Mifflin Weather Patterns

Posted by on April 7, 2012

From a weather standpoint, May is a transition period between the vigorous systems of winter and the more tranquil and stable airmasses typical of summer in the northeast US. In other words, soaring pilots can experience everything associated with polar continental and maritime tropical, and mixtures thereof.

Typically, weather systems in May cycle through a sequence starting with the passage of a cold front, followed by a high-pressure system giving way to increasing moisture and a warm southwesterly flow until another cold front five or so days later repeats the process.

Cold fronts that are followed by strong (15+ mph) winds give this region of the country its famous ridge running conditions. Generally, these fronts also usher in an air mass with good visibility and the strongest thermals.

Increasing moisture in the southwesterly flow around the backside of the Bermuda High brings lower visibility and warmer temperatures. Cumulus clouds are more frequent but the cloudbases in this air mass are usually on the order of 4000’ to 5000’ above ground. Bases at 7,000’ to 9000’ agl are not uncommon a day or two after a May cold front.

Previous contests held at this site in May have had atypical weather as well. Sometimes an omega block develops in the upper air pattern and depending on where that is it can be good or bad for soaring. In 1991 the region was stuck in a hot, hazy high that begrudged us six flyable days. In 1998 good weather remained over the area and there were nine strong contest days. In 2004 lousy weather resulted in the 15 Meters Nationals not achieving a contest.

Broadly speaking, pilots can expect contests held in this part of the country to feature seven contest days.  Statistically, there will be one day with ridge running, a day with cumulus at 7,000’, a blue day with good lift to 6,000’, a couple days of cumulus at 5000’ and perhaps a squeaker day with cirrus interfering with convectivity.