Precipitation Shadows in the Hudson Valley

Hudson Valley Ambient Meteorology Study

(HVAMS)

National Science Foundation, Physical Meteorology SectionDavid R. Fitzjarrald, Atmospheric Sciences Research Center,

UAlbany, SUNYJeffrey M. Freedman, Atmospheric Information Services

and Ricardo K. Sakai1, Matt Czikowsky1, Alex Tsoyref1, and Jessica Neiles2

1. ASRC2. NWS, Wilmington, NC

Thomas Cole: River in the Catskills (1830s)

The Hudson Valley

ALB

Catskills

Hudson ValleyKingstonNYC

HPN

Source: http://visibleearth.nasa.gov/U_S__States/New_York/32_6.html

Northeast Escarpment

100 km

Hudson Valley Ambient Meteorology Study

Opportunistic events: heavy rains and rain shadows during IFC

KENX

P: ISFFH: HOBOs

KEY: Dense network of stations

20 km

South Albany (P8) through Freehold (H2), East Jewett (H2) to Phoenicia

Freehold(H2)

East Jewett (H3) Phoenicia

Catskills

So. AlbanyP8

History

Three Cases

•23 September 2003

•26 - 27 October 2003

•29 October 2003

Briefly examine the first two…

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)

1200 UT 23 September 2003

1200 UT 23 September 2003

1200 UT 23 September 2003

KENX Storm Total Precipitation

Escarpment

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)

1200 UT 27 October 2003

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.

KENX VAD Profile1052 - 1146 UT 23 Sep 2003

KENX VAD Profile1227 - 1320 UT 27 Oct 2003

Eta Model Sounding

0600 UT 23 September 2003

From ASRC Air Quality Forecasting Modeling System

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

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)

•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

Facilities made available through the Deployment Pool funds ofThe 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 ofAlabama, Huntsville: MIPS

• Collaboration with NOAA/NWS Radar wind profiler at Schenectady airport Additional balloon soundings at the National Weather Service

Forecast Office, Albany.

Acknowledgments