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10-Day Outlook: Tranquil Weather Returns

Josh Larson @ 11:00 PM

Today's Weather

Today's forecast calls for mostly sunny and breezy conditions with much more comfortable humidity levels (dew points near 60). Temperatures will reach the upper 80s in most locations. Expect mostly clear and comfortable weather tonight, with lows in the mid 60s downtown, slightly cooler across the suburbs.

Quick Pattern Overview

In the wake of Katrina, we will see high pressure building into the mid-Atlantic and Northeast behind a frontal system which passed through the region yesterday and lowered humidity levels. We will generally hold onto a weak mean trough generally positioned over the Eastern US, allowing for air aloft to enter our region from the west or northwest instead of the more humid (and warmer) south or southwest. There is little indication of an organized precipitation outbreak for our region over the period. We should continue to watch the Tropics over the next ten days as atmospheric and oceanic patterns that are conducive to tropical development will linger.

The next 5 days (Sept 1-5)
Forecast high/low: 84/62 (normal = 83/66)
Forecast precip: below normal

After today's mostly sunny and warm, though noticeably less humid, weather, Friday will feature almost carbon copy conditions. Expect abundant sunshine, comfortable humidity levels and temperatures near 89/64. The long holiday weekend looks absolutely terrific, with the continuation of abundant sunshine and pleasant humidity levels, and the added bonus of cooler temperatures: expect temperatures Saturday near 84/61, with temperatures on Sunday near 80/59. (Expect crisp overnight lows in the lower to middle 50s across the cooler suburbs over the weekend.) Labor Day Monday looks to be a picture-perfect weather day, with seasonably cool temperatures and mostly sunny skies. Expect temperatures near 77/59 downtown, with cooler overnight lows in the suburbs.

The following 5 days (Sept 6-10)
Forecast high/low: 80/62 (normal = 82/64)
Forecast precip: below normal

Global long-range models suggest a continuation of tranquil, dry, very comfortable weather extending into most of next week. As such, the forecast for the following 5 days is quite simple: Expect most days to feature mostly sunny skies (with mostly clear nights), with little or no chances for precipitation. Highs during this period will likely range from the upper 70s to the lower 80s, with overnight lows from the upper 50s to the lower 60s downtown (though once again cooler across the suburbs). Enjoy!

Verification of Last Week's Outlook

Mixed is the best way I can describe the performance of last week's 10-day outlook. From the period last Thursday through yesterday my high temperature forecast was off by 3 degrees, which, according to's demanding grading scale gives me a B-/C+; however, the vast majority of the 3-degree forecast error was due to the highly unanticipated very cool temperatures last Saturday (the high was only 73, whereas I had forecast a high of 85). If we remove Saturday from my forecast grade, I was only off by 1.5 degrees (forecast error is cut in half), which nets me an A.

As for precipitation, I believe I had an early, good handle on the potential impacts of Katrina, suggesting last Thursday that the she would likely bring to our area "a 25% chance of no impacts; a 40% chance of scattered showers and thunderstorms; and a 35% chance for a heavy rain event." Indeed, the scenario which I saw as most likely -- scattered showers and gusty thunderstorms -- came to fruition....

....One of the area storms produced a likely F0 tornado which, according to the visitor, Paul Coletti, who shot this photo, left an uneven path of damage "in about a mile stretch from SE to NW, just south of I-66, 1/4 mile west of exit 27 (Rt55)" near Marshall, VA in Fauquier County.

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