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Wsr-88 D Observations of Mesoscale Precipitation Bands over Pennsylvania
| Content Provider | Semantic Scholar |
|---|---|
| Author | Grumm, Richard H. Nicosia, David |
| Copyright Year | 2011 |
| Abstract | Weather Surveillance Radar-1988 Doppler (WSR-88D) located in central Pennsylvania detected a large area of snow, mixed precipitation, and rain over the central part of the state on 30-31 October 1993. It also detected an area of locally heavy rain over southeastern Pennsylvania on 4-S December 1993. In both cases, distinct bands of enhanced precipitation were embedded within broader areas of precipitation. The bands were oriented along the 1000to SOO-mb thermal wind vector and were nearly parallel to the 8S0-mb isotherms. For both cases, the WSR88D velocity azimuth display (VAD) wind profile (VWP) indicated a low-level northeasterly flow, which veered with height and became southwesterly aloft. Base velocity data from the O.S degree elevation scan revealed the classic warm advection "S"~shaped_ pattern over central Pennsylvania. The base reflectivity data showed several bands of precipitation, which were later determined to have formed in a conditionally stable to conditionally neutral atmosphere. For the October case, the rain / snow line remained near or just east of the Radar Data Acquisition (RDA) site during the event, which resulted in bright band contamination of the base reflectivity data in the band near the RDA. In both cases, the precipitation bands formed in a jet entrance circulation with low-level northerly ageostrophic winds that reinforced the cold air. For the October case, the surface low and warm front remained well south of the area. Soundings from Pittsburgh, Pennsylvania, and Dulles, Virginia, showed near neutral static stability and strong vertical wind shear. These two conditions are necessary for the development of Conditional Symmetric Instability (CS1) precipitation bands. Cross sections of equivalent potential temperature and geostrophic angular momentum (M) surfaces from both rawinsonde and model gridded data revealed that areas susceptible to CSI were present over central Pennsylvania for both cases. Low-level frontogenesis was also present for both cases and contributed to the formation of the banded precipitation over Pennsylvania in conjunction with the CSI present. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://nwafiles.nwas.org/digest/papers/1997/Vol21No3/Pg10-Grumm.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
