textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 18Z TAFs.

KEY MESSAGES

- 1. Beautiful weather expected to continue through the end of this week.

- 2. More active weather returns this weekend, but rain chances still remain relatively low.

DISCUSSION

Key Message 1: Beautiful weather expected to continue through the end of this week. The persistently beautiful weather we have been experiencing for a week and a half now is forecast to continue into the end of this work week. Strong high pressure remains anchored at the surface to our northeast, funneling drier air into the area beneath strong subsidence aloft. This is forecast to slowly but surely shift as the week goes along, with at least the initial high forecast to shift eastward by Friday. This should be followed up by another strong surface high moving in this weekend, but the weather around that will likely be different that we are experiencing this work week. Moisture is forecast to slowly but surely increase over the next few days, with slightly warmer highs and lows expected by the end of this week (its modest - highs around 80 by Friday and lows in the low to mid 50s).

Key Message 2: More active weather returns this weekend, but rain chances still remain relatively low.

A series of phasing troughs will march across the US this week and begin to erode the persistent ridging across the Mid- Atlantic and northeast CONUS. There is still quite a bit of ensemble disagreement over exactly how robust these troughs will be and whether the ridging will truly erode or not, but regardless, rain chances start to increase late Saturday into Sunday as southerly component flow and moisture. ECE and AI guidance continue to hold the persistent ridging in place for the most part which generally limits the PWAT return and therefore rain potential. GEFS guidance is more aggressive with a stronger mid-level trough and corresponding southwesterly moisture return over the area. An ECE-like solution looks most probable, with a quasi-wedge developing for most of the area starting late Saturday into Sunday. This would yield some showers around with significantly more cloud cover, but a true looks unlikely since moisture is limited along with southeasterly flow from 850-700mb rather than southwesterly like we would expect.

Beyond the weekend, this more chaotic pattern at mid-levels will continue to throw stronger troughs in the unstable southern and northern stream jets. Where these phase and interact will determine how much of a weather impact we have and predictability at this range and time is difficult. A high amplitude meridional flow pattern looks plausible given the larger scale teleconnection and corresponding jet impacts in the Pacific. Regardless, and while this isn't saying much, next week looks notable more active than the past few.

AVIATION /18Z WEDNESDAY THROUGH MONDAY/

VFR conditions are expected through the TAF period at this time, but brief restrictions from stratus cannot be ruled out tonight.

Northeasterly winds gusting up to 15-18 kts should continue through the afternoon as FEW to SCT cumulus develop with increasing moisture in the region. Winds should become light this evening and overnight out of the northeast as increased cloud cover moves in with greater low level moisture. This is depicted across much of guidance and model soundings where a deck around 3500 to 5000 ft should develop overnight into early Thursday. There is higher uncertainty if any lower stratus could develop toward early Thursday morning, thus have left this out of the TAF for now. After 14-16z Thursday northeasterly winds once again pick up near 5-8 kts with any cloud cover gradually scattering out.

EXTENDED AVIATION OUTLOOK...Widespread restrictions are not expected into Friday before restrictions may return moving into the weekend as moisture and rain chances begin to increase.

CAE WATCHES/WARNINGS/ADVISORIES

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