Squeeze Play Sends Fine Weather Into Extra Innings

An atmospheric squeeze play is extending the fine spring weather from April into May in the Washington DC metro area. A ridge of high pressure extending along the entire east coast of North America is being squeezed from two directions by "cut off" low pressure areas over the upper Midwest and near Bermuda. While the ridge holds in place, the sunny, dry weather will continue over the Mid Atlantic area as Jason describes below, but the unusual northwestward motion of the eastern low will bring the threat of some clouds and rain to New England.

Surface pressure (solid lines) and 500 mb height (colors) at 8am today from Unisys

At mid afternoon today, 68° was the lowest reported reading around the region; most places were 70° or higher. The bright sun was accompanied by delightfully dry dewpoints of 45° or less. The nearest showers were over the lower Ohio Valley and eastern New England.

Tonight and Tomorrow

Mostly clear skies should continue through tomorrow afternoon, with only a few clouds late in the day. Lows tonight under light winds should again be in the mid to upper 40s city to near 40 in the colder 'burbs. Highs tomorrow will be near 72.

Capitol Climate

The American Meteorological Society has posted more details on the next Capitol Hill Environmental Science Seminar this week:

• Topic: Changes in Cold Places: A Look at the Greenland Ice Sheet, Arctic Sea Ice and the Antarctic Ice Sheet
  
• Date: Wednesday, May 3, 2006
  
• Time: 12:00 Noon - 2:00 pm
  
• Location: Russell Senate Office Building, Room 428

The public is invited; no pre-registration required.

The questions to be addressed are:

Are parts or all of the Greenland and Antarctic Ice Sheets undergoing a net melting? What is the nature of the observational evidence of melting? How far back in time do these observations extend? Are the melting and rates of melting consistent with model simulations and projections of melting? What are the factors deemed responsible for the melting? Is Arctic Sea Ice thinning? If so, by how much and over what period of time? What is the nature of the observational evidence for this thinning? Are the thinning and rates of thinning consistent with model simulations and projections of thinning? What factors are deemed responsible for the thinning of Arctic Sea Ice? Are there implications with respect to sea level rise? Is there any evidence of a fundamental change in the rate at which the Greenland ice sheet is changing and the manifestation of those changes? If so, why? How well do model simulations capture the dynamics of ice sheets and sea ice relative to observations? How well are these ice sheet models poised to project future changes in ice sheets, sea ice and sea level?

Photo, via AMS, is also the cover picture for the April 2006 Weather Magazine of the Royal Meteorological Society (Special Issue: Climate Change in high latitudes 2). It shows surface melt water entering a moulin in the Greenland Ice Sheet.