1 / 52

Cool-Season High Wind Events in the Northeast U.S.

Cool-Season High Wind Events in the Northeast U.S. Jonas V. Asuma , Lance F. Bosart , Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany/SUNY John S. Quinlan, Thomas A. Wasula , Hugh W. Johnson, Kevin S. Lipton NOAA/NWS, Albany, NY

rasul
Download Presentation

Cool-Season High Wind Events in the Northeast U.S.

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Cool-Season High Wind Events in the Northeast U.S. Jonas V. Asuma, Lance F. Bosart, Daniel Keyser Department of Atmospheric and Environmental Sciences University at Albany/SUNY John S. Quinlan, Thomas A. Wasula, Hugh W. Johnson, Kevin S. Lipton NOAA/NWS, Albany, NY Master’s Thesis Seminar 8 July 2010 NOAA/CSTAR Grant NA07NWS4680001

  2. Overview Nonconvective wind fatalities • Motivation • Cool-season high wind events can be damaging and in some cases challenging to forecast • Objectives • Assess frequency of high wind events • Identify mechanisms that lead to severe surface winds • Present case study of one extraordinary event Tree-related nonconvective wind fatalities Fatalities due to various wind-related hazards, 1980–2005. From Ashley and Black (2008)

  3. Outline • Background • Data/Methodology • Climatology • Composite Analysis • Case Study • Synthesis/Conclusions

  4. Background: Thunderstorm winds • Thunderstorm wind climatology • Kelley et al. (1985): Nontornadic severe thunderstorm wind • Thunderstorm winds driven by evaporatively-cooled downdrafts • Downbursts (Fujita and Byers 1977), bow echos (e.g., Fujita 1978), derechos (Johns and Hirt 1987) • Mesovortices can modulate location of strongest winds (e.g., Trapp and Weisman 2003) • Johns (1993): • Described favorable cool-season pattern for development of squall lines with extensive bow echo-induced wind damage From Kelley et. al (1985) From Johns (1993)

  5. Background: Gradient winds • Kapela et al. (1995) constructed a checklist of features associated with the occurrence of strong post cold-frontal winds: • Strong unidirectional flow throughout the troposphere, tropospheric-deep cold advection, steep low-level lapse rates, subsidence, presence of a dry intrusion, strong isallobaric gradient • Niziol and Paone (2000): Identified typical cyclone track associated with high winds impacting Buffalo, NY • Also noted many features determined by Kapela et al. (1995) L L L t = 00 h t = −12 h t = +12 h

  6. Background: Case Studies • McCann (1978) determined necessary conditions for convective storms to produce high winds without lightning: • Small amount of potential instability, synoptic scale lifting, strong winds at 3 to 5 km above surface • Conditions met during winter • Koch and Kocin (1991) and Browning and Reynolds (1994) studied high-wind producing rain bands • Noted importance of dry intrusion on rain band and high wind development • High winds occurred during and shortly after cold front passed • Van den Broeke et. al (2005) studied the lightning production of two low CAPE, high shear convective lines • Conclusions suggest the occurrence of high wind during the cool season not as dependent on CAPE as in the warm season

  7. Data • Climatology • NCDC thunderstorm and high wind reports • National Lightning Detection Network (NLDN) data • Composites • NCDC thunderstorm and high wind reports • NCEP/NCAR 2.5° Reanalysis data • Case Studies • NCDC thunderstorm and high wind reports • 1° Global Forecasting System (GFS) analyses • WSI 2-km NOWRAD Radar composites • National Lightning Detection Network (NLDN) data • Hourly surface observation data

  8. Methodology (1 of 2) • Event determination • Domains: High wind reports from the Northeast (NE) for 15 Oct 1993 through 31 Dec 2008 • High wind definition: Wind measured ≥ 25 m s−1 or damaging winds of any magnitude • Event definition: Any series of storm reports that are separated from each other by ≤ 12 h • Events defined by type: • Pure Gradient (PG): Only gradient wind reports • Hybrid (HY): Both thunderstorm and gradient wind reports • Pure Convective (PC): Only thunderstorm wind reports • PG events: If lightning struck within 1° radius and 1 h from any gradient wind report, PG event becomes HY event

  9. Methodology (2 of 2) • Composite • HY and PG event types subdivided based upon location of initial NE report relative to surface cyclone • Northeast, Southeast, Southwest, Northwest quadrants • PC events subdivided into trough and ridge categories • Composite time (t = 00 h): Determined to be hour (00, 06, 12, or 18 Z) closest to initial NE report • For reports at 03, 09, 15, or 21 Z  earlier hour chosen • Events composited by event type and subcategory • Created report-relative composites • Grids shifted to location of initial NE report • Composites centered on centroid of initial NE reports for each event type and subcategory

  10. Climatology: High-wind days Thunderstorm Gradient (%) Shaded represents the percentage of the total days (N = 3260) studied that high winds occurred.

  11. Climatology: High-wind days Thunderstorm Gradient (%) Shaded represents the percentage of the total days (N = 3260) studied that high winds occurred.

  12. Climatology: Event type Histogram depicting the frequency of occurrence based upon the type of event

  13. Climatology: Yearly Histogram depicting the frequency of occurrence based upon the month in which the initial NE report occurred

  14. Climatology: Monthly Histogram depicting the frequency of occurrence based upon the month in which the initial NE report occurred

  15. Climatology: Hourly Histogram depicting the frequency of occurrence based time of the initial NE report

  16. Climatology: Societal Impact Events that accumulated > 100 reports: HY: 27; PG: 2; PC: 0 Approximate average reports per event: HY: 60; PG: 20; PC: 11 Histogram depicting the frequency of occurrence based upon the number of reports accumulated

  17. Climatology: Subcategories Histogram depicting the frequency of occurrence based either the location of the initial report or upper-level flow pattern

  18. Climatology: Subcategories Focus on these for composite analysis Histogram depicting the frequency of occurrence based either the location of the initial report or upper-level flow pattern

  19. Southeast Composite: Surface t = 00 h HY (N = 71) PG (N = 45) (mm) MSLP (hPa, solid); precipitable water (mm, shaded); 1000–500 hPa thickness (dam, dashed); 1000 hPa total wind (kt, barbs); initial report (star)

  20. Southeast Composite: Cyclone Track +24 h PG (N = 45) −24 h HY (N = 71) t = 00 h Loci of initial report Six Hourly Southeast Composite Cyclone Track: Pure Gradientvs. Hybrid; MSLP (hPa) is boxed; initial NE report (star)

  21. HY Southeast Composite: Cross Section HY (N = 71) (%) θe(K, black); relative humidity(%, shaded); vertical motion (μb s−1, solid; red-upward, blue-downward); total wind (kt, barbs); initial report (star)

  22. PG Southeast Composite: Cross Section PG (N = 45) (%) θe(K, black); relative humidity(%, shaded); vertical motion (μb s−1, solid; red-upward, blue-downward); total wind (kt, barbs); initial report (star)

  23. PG Southwest Composite: Surface t = 00 h PG (N = 55) (mm) MSLP (hPa, solid); precipitable water (mm, shaded); 1000–500 hPa thickness (dam, dashed); 1000 hPa total wind (kt, barbs); initial report (star)

  24. PG Southwest Composite: Cross Section t = 00 h PG (N = 55) (%) θe(K, black); relative humidity(%, shaded); vertical motion (μb s−1, solid; red-upward, blue-downward); total wind (kt, barbs); initial report (star)

  25. PG Southwest Composite: Sounding PG (N = 55) Composite sounding taken at the location of composite initial NE report at t = −06 h, t = 00 h, and t = +06 h

  26. 17 Feb 2006: Overview 85 kt gust at 15 Z • Resulted in two fatalities • Caused $3.5 million in damage in New York State • Produced 85 kt wind gust recorded at Saratoga County Airport • Accumulated most high wind reports in the NE (267 total reports) • 242 gradient reports • 25 thunderstorm reports • Fits the HY southeast and PG southwest paradigms All High Wind Reports Gradient Thunderstorm

  27. 17 Feb 2006: Cyclone Track +24 h −24 h 17 Feb case HY composite (N = 71) t = 00 h Loci of initial NE report Six Hourly Cyclone Track: MSLP (hPa) is boxed; initial NE report (star)

  28. 16 Feb 2006: Surface t = −12 h 18 Z storm reports Composite (mm) MSLP (hPa, solid); precipitable water (mm, shaded); 1000–500 hPa thickness (dam, dashed); 1000 hPa total wind (kt, barbs)

  29. 17 Feb 2006: Surface t = 00 h 06 Z storm reports Composite (mm) MSLP (hPa, solid); precipitable water (mm, shaded); 1000–500 hPa thickness (dam, dashed); 1000 hPa total wind (kt, barbs)

  30. 17 Feb 2006: Surface t = +12 h 18 Z storm reports Composite (mm) MSLP (hPa, solid); precipitable water (mm, shaded); 1000–500 hPa thickness (dam, dashed); 1000 hPa total wind (kt, barbs)

  31. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 12 Z t = +06 h

  32. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 12 Z t = +06 h Lightning Gradient Thunderstorm

  33. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 15 Z t = +09 h Post-Frontal Gusting Pre-Frontal Gusting Multiple Bowing Segments

  34. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 15 Z t = +09 h Lightning Gradient Thunderstorm

  35. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 18 Z t = +12 h

  36. 17 Feb 2006: Radar/Surface Obs 17 FEB 06: 18 Z t = +12 h Lightning Gradient Thunderstorm

  37. 17 Feb 2006: CAPE/Shear t = +12 h 18 Z t = +06 h 12 Z storm reports storm reports (J kg−1) 500 hPaZ (hPa, solid); CAPE (J kg−1, shaded); 1000–500 hPa shear (kt, barbs)

  38. 17 Feb 2006: Dry Intrusion 12 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W (%) θ(K, red); relative humidity(%, shaded); potential vorticity (10−6 K m2 s−1 kg−1, black)

  39. 17 Feb 2006: θe Advection 12 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W (10−4K s−1) θ(K, solid),θeadvection (10−4K s−1, shaded), potential instability (K km−1, dashed)

  40. 17 Feb 2006: Frontogenesis 12 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W [K (100 km)−1 (3 h)−1] θ(K, solid), Petterssen front. [K (100 km)−1 (3 h)−1, shaded], vertical motion (μb s−1, dashed; red-upward, blue-downward)

  41. 17 Feb 2006: Wind Profile 12 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W θ(K, solid), vertical motion (μb s−1, dashed; red-upward, blue-downward), total wind (kt, barbs)

  42. 17 Feb 2006: Dry Intrusion 18 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W (%) θ(K, red); relative humidity(%, shaded); potential vorticity (10−6 K m2 s−1 kg−1, black)

  43. 17 Feb 2006: θe Advection 18 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W (10−4K s−1) θ(K, solid),θeadvection (10−4K s−1, shaded), potential instability (K km−1, dashed)

  44. 17 Feb 2006: Frontogenesis 18 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W [K (100 km)−1 (3 h)−1] θ(K, solid), Petterssen front. [K (100 km)−1 (3 h)−1, shaded], vertical motion (μb s−1, dashed; red-upward, blue-downward)

  45. 17 Feb 2006: Wind Profile 18 Z ERI BOS BGM ERI BGM BOS 42 N, −90 W 42 N, −60 W θ(K, solid), vertical motion (μb s−1, dashed; red-upward, blue-downward), total wind (kt, barbs)

  46. 17 Feb 2006: Isallobaric Wind t = +12 h 18 Z t = +06 h 12 Z −32 −28 +28 +24 storm reports storm reports MSLP (hPa, solid), 12-hr centered pressure change (hPa (12 h)−1, dashed); 1000 hPaisallobaric wind (kt, barbs)

  47. Case Study Conclusions • Strong forcing associated with the passage of a front in the presence of a potentially unstable air mass leads to development of a convective line • Vertical differential θe advection and an upper-tropospheric dry intrusion lead to mid-level drying • Deep cold-air advection in the presence of steep low-level lapse rates and strong low-level flow leads to high winds behind the cold front • Boundary layer stability and kinematic profile favorable for turbulent momentum transport • Isallobaric wind likely enhanced low-level flow

  48. Synthesis/Conclusions • This work represents the first time thunderstorm AND gradient wind events have been looked at from a climatology and composite perspective • 17 Feb 2006 case is consistent with previous studies of cool-season high wind events • HY events tend to be the highest impact events • HY synoptic set up is essentially a combination of the composites constructed by Niziol and Paone (2000) and the conceptual model of Johns (1993)

  49. Synthesis/Conclusions Gradient Tstorm • HY event conceptual model • High wind threat area in red shading Conceptual Model of the typical HY event

  50. Thank You! • Lance and Dan • John, Tom, Hugh, and Kevin • Stuart Hinson at NCDC • Fellow graduate students • Most notably: Ben, Natalie, Melissa, Tom, Jay, Nick, Heather, Alan, Matt • Professors and Faculty • Ross, Kevin, Vince, Paul, Mathias, Chris, Ryan, etc. • And of course, my family

More Related