Garmin Flight Deck 100 Marine Instruments User Manual


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Embraer Prodigy
®
Flight Deck 100 Pilot’s Guide
190-00728-04 Rev. A
366
HAZARD AVOIDANCE
In areas ofmultiple heavycells, usethe Vertical Scanfeaturealong withantenna tiltmanagement to
examinetheareas.Remembertoavoidshadowedareasbehindtargets.
Figure 6-58 The Blind Alley
The Blind Alley at Close Range The Large Storm Behind
tornaDoes
Therearenoconclusiveradartargetreturncharacteristicswhichidentifyatornado.However,tornadoes
maybepresentifthefollowingcharacteristicsareobserved:
•Anarrow,nger-likeportionextendsandinashorttimecurlsintoahookandclosesonitself.
•Ahook,whichmaybeinthegeneralshapeofthenumeral6(numeral9inthesouthernhemisphere),
especially if bright andprojecting from the southwest quadrant(northeast quadrant in the southern
hemisphere)ofamajorthunderstorm.
•V-shapednotches.
•Doughnutshapes.
Theseshapesdonotalwaysindicatetornadoes,andtornadoreturnsarenotlimitedtothesecharacteristics.
Conrmedradarobservationsoftornadoesmostoftenhavenotshownshapesdifferentfromthoseofa
normal thunderstorm display.
hail
Hail results from updrafts carrying water high enoughto freeze.  Therefore, the higherthe top of a
thunderstorm, the greater the probability that it contains hail. Vertically scanning the target return can
givetheradartopofathunderstormthatcontainshail.Radartopisthetopofastormcellasdetectedby
radar.Itisnottheactualtop,ortruetopofthestorm.Theactualtopofastormcellisseenwiththeeyes
inclearairandmaybemuchhigherthantheradartop.Theactualtopdoesnotindicatethetopofthe
hazardous area.
Hailcanfallbelowtheminimumreectivitythresholdforradardetection.Itcanhavealmofwateron
itssurface,makingitsreectivecharacteristicssimilartoaverylargewaterdroplet.Becauseofthislmof
water, and because hail stones usually are larger than water droplets, thunderstorms with large amounts
ofwethailreturnstrongersignalsthanthosewithrain.Somehailshaftsareextremelynarrow(100yards
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