textproduct: Columbia

WHAT HAS CHANGED

Convective debris clouds have largely hindered fog development this morning.

KEY MESSAGES

- 1. A more typical summer pattern is expected through Wednesday before drier conditions move in for the late week.

DISCUSSION

- 1. A more typical summer pattern is expected through Wednesday before drier conditions move in for the late week. Rain chances expected to increase again next weekend.

A relatively quiet week of weather is forecast, with some notable potential exceptions, especially on Tuesday evening. The weather this week across the CONUS is forecast to be dictated by two distinctly anomalous upper level features. The dominant one will be an intense ridge of high pressure, currently over the southern Rockies and forecast to slowly retrograde to the west as the week goes along. Guidance suggests this feature is on the order of 2-3 standard deviation above normal, and will help to force a trough along the eastern seaboard nearly that strong as well. As the ridge retrogrades westward through the week, the trough is forecast to build southward and slightly westward, hanging out over the Carolinas for much of the week. The impetus for this trough digging is forecast to be a shortwave trough, currently moving through the Great Lakes and heading towards the Mid-Atlantic region by Wednesday. This will push a cold front towards the area Tuesday night through midday Wednesday. An increase in showers/storms is expected with this, though coverage is still fairly uncertain. The front won't be approaching until later on Tuesday and the best forcing and shear looks well to our north. The front should be pushing through by early afternoon Wednesday, with the best focus for convection expected in the coastal plain. So we find ourselves staring at another event where, in theory, we should get rain but the reality is that we will likely miss out on widespread rain again on Tuesday/Wednesday. It is forecast to be quite hot on Tuesday ahead of the front. Highs are forecast to be in the upper 90s and dewpoints should be at least in the low 70s. If those creep up into the mid 70s or higher (seems like a stretch considering how dry the soil is), we may need Heat Advisories across the area.

Regardless of rain chances, the weather Wednesday afternoon through Friday looks quite nice. While high temps won't really take a dip (remaining in the low 90s), surface moisture is forecast to be well-below normal for this time of year. PWs near or below 1" are forecast behind the front, which is ~10th percentile for this time of year. This should result in a nice break in the humidity as afternoon dewpoints will likely bump down into the low to mid 60s! By next weekend, the troughing is forecast to continue retrograding slowly west in conjunction with the ridge, and guidance is in good agreement that a relatively favorable setup for rainfall may occur. In the background of this entire forecast is quite good agreement in the guidance for much of the week, with increasing divergence amongst scenarios surrounding next weekend. Overall confidence is high in the forecast for the majority of this period.

AVIATION /12Z MONDAY THROUGH FRIDAY/

Brief restrictions likely early this morning at all sites but OGB which will continue LIFR vis through 13Z.

NW flow over the area will allow dry air to push into the region. Lingering surface moisture and dry air aloft are a favorable setup for early morning fog development. Models have been consistent with widespread visibility restrictions, however convective debris cloudiness from overnight thunderstorms to our north and west have largely hindered fog development with the exception of OGB which will continue to see LIFR vis through 13Z. Elsewhere, brief MVFR vis and cigs will continue through sunrise.

Improving conditions to VFR expected by mid to late morning with scattered cumulus in the afternoon. Convective coverage today is expected to be low, so no storms or showers mentioned at the moment. Winds generally light and variable, favoring a northwesterly direction.

EXTENDED AVIATION OUTLOOK...Rain chances increase mid-week with restrictions possible as a front pushes into the Southeast. Drier air moves in for the second half of the week.

CAE WATCHES/WARNINGS/ADVISORIES

SC...None. GA...None.