textproduct: Columbia

WHAT HAS CHANGED

Aviation discussion updated for 12z update.

KEY MESSAGES

- 1. The high heat and humidity continues with temperatures likely peaking on Monday.

- 2. Isolated to scattered showers and thunderstorms possible later today, especially across the eastern Midlands.

DISCUSSION

1. The high heat and humidity continues with temperatures likely peaking on Monday.

Little change has been made to the temperature forecast during the next few days. Broad upper ridging remains in control of the region and should result in another hot and humid day with forecast highs in the lower to mid 90s, perhaps a few degrees lower than yesterday. A Heat Advisory remains in effect until 8pm this evening with max heat index values once again reaching the 105 to 110 range in most locations. Monday still looks like the hottest day of the week, with highs in the upper 90s to around 100 degrees. If trends continue, heat products will likely be needed for Monday as well since the humidity is unlikely to relent. A trough during the mid to late portion of next week may finally break the threat of extreme heat with daytime temperatures closer to seasonal values.

2. Isolated to scattered showers and thunderstorms possible later today, especially across the eastern Midlands.

Unlike previous days, model guidance is less bullish with the convective potential across the forecast area today, with the highest probabilities along and east of the I-95 corridor. Modeled soundings at CAE show the development of a low-level capping inversion which would limit convective development despite ample moisture and CAPE. Having said that, a pop up shower or thunderstorm is always possible anywhere across the region. Guidance has kept the chance for precipitation low on Monday and this appears to be due to the highly anomalous 850mb temperatures. This should result in sufficient capping over the forecast area once again, with any rain arriving towards evening as a shortwave moves in from the northwest, potentially eroding the cap. More typical August rain chances are then anticipated, perhaps increasing during the mid to late portion of next week when a trough may set up over the eastern CONUS.

AVIATION /12Z SUNDAY THROUGH THURSDAY/

Some morning fog-stratus around sunrise possible, otherwise typical summer conditions with VFR outside of afternoon storms.

Elevated low level moisture and light winds this morning may yield some sunrise surprise fog across the region. Confidence is fairly low in widespread restrictions, but included a tempo for MVFR vsby and MIFG through 13z. Beyond this morning, typical summer conditions expected with a cu field developing by late morning and then scattered thunderstorms likely after 19z. Prob30 group included for tsra through 00z.

EXTENDED AVIATION OUTLOOK...Diurnal chances for thunderstorms continue each day through the weekend.

CAE WATCHES/WARNINGS/ADVISORIES

SC...Heat Advisory until 8 PM EDT this evening for SCZ016-018- 020>022-025>031-035-037-038-041-115-116-135>137. GA...Heat Advisory until 8 PM EDT this evening for GAZ040-063>065- 077.