Marine Weather and Tide Forecast for Middleburg, NC

NEAR TERM /THROUGH TONIGHT/
As of 950 PM Thursday...

The Severe Thunderstorm Watch has been cancelled for the entire forecast area. Showers and thunderstorms across the eastern portion of the forecast area have fallen apart. However, several runs of the HRRR show the potential for some showers to move into western portions of the forecast area late tonight toward sunrise, and have added some slight chance pops to account for that. In addition, some patchy fog cannot be ruled out considering there has not been a change in airmass and there is plentiful low level moisture. Lows will be in the mid and upper 60s.

SHORT TERM /FRIDAY AND FRIDAY NIGHT/
As of 230 PM Thursday...

* A conditional risk of severe storms will exist across the nrn half of cntl NC on Fri, based on lower predictability, mesoscale influences from upstream convection across the lwr OH Valley today- tonight.

12Z guidance this morning continues to highlight an uncertain forecast wrt to convection Friday. An upstream, decaying MCS is still forecast by several models (e.g. NamNest, HRRR, NSSL) to cruise across the mountains and foothills early Friday morning.
Strong sfc gusts (possibly 35 to 45 kts) associated with it's cold pool still look plausible early to mid Friday morning across the northern Piedmont. This scenario would favor less convective potential later Friday afternoon, as lingering cooler air and cloud debris limit sfc heating across northern areas. Alternatively, the FV3 and ARW CAMs continue to simulate the morning MCS further north into Virginia. This scenario would favor strong heating across all of central NC and the development of strong CAPE by Friday afternoon. Any convection that develops in this environment would favor explosive updrafts and supercells capable of large hail and damaging wind gusts. Given this potential scenario, the SPC has introduced a Marginal Risk for severe storms over our northern tier of counties. However, given some models limit afternoon convection, decided to maintain just slight chance PoPs across generally northern locations Friday afternoon and evening.

During the overnight hours, yet another round of upstream, decaying MCSs are forecast to move into the mountains and foothills through sunrise. Like clockwork, there is little guidance consensus on the evolution of these features. However, its worth noting that some CAMs do indicate the potential for another round of strong sfc gusts embedded within associated cold pools early Saturday morning. Worth watching for sure.

LONG TERM /SATURDAY THROUGH THURSDAY/
As of 355 PM Thursday...

The mid/upper low and occluded surface low will track east across southern Ontario/Quebec and the Great Lakes on Saturday and Saturday night, dragging a cold front to the south that will pass through central NC during the afternoon and evening. Model guidance indicates an MCS will approach from the TN Valley on Friday night, but weakening significantly as it crosses the Appalachians and approaches central NC on Saturday morning, with outflow surging out ahead of it. Models struggle with depicting the strength and timing of these MCS's, especially this far out, and that will be critical for the severe storm threat later in the day. A weaker MCS that passes through earlier on Saturday would favor more daytime heating and destabilization compared to vice versa. The NAM Nest is the only high-res guidance that goes out this far, and it does depict ample instability resulting in a broken line of showers and storms developing along the cold front from Saturday mid-afternoon into the evening. However, lower-res guidance is mostly dry, and moisture with the front does not look impressive, as the flow aloft is from a westerly direction. Furthermore, we will only get weak upper forcing with the low tracking so far to our north. GFS/ECM/CMC ensemble mean QPF continues to trend drier and is less than a tenth of an inch. So while convective coverage is still unclear, think it should be pretty isolated, and only have slight to low chance POPs. Still, there is a conditional threat of a few strong to severe storms with large hail and damaging winds developing along and ahead of the front, as surface-500 mb bulk shear will be as high as 40-50 kts.
Also can't rule out some strong cold pool induced wind gusts with what is left of that MCS on Saturday morning. Saturday's temperatures may be kept down in the morning by outflow and clouds from the system, but we should still get good surface heating in the afternoon as clouds break and we get strong SW winds ahead of the front (gusting up to 20-30 mph even outside of any storms). So forecast highs are still mid-80s to lower-90s, not quite as warm as Friday, but heat indices in the mid-to-upper-90s will still be possible in the SE.

The mid-level flow will turn NW from Sunday into Tuesday, as we are caught between the low slowly drifting east over New England and the Canadian Maritimes and ridging that strengthens and builds east from the MS Valley to the Deep South and TN Valley. At the surface, a backdoor cold front looks to move through central NC on Sunday night. This front then looks to lift back slowly north on Monday and Tuesday, and latest guidance has trended toward the front lingering more on top of our region instead of to our SW. Precipitation chances could be enhanced by a series of MCS's that move overtop the ridge and through the southern Mid-Atlantic. So expect gradually increasing shower and storm chances each day, but there is still plenty of uncertainty.

The next mid/upper low will move east from the Central Plains on Tuesday, but models disagree on the pattern evolution after. The GFS picks it up by a northern stream low over the Great Lakes and is more progressive, while the ECMWF keeps the systems separate and thus hangs them back longer. This will have a big impact on precipitation chances as well as temperatures, but it looks like an associated cold front will move through sometime Wednesday or Thursday. For now have POPs increasing to high chance to likely on Wednesday, decreasing somewhat on Thursday as the GFS and most of its ensembles are dry by then while the ECMWF and CMC are still wet.

As cool high pressure extends south from the Hudson Bay into the Eastern US, expect at least slightly cooler temperatures from Sunday into Tuesday with highs mainly in the 80s and lows in the upper-50s to mid-60s. Dew points will be more tolerable compared to now, generally mid-50s to lower-60s. A sharp drop to below-normal temperatures should occur late next week once the Wednesday/Thursday cold front moves through.

AVIATION /06Z FRIDAY THROUGH TUESDAY/
As of 230 AM Friday...

24 hour TAF period: An isolated shower/storm or two remains possible overnight. Otherwise, with the exception for some variable restrictions at fog prone KRWI, all remainder TAF sites should remain VFR through daybreak.

Forecast confidence is lower than normal wrt to storm potential this afternoon and evening.

Upper level disturbances spilling atop a strong upper level ridge in place across the region may support isolated to scattered storms across the northern portions of the forecast area this afternoon and evening. Alternatively, the upper ridge could largely suppress/stifle compression, keeping the area free of convection.
Should storms hold together, strong instability and shear would be conducive for strong wind gusts of 30-50kt+, hail and sub-VFR conditions for any northern TAF site(KINT, KGSO, KRDU, and KRWI)that takes a direct hit.

Given the uncertainty, will omit any mention of storms and restrictions at this time. But a period of storms/restrictions may need to be added with later TAF issuances.

Outlook: Chances for diurnal isolated to scattered showers and storms will continue through much of the period. Morning fog and low stratus will be possible each morning, especially in areas that received significant rainfall the previous day.

RAH WATCHES/WARNINGS/ADVISORIES
None.