The Central American Cold Surge: An Observational Analysis of the Deep Southward Penetration of North American Cold Fronts
Abstract
The occurrence and structure of the Central American Cold Surge (CACS) is quantified using surface and upper air observations, GOES satellite imagery and satellite estimates of total precipitable water (TPW) and rain rate. A quantitative CACS definition, similar to established East Asian Cold Surge definitions, is developed and used to construct an eleven winter season climatology of CACS frequency and relative strength. Central America experiences between 11 and 21 CACS events each winter season, with a winter season average of 16 events. GOES imagery is analyzed to quantify the duration and southward penetration of CACS events. Each cold surge typically affects Central America for 3 to 6 days, but may persist for up to 13 days. The mean CACS southward penetration ranges from 12 deg N to 14 deg N, while the maximum southward penetration is approximately 7 deg N. Over 76% of CACS events penetrate south of 15 deg N and over 26% penetrate south of 10 deg N. CACS onset characteristics are described from Belize City, Belize surface observations. A wind shift to the north, sharp rise in sea level pressure and increase in low-level cloud cover are the best cold surge indicators. CACS events contribute from 70% to 90% of the winter season precipitation across Central America. Temporal cross sections of upper air data are constructed to quantify the vertical structural characteristics of the pre- and post-CACS atmosphere. The most common feature is an increase in the depth of the moist layer after frontal passage. TPW and rain rate are estimated from satellite microwave observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1992
- Accession Number
- ADA268592
Entities
People
- Philip J. Reding
Organizations
- Texas A&M University