... The remnants of Tropical Cyclone Ian will slowly drift toward the Virginia coast through tonight. A coastal low is likely to develop off the Eastern Seaboard as the remnants of Ian move offshore by Monday. High pressure will build into the region by Tuesday ushering in drier conditions. Temperatures briefly warm up mid-week ahead of a strong cold front moving through on Friday.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... The overall pattern remains largely unchanged as a mixture of light rain showers and drizzle impact the region. Recent KLWX radar imagery shows these precipitation elements racing off toward the northwest. This will continue through the overnight hours as moisture spirals around the former Tropical Cyclone Ian which sits over west-central Virginia.
The main focus for any more concentrated showers activity would be along the eastern slopes of the higher terrain as low-level forcing associated with the low itself briefly wanes.
Temperatures will probably only drop about 5 to 10 degrees tonight from their afternoon readings given abundant cloud cover and a steady northeast wind.
SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... The area of low pressure over VA drifts eastward, eventually merging with a large upper trough moving into the region from the Great Lakes/Canada. There is great model agreement that a coastal low develops off the Eastern Seaboard on Monday, as high pressure builds into the area from the northwest. Rain chances remain high on Sunday as lingering moisture and sufficient forcing for ascent produces widespread showers, perhaps a band of moderate rain on the NW side of the developing offshore low as the upper low moves overhead.
Conditions dry out from west to east Monday morning, with a few showers lingering along/east of I-95 through the afternoon.
Below normal temperatures are expected on Sunday as highs only reach the upper 40s to mid 50s in the mountains, and upper 50s to mid 60s east of the Blue Ridge. Cloud cover across the eastern half of the area should keep temperatures well below normal, around 60 degrees, on Monday. It may actually be warmer in parts of the mountain valleys where temps reach the lower 60s. Cooler air moves into the area Monday night as temperatures drop to the 40s in most places.
LONG TERM /TUESDAY THROUGH SATURDAY/... The upper-level low is forecast to be near the Chesapeake by Tuesday morning with a surface low farther offshore. Current forecasts are for these lows to ever so gradually move eastward through Tuesday night. It appears rain will be limited on the rear flank of this system, but some lingering showers could continue near and east of I-95. High temperatures will be dependent on the amount of cloud cover (which won't completely clear out), with lower to mid 60s where it's cloudier, and mid to upper 60s elsewhere. Tuesday night lows will be in the 40s for most.
The system should be far enough east to allow surface high pressure and shortwave ridging to build across the area Wednesday and Thursday. This will lead to more sunshine and a warming trend. In fact, by Thursday, highs may be a little above normal (mid to upper 70s).
A northern stream trough will quickly dig into the Great Lakes Thursday night into Friday with low pressure strengthening over the St. Lawrence Valley. The trailing cold front will likely cross the area Friday. It will be moisture-starved, so the best chance of showers will be near the Appalachians. Friday's highs will be dependent on the frontal timing as sharp cold advection will follow. Some of the higher elevations could fall to freezing by Saturday morning as 850 mb temperatures drop below 0C. Saturday's highs will be well below normal, only in the upper 50s and lower 60s.