textproduct: Columbia

WHAT HAS CHANGED

Wedging conditions continue to weaken this afternoon, with temperatures warming more than forecast across the southern forecast area. Rain chances late this week continue to decrease with stronger upper ridging forecast. Aviation discussion updated for 18z TAFs.

KEY MESSAGES

1. Weaker wedge over the area leads to a strong temperature gradient this afternoon.

2. Well above normal temperatures with showers and isolated thunderstorms possible later this week.

DISCUSSION

KEY MESSAGE #1: Weaker wedge over the area leads to a strong temperature gradient this afternoon.

A cold front which swept through the area earlier this morning is now hung up south of the area this afternoon. However, a lack of moisture and virtually no precipitation in our area is leading to a weaker wedge despite the northeasterly flow and cold advection. The result is cooler temperatures closer to the SC/NC border (generally around 50) with a notable gradient to the southwest, where temperatures in the CSRA are nearing 70 degrees. This is somewhat expected given flow aloft trending more westerly, which is fairly evident on satellite imagery as clouds around 10k ft MSL are streaming in from the west. Some variation in temperatures is still likely this afternoon as cloud cover shifts a bit, but overall most areas, except for the eastern Midlands and Pee Dee region, won't be totally locked in a CAD situation today.

KEY MESSAGE #2: Well above normal temperatures with showers and isolated thunderstorms possible later this week.

High pressure over New England is expected to shift offshore midweek with upper ridging strengthening from the south. This setup is expected to lead to well above average temperatures with a relatively high confidence temperature forecast from Wednesday into the weekend. NBM and LREF members continue to show interquartile ranges of 4 degrees or less for this period, with highs generally in the upper 70s to low 80s and lows in the upper 50s to low 60s.

The rain forecast is less certain, though PWAT values should rise to 1" or more by Friday as southerly to southwesterly flow persist through the column. The overall strength of the surface high and upper ridge will be a limiting factor for precipitation given a lack of any forcing mechanism or upper level support amid the increased moisture. As a result, blended guidance has trended lower with pops for the second half of the week and into the weekend. With a relatively hot and humid air mass for this time of year, diurnal showers and possibly isolated thunderstorms will be possible each day particularly Friday into the weekend. The severe threat remains low.

AVIATION /18Z MONDAY THROUGH SATURDAY/

Generally VFR ceilings into tonight before MVFR ceilings return.

The MVFR ceilings from earlier in the day have cleared out for the most part. The main exception is over the eastern Midlands, so have a tempo group at OGB to account for this. Latest satellite imagery shows some mid to high level cloudiness streaming in from the west and is expected to be over the region into tonight. After sunset, ceilings are forecast to drop to MVFR around the 03z-04z timeframe and remain there through late in the TAF period. Confidence remains low that any IFR ceilings develop, so have left them out of the TAF for now. Winds are expected to be predominantly from the east to northeast through the TAF period, peaking near 10 kts this afternoon and gradually diminishing overnight.

EXTENDED AVIATION OUTLOOK...There is potential for morning stratus or fog into the latter half of the week along with increased shower chances for the weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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