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The 17 Feb 2006 Severe Weather and High Wind Event across Eastern New York and New England. Thomas A. Wasula and Neil A. Stuart NOAA/NWS at Albany Alicia C. Wasula SUNY/University at Albany Northeast Regional Workshop 8 November 1-2, 2006. Motivation.

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The 17 Feb 2006 Severe Weather and High Wind Event across Eastern New York and New England

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The 17 Feb 2006 Severe Weather and High Wind Event across Eastern New York and New England

Thomas A. Wasula and Neil A. Stuart

NOAA/NWS at Albany

Alicia C. Wasula

SUNY/University at Albany

Northeast Regional Workshop 8

November 1-2, 2006


Motivation

  • Cool season severe weather events are very uncommon in the Northeast (very few events in February)

  • To understand why the severe weather occurred in the morning of this case study and what caused the anomalous high wind event

  • To test the hypothesis that the line of severe convection was a Narrow Cold Frontal Rainband (Strongly Forced High Shear-Low Instability Convective Line)


Data

  • Thunderstorm Day data from NCDC

  • Observational surface and upper air data

  • Anomaly plots based on the NCEP/NCAR Global Reanalysis Dataset (1960-1990 21-day mean)

  • LAPS and MSAS Hourly data

  • NAM12 model data

  • Satellite/Water Vapor and Lightning data

  • KENX 8-bit radar data


Albany has only ~6 in over 60 yrs in FEB !

Albany Averages 24 T-storm Days/Year

Data Source: NCDC


Background on 17 FEB 2006 Event

  • Severe weather ahead of cold front not well anticipated (High wind event was well anticipated)

  • 12+ severe weather events from bowing segments in narrow cold frontal rain band

  • Much of eastern New York in left front quadrant of mid- and upper-level jet streaks

  • Powerful shortwave trough and arctic front were lifting mechanisms


High Wind Event 2/17/06

  • National Grid reported 100,000+ customers out of power in eastern New York. Saratoga and Warren Counties were hit especially hard (i.e. Saratoga Springs significant tree and utility pole damage)

  • Post-frontal wind gusts of 60 to 85 mph were common

  • Infamous gust to 143 mph atop Stratton mountain (3885 ft) in southern VT

  • Wind gusts and widespread damage similar to July 15,1995 and the Labor Day 1998 Derechoes


Mosaic Radar Loop 12Z-1930Z 17 FEB 2006

www.spc.noaa.gov


Severe Weather 17 February 2006

16 FEB reports

57 hail 40 wind 1 tornado

www.spc.noaa.gov


Thanks to John Quinlan for this slide


1200Z 17 FEB 2006 Surface Map

Albany Forecast Area in warm sector (Sfc temps~10°C and dewpoints ~5°C)


1200 UTC 17 FEB 2006 500 hPa Heights, Isotachs and Temps

www.spc.noaa.gov


1200 UTC 17 FEB 2006 300 hPa Heights, Isotachs and Temps


1200 UTC 17 FEB 2006 850 hPa Heights, Isotachs and Temps


12Z 17 FEB 2006 Low Level Standardized Anomalies (vs. 1960-1990 climo.)


12Z 17 FEB 2006 850 hPa U and V Standardized Anomalies


SPC Severe Weather Outlooks

This event was extremely challenging on all levels !!!

1300Z 17 FEB 2006

1630Z 17 FEB 2006


Severe Weather Composite (700-500 mb lapse rates)

Little SBCAPE to work with…but steep mid level lapse rates (based on RUC from SPC)


1200 UTC 17 FEB 2006Albany Sounding

Unidirectional 300-850 hPa flow

***12Z BUF Sounding FROPA with MLCAPE < 50 J kg-1 and 0-6 km shear 89 kts***


1415Z Water Vapor Image

Convective initiation occurs in clear slot behind pre-frontal trough


1445Z Visible Satellite Picture and 15 Min LTG

Clearing ahead of cold front.


12Z NAM12 0-6 km Bulk Shear and 0-10 km MUCAPE for 15Z 17 FEB 2006

0-6 km Bulk Shear values 65-85 knots

MUCAPE < 100 J kg-1


12Z NAM12 F1500Z Cross-section down the Hudson River Valley (Omega, Theta-e and Winds)

White arrow indicates weak convective instability (theta-e decreasing with height)


16Z KPOU LAPS Sounding


16Z LAPS SBCAPE and Lifted Indices

SBCAPE < 200 J kg-1


16Z MSAS 3-hr MSLP Change

3-hr pressure rises up to 14 hPa


Meteograms: 17/06Z-17/18Z

G48 G40

G40 G52 G52 G44 G42 G42

TEMP (F)

DWPT (F)

PMSL

SYRALB


17 FEB 2006 KENX Severe Weather Radar Highlights


1320Z 0.5° KENX Reflectivity

ALY

Approaching developing line of convection with the cold front.

Prefrontal trough showery activity helps moisten the boundary layer.


1400Z 0.5° KENX Reflectivity

Convective line more organized… no lightning yet !


1453Z KENX Base Reflectivity

Bow Echo develops and first warning issued at 1454Z.


1459Z 0.5° KENX REF and Velocity

Significant BowEcho

Shallow mesocyclone develops N/NE of RDA. Roof blown off home in Edinburgh with northern bow. Southern bow had 62kt gust.

Saratoga County velocity values > 55 knots at 3.3-5.3kft AGL


1511Z Base Reflectivity and Velocity

Washington County hit hard next with 55-65 kts AGL at 3.5-6.5kft. MESO base and top (5.1; 7.5kft)


1510Z Composite Reflectivity Cross-section (Penny Size Hail)

45 dBz to ~10kft!


1516Z KENX VIL and 15 min LTG

VIL 15 kg m2


1534Z 0.5° KENX Reflectivity and Velocity

Squall line passed east of ALY with winds 65-75kts 2-3kft AGL

Winds 80-100 kts 3.5-5kft AGL. KDDH 57kt gust.


1545Z KENX Echo Tops

ETs 15-20kft


Preliminary Results

  • Highly anomalous February severe weather event in Northeast US

  • 925/850 hPa wind anomalies of +/- 2-3 

  • Low CAPE/high shear environment

  • Convective initiation occurs in clear slot behind pre-frontal trough after PBL is moistened

  • Narrow cold-frontal rainband results from strongly forced linear convective line


Future Work

  • Frontogenesis calculations at surface, 925, 850 hPa

  • Develop climatology of cool season severe weather events in Northeast US to improve forecaster recognition 24+ hours in advance


Acknowledgements

  • John Quinlan (GIS Wind Damage slide)

  • Rich Grumm (Anomaly slides of the event)

  • Warren Snyder (WES upgrade and case download)

  • Robert Tracey (SUNYA undergrad) for his help with the radar loop


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