Central 14th Street / WMATA Northern Bus Barn, DC Weather

What Has Changed

The benign weather pattern continues on with seasonable to above normal temperatures through the remainder of the workweek.

Key Messages

- 1) Benign weather continues through the remainder of October with near to above normal temperatures expected.

- 2) Precipitation chances return in early November.

Discussion

KEY MESSAGE 1...Benign weather continues through the remainder of October with near to above normal temperatures expected.

Surface high pressure will continue to build south and west toward the central Appalachians and Mid-South tonight. Meanwhile, low pressure over the Canadian Maritimes will drive a weakened cold front into the region from the north and west Tuesday. The front will cross the area Tuesday morning before stalling/washing out to the south/east Tuesday afternoon. By Wednesday morning, the same front will retreat back to the north as a warm front with another large area of high pressure building to the north Thursday through Saturday. As a result, expect passing high clouds and a series of wind shifts with each of the frontal passages. Winds will remain light out of the north and northwest this evening through Tuesday. Winds will change to the south and southwest late Wednesday through Friday. This will yield seasonable to above normal temperatures for the remainder of the workweek. Highs will generally range from the mid 60s and low 70s though Wednesday with low to mid 70s Thursday and mid to upper 70s Friday. This is thanks to the position of the high to the north leading to increased southeast to southwest winds across the region. Overnight lows will remain warm as well in the mid 40s and low 50s.

Dry conditions will continue through Saturday although this will be a day of transition as the pattern begins to loosen. Upper level ridging will buckle with an incoming trough from the Midwest region. This trough will ultimately bring an end to the dry conditions with increasing cloud cover and precipitation chances heading into the first few days of November. Despite the increased cloud cover, expect highs Saturday back in the upper 60s and low 70s.

KEY MESSAGE 2...Precipitation chances return in early November.

Upper-level ridging overhead breaks down into zonal flow beginning Saturday into Sunday. Conditions likely start to become cloudier throughout the day Saturday as troughing develops over the Ohio River Valley before heading east Sunday into Monday. This likely brings the first chances for precipitation over the Mid- Atlantic in over a week, although overall breadth and total rainfall from this system remain uncertain at this time.

Temperatures likely drop back to the low-70s over the weekend in the wake of another weak front. With overnight lows generally remaining in the 40s and 50s, this ranges somewhat above normal for the beginning of November. Looking ahead, model guidance hints at a second, potentially more potent upper-level trough approaching the area that could bring additional chances for precipitation sometime next week.

Aviation

Prevailing VFR conditions are expected through Tuesday night. Winds will remain light out of the west and northwest this evening before becoming northerly late tonight into Tuesday morning as a dry cold front pushes through. Patchy fog remains possible, but does not appear as prevalent this morning outside of sheltered valley locations west of Blue Ridge and those directly along the water. Milder temperatures combined with subtle mixing along the front will yield the lower confidence for fog tonight across the terminals.

Winds will change from the north Tuesday to the northeast Tuesday night into Wednesday ahead of an incumbent warm frontal boundary. This will leads to the potential for low clouds and fog, especially at CHO and MRB given the marine influence /increased surface moisture banking along the eastern side of the Blue Ridge mountains. Confidence in this is low although hi-res models have shown some consistency in recent cycles. VFR conditions are expected Wednesday night through Saturday as high pressure builds along the coast. Winds will turn south to southwesterly Thursday before becoming easterly Saturday. The next chance for rain showers occurs Sunday with an incoming cold front, but uncertainty remains high at this time.