Severe Weather Radar Features

Weak Echo Region (WER) Region of low radar reflectivities on inflow side of storm o Near the surface High reflectivities on only one side o High reflectivity gradient Forms as updraft intensifies o Rain and hail are carried upward by the updraft leaving a region of low reflectivity o Precip “hangs over” the WER as well WER is capped by high reflectivities in the vertical.

Weak Echo Region (cont.) WER Sharp reflectivity gradient

Weak Echo Region Vertical Structure Capped by high reflectivities WER Strengthening updraft WER

Bounded Weak Echo Region (BWER) Region of lower reflectivities bounded on most or all sides by high reflectivities o WER continues to develop and precip now falls on all sides of updraft o Not present in all storms or supercells Seen high in storm o Begin at 8-25 thousand feet o Must use higher tilts to see o “Doughnut” appearance Associated with very strong updrafts o Can imply a transition to severe status

BWER (cont.) BWERLess distinct BWER Very good example by OCS showing BWER with height BWER

BWER Vertical Structure BWER Strong updraft BWER

Three-Body Scatter Spike Radar energy reflects off the hail, to the ground, back to the hail, and then finally back to the radar. o Creates “spike” of reflectivity behind the storm Relative to the radar (“downstream from the radar”) o Extends back from the high reflectivity core Feature gets clearer at elevated heights o Use higher scans o Feature appears larger with height Can indicate large hail o Severe storms o 1/3 of severe storms have three-body scatter spikes

Three-Body Scatter Spike

Rear Inflow Jet Seen usually with squall lines (Quasi Linear Convective Systems) “Bowing” of the line segment Can indicate strong straight-line wind potential Descending core of strong winds Originates aloft (~10,000 feet)

Rear Inflow Jet (cont.)

Hook Echo Precip is wrapped around updraft by mid-level mesocyclone o Hook will have cyclonic shape Indication of rotation o Tornado possible Region of low reflectivities inside hook, marks the updraft

Velocity Couplet Seen in velocity images o Green: air moving toward radar o Red: air moving away from radar Indicates rotation o Possible tornado If persistent and occurs at different levels Should correlate with a hook echo in supercells. o Make sure to always correlate with reflectivity.

Warning or no Warning