Record Details
The late spring secondary precipitation maximum in the interior Pacific Northwest
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | The late spring secondary precipitation maximum in the interior Pacific Northwest |
| Names |
Quinn, Robert
(creator) Lahey, James F. (advisor) |
| Date Issued | 1976-08-16 (iso8601) |
| Note | Graduation date: 1977 |
| Abstract | The Late Spring Secondary Precipitation Maximum in the Interior Pacific Northwest results from a complex system of climatic controls. The Secondary Maximum is most strongly developed over the high plateau of Oregon immediately in the lee of the Cascade Mountains. Local topographic organization exerts strong control over the magnitude and timing of the secondary maximum in the inter-montane region. There is a detectable poleward shift of the precipitation maximum in the interior Northwest from April to June. A synoptic precipitation climatology was developed for the Pacific Northwest for the months of February to July. Surface and 500 millibar circulation maps indicate reorganization of atmospheric flow from strongly zonal flow in midwinter to more highly meridional flow in May and June. Precipitation producing synoptic disturbances manifest a decided evolution from those dominated by warm advection in winter to those dominated by strong, cool advection in May and June. Spokane radiosonde data indicate that increased destabilization of the atmosphere accompanied by increased precipitable moisture is primarily responsible for the increase in average rainfall in May and June. The Secondary Precipitation Maximum is characterized by an increase in precipitation intensity, but is not accompanied by an increase in precipitation frequency. A case history of an early and late spring precipitation producing synoptic sequence is presented. Seasonal changes in precipitation intensity west and east of the Cascades must be related to corresponding changes in the sensible and latent heat budget of the region. Average monthly equivalent potential temperature data indicate pronounced reorganization of the surface temperature field west and east of the Cascades during the period of February to July. Large sensible and latent heat additions occur east of the Cascades in May and June and should be effective in destabilizing maritime polar air masses moving across the interior. |
| Genre | Thesis/Dissertation |
| Topic | Precipitation (Meteorology) -- Northwest, Pacific |
| Identifier | http://hdl.handle.net/1957/45944 |
