winds or wind greater than 50 Knots (58 MPH), and or a tornado.
Weather Fronts
Cold Front - a zone separating two air masses, of which the cooler, denser mass is advancing and replacing the warmer.
Warm Front - a transition zone between a mass of warm air and the cold air it is replacing.
Stationary Front - a front between warm and cold air masses that is moving very slowly or not at all.
Trough - an elongated area of relatively low atmospheric pressure; the opposite of a ridge. On HPC's surface analyses, this feature is also used to depict outflow boundaries.
Occluded (Blocking) Front - a composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front. Two types of occlusions can form depending on the relative coldness of the air behind the cold front to the air ahead of the warm or stationary front. A cold occlusion results when the coldest air is behind the cold front and a warm occlusion results when the coldest air is ahead of the warm front.
High - A region of high pressure, marked as a blue "H" on a weather map. A high is usually associated with fair weather.
Low - A region of low pressure, marked as "L" on a weather map. A low center is usually accompanied by precipitation, extensive cloudiness, and moderate winds.
