Forecasting Technique: Pattern Recognition

• Associating a “weather pattern” to a “weather event”

• Significant weather events have patterns– surface features

– upper level features

– 4-panel maps useful

Pattern Recognition: Severe Weather

• Dynamics– Wind-driven

• Thermodynamics– Stability-driven

Pattern Recognition: Severe Weather

• Dynamics (winds)– Shortwaves

• jet streaks, vortmax’s

– Fronts• mech. lift

• Thermodynamics (stability)– LI’s, CAPE– Low-level moisture (Td’s)

Severe1: Radar

Severe1: Severe WX Reports

Severe1: 500mb

Potentshortwaveapproaching- > 28 max-> cold air

Case 1: 700mb

Slight drypunch at700mb->pot inst

Vigorousflow at700mb

Case 1: Surface

Cold frontapproaching

Case 1: ETA Lifted Index

Apex/tongue oflow stabilityair

Case 1: ETA/NGM Precipitation

Local max higher in ETA Local max lower in NGM

Case 2: Radar

Case 2: Severe Wx. Reports

Case2: 4-PANEL MAP, 18Z

Case2: 4-PANEL MAP, 00Z

Change of 700mb UVV

Signature of Intensification!

18z 00z

Case2: CHANGE OF Vertical Velocity

Case2: Lifted Index

Apex/tongue oflow stabilityair

Severe2: Sounding

Is this sounding conducive for deep convection?

Severe2: Surface features

High Td’s+High T’s = High

Other patterns

• Strong shortwave coming from the Rockies– Adds additional lift– Brings the dryline into play– Can draw high theta-e air north from Gulf– Warming on Front Range of Rockies from

downsloping