Marine Weather and Tide Forecast for Cornelius, NC

NEAR TERM /THROUGH SATURDAY/
Key Messages:

1) Severe Thunderstorm Watch remains in effect for the NW corner of the CWA through 22Z/6 PM.

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

3) Temps around 10 degrees above normal.

As of 145 pm EDT Friday: Latest regional mesoanalysis depicts a moderate-to-strongly unstable, but capped air mass across our forecast area this afternoon. Meanwhile, extensive cirrus shield associated with upstream convection has also hindered heating somewhat and acted to suppress cumulus development across our area.
The cap does weaken a bit toward the NW, and a Severe Thunderstorm Watch remains in effect for the northwest corner of the CWA Having said that, regional radar imagery is probably depicting the location of the cap quite well, as cold pool associated with ongoing strong/ severe convection that has been moving E/NE across southern/ eastern Kentucky has struggled to initiate new cells into northeast TN. As such, this convection is forecast to pass comfortably north of our area through mid- afternoon. We will continue to advertise small PoPs north of I-40 late this afternoon into the evening, but the latest convection-allowing models have trended toward the idea of the cap holding through this evening...even across the northern areas. IF any deep convection is able to initiate in our area, shear parameters are more than adequate for supercells and attendant threats of very large hail, damaging downbursts, and possibly an isolated tornado.

The next round of strong-to-severe convection is expected to begin organize ahead of a cold front within a very unstable and strongly sheared environment across the western Ohio and Tennessee Valleys late this afternoon and evening. All guidance sources generally agree that convection will congeal along a larger scale cold pool across TN/KY by late evening and accelerate toward the southern Appalachians, likely reaching western NC between midnight and 3 AM, bringing the potential for widespread strong-to-damaging wind gusts...especially the counties bordering TN. However, convection will likely weaken/become less organized as the complex terrain disrupts the cold pool/shear balance. The big question then becomes whether convection can reorganize along the cold pool as it moves off the high terrain into the foothills and Piedmont during the pre-dawn hours. The environment east of the mountains is expected to remain largely capped...arguing against the potential for reorganization
Additionally, shear parameters are strong
and studies have shown that strong shear cam actually be detrimental for regeneration along a terrain-crossing cold pool. 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.

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 /19Z FRIDAY THROUGH WEDNESDAY/
At KCLT and elsewhere: VFR is forecast through the period. Isolated thunderstorms are possible late this afternoon near KHKY, but the probability of a storm in the vicinity is around 20%, and therefore not worthy of a TAF mention. A line of thunderstorms organizing over the TN/OH Valleys later this afternoon/evening is expected to begin weakening as it moves E/SE across east TN and western NC late this evening into the early part of the overnight. At this time, it is not clear whether this convection will hold together long enough to reach any of the TAF sites. Nevertheless, Prob30s for TSRA are warranted at most sites at some point between 06-12Z Saturday. Gusty winds are likely if the convection holds together. (Even if the convection doesn't hold together, remnant outflow boundary may still be capable of gusty winds.) Otherwise, S/SW winds are expected to increase to around 10 kts by this evening...generally persisting through tonight before increasing to 10-15 kts with higher gusts by early afternoon Sat.

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.