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Abstract A prolonged period of winter monsoonal flow brought heavy sea-effect snowfall to the Hokuriku region along the west coast of the Japanese island of Honshu from 2 to 7 February 2010. Snowfall in some locations exceeded 140 cm, but the distribution within the event was highly variable. We examine the factors contributing to these variations using data from a Japan Meteorological Agency (JMA) C-band surveillance radar, JMA soundings, surface precipitation observations, and a Weather Research and Forecasting (WRF) Model simulation. There were three distinct periods during the event. Period 1 featured relatively weak flow with precipitation confined mainly to the coast and lowlands. Precipitation maxima were located where the flow ascended: 1) over terrain-blocked air, 2) at the foot of a high flow-normal barrier, or 3) relatively unimpeded over the lower mountain ranges. Flow strengthened during period 2, yielding stronger vertical velocities over the terrain with precipitation maxima shifting inland and to higher elevation. The flow strengthened further in period 3, with the precipitation maxima shifting higher in elevation and into the lee, with almost no precipitation falling in the lowlands. Thus, greater inland penetration and enhancement of precipitation occurred as the flow speed increased, but additional factors such as the subcloud sublimation of hydrometeors and the convective instability also contribute to differences between periods 2 and 3. These results illustrate the importance of incident flow strength in modulating the distribution and enhancement of snowfall in global lake- and sea-effect regions.
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Characteristics of Lake-Effect Precipitation over the Black River Valley and Western Adirondack Mountains
Potential factors affecting the inland penetration and orographic modulation of lake-effect precipitation east of Lake Ontario include the environmental (lake, land, and atmospheric) conditions, mode of the lake-effect system, and orographic processes associated with flow across the downstream Tug Hill Plateau (herein Tug Hill), Black River valley, and Adirondack Mountains (herein Adirondacks). In this study we use data from the KTYX WSR-88D, ERA5 reanalysis, New York State Mesonet, and Ontario Winter Lake-effect Systems (OWLeS) field campaign to examine how these factors influence lake-effect characteristics with emphasis on the region downstream of Tug Hill. During an eight-cool-season (16 November–15 April) study period (2012/13–2019/20), total radar-estimated precipitation during lake-effect periods increased gradually from Lake Ontario to upper Tug Hill and decreased abruptly where the Tug Hill escarpment drops into the Black River valley. The axis of maximum precipitation shifted poleward across the northern Black River valley and into the northwestern Adirondacks. In the western Adirondacks, the heaviest lake-effect snowfall periods featured strong, near-zonal boundary layer flow, a deep boundary layer, and a single precipitation band aligned along the long-lake axis. Airborne profiling radar observations collected during OWLeS IOP10 revealed precipitation enhancement over Tug Hill, spillover and shadowing in the Black River valley where a resonant lee wave was present, and precipitation invigoration over the western Adirondacks. These results illustrate the orographic modulation of inland-penetrating lake-effect systems downstream of Lake Ontario and the factors favoring heavy snowfall over the western Adirondacks.
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- Award ID(s):
- 1929602
- PAR ID:
- 10469618
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of Applied Meteorology and Climatology
- Volume:
- 62
- Issue:
- 9
- ISSN:
- 1558-8424
- Page Range / eLocation ID:
- 1347 to 1366
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1175/JAMC-D-23-0026.1
