... Weak high pressure slides out of the region today with just a few afternoon and evening isolated showers and storms. Shower and storm chances increase as we head into midweek as a surface trough of low pressure drifts in from the Ohio River Valley. The surface trough will merge with a stalled front to our north and west and an upper level trough swinging in from the Great Lakes to keep precipitation chances on the high side through late week. Temperatures will remain at or slightly above average through the period.
NEAR TERM /THROUGH TONIGHT/... As of 945 AM EDT Monday...
Morning satellite imagery shows that while some isolated patches of stratus remain from last night, most of the low clouds and fog have burned off. This is allowing for a good deal of sunshine across the Appalachians and central mid Atlantic region. However, radar does show some shower/thunderstorms activity not too far off to the west along a diffuse frontal boundary. Modified morning RNK sounding allows for some modest instability but mid/upper level lapse rates are not very steep and shear is weak.
Expect the front will remain just off to our west and keep the bulk of afternoon convection streaming by to our west. However there should be enough surface based instability to cook up some scattered showers/thunder this afternoon in our neck of the woods, especially south of route 460 and west of Interstate 77.
Skies remain relatively clear this morning with a few areas of patchy fog and low clouds rolling through. Fog will be persistent in the New and Greenbrier River Valleys along with the I-77 and US-29 corridors. All fog should start to burn off after 9-10am with mostly sunny to partly cloudy skies. A few more clouds will be noted by lunchtime and into the early afternoon as a warm frontal boundary from east Tennessee and central Kentucky slowly starts to push in. This boundary will build back moisture for a few isolated to scattered diurnally driven storms. Coverage overall looks to be confined to the mountains with most of the hi-res guidance showing not much at all.
Temperatures look to remain at or above average for the period with highs back around 90 degrees in most locations east of the Blue Ridge Monday and mid to upper 80s over the mountains out west. Overnight lows will fall back into the mid to upper 60s out west and low 70s east of the Blue Ridge heading into Tuesday morning. Humidity values will also comeback up with limited relief heading into the short term period as the surface trough of low pressure moves in.
Confidence remains high for temperature and precipitation in the near term. Moderate confidence on thunderstorms based upon the placement of the incoming boundary and how much subsidence is leftover from our departing high. Winds will remain light through the period.
SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... As of 200 AM EDT Monday...
A cold front will move over the Ohio River Valley and stall Tuesday. This front will then washout before it can get to the western ridges Wednesday. Without a bonafide boundary in the region, diurnal showers and thunderstorms will become the norm each day through the rest of the work week. Convection should also ramps up in coverage and intensity each day as a Bermuda High sends tropical short waves over the region. The severity of storms (isolated to scattered) may be similar each day, but the threat for flooding will likely increase with repeated days of heavy rains.
Daytime temperatures will run a degree or two warmer than normal. Overnights will remain muggy, generally running in the mid 60s to low 70s.
LONG TERM /THURSDAY THROUGH SUNDAY/... As of 200 PM EDT Sunday...
The stalled front from the work week hangs into the weekend before a trough swings through the Great Lakes region. This will eventually help start to disrupt the stalled front over the area and begin ending the diurnal flux of showers and thunderstorms. Before it though, scattered to widespread showers and thunderstorms continue to remain possible each afternoon with potentially heavy downpours with PWATs projected to remain above one standard deviation above average until Sunday. Temperatures continue to remain near to slightly above average.