... A weak disturbance from the Tennessee River Valley continues east of the region tonight. High pressure builds overnight into Sunday with a dry and slightly cooler end to the weekend. Our next cold front crosses the region Monday bringing with it mountain showers and gusty winds Monday afternoon. A potentially stronger system with widespread precipitation is expected to impact the area Tuesday into Wednesday.
NEAR TERM /THROUGH TODAY/... As of 935 PM EST Saturday...
Some subtle changes in temperatures, dewpoints, and cloud cover especially west of the Blue Ridge overnight.
Overall the forecast package remains on track. We continue to see clearing skies west of Blue Ridge with just a few pockets of mid to high level clouds streaming through the North Carolina foothills and Roanoke Valley. Cloud coverage will remain scattered to broken at times through the overnight especially south and east of the BLue Ridge as our weak disturbance from earlier this afternoon pushes off the Atlantic Coast. Meanwhile areas west of the Blue Ridge will likely see mostly clear to partly cloudy skies overnight with an emphasis on scattered to broken mid to high level clouds building Sunday morning.
For that reason, overnight lows will not drop a whole lot. We may actually see a ridge valley split where it's warmer on the ridges compared to the valleys below. The coldest air will reside in the Greenbrier Valley and Alleghany Highlands with dry dewpoint values in the mid to upper 20s and air temperatures in the low to mid 30s. Elsewhere upper 30s and low 40s are expected with mid 40s across the North Carolina foothills/Virginia Southside.
Mid to high clouds will continue to thicken Sunday morning as high pressure shifts north and east. Weak wedging will set up with southeasterly flow which means a slightly cooler days ahead. Highs will range from the mid to upper 40s over the mountains to low 50s out east under milky sunshine.
As of 555 PM EST Saturday...
Mid to high level clouds look to remain through tonight with slightly cooler conditions Sunday as high pressure returns...
Synoptically not much has really changed with our upper trough continuing to dig in from the Ohio River Valley. It's a battle between two disturbances with low pressure exiting to our east and high pressure approaching the Great Lakes/Ohio River Valley this evening. The high looks trek just to the north of our region overnight into Sunday before shifting further north and east toward New England Sunday afternoon. With that said, this will set us up for a weak wedge scenario with low level winds shifting from the north and northeast tonight to the east and southeast Sunday afternoon.
As a result, mid to high level clouds will likely remain along with slightly cooler temperatures to round out the weekend ahead. Lows tonight will range from the low to mid 30s over the mountains to upper 30s and low 40s out east. Areas such as the Greenbrier Valley and Alleghany Highlands are likely to be a bit cooler than everyone else due to clearer skies from the close proximity to the incoming high and distance away from our departing system south of the VA/NC line. Elsewhere mid to high level clouds remain this evening especially across the Roanoke and New River Valley, but even these areas look to see filtered breaks overnight allowing temperatures to drop.
With the wedge, highs Sunday look to be tampered. Highs will be a bit more seasonable with upper 40s in the mountains to low to id 50s out east. Mid to high level clouds in the morning combined with increasing clouds in the afternoon out ahead of our encroaching front aid in a consensus of going a bit lower than guidance and staying with the numbers inherited from the previous forecast solution. Hi-res cams and short term synoptic guidance also continues to add further confidence in this general thinking as the weak wedge establishes itself in the afternoon and evening with excess clouds to reduce high temperatures across our region.
Sunday still remains dry as all model guidance suggest a slower arrival time on our next front. For that reason, have continue to trim PoPs back along the North Carolina mountains and back to the west across southeast West Virginia. Shower chances pick up late Sunday night as low level moisture continues to build and front starts to move in. Best chances for precipitation though still look to be west of the Blue Ridge across Grayson Highlands, western North Carolina mountains, and southern coalfields of West Virginia.
Upper trough will be digging over the Great Lakes and Ohio Valley by tonight. At the surface, high pressure tracks east off the Mid Atlantic coast. Once the high is to the east, surface and low level winds pick up out the southeast. This will produce some upslope clouds along the southern Blue Ridge. Will be lowering the small probability of precipitation in northwest North Carolina and trimming back until late in the day Sunday.
With a weak surface based wedge in place on Sunday and multiple layers of clouds, daytime temperatures will be cooler than today and Friday, and close to normal for this time of year. Fairly large spread in solutions in the guidance for highs on Sunday. Staying cooler than MAV numbers and have lowered maximum temperatures a couple degrees from inherited forecast.
SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... As of 245 PM EST Saturday...
High pressure ushered out ahead of approaching cold front.
We finally see a break in the high pressure that has been keeping us in a dry pattern for so long. Late Sunday and into Monday troughing begins to dig into the Midwest, bringing a cold front into the area. Considerable rainfall will cross the TN and OH valleys before getting near the NRV and Blue Ridge region of the Appalachian Mountains. The rainfall from this system rapidly shrinks in quantity as it crosses our CWA, creating an all-too familiar pattern of more rain west of the Blue Ridge, much drier conditions east into the Piedmont. Mountain Empire and Greenbrier Valley areas could receive up to a half of an inch, while Piedmont locales will likely get under a tenth of an inch. Most rain will occur Monday morning and early Monday afternoon, quieting down later Monday. However, a strong pressure gradient behind the front will give rise to strong post frontal winds. Will have to monitor the situation for potential advisory level winds (gusts up to 40MPH in high elevation counties) Monday afternoon/evening.
Temperatures will be above average ahead of the front as we sit in the warm sector, highs on Monday in the upper 50s and 60s.
LONG TERM /TUESDAY THROUGH SATURDAY/... As of 430 AM EST Saturday...
Better widespread rain chances in the middle of the week.
Broad troughing over much of the eastern half of the CONUS begins to tighten up and deepen as the axis comes to the east coast. This aids in some frontogenetic action south of low pressure passing through the northern Appalachians. That will interact favorably with a newly moistened atmosphere, creating the best chance for rain in quite some time for the Piedmont. Some colder air tries to fold in, but given a warm nose present on model soundings Tuesday night/Wednesday morning keeping mostly rain for this system, but the potential for wintry precip is there. Definitely something to keep an eye on in coming model runs.
A progressive setup will keep sending fronts across our area every couple days, and we will remain in an unsettled environment through much of this forecast period. Timing of these systems varies between guidance as we extend out to the end of the forecast period, so pinning down specific days later in the week for heaviest rain is difficult. Cloudy and temperatures largely near normal for this time of year.