Thursday, March 17, 2005
St. Patrick's Day Update
Steve Scolnik @ 1:45 PM
Currently
Persistent cloudiness has been keeping temperatures well below our forecast from yesterday, although sun is beginning to break through here in Montgomery County. Temperatures in the low 40's in most places at 1pm ranged up to 45 at Culpeper, Winchester, and Leesburg. Meanwhile, radar around 11:30 was showing a fairly impressive area of precipitation extending as far north as southwestern Virginia past Charlottesville, through Fairfax and Montgomery counties and through Baltimore and northeastern Maryland. By 1:00, it had moved mostly east of I-95. This was not reaching the ground in the northern areas, but at noon several stations in central Virginia reported precipitation: Richmond (flurries), Petersburg (rain), Hanover (mix), and Charlottesville (light snow). The snow at Charlottesville ended shortly after having been reported for 3 hours.
Temperatures should reach highs in the mid 40's, upper 40's in sunnier locations, this afternoon under gradually decreasing cloudiness. Tonight's lows should be in the low 30's.
Analogs
The "blocking" pattern we have seen for the last couple of weeks inspired a lot of speculation in certain places about analogs, or similar situations in the past. In the days before numerical weather prediction, this was a reasonable attempt to solve the atmospheric equations from a given starting condition: Let nature provide the solution from one that had already occurred in the past. Of course, this was also before the days of chaos theory, which showed that tiny changes in the initial conditions can produce huge changes in the solution. Probably the most controversial advocate of this theory was Irving Krick in the late 1940's and 1950's. His work became so controversial at Caltech, that it resulted in the meteorology department being shut down. Krick's theories were still followed more recently by a certain popular broadcaster no longer in this area.
The most notable analog that was given for the current situation was March 18-21, 1958. Since this was a storm which set all-time snowfall records in central Maryland and southeastern Pennsylvania, it generated a lot of excitement among the snow fanatics. However, as this pattern is now breaking down (see Josh's post below), we can see (if you can stand the metaphor), that there are a lot of recipes that can be made from the same set of ingredients.
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