The 8-9 March 2008 Winter Storm in Upstate New York: An Example of a “Multi-Hazard” Event

1. The 8-9 March 2008 Winter Storm in Upstate New York: An Example of a “Multi-Hazard” Event Brian Frugis NOAA/NWS - Albany, NY NROW X November 5-6, 2008

2. Outline • What is a “multi-hazard” storm? • Has this been examined before? • Synoptic overview of 8-9 March 2008 • Analysis of each hazard • Conclusions and future research

3. Multi-hazard? • A storm that features more than one type of weather requiring two or more headlines across the County Warning Area (CWA) • Ex: Both Winter Storm Watches/Warnings AND Flood Watches/Warnings • Somewhat common during the winter season here at ALY, especially during heavy mixed precipitation events commonly associated with inland low track events • Winter Storm Watch/Warnings AND Severe Thunderstorm Watch/Warnings • Rare and unique events • The 8-9 March 2008 event contained 4 hazards across the CWA: flooding, snow/ice, wind AND severe thunderstorms

4. Past Research • Most research has concentrated on just one hazard • Either winter storms or warm season severe weather have been common research topics for the ALY area • Keeter et. al (1995) found that there was a great deal of variability in winter weather across the Carolinas and Virginia • Winter precipitation, strong convective storms and coastal flooding all occurred • Due to topography, latitude, proximity to warm waters of Gulf Stream, evolution of cyclogenesis, cold air damming and frontogenesis • Similar factors can likely be attributed to multi-hazard winter storms across eastern New York

5. Cool Season Severe T-storms – Previous Research • Goetsch (1988) found that “cold core” outbreaks frequently have a stacked low, a low level convergence feature, a well defined look on satellite imagery, and a low level moisture axis protruding towards the surface low. • van den Broeke (2005) has shown that that CG Lightning strikes are not necessarily needed for low-instability convective lines that produces wind damage

6. Cool Season T-Storms Previous Research in ALY Area • Wasula and LaPenta (2004) examined a cool season severe case from 25 Nov 2004 • Low CAPE, high shear environment • Low topped convection developed into a line and produced widespread wind damage • Wasula et. al (2008) also examined the 16 February 2006 outbreak in upstate New York • Little instability ahead of cold frontal passage • Narrow cold frontal rainband contained damaging wind gusts • Region was in left front quad of strong mid and upper level jet streak

7. 8-9 March 2008 • “Most extreme multi-hazard case I’ve ever seen in this area” – Steve D. – Senior Service Hydrologist • Storm Impacts • State of emergency due to ice storm in Warren Co. • Widespread 1.50-3.00 inches of rain/liquid equivalent precipitation causing several main stem rivers to go above flood stage, as well as urban and small stream flooding • Wind gusts 40-50 MPH, mainly on backside of storm • Several reports of trees down due to convective line across Litchfield and Berkshire Counties in western New England

8. In addition, one severe thunderstorm warning polygon was issued, as well as several SPSs for near-severe convection.

9. Surface MSLP/IR Satellite 12 UTC 8 Mar 2008 – 12 UTC 9 Mar 2008 • Strong surface low lifted northward from mid-Atlantic into Northeast across the ALY CWA

10. 500 hPa Heights and Wind • 9 Mar 2008 00 UTC NAM 00 hr map (during the middle of the event) • 120+ knot jet streak at 500 hPa centered just south of the ALY CWA, putting the region in the left exit region

11. 00 UTC 9 March 2008 ALY Sounding • Strong low-level wind field with impressive 0-1 km helicity values • Cold air trapped at surface under strong inversion • Very moist low levels

12. Flooding • Antecedent Conditions • February was a wet month (5-6” liquid equivalent across the CWA) with heavy snow across higher terrain • Hard freeze at beginning of the month (Feb 28-Mar 2) resulted in very frozen ground conditions • Entire region saw 1-3” of rain/liquid equivalent during 4-5 March Event (2.53” fell at KALB); some flooding occurred across SE parts of CWA • Temperatures from March 3-7th were mild; high temps averaged in the 40s

13. 00 UTC 9 Mar 2008 1000 hPa – 850 hPa Moisture Transport Vectors and Layer Precipitable Water • High Precipitable Water values for March • Values across eastern New England are 3-4 std above normal (not shown) • Moisture transported from Gulf of Mexico and tropical Atlantic regions

14. 0.5° Mosaic Radar Reflectivity 2212 UTC 7 Mar 2008 – 0430 UTC 8 Mar 2008 • Three rounds of precipitation • First round was overnight between Mar 7th and Mar 8th • Rain across much of the region with light snow/sleet in the Adirondacks

15. 0.5° Mosaic Radar Reflectivity 1706 UTC 8 Mar 2008 – 2200 UTC 9 Mar 2008 • Second round was late morning through afternoon on Mar 8th • Sleet and freezing rain across the Adirondacks, but mainly rain elsewhere

16. Multisensor Precipitation Estimation Total precipitation between 1200 UTC 7 Mar 2008 and 1200 UTC 8 Mar 2008 Total precipitation between 1200 UTC 8 Mar 2008 and 1200 UTC 9 Mar 2008

17. County-Wide Flood Warnings 8-9 Mar 2008 • In addition to the county-wide warnings, river flood warnings were issued for 19 points along 12 different rivers • 7 of these points reached moderate flood stage

18. Severe T-Storms Data Source: NCDC (Slide Courtesy of Tom Wasula)

19. 00 UTC 9 Mar 2008 850 hPa – 500 hPa Most Unstable Cape • NAM initial 00 hr map • Elevated layer of unstable air • MUCAPE values 100-300 J/kg across southern parts of the CWA • Low CAPE, high shear environment, (similar to cases studied by Wasula)

20. 00 UTC 9 Mar 2008 0.5° Mosaic Radar Reflectivity and Station Observations • Weak line of elevated convection approaching dewpoints of 10-14° C across Taconic Mountains and Litchfield CT

21. 0.5° Mosaic Radar Reflectivity 2348 UTC 8 Mar 2008 – 0148 UTC 9 Mar 2008

22. Severe Thunderstorm Polygon and Locations of Storm Reports • Several storms reports of wind damage across Berkshire County, MA and northern Litchfield County, CT • Non-severe hail (0.50” in diameter) in Schoharie County, NY Image courtesy of IEM Storm Cow Webpage

23. 925 hPa Aegostropic Wind and 23 UTC 8 Mar 2008 Surface Temperatures • 00 UTC 9 Mar NAM 00 hr map • Strong ageostrophic flow kept cold air in place at low levels across the Adirondacks

24. 00 UTC 9 Mar 2008 RUC Sounding • Sounding for Gore Mountain in Warren Co. • Surface layer just below freezing • Very moist up to 700 hPa • No ice in cloud (all below -10°C) allowed for precipitation to fall entirely as freezing rain

25. 8-9 Mar 2008 Ice Storm Pictures • Heavy ice accretion across eastern Hamilton and northern Warren Counties • No official measurements, but pictures show at least two inches of ice accretion • Some ice may have been from storm earlier in the week

26. 3 hr Pressure Change 21 UTC 8 Mar 2008 - 08 UTC 9 Mar 2008 • Frequent gusts 30-45 mph driven by strong low center and powerful rise-fall couplet

27. Conclusions • “Multi-hazard” storms can be a difficult situation • Damaging cool season convection is hard to predict in advance • Public may be confused by multiple headlines in place • Operationally handling a storm of this magnitude can be overwhelming at times

28. Future Research • Create a “multi-hazard climatology” • See which parameters are common with “multi-hazard” storms featuring severe thunderstorms • Create a “checklist” for office use • Help predict when “multi-hazard” storms are likely to occur to help with office staffing • Based on this one case, may depend much on low track and intensity, low-level jet structure, antecedent ground conditions and boundary layer temperature/moisture profile.

29. Acknowledgments • Many thanks to Joe Villani, Tom Wasula, Neil Stuart and Steve DiRienzo for their help with this study!

30. Questions? Any questions or comments? Brian.Frugis@noaa.gov