1. Precipitation Shadows in the Hudson Valley Hudson Valley Ambient Meteorology Study (HVAMS) National Science Foundation, Physical Meteorology Section David R. Fitzjarrald, Atmospheric Sciences Research Center, UAlbany, SUNY Jeffrey M. Freedman, Atmospheric Information Services and Ricardo K. Sakai 1, Matt Czikowsky 1, Alex Tsoyref 1, and Jessica Neiles 2 1. ASRC 2. NWS, Wilmington, NC Thomas Cole: River in the Catskills (1830s)

2. The Hudson Valley ALB Catskills Hudson Valley Kingston NYC HPN Source: http://visibleearth.nasa.gov/U_S__States/New_York/32_6.html Northeast Escarpment 100 km

3. Hudson Valley Ambient Meteorology Study Opportunistic events: heavy rains and rain shadows during IFC

4. KENX P: ISFF H: HOBOs KEY: Dense network of stations 20 km

5. South Albany (P8) through Freehold (H2), East Jewett (H2) to Phoenicia Freehold (H2) East Jewett (H3) Phoenicia Catskills So. Albany P8

6. History

7. Three Cases 23 September 2003 26 - 27 October 2003 29 October 2003 Briefly examine the first two…

8. 23 September 2003 Short event (most precipitation in 2 - 4 hr period) Heaviest rainfall over southern Catskills (70+ mm) Distinct precipitation shadow to north- northeast (< 20 mm)

9. 1200 UT 23 September 2003

12. KENX Storm Total Precipitation Escarpment

13. 26 - 27 October 2003 Steady rain for 24+ hours Heaviest rainfall over central Catskills (90+ mm) Again, distinct precipitation shadow to north- northeast (< 30 mm)

14. 1200 UT 27 October 2003

18. Mountain Waves? Comparatively modest terrain, but… Brady and Waldstreicher (2001) Poconos of NE PA Conditions favoring mountain waves: Decreasing static stability with height Stable layer near mountain top level Decrease of cross barrier flow with height.

19. KENX VAD Profile 1052 - 1146 UT 23 Sep 2003

20. KENX VAD Profile 1227 - 1320 UT 27 Oct 2003

21. Eta Model Sounding 0600 UT 23 September 2003 From ASRC Air Quality Forecasting Modeling System

25. Conclusions(?) Distinct precipitation shadows downwind of Catskill Escarpment Hint of mountain waves (ducted gravity waves?) Need further study: incorporate data from other networks (NYCDEP); stability parameters from model soundings

26. Acknowledgments University at Albany participation: ASRC: Scientists David Fitzjarrald, Ricardo Sakai (Ph. D. ‘00) Technician Alex Tsoyref Graduate Student: Matt Czikowsky (M. Sc. ‘03) Project Assistant: Jessica Neiles (B. Sc. ‘03) Undergraduate students: Jason Herb Kim Sutkevich Aaron Feinberg Atmospheric Information Services: Co-Investigator: Jeff Freedman, (Ph. D. ‘00)

27. Brazilian collaborators from the U. of Santa Maria, RS: Osvaldo Moraes (postdoctoral visitor ‘90) Otávio Acevedo (Ph. D. ‘01) Rodrigo da Silva (visiting grad. Student ‘02,’03) Acknowledgments

28. Facilities made available through the Deployment Pool funds of The NSF: Wyoming King Air instrumented aircraft 9 ISSF automatic weather stations from the National Center for Atmospheric Science (NCAR), Boulder CO TAOS tethered balloon sounder (NCAR) Facility available through collaboration with the University of Alabama, Huntsville: MIPS Collaboration with NOAA/NWS Radar wind profiler at Schenectady airport Additional balloon soundings at the National Weather Service Forecast Office, Albany. Acknowledgments