textproduct: Columbia

WHAT HAS CHANGED

Temperatures reduced for Monday and Tuesday with expected wedge conditions. Continued expectation for above normal temperatures late this week. Aviation discussion updated for 18z TAFs.

KEY MESSAGES

1. Significant temperature drop into Monday as wedge conditions develop.

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

DISCUSSION

KEY MESSAGE #1: Significant temperature drop into Monday as wedge conditions develop.

Skies are clear across the are this afternoon under broad surface high pressure. Temperatures have increased into the upper 60s and low 70s, with additional warming still likely for a few more hours given northwesterly downsloping at H85 and above. Highs should top out in the mid to upper 70s. Some high cloudiness will move into the area this evening as a weak shortwave passes to the north, then a backdoor front will edge into the forecast area from the northeast after midnight. This will be reinforced by another area of high pressure to our north moving east over New England and ridging down the Eastern Seaboard, with strengthening northeasterly surface flow. With 850mb winds out of the south to southwest and westerly to northwesterly flow aloft, CAD conditions are anticipated to develop for Monday. As is typical, model guidance tends to struggle with the temperature forecast and NBM highs for Monday were nudged down several degrees, though potentially not low enough. Precip should generally remain north of us on Monday with widespread low clouds and breezy northeast winds. Temperatures will generally be in the 50s, though some spots may struggle to get out of the 40s. Some improvement is expected on Tuesday with high pressure shifting offshore and the wedge front lifting back north.

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

High pressure will situate offshore for the second half of the week, with a strengthening upper ridge and storm track north of the area. NAEFS and ENS mean heights above 850 mb are generally above the 90th percentile during the period, supporting the expectation of well above average temperatures. As such, blended guidance indicates high confidence in highs in the upper 70s to low 80s and lows in the upper 50s to low 60s Wednesday into the upcoming weekend. Unsettled conditions remain possible particularly Friday and Saturday with moisture rising and PWATS lingering around 150-200% of normal. It should also be mentioned that GEFS probability of >500 J/kg surface based CAPE is >40% Friday and Saturday. The threat for severe weather remains limited with a notable lack of upper forcing or appreciable wind shear during this period.

AVIATION /18Z SUNDAY THROUGH FRIDAY/

VFR conditions for much of the TAF period, with MVFR conditions moving in late.

Generally VFR conditions are being reported at the 5 TAF sites, with the exception being AGS where some lowered visibility due to haze is being reported. Expect mainly VFR conditions to prevail through much of the TAF period. A back door front is expected late tonight into early Monday likely bringing MVFR ceilings to CAE/CUB/OGB. Guidance continues to indicate the lowered ceilings won't make it to AGS/DNL, so have left them out of the TAF for this issuance. Without the lowered ceilings, AGS could see some lower visibility at times overnight.

EXTENDED AVIATION OUTLOOK...Low clouds expected to continue into Tuesday.

CAE WATCHES/WARNINGS/ADVISORIES

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