severe weather radar features. weak echo region (wer) region of low radar reflectivities on inflow...

Severe Weather Radar Features

Weak Echo Region (WER)

• Region of low radar reflectivities on inflow side of stormo Near the surface

• High reflectivities on only one sideo High reflectivity gradient

• Forms as updraft intensifieso Rain and hail are carried upward by the updraft leaving a

region of low reflectivityo 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 reflectivitieso WER continues to develop and precip now falls on all sides of

updrafto Not present in all storms or supercells

• Seen high in storm o Begin at 8-25 thousand feeto Must use higher tilts to seeo “Doughnut” appearance

• Associated with very strong updraftso Can imply a transition to severe status

BWER (cont.)

BWER Less distinct BWERVery good example by OCS showing BWER with height

BWER

BWER Vertical Structure

BWERStrong updraft

BWERBWER

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 heightso Use higher scanso Feature appears larger with height

• Can indicate large hailo Severe stormso 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

mesocycloneo Hook will have cyclonic shape

• Indication of rotationo Tornado possible

• Region of low reflectivities inside hook, marks the updraft

Velocity Couplet• Seen in velocity images

o Green: air moving toward radaro Red: air moving away from radar

• Indicates rotationo 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