Wednesday, August 25, 2004
Moisture in our midst?
Josh Larson @ 11:44 PM
Moisture, local as well as more global, will dominate our assessment of the weather today -- though perhaps not in the ways you might first expect.
Local moisture: A somewhat-usual atmospheric setup for August may provide significant cloud cover (at least for the first half of the day) and slightly below normal temperatures for the Mid-Atlantic region today. As our local NWS forecaster describes:
HEIGHT RISES AND THE PLACEMENT OF THE WARM RIDGE ALOFT CONTINUES TO SUPPORT THE COLD AIR DAMMING SIGNATURE OFTEN SEEN ON WINTER SURFACE MAPS EAST OF THE APPALACHIANS.
A translation to laymen's terms reveals that a strong area of high pressure to our northeast (offshore) is providing the region with easterly or southeasterly winds, sweeping in lots of low-level moisture from the Atlantic.
The result will be mostly cloudy to overcast skies during the first part of the day. However, with a strong August sun, we expect that some cloud-cover and haze will burn off by later in the day -- or, as meteorologists like to say, the "marine layer will gradually begin to decay."
So, expect partly to mostly cloudy skies with temperatures in the 60s and 70s through early afternoon, with gradual clearing giving way to partly to mostly sunny skies by late afternoon, with high temperatures topping out in the low 80s - just a bit below our average high in the mid 80s.
Global moisture: The other moisture in our midst is Tropical Storm Francis, which is presently no concern to us here in Washington, DC, or for the immediate future, to the continental U.S., as it is still a whopping 1400 miles east of the Lesser Antilles. However, it is the sixth named storm of the hurricane season, and some models suggest that in the next week it may strengthen significantly as it heads westward towards the Caribbean.
--> Interesting weather tibit of the day: The last 90 degree day in Washington, DC was over three weeks ago: Wednesday, August 4. <--
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