textproduct: Columbia

WHAT HAS CHANGED

Updated Key Message #1 to discuss upstream convection. Aviation discussion updated for 00z TAFs.

KEY MESSAGES

- 1. Storms with strong downburst winds possible through Thursday. - 2. Above normal temperatures likely, Heat Advisory possible, through early next week.

DISCUSSION

- 1. Storms with strong downburst winds possible through Thursday.

Upper level ridging to our west will allow several disturbances to dig into the Carolinas through early Thursday. In addition to typical diurnally driven storms, there is some potential for organized convection from decaying MCSs upstream. Mid-level dry air will allow for DCAPE values in excess of 1000 J/kg, so any diurnally driven pulse- convection will pose a threat of isolated downburst winds.

In terms of a more widespread wind threat, MCSs are expected to develop in the Midwest and dig into the Mid Atlantic States by the late evening time frame. In this setup, we typically see a decaying MCSs digging into the northern FA well after peak heating. However, there are times when convection persists longer than models anticipate leading to a cold pool driven line of storms causing scattered power outages and wind damage. One these lines of storms is seen back in southern KY, moving into northern TN as of writing this. This is on track to reach the northern FA by 04-06z, but with on-going convection across the Upstate toward the far northern Midlands, confidence in this MCS remaining organized by the time it reaches is low at the moment. Another chance for decaying organized convection to near the CWA could could be possible again Wednesday late Wednesday morning into the mid day.

- 2. Above normal temperatures likely, Heat Advisory possible, through early next week.

Northwest, downslope flow and rising heights favor above normal temperatures through much of the 7 day forecast period. If convection does not hamper heating, we will likely have highs in the mid 90s to upper 90s. The NBM may be too warm given its verification through the spring/summer season however highs of around 100 degrees can't be ruled out late this week and early next week as ridging builds overhead. Heat Index values should range from 100 to 105 through Friday with values in the 105 to 110 range possible Thursday and Friday. That said with convection possible both days confidence in reaching Heat Advisory is low at this time.

AVIATION /00Z WEDNESDAY THROUGH SUNDAY/

VFR conditions expected to persist during the TAF period at this time.

Convection is on-going in the Upstate with a more organized system further northwest, working toward the area. Confidence in additional convection impacting the terminals is not high, but will remain possible mainly before 04-08z, thus have a PROB30 group for most sites except the Augusta terminals. Besides this, light westerly winds are expected tonight with lingering debris cloudiness from convection. Due to this cloud cover, guidance shows minimal if any fog/stratus formation and an overall persistence of VFR conditions. Winds then pick up again around 15z Wednesday out of the west near 5-10 kts. Scattered cumulus should develop through the day with isolated storm chances possible through the end of the TAF period, but confidence in impacts at any one terminal is too low to add in the TAF at the moment.

EXTENDED AVIATION OUTLOOK...A hot and drier weather pattern develops through the week. Convective coverage will likely be low and restrictions likely minimal as highs push into the upper 90s.

CAE WATCHES/WARNINGS/ADVISORIES

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