textproduct: Columbia

SYNOPSIS

A dry, cold front will move into the region this morning reinforcing the quiet weather pattern. Temperatures will be near to above normal through the weekend. The next chance of rain holds off until Friday night with a significant pattern change likely early next week. Well below normal temperatures look increasingly likely by Mon/Tues of next week, with a hard freeze possible Monday night.

NEAR TERM /THROUGH TONIGHT/

Key message(s):

- Dry with near normal temperatures

Based on latest observations, a cold front continues to work into the Mid Atlantic States and will then dip into the forecast area today. This will allow dewpoints to drop into the 30s across the northern half of the FA this afternoon. Very limited atmospheric moisture during the frontal passage will prevent any rain. Light and variable winds this morning will shift to out of the NE behind the front for the afternoon.

Clear or mostly clear skies expected through the near term with just a few high clouds expected overnight. Highs are forecast to be in the low to mid 70s. Lows will likely be in the low to mid 40s across the area but wouldn't be surprised to see some upper 30s in sheltered locations Friday morning.

SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/

Key message(s):

- Mostly sunny and warm on Friday with increasing clouds late.

- Clouds continue to move in Friday night with showers possible towards daybreak in the CSRA.

- Continued warm this weekend with a chance of showers both days, though likely higher on Sunday ahead of an approaching cold front.

- The cold front crosses the region Sunday night bringing the coldest air of the season thus far.

The FA will be at the base of a longwave trough during much of the short term with southwesterly flow aloft. This trough deepens significantly on Sunday and Sunday night as its axis approaches from the west. At the surface, high pressure will be offshore at the start of the period, so the day will begin with southeasterly winds that eventually turn south then southwest and remain that direction until a cold front moves through Sunday night. This will translate to a mostly sunny and warm Friday courtesy of departing high pressure with increasing cloudiness towards evening and especially at night. A few showers will be possible in the CSRA towards daybreak on Saturday as a shortwave passes to the north. Shower chances continue through the weekend but probabilities are low to moderate, 20 to 40 percent. A tightening pressure gradient could result in breezy winds on Sunday. Temperatures this weekend will continue to be near to above normal. The cold front crosses the region Sunday night bringing the coldest air of the season thus far.

LONG TERM /MONDAY THROUGH WEDNESDAY/

Key message(s):

- Well below normal temperatures are expected on Monday and Tuesday behind a strong cold front.

- A hard freeze is possible on Monday night into early Tuesday.

- Warmer temperatures are expected towards the middle of next week.

Confidence remains high regarding the weather pattern during the extended. An anomalously strong trough moves through the region on Monday, passing to the east on Tuesday. At the surface, high pressure will build in from the west on Monday, passing overhead on Tuesday, and then offshore on Wednesday. This pattern will usher in the coldest air of the season thus far with much colder temperatures on Monday and especially Monday night. The pressure gradient should weaken on Monday as high pressure approaches, but continued breezy conditions will make it feel even colder outside. While confidence in subfreezing temperatures remains high for Monday night, the position of the aforementioned anticyclone is the primary factor that could limit how cold the FA gets at night. If high pressure is not directly overhead by Monday night, winds may remain high enough to prevent idealized radiational cooling, though NBM guidance shows lows in the 20s despite the high being centered to the west. This means that while a hard freeze may not occur, temperatures will likely drop below freezing and end the growing season for much, if not all, of the forecast area. Tuesday will be another anomalously cold day and night with some improvement near the end of the extended. The chance of rain during the long term is low, less than 10 percent.

AVIATION /07Z THURSDAY THROUGH MONDAY/

River valley fog may cause restrictions at fog-prone AGS/OGB

A dry, cold front will approach from the north early this morning. Light SW expected ahead of the front but may become calm or variable at times. As the front moves through around 10Z to 15Z, winds will turn more northeasterly. NE winds will continue through the day around 10 knots until becoming light and easterly around sunset. The air mass remains dry ahead of the front and mixing will also help to prevent widespread fog. However fog may still develop in the river valleys as shown in the HRRR. This may cause periodic "waves" of restrictions at AGS as is commonly observed in the early mornings. Lower confidence in OGB. Otherwise no restrictions expected.

EXTENDED AVIATION OUTLOOK...The next system will bring increasing chances for restrictions and rain from Friday night to Sunday night.

CAE WATCHES/WARNINGS/ADVISORIES

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