textproduct: Columbia

WHAT HAS CHANGED

No significant changes to the forecast. Showers and a few thunderstorms are possible this afternoon and evening. Areas of fog possible tonight. Aviation discussion updated for 18z TAFs.

DISCUSSION

KEY MESSAGE #1: Showers and a few thunderstorms are possible this afternoon and evening.

Midday radar imagery shows a line of light showers moving into the western CSRA. Model guidance suggests that this band will pivot through the forecast area with isolated shower and thunderstorm development possible across the region this afternoon and evening outside of this band. With the best dynamics passing to the north, the severe threat should be limited with only Chesterfield County remaining in the latest SPC convective outlook. Based on satellite data, the most sunshine has occurred across the Pee Dee so would not be surprised if there is sufficient instability there for an isolated severe threat. Rain chances should quickly diminish from west to east this evening. Lingering moisture could result in patchy fog tonight, especially areas that see rain today.

KEY MESSAGE #2: Temperatures continue to be well above normal through mid-week.

The upper pattern during the early to mid week period will be driven by a cut off low anchored over Baja California. This feature will sluggishly move east through Wednesday before opening into an open trough as it rejoins the main flow. The weak ridging over the Southeastern and South-Central CONUS will build in response to this feature with the ridge axis passing overhead on Wednesday. This pattern will support a continuation of above normal temperatures through mid-week, with Wednesday slated to be the warmest day of the week when records may be challenged. Both the NAEFS and ECMWF EFI show that temperatures on Wednesday are at the top of the climatological chart for this time of year. Meanwhile, the NBM 75th percentile is 89F at both CAE and AGS on Wednesday. This gives us a decent shot at meeting or exceed the record highs, which happen to be 88F at both locations.

KEY MESSAGE #3: The next significant storm system arrives late this week, bringing a chance of rain and near normal daytime temperatures.

The aforementioned trough is forecast to move through the region on Thursday with an attendant cold front. Outside of an isolated shower or two on Tuesday, this will be the next chance for rain. The timing of the frontal passage will have an impact on any convective chances and trends will need to be monitored as the week goes on. In terms of temperatures, expect near normal daytime temperatures to close out the work week with near to below normal temperatures Thursday and Friday night.

AVIATION /18Z SUNDAY THROUGH THURSDAY/

VFR conditions exist currently across the region. Showers and isolated thunderstorms are expected to develop this afternoon and potentially bring brief restrictions to the TAF sites. Uncertainty exists about whether restrictions redevelop tonight or not - however, persistence leans towards another round of at least MVFR ceilings.

The stratus from this morning quickly cleared and gave way to partly sunny skies across the area. An interesting forecast exists for the rest of the afternoon. There is an area of light stratiform rain moving eastward from central Georgia, with the cloud cover creating a boundary across central SC. Scattered thunderstorms are expected to develop along said boundary over the next few hours, potentially impacting all sites. Light rain is likely to move in after this and into the evening hours, but the extent of thunderstorms is still currently uncertain. It seems like the best chance will be at Orangeburg which is east of the currently bubbling cumulus. A PROB30 for convection has been add to all sites for a few hours this afternoon, with Orangeburg potentially closest to needing a TEMPO group. The light rain from mid afternoon through early evening will likely curtail any thunderstorm threat deeper into the evening. Overnight, there is a persistent signal amongst guidance for some form of restrictions to redevelop as the weakening front pushes through the region. It seems less likely that fog will be the driver of these tonight as a low- level jet around 15 knots may be just enough to keep us mixed. Stratus has been common all week, and there really isn't much of an airmass change tonight despite a weak front pushing through. So expecting stratus to form for at least a period overnight tonight, probably in the 06z-12z timeframe. This should lift by mid-morning monday. Southwesterly to westerly winds are expected through the period.

EXTENDED AVIATION OUTLOOK...Overnight stratus will likely remain a threat through midweek. The next good chance of rain is expected Wednesday night and into Thursday.

CAE WATCHES/WARNINGS/ADVISORIES

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