Marine Weather and Tide Forecast for Indian Trail, NC

NEAR TERM /THROUGH SATURDAY/
Key Messages:

1) A line of strong-to-severe thunderstorms is expected to impact the mountains late tonight into Saturday morning, with the threat decreasing eastward.

2) Confidence remains low, but there's potential for severe weather east of the mountains leading up to dawn.

3) Temps around 10 degrees above normal.

As of 953 PM EDT Friday: Only major change to the forecast this round was to bump dewpoints up, as they've been consistently a couple degrees higher than forecast all evening. All quiet across the forecast area tonight as we watch and wait for upstream convection to evolve. Multiple bands of organized convection are visible on regional radar imagery over the Cumberland Plateau and central Kentucky. 00z soundings over the Tennessee Valley depict an impressive EML, which should advect into the Carolinas and Mid-Atlantic over the next few hours ahead of a robust shortwave visible on water vapor imagery. Hi-res guidance consensus continues to be that convection will struggle to hold together as it crosses the complex terrain of the Appalachians...owing in large part to the upstream capping advecting into the Carolinas, and the disruptive nature of shear of the ragtag line.

Nevertheless, there's more than enough uncertainty to advertise chance PoPs east of the mountains. While the main severe wx threat overnight will be from damaging wind gusts...low level shear will be adequate for brief spin-ups, mainly across the TN border counties.
Somewhat concerningly, the 00z HRRR has come in with increasingly impressive redevelopment of embedded thunder within the line, especially over the Upstate and Charlotte-Metro area...likely in response to marginally better lapse rates in this most-recent run, as well as somewhat higher forecast surface dewpoints.

The cold pool will effectively push a frontal boundary through the CWA Saturday morning, leaving behind lower theta-E air (mainly manifest as lower surface dewpoints). As such, forecast soundings during the daylight hours feature much weaker instability, and CAMs develop little in the way of diurnal convection. Therefore, after some lingering token small morning PoPs, chances drop to less than 20% across most of the area during the afternoon.

SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
As of 130 PM EDT Friday: Most of the model guidance are in agreement with the synoptic frontal boundary completing a full fropa across the CFWA and stalling south of the I-20 corridor by Saturday evening as the vertically stacked parent low sets up shop over the northeastern CONUS. The frontal boundary will be draped from the Southern Plains through the Lower MS Valley and Deep South Saturday night as the cold front becomes reactivated when convection initiates over the Southern Plains and Ozarks Saturday evening before becoming clustered and translating east. The flow aloft becomes more progressive Sunday into Monday as a digging upper low over the western CONUS carves out a ridge over the central CONUS, while orientating the flow from the northwest to southeast across the CFWA. Early Sunday morning, the flow aloft won't be fully established, but a potential decaying MCS could make a run at the southwest mountains and Savannah River Valley. Model guidance differ with the overall evolution, with the ECMWF/CMC indicating very little SBCAPE, while the NAM/GFS show a couple hundred J/kg of SBCAPE as it slips towards the area. Kept some mentionable PoPs in this region of the CFWA as a result, while any convective debris could alter afternoon highs on Sunday, but warm thicknesses and slightly lower dewpoints (upper 50s-lower 60s) will help afternoon highs top out ~5 degrees above normal.

Deep layer northwesterly flow becomes better established later Sunday as the upper ridge axis gradually shifts over the MS Valley, while an upper low churns over the western CONUS and the other upper low meanders over New England, creating an Omega-like blocking pattern. In this case, drier air will filter into the area, but convective initiation on the leeside of the western upper low and dryline across the Plains will create an assembly line for the activity to grow upscale and make a couple of MCS runs towards the CFWA during the early part of next week with the first MCS possibly tracking towards the area sometime on Monday. Confidence is low on the exact timing and placement of the MCS, but the synoptic setup is favorable and will likely throw a monkey wrench into the temperature and PoP forecast with the associated QPF response and convective debris. However, higher heights build into the area by early next week and should keep temperatures on track to rise a category or so above normal outside of the monkey wrench.

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
As of 230 PM EDT Friday: The upper ridge gradually shifts further east towards the eastern-third of the CONUS, while breaking down as the upper low over the western CONUS gets pushed from behind as a Pacific Northwest jet punches in. This will disorientate the northwesterly regime, but guidance try to send one more MCS towards the region late Monday into Tuesday, but will likely hit the northern tier of the CFWA this time around or miss to the north altogether. Diffluent flow aloft becomes better establish later Tuesday into Wednesday as the ridge continues to slide eastward and the upper low deepens into a closed low, which eventually becomes established across the Great Lakes region. Expect an increase in deep layer shear as a result, which will coincide with daily diurnal instability to help instigate strong to severe storms ahead of an encroaching frontal boundary. Model guidance also show a potent shortwave rounding the base of the closed low Wednesday into early Thursday to help the frontal boundary advance eastward and complete a fropa sometime during the first half of Thursday. Drier air is expected behind the front as broad cyclonic flow aloft remains in place and low-level CAA filters in with weak high pressure, setting the stage for a post-frontal regime by the latter half of the forecast period. Northwesterly flow will commence and could produce a few orographically enhanced showers along the TN border. Continued northwesterly flow pattern remains in place through the end of the forecast period and could make the area vulnerable to another favorable MCS pattern, but likely to become more set and stone after D7. Temperatures will be at or slightly above normal Tuesday and Wednesday, before the post-frontal regime allows temperatures to fall a category or so below normal Thursday and Friday.

AVIATION /02Z SATURDAY THROUGH WEDNESDAY/
At KCLT and elsewhere: Still expect VFR through the period, except for brief restrictions during active convection. A line of organized thunderstorms currently located over Kentucky will arrive from the Tennessee Valley around or after midnight.
It remains unclear how well this system will hold together, but confidence is improving that it'll at least affect KAVL, before deteriorating as it exits the NC mountains. PROB30s for TSRA are still advertised at some sites, and gusty winds remain advertised for all the TAF sites during and after the passage of the system.
Those gusts will persist through Saturday afternoon, before quieting Saturday evening. Little more than a widely scattered and capped cu field is expected during the daylight hours Saturday.

Outlook: The potential for mainly diurnal convection increases again Sunday, with chances continuing through the middle of next week.
Early morning fog/low stratus will be possible, especially in the mountain valleys and in locations where appreciable rain fell the previous afternoon/evening.

GSP WATCHES/WARNINGS/ADVISORIES
GA...None.
NC...None.
SC...None.