textproduct: Columbia

WHAT HAS CHANGED

Dry and warmer this weekend before cold air damming results in cooler temperatures Monday and Tuesday, followed by another warm up during the extended period. Aviation discussion updated for 18Z TAFs.

KEY MESSAGES

1. Rain comes to an end this afternoon. Patchy fog possible tonight.

2. Dry and warmer this weekend followed by cooler temperatures Monday and Tuesday.

DISCUSSION

KEY MESSAGE #1: Rain comes to an end this afternoon. Patchy fog possible tonight.

Midday radar imagery shows the bulk of the heavy rain has moved off to the east with light to moderate returns across the southeastern Midlands and Burke County, GA. A few scattered showers associated with weak isentropic lift are ongoing across parts of the Midlands. Rain chances should diminish from northwest to southeast this afternoon as drier air filters into the region. Skies remain mostly cloudy tonight with hi-res guidance showing the potential for fog development due to lingering moisture near the surface. Currently, fog development looks patchy at best and focused near bodies of water, but trends will be monitored tonight to see if a Dense Fog Advisory will be needed.

KEY MESSAGE #2: Dry and warmer this weekend followed by cooler temperatures Monday and Tuesday.

Expect decreasing cloudiness and warmer temperatures on Saturday as high pressure builds into the region. The warming trend continues into Sunday with the 50th percentile for highs across the forecast area in the mid to upper 70s. A backdoor cold front shifts winds to the northeast Sunday night. Strong high pressure over New England ridges south along the spine of the Appalachians to produce cold air damming on Monday and Tuesday resulting in another pair of days featuring clouds and below normal temperatures. Upper ridging and surface high pressure anchored near Bermuda result in a pattern change during the extended period with warmer and wetter conditions favored.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Restrictions are expected for much of this period with low level moisture remaining in place.

Rainfall is currently in the process of pushing east of the majority of the forecast area, with taf sites no longer indicating rain. Can not completely rule out a brief light shower from 18z-22z, but majority of the period will remain dry going forward. Winds expected to turn more variable around 5 knots through sunset, then light and variable to calm overnight. Northerly winds around 5 knots should prevail on Saturday. Now for the biggest issues this taf period, ceilings and visibilities. There has been a pesky mixture of ifr and vfr ceilings through the morning as the rain moved off to the east. Ceilings trending more into the mvfr category by 18z, with periods of ifr still possible the next several hours. Guidance continues to show ceilings trending downward later this evening and overnight, with ifr/lifr ceilings expected late tonight and into Saturday morning. Have continued with that trend with latest taf forecasts. In addition, there could be visibility restrictions in br/fg tonight, especially after 06z. Deterministic NAM/GFS MOS guidance really indicating lifr visibilities towards morning, while the GFS-Lamp and the Blended guidance shows slightly better mvfr conditions. With the amount of moisture around, along with light winds and lowering ceilings, have generally gone with prevailing ifr visibilities, and a tempo for lifr restrictions towards sunrise. Either way, with the combination of both ceiling and visibility restrictions, lifr conditions remain a high probability late tonight at all sites. There should be some improvement back into mvfr after 15z Saturday for all locations.

EXTENDED AVIATION OUTLOOK...Some improvement back to vfr possible on by Saturday afternoon and evening as clouds begin to clear out. Nightly br/fg restrictions will remain possible over the weekend and into next week.

CAE WATCHES/WARNINGS/ADVISORIES

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