textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated.

KEY MESSAGES

- 1) Well above normal temperatures expected later this week. Highs in the 70s and 80s are expected Thursday/Friday.

- 2) Rain is expected again this weekend but the details and timing of that rain are quite uncertain.

DISCUSSION

KEY MESSAGE #1: Well above normal temperatures expected later this week. Highs in the 70s and 80s are expected Thursday/Friday.

Our warming trend is forecast to persist into the end of the week. Heights will continue to rise over the next 36-48 hours as a large, deep (and complex) upper level trough digs into the western CONUS and amplifies the overall downstream pattern. Southwesterly flow will gradually increase across the area through the end of the week, with 90th-95th percentile 850 hPa temps expected to overspread the area by Thursday and Friday. ECE EFI values suggest anomalous warmth with record temperatures possible. Thursday's record high at CAE is 80F and at AGS is 82F. Friday's record high at CAE is 84F and at AGS is 83F. For a variety of reasons, it seems like it'll be difficult to achieve that. Clouds should be too copious on Friday & we probably won't be quite warm enough yet on Thursday. However, its really not out of the question that we see low 80s either day across the area. The warmth on both days is seemingly the only part of the forecast that medium range guidance agrees on.

KEY MESSAGE #2: Rain is expected again this weekend but the details and timing of that rain are quite uncertain.

There is significant uncertainty in the forecast this weekend, driven primarily by the complexity of the western CONUS. IQR spread in the LREF for the 500 hPa heights is enormous for the medium range, with cluster analysis really not adding a ton of value to the forecast at this point. Given broad and persistent southwesterly flow for much of this week, anomalous moisture should be in place ahead of an approaching front early on Friday. Rain chances should increase on Friday ahead of this front but really don't look to increase until Saturday evening or Saturday night. We'll have access to PWs in the 80th to 90th percentile ahead of the next shortwave emerging from the western CONUS, so our best best rain chances should be Saturday afternoon through midday Sunday. Its hard to forecast more than this at this point as the spread amongst the ensemble guidance is extremely high.

AVIATION /06Z TUESDAY THROUGH SATURDAY/

Fog possible this morning especially near AGS and OGB, but may expanded closer to Columbia terminals. VFR conditions expected outside of this.

FEW to SCT high cirrus continue to stream into the region with winds being calm at most locations. Outside of these cirrus, the main concern will be fog after 08-10z tonight. Guidance has trended a bit more aggressive, especially towards OGB where the highest confidence in fog exists. Shallow ground or river fog could be possible before this time frame but after 09z, IFR to MVFR visibilities are most likely at AGS/OGB where periods of LIFR visibilities cannot be ruled out. For the Columbia terminals, greater uncertainty exists in the northern extent of fog, but probabilities for MVFR visibilities have increased and thus a couple hours with this seems reasonable between 11-13z. Any fog is expected to burn off after 14-15z and give way to VFR conditions with light winds out of the south to south-southwest much of the day. Toward the end of the period, some more cirrus may begin moving in.

EXTENDED AVIATION OUTLOOK...Moisture increases through the week leading to increasing chances of morning fog/stratus. The next chance of rain is trending toward the late week and this weekend.

CAE WATCHES/WARNINGS/ADVISORIES

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