Radar Palette Home Click Conventional Pre-warm Frontal 1 Ahead of WCB Classic area for virga...

Pre-warm Frontal 1Radar Palette Home Click Conventional

Ahead of WCB

• Classic area for virga• Probability of virga increases with strength and

dryness of the CCB and the strength and moisture of leading branch of the WCB

• Katabatic portion of warm front

Click for the Conceptual Model and Explanation


WCB

CCB

Warm Frontal Cross-section along Leading Branch of the Warm Conveyor

Belt (WCB)

Cold air in Cold Conveyor Belt (CCB) deep and dry

Moist portion of Warm Conveyor Belt (WCB) is high and veered from frontal perpendicular – katabatic tendency

Dry lower levels of WCB originate from ahead of the system and backed from frontal perpendicular

Mixing Zone

SurfaceWarm Front

Frontal slope is more shallow than the typical 1:200

Precipitation extends equidistant into the unmodified CCB

Precipitation extends further into the moistened, modified CCB

Increasing CCB Moistening

WCB oriented for

maximum frontal lift

WCB oriented for

less frontal lift

Virga Precipitation

Lower

Hydrometeor

Density

Common location for virga A

B

A B

WCB typically veers with height (it is after all, a warm front)

Link to ClassicExample


Vertical Deformation Zone Distribution and the CBMSummary

C

C

C

C

C

WC

B

DCB

CCB

DCB

C


Inactive or Katabatic Warm Front


Ahead of WCB Ex 3C


Under WCB

• Virga only likely on the leading edge of the WCB• The CCB is becoming increasingly moist• Frontal overrunning and isentropic lift is

increasing thus increasing the intensity of the precipitation process.

• Warm front becoming more likely Anabatic



WCB

CCB

Warm Frontal Cross-section along Central Branch of the Warm Conveyor

Belt (WCB)

Cold air in Cold Conveyor Belt (CCB) more shallow and moist

Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and perpendicular to front

Lower levels of WCB have the same origin as the upper level of the WCB - frontal perpendicular

Mixing Zone

SurfaceWarm Front

Frontal slope is near the typical 1:200

Precipitation extends further into the moistened, modified CCB. Horizontal rain area begins to expand as CCB moistens.


WCB oriented for


Virga Precipitation

Lower

Hydrometeor

Density


B

A B

WCB shows little directional shift with height. A greater WCB depth is frontal perpendicular

PrecipitationAt Surface



C

C

C

C

C

WC

B

DCB

CCB

DCB

C


Active or Anabatic Warm Front


Behind WCB

• Virga much less likely• The CCB has become moist• Frontal overrunning and isentropic lift is

maximized thus maximizing the intensity of the precipitation process.

• Warm front is likely Anabatic



WCB

CCB

Warm Frontal Cross-section along Trailing Branch of the Warm Conveyor

Belt (WCB)

Cold air in Cold Conveyor Belt (CCB) even more shallow and more moist

Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and backed from frontal perpendicular – anabatic tendency

Lower levels of WCB have the same origin as the upper level of the WCB

Mixing Zone

SurfaceWarm Front

Frontal slope likely steeper than the typical 1:200

Precipitation extends further into the moistened, modified CCB. Horizontal rain area expands rapidly as CCB moistened.


WCB oriented for


Virga Precipitation

Lower

Hydrometeor

Density


B

A B

WCB probably backs slightly with height in spite of the warm air advection. A greater WCB depth is frontal perpendicular

PrecipitationAt Surface



C

C

C

C

C

WC

B

DCB

CCB

DCB

C


Active or Anabatic Warm Front


Behind WCB


This must be and remain as Slide 31.

• The links to the three sections of the airflows that comprise each of the conveyor belts are located at Slide 1,11 and 21.

• Slide 11 is always the central, col limited circulation.

• This leaves 10 PowerPoint slides for the development of the training material which should be more than adequate.

Radar Palette Home Click Conventional Pre-warm Frontal 1 Ahead of WCB Classic area for virga...

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