textproduct: Columbia

SYNOPSIS

After a day featuring above-normal temperatures, a backdoor cold front will move through tonight resulting in cooler temperatures for much of the forecast area on Thursday. Near record high temperatures remain possible on Friday ahead of the next storm system. A few showers or thunderstorms are possible on Saturday with a cold front before high pressure returns for Sunday and Monday.

NEAR TERM /THROUGH TONIGHT/

Key message(s):

- Warm and dry conditions expected today

High clouds are passing through the area currently as a shortwave passes through the Ohio Valley and into the Mid-Atlantic at this hour. Some of these clouds are just debris cloudiness originating from convection in TN but some of it is mid-level stratus developing as moisture slowly increases from the west. Overall, though, the weather is quiet. Temperatures are much warmer than they were last night, owing to an increase in surface moisture. Additionally, low- level winds are forecast to pick up as the primary surface low passes to our north and increases the pressure gradient across the area through the night. Lows should stay elevated in the mid 40s for most.

As we get into the day today, a mix of sun and clouds is expected across the area. The shortwave trough is forecast to pass to our north and this should keep the bulk of the forcing for ascent well north of the area. Still, as a weak front approaches the region from the west, moisture will increase relatively quickly as there is a pool of 50s and 60s dewpoints to our west. Southwesterly flow should be common to start the day but will gradually shift more westerly as the day progresses. Flow above the surface is expected to gradually veer through the day and become northwesterly by this evening. This is important because there is some guidance trying to suggest isolated showers developing this evening. While this is certainly possible, especially in a better low-level moisture regime, it seems unlikely as we should see increased downslope flow above the surface by this afternoon and evening. This is typically unfavorable to precipitation across the area. Highs today look quite warm but may be muted by cloud cover, with highs expected to be in the upper 70s to around 80. Tonight, expect high clouds to continue passing through the area as the front/backdoor front slowly works its way into the area. Lows are forecast to be in the low 50s. Some patchy fog is possible but is very uncertain right now and seems like it may be limited in aerial extent.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/

Key message(s):

- Not as warm on Thursday due to northeast flow behind a backdoor cold front.

- Near record highs possible on Friday as winds shift back to the southwest.

Thursday and Thursday Night: The passage of a backdoor front should promote northeasterly flow at the surface for locations north of the boundary. Much of the FA will spend the day on the cool side, resulting in lower daytime temperatures than today. Forecast highs range from the lower 70s in the Northern Midlands to around 80 degrees in Burke County, Georgia which will be the last to see the wind shift. Despite the presence of the front, rain is not expected. Clouds increase in coverage Thursday night ahead of the next storm system limiting overnight cooling. Forecast lows are generally in the mid-50s.

Friday and Friday Night: An upper ridge axis will be positioned over the FA on Friday, flattening at night in response to an approaching shortwave. At the surface, winds shift southwest early as the boundary from the previous day becomes a warm front and shifts north of the region, promoting moisture and warm air advection. Near record high temperatures remain possible on Friday, with forecast highs in the mid-70s to lower 80s, but how warm the region gets will be dependent on the cloud cover, which should lower and thicken as the day goes on. A cold front associated with the next storm system approaches Friday night, with a chance for a few showers towards daybreak especially north and west of I-20. A mild night is expected with lows near 60 degrees.

LONG TERM /SATURDAY THROUGH TUESDAY/

Key message(s):

- A cold front crosses the region on Saturday with a chance of a few showers or thunderstorms early in the day.

- Sunday and Monday are warm and dry.

- The next chance for rain arrives on Tuesday.

A shortwave quickly passes north of the region on Saturday. Meanwhile, low pressure centered over North Carolina at daybreak Saturday moves eastward, dragging a cold front through the FA, shifting winds from southwest to northwest by daybreak Sunday. A few showers or thunderstorms could accompany the frontal passage during the first half of the day, followed by clearing skies as a drier air mass filters in behind the front. Temperatures could be tricky and highs may end up lower than currently advertised due to timing differences with the front, but values will likely remain well above average. Winds could be breezy at times and may stay up into the night, limiting radiational cooling.

A new upper ridge approaches the region on Sunday, passing overhead on Monday. Meanwhile at the surface, high pressure centered to the north will keep the region dry through Monday night. Temperatures both days should be above seasonal values. The next chance of rain arrives near the end of the extended as upper ridging and high pressure are pushed east in response to a developing storm system emerging from the Southern Great Plains.

AVIATION /05Z WEDNESDAY THROUGH SUNDAY/

VFR expected through the period.

Mid to high level clouds are working their way across the forecast area. There is some altostratus noted across the upstate and western Georgia but is struggling to develop eastward. Moisture is slowly increasing across the area, hence the overall increase in cloud cover, but it isn't expected to yield much in terms of aviation impacts. Low-level winds are forecast to increase over the next few hours but should be weak enough to avoid any LLWS. As we get into today, we should see a mix of sun and clouds with ceilings generally settling into the 4-6 kft range this afternoon. Winds should be southwesterly to start, veering to westerly by this evening. The low-level jet should mix through early afternoon, with 7-12 knot winds and gusts up to 20 knots possible. Tonight, high clouds should continue to hang around with winds falling near calm again. VFR conditions continue to prevail.

EXTENDED AVIATION OUTLOOK...VFR conditions likely continue through most of the week with dry air in place. Increasing moisture Friday night will lead to chances for rain and possible restrictions.

CAE WATCHES/WARNINGS/ADVISORIES

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