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Winter Weather Pattern Recognition

Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

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Page 1: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Winter Weather Pattern

Recognition

Page 2: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (500mb)• Trough or upper level low to the west

o Source for upper level divergence (rising motion) and southerly winds which bring moisture and low-level warmer air northward

• Short wave trough or long wave trough generally to the northeasto Source of near surface cold air

• Cold front associated with the upper level trough • Typically shallow arctic air

Page 3: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (500mb)

Page 4: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (500mb)

Page 5: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (850mb)• Southerly component to the wind

o Warm air advection

• Warm (above freezing) temperatures o Must melt the falling snow

Page 6: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (850mb)

Page 7: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (Surface)• Surface temperatures obviously must be below

freezing• Low pressure to the west• High pressure in the northern plains or upper

Midwest• Northerly component to the winds

o Cold air advection

Page 8: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm (Surface)

Page 9: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Typical Sounding

Page 10: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (500mb)

• Long wave trough with embedded short wave trough or upper-level closed lowo Upper-level low tends to track over northern Texas

Page 11: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (500mb)

Page 12: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (850mb)

• Low pressure to the east• Cold air (below freezing)• Northerly winds

o Cold air advectiono Frequently strong

• Blizzard

• Gulf moisture to the east or southeasto Advected around the cyclone

Page 13: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (850mb)

Page 14: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (850mb)

Page 15: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (Surface)

• Surface low to the east• Sustained winds (or frequent gusts) of 35+ mph

and visibility of less than ¼ mileo Must be present for at least 3 consecutive hours for a blizzard

• Dense packing of isobars (blizzard)o “Tight” pressure gradient

• Strong winds

• Northerly component to wind

Page 16: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Blizzard/Snow Storm (Surface)

Page 17: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Typical Sounding

Page 18: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

500mb Vorticity Average Tracks

From Vanyo 2010

Page 19: Winter Weather Pattern Recognition. Ice Storm (500mb) Trough or upper level low to the west o Source for upper level divergence (rising motion) and southerly

Ice Storm, Blizzard, or Snow

Storm?

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