More examples?

Where do you expect what kind of fronts?

Slim WF?

Stronger kinkWeaker kink

0

0,2

0,4

0,6

0,8

1

1,2

0 20 40 60 80 100

phi (min (Azi-dir))

co

s p

hi

Stronger

weaker

Vrcos term related to sight azimuth

(1)

(1): line of same radar sight. Any change of Vr due to wind dir (or wind speed).(2): Front line at least line of wind dir change, so Vr change ( „Radial shear“).

(2)

Uniform wind veering at front (arrows)

Zero

line

Frontal signs more intense near zero line sector

Frontal change:

Phi (angle Dir, Azi)

phi1

phi2

~20°

const. sight

Radial shear

Azi

sh

ear

Prefrontal: blue line Vr intensifies radially red line Vr decreases radially

Radar

Radar

Often the frontal wind shift is only a narrow corridor

Postfrontal: blue line Vr ….……….. radially red line Vr ….………… radially

Radar

Remember: Vr closer to zero line: weaker!

Pull right line into diagramm position:

intensifies decreases

?

?stronger

CAPPI1

?

Vr increase postfrontal?

Warm con belt

Cold con belt

PU4UMD

MUC

MUC

When , compared to high warm air advection a very different low wind is indicated, it is then the cold prefrontal wind, nearly front parallel.

CAPPI 1-4, wind shift

UMD

Extreme CAPPI shear in H4

4

1

LIN, 18UTC

warmCCB warmwarmcold

slow

Wind backing!?

Discrepancy between height of assumed VAD frontal zone and surface position?

CAPPI1 PPI

H2

Stationary fronts, same case

12UTC

2

Close to surface warm front?

Weak flow, stationary front

WA

coldCAPPI3CAPPI1

CAPPI H1

1

2

Front position?

Band in H3km?

2

1

Here frontal wind shift identical with max. vertically veering?

…slow front

BB

band

06UTC

WF

PPI 0,3°

low

higher

What we want is a spatial front position: Severe kink in zero line = front there

Zero line