textproduct: Columbia

WHAT HAS CHANGED

Another locally heavy rainfall risk may materialize today in areas that realized higher end amounts on Monday. Wednesday has trended a bit drier. Aviation discussion updated for 12z TAF.

KEY MESSAGES

- 1. Isolated to widely scattered showers and storms possible again today before chances become more spotty Wednesday. Warming temperatures and returning diurnal rain chances expected for the late week.

DISCUSSION

Key Message 1: Isolated to widely scattered showers and storms possible again today before chances become more spotty Wednesday. Warming temperatures and returning diurnal rain chances expected for the late week.

After multiple active days, things look to slowly wind down into the mid week with temperatures remaining cooler than normal. As of writing this, the atmosphere has become increasingly worked over and thus rain rates in lingering activity have diminished significantly, largely bringing the main flash flood risk to an end. The frontal boundary appears to have sank south of the CSRA now, but lingering mid level forcing with PWATs near 2.20-2.30" should continue to drive isolated to scattered rain chances into the early parts of the morning. During the afternoon and into the evening, MUCAPE on the order of 1000-1800 J/kg should be able to develop as dewpoints remain in the low to mid 70s and PWAT's stick around 2.25". This should yield more scattered convection, mainly along and west of the I-26 corridor, where the overall severe risk is low but a locally heavy rainfall risk will once again exist. This risk is worth monitoring especially in parts of the CSRA and southeastern Midlands as these locations picked up 2-4.5" of rainfall with Monday's activity. Soundings remain conducive for this risk with the long/skinny CAPE profiles and moist adiabatic conditions. While HREF LPMM amounts are not nearly as aggressive as what was seen yesterday, spots of 1.50-3.50" cannot be ruled out in slow moving clusters or training convection along outflow boundaries. These localized higher amounts are also supported in the 00z CAM suite. It is worth noting that despite the lower severe risk, antecedent high soil moistures in parts of the FA could make some trees more susceptible to falling in sub-severe wind gusts from convection.

The main change comes Wednesday with guidance trending a bit drier as the front remains south of the area and any forcing the mid level low retrogrades out of the region. The axis of PWAT's near 2.25" is expected to slowly pivot out of the FA toward the west, but PWAT's near 2" still may aid in bringing at least isolated activity during the afternoon. Heading into the late week, ensembles and global models depict an elongated upper ridge stretching from the central CONUS, toward the Ohio Valley. This may aid in bringing weak height rises to the FA as low level southerly to southwesterly flow brings back 850mb temps near the NAEFS 90th percentile. This setup should support warming temperatures near to just above normal late this week into the weekend. Moisture is expected to be fairly seasonable, thus cannot rule out typical diurnal convection chances, especially by the weekend.

AVIATION /12Z TUESDAY THROUGH SATURDAY/

A mix of conditions continues early this morning as precipitation increasing across the region. Widespread MVFR and IFR ceiling restrictions are then expected through mid-morning.

Winds should be light and variable or easterly/northeasterly this morning with increasing light showers across DNL and AGS. IFR conditions will continue through roughly 15z for all terminals and there is potential for some brief LIFR conditions as well. Lingering MVFR/IFR cigs will hold on through midday with northeast winds around 5-8 kts persisting. Scattered showers and a few thunderstorms are possible this afternoon, especially at the southern terminals of AGS/DNL/OGB in particular. Less confidence at CAE/CUB/AIK.

EXTENDED AVIATION OUTLOOK...A good chance for afternoon showers and thunderstorms with associated restrictions is expected through today. The threat for restrictions eases Wednesday into the upcoming weekend as conditions begin to dry out.

CAE WATCHES/WARNINGS/ADVISORIES

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