# Presentation: 274546

## Case Study:  
Ivan - September 2004

- Ivan - September 2004

**Jared Klein – SUNY-Albany**

## 300 hPa Analyses:  1200 UTC 16 September 2004

**300 hPa Analyses****:  **1200 UTC 16 September 2004

**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****)**

## 300 hPa Analyses:  1200 UTC 17 September 2004

**300 hPa Analyses****:  **1200 UTC 17 September 2004

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

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

**1.0°**** GFS**

**Frontogenesis in jet-entrance region**

**Confluent flow in equatorward jet-entrance region**

## 300 hPa Analyses:  1200 UTC 18 September 2004

**300 hPa Analyses****:  **1200 UTC 18 September 2004

**Strengthening downstream ULJ and ridge**

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

**1.0°**** GFS**

**Strong frontogenesis in jet-entrance region**

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

## 925 hPa Analyses:  1200 UTC 16 September 2004

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

**WSI radar, 925 hPa ****θ****e ****(K)**** and wind barbs (kt)**

**Pre-existing baroclinic zone**

**Symmetric reflectivity structure**

**1.0°**** GFS**

## 925 hPa Analyses:  1200 UTC 17 September 2004

**925 hPa Analyses****:  **1200 UTC 17 September 2004

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

**WSI radar, 925 hPa ****θ****e ****(K)**** and wind barbs (kt)**

**Northeastward extension of precip field along baroclinic zone**

**1.0°**** GFS**

**Band of frontogenesis along baroclinic zone**

## 925 hPa Analyses:  1200 UTC 18 September 2004

**925 hPa Analyses****:  **1200 UTC 18 September 2004

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

**WSI radar, 925 hPa ****θ****e ****(K)**** and wind barbs (kt)**

**Highest reflectivity near nose of LLJ/****θ****e ****ridge axis**

**1.0°**** GFS**

**Strong frontogenesis along warm frontal zone**

## 925 hPa Q Vector Diagnosis:  0000 UTC 18 September 2004

**925 hPa Q Vector Diagnosis****:  **0000 UTC 18 September 2004

**Radar at 1200 UTC 17 September 2004**

**Q**

**Q****n**

**Q****s**

**Radar at 0000 UTC 18 September 2004**

**Highest reflectivity near strongest QG forcing for ascent**

**Radar at 0000 UTC 18 September 2004**

**WSI radar**

**Q****s**** div–con couplet within thermal trough–ridge**

**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**

**Q****n**** div–con bands within frontal zone**

**1.0°**** GFS**

## 925 hPa Q Vector Diagnosis:  0600 UTC 18 September 2004

**Radar at 1200 UTC 17 September 2004**

**Q**

**Q****n**

**Q****s**

**Radar at 0000 UTC 18 September 2004**

**Highest reflectivity near strongest QG forcing for ascent**

**Radar at 0600 UTC 18 September 2004**

**WSI radar**

**925 hPa Q Vector Diagnosis****:  **0600 UTC 18 September 2004

**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**

## 925 hPa Q Vector Diagnosis:  1200 UTC 18 September 2004

**Radar at 1200 UTC 17 September 2004**

**Radar at 0000 UTC 18 September 2004**

**Radar at 1200 UTC 18 September 2004**

**Q**

**Q****n**

**Q****s**

**WSI radar**

**925 hPa Q Vector Diagnosis****:  **1200 UTC 18 September 2004

**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**

**Highest reflectivity near strongest QG forcing for ascent**

## Cross Section of Fn Magnitude:  0000 UTC 18 September 2004

**Cross Section of F****n**** Magnitude:  **0000 UTC 18 September 2004

**Deep frontogenesis tilting toward cold air w/height**

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

**F****n**** 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**

**1.0°**** GFS**

## Cross Section of Fn Magnitude:  1200 UTC 18 September 2004

**Cross Section of F****n**** Magnitude:  **1200 UTC 18 September 2004

**Deep frontogenesis tilting toward cold air w/height**

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

**1.0°**** GFS**

**F****n**** 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**

## 6-h precipitation (in) ending at 

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

**6-h precipitation (in) ending at **
**0600 UTC 18 September 2004**

**0000 UTC 18 September 2004**

**NPVU QPE**

**Flow of tropical air into surface boundary**

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

**~0.6°**** surface data**

**0600 UTC 18 September 2004**

## 6-h precipitation (in) ending at 

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

**6-h precipitation (in) ending at **
**1200 UTC 18 September 2004**

**0600 UTC 18 September 2004**

**NPVU QPE**

**Flow of tropical air into surface boundary**

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

**~0.6°**** surface data**

**1200 UTC 18 September 2004**