Case Study:

Ernesto

August–September 2006

Jared Klein – SUNY - Albany

300 hPa Analyses: 1200 UTC 31 August 2006

300 hPa frontogenesis [K (100 km)−1 (3 h)−1], θ (K), and wind barbs (kt)

Jet much farther downstream than with Ivan (2004)

1.0° GFS

Precipitable water (mm), 300 hPa h (dam), wind speed (m s−1), and div (10−5 s−1)

300 hPa Analyses: 1200 UTC 1 September 2006

300 hPa frontogenesis [K (100 km)−1 (3 h)−1], θ (K), and wind barbs (kt)

1.0° GFS

Precipitable water (mm), 300 hPa h (dam), wind speed (m s−1), and div (10−5 s−1)

925 hPa Analyses: 1200 UTC 31 August 2006

925 hPa frontogenesis [K (100 km)−1 (3 h)−1], θ (K), and wind barbs (kt)

WSI radar, 925 hPa θe (K) and wind barbs (kt)

1.0° GFS

925 hPa Analyses: 1200 UTC 1 September 2006

925 hPa frontogenesis [K (100 km)−1 (3 h)−1], θ (K), and wind barbs (kt)

WSI radar, 925 hPa θe (K) and wind barbs (kt)

Highest reflectivity near nose of LLJ/θe ridge axis

Strong frontogenesis along warm frontal zone

1.0° GFS

Radar at 0000 UTC 1 September 2006

Qn div–con bands within coastal boundary as Ernesto nears landfall

Strong forcing for descent–ascent associated with Qn and Qs div–con

925 hPa Q Vector Diagnosis: 0000 UTC 1 September 2006

Q Qn

Qs

WSI radar

Q vectors (10−10 K m−1 s−1 beginning at 2.5 × 10−11), θ (K) contoured in green, and Q div–con (10−15 K m−2 s−1) shaded in cool–warm colors

1.0° GFS

Radar at 0600 UTC 1 September 2006

925 hPa Q Vector Diagnosis: 0600 UTC 1 September 2006

Q Qn

Qs

WSI radar

Highest reflectivity near strongest QG forcing for ascent

Q vectors (10−10 K m−1 s−1 beginning at 2.5 × 10−11), θ (K) contoured in green, and Q div–con (10−15 K m−2 s−1) shaded in cool–warm colors

1.0° GFS

Radar at 1200 UTC 1 September 2006

925 hPa Q Vector Diagnosis: 1200 UTC 1 September 2006

Q Qn

Qs

WSI radar

Highest reflectivity near strongest QG forcing for ascent

Q vectors (10−10 K m−1 s−1 beginning at 2.5 × 10−11), θ (K) contoured in green, and Q div–con (10−15 K m−2 s−1) shaded in cool–warm colors

1.0° GFS

Cross Section of Fn Magnitude: 0000 UTC 1 September 2006

925–500 hPa layer-avg Fn vectors (10−10 K m−1 s−1),θ (K) contoured in green, and Fn div–con (10−15 K m−2 s−1) shaded in cool–warm colors

Strongest frontogenesis focused near surface

1.0° GFS

Fn magnitude [K (100 km)−1 (3 h)−1] shaded in green–blue, RH shaded in orange, θ (K) contoured in gray, wind barbs (m s−1), and ω<0 (µb s−1) contoured in red

Cross Section of Fn Magnitude: 1200 UTC 1 September 2006

925–500 hPa layer-avg Fn vectors (10−10 K m−1 s−1),θ (K) contoured in green, and Fn div–con (10−15 K m−2 s−1) shaded in cool–warm colors

Strongest frontogenesis focused near surface

1.0° GFS

Fn magnitude [K (100 km)−1 (3 h)−1] shaded in green–blue, RH shaded in orange, θ (K) contoured in gray, wind barbs (m s−1), and ω<0 (µb s−1) contoured in red

Heaviest 6-h precip along and on cold side of surface boundary

6-h precipitation (in) ending at 1200 UTC 1 September 2006

0600 UTC 1 September 2006

NPVU QPE

Fn vectors (10−10 K m−1 s−1 beginning at 1.0 × 10−10), θ (K) contoured in green, streamlines contoured in black, and Fn div–con (10−14 K m−2 s−1) shaded in cool–warm colors

1200 UTC 1 September 2006

~0.6° surface data

Heaviest 6-h precip along and on cold side of surface boundary

6-h precipitation (in) ending at 1800 UTC 1 September 2006

1200 UTC 1 September 2006

NPVU QPE

Fn vectors (10−10 K m−1 s−1 beginning at 1.0 × 10−10), θ (K) contoured in green, streamlines contoured in black, and Fn div–con (10−14 K m−2 s−1) shaded in cool–warm colors

1800 UTC 1 September 2006

~0.6° surface data