Forecast Discussion
Summary
SYNOPSIS
... A warm front will remain just to the north through tonight, but a cold front should arrive by Saturday morning to bring showers. High pressure will follow on Saturday night to provide drier conditions for Sunday, but an area of low pressure could bring the next chance of rain during the early part of the work week.
NEAR TERM /THROUGH SATURDAY/... As of 521 PM EDT Friday...
Made some minor adjustments in pops and weather to capture the latest radar trends. In general, allowed for a chance of rain further south in the unstable air. The combination of outflow boundaries and low level convergence could generate some isolated showers. More changes later this evening.
Previous discussion: As of 140 PM EDT Friday...
Confidence is high for a cold front arriving by Saturday.
A warm front will remain draped just to the north across central Virginia and West Virginia for the remainder of today into tonight. Showers and perhaps some embedded thunderstorms will ride along this frontal boundary during this time. Rain chances have been kept mostly confined to the Interstate 64 corridor through this evening. Because areas to the south will remain in the warm sector and stay away from the chances of rain, temperatures will remain well above normal with highs soaring into the upper 60s to the upper 70s along and west of the Blue Ridge and into the lower to mid 80s in the Piedmont.
The warm front will head further northward after sunset, which should provide a temporary reduction in rain chances. The flow will turn toward the east across portions of the Piedmont overnight, which will help to bring a weak wedge of cooler air with temperatures falling toward the mid to upper 40s. However, outside of this cool wedge, a good southwest breeze should persist to keep temperatures from falling lower than the 50s. A cold front will approach the Ohio River Valley after midnight tonight. Showers with some isolated thunderstorms running ahead of the front will approach the Appalachian Mountains toward the early morning hours of Saturday morning.
The showers and will head eastward as the cold front crosses the Mid Atlantic by midday Saturday, while any thunderstorms should weaken due to lower instability from the lingering cool wedge to the east that the front should eventually erode. Winds will increase from the southwest in the afternoon with gusts up to 40 MPH possible in the higher elevations of southeast West Virginia and up to 30 MPH elsewhere. Because there is no cold air mass behind the frontal passage, temperatures on Saturday will only drop a few degrees compared to Friday and still remain above normal for this time of year.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/... As of 150 PM EDT Friday...
Dry for Sunday with rain returning to parts of the region on Monday...
On the backside of the departing Saturday system, some residual upslope moisture across Western Greenbrier County, WV will provide for some isolated evening showers. High pressure will start building into the region overnight, and its axis will be our region by late Sunday afternoon. Between these two times, a tight pressure gradient will exist Saturday night and provide form winds gusting across the mountains in the 25 to 35 mph range with 15 to 25 mph gusts across the Foothills and Piedmont regions. Winds will gradually decrease as we head into and through the day on Sunday.
Sunday night into Monday, guidance offers a variety of solutions for our region. Specifically, there is notable differences between the NAM solution and those of the GFS, European and Canadian solutions. While all offer a solution of a shortwave trough moving across the Southeast US. However, the NAM offers a generous swath of rain crossing our area. Its aforementioned model counterparts keep this feature south, but not too far south, of the area. Our forecast will reflect a small chance of precipitation for the area Sunday night into Monday morning, but not to the levels the NAM is offering.
Late Monday into Monday night, we will be watching a shortwave trough moving east through the Great Lakes region. The southern extent of this feature may cross Southeast West Virginia, bringing some isolated showers.
Temperatures during this portion of the forecast will average ten to fifteen degrees above normal.
Confidence in the above weather scenario is high Saturday night into Sunday, drops to low-moderate by Sunday night into Monday, rises slightly to moderate for Monday night.
LONG TERM /TUESDAY THROUGH FRIDAY/... As of 1240 PM EDT Friday...
Slightly above normal temperatures through the period with rain chances Tuesday and Friday...
Our weather on Tuesday looks to have some rain in it, but the question will be from what feature. Deterministic solutions during this portion of the forecast have either a cold front moving through the area, with precipitation in the form of isolated to scattered showers across the mountains, with best coverage over Southeast West Virginia. Or, a shortwave trough will head northeast along a frontal boundary stalled to our south, and this feature will bring more of patchy light rain to primarily southeastern parts of the region. We will continue to maintain persistence with our forecast and still offer a consensus of these two potentials. Tuesday weather will extend into Tuesday evening, but coverage is expected to be on the decrease.
By Wednesday, most solutions are in good agreement of drier and cooler high pressure settling over the region.
Wednesday night into early Thursday, our pattern shifts again with a shortwave trough expected to head east through the Ohio Valley. The southern tail of this system may glance Western Greenbrier County with light isolated rain/snow showers Thursday morning.
Thursday night through Friday an upper trough is expected to deepen across the Central Plains states and head northeast towards the Great Lakes region. Its associated surface low will parallel the track of the upper system but be positioned farther east. This system associated warm front is expected to lift northeast towards the area Thursday night and slowly cross the region, or stall over it, on Friday. Look for increasing chances of rain during this time period.
Confidence in the above weather scenario is low on Tuesday but moderate Wednesday through Friday.