Although no major weather events are on the horizon, a few rainy days are on the horizon for next week. A deep southwesterly flow will combine with a cold front currently in the Plains that is heading east. The strong upper-level jet stream, or zone of strong winds high in the atmosphere, ahead of the front will allow rain to arrive Tuesday and continue through Wednesday. A low pressure will develop along the front as it moves across the Interstate 95 corridor, enhancing the rainfall. Before all is set and done Wednesday evening, 1 inch appears likely in the District with up to 1.50 inches in the Potomac Highlands. This amount of rain will likely erase the going November rainfall deficit while the yearly departure remains above average.
With that in mind, let’s break down the monthly precipitation departures from average starting with January for the official weather recording station in Washington, D.C., Reagan National Airport. The surplus in precipitation in August and September is attributed to Hurricane Irene and the remains of Tropical Storm Lee.
Looking down the road, temperatures will likely remain near average with a hint of a colder pattern possible by the end of November/beginning of December. Fast zonal flow in the upper-levels of the atmosphere will likely drive Pacific cold fronts quickly across the country through the end of the month with rain chances at least once a week through the end of November. Since they likely won’t have a Canadian or Arctic connection, temperatures in the wake of each front will only dip to slightly below average levels.
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