Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
745 FXUS62 KCAE 041134 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 734 AM EDT Mon Aug 4 2025 .SYNOPSIS... Wet weather is favored this week as a stalled boundary lingers across the region. Expect chances for rain and perhaps a few thunderstorms each day, especially across the southern Midlands and CSRA. Temperatures will remain below average, potentially warming towards the end of the week. && .NEAR TERM /THROUGH TONIGHT/... Key Message(s): - Cooler conditions continue with periods of rain today. The overall synoptic pattern today will be very similar to yesterday. Southwest flow aloft will continue to support deep layer moisture across the area with PWATs generally expected to be between 1.8 to around 2 inches. Strong high pressure will build back into southern Canada and reinforce the unusual August pattern of cold air damming into the area. With the front remaining south of the area, periods of rain will once again be possible today beginning this morning in the CSRA and pivoting into the Midlands in the early afternoon, favoring the western and southern portions of the forecast area. This will be owing to increasing isentropic lift and weak shortwaves pivoting through the overall southwest flow in place across the area. This will lead to another cool and cloudy day with highs around 15 to 20 degrees below average, in the mid 70s in the CSRA to low 80s in the northeastern portion of the forecast area where precip chances area generally lower. Cooler conditions continue into tonight with lows in the mid to upper 60s. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Key message(s): - Below average temps with widespread showers expected Tuesday and Wednesday. Persistent surface ridging lee of the Appalachians will continue the fairly rare summer CAD event throughout the middle of the week. Southwesterly flow will continue aloft as the diffuse trough to our west only slowly slides east, providing above average PWAT`s over the low level ridging. 850mb winds and associated isentropic lift with generally continue a southeasterly component, so combined with PWAT`s near 2.0", widespread showers are likely both Tuesday and Wednesday. Guidance is pretty consistent in the highest moisture convergence and PWAT plume across the area Tuesday. Orographic lift and the strongest 850mb flow should focus the highest PoP`s and rainfall amounts across the western Midlands and Upstate. There is still notable inconsistency across guidance, but generally expecting 1-3" through Wednesday for much of the area with highest amounts focused in the western Midlands and CSRA, decreasing to the east. As noted before, this type of setup is unique with a summer wedge providing only weak isentropic lift but there is consistent, albeit weak, CAPE aloft. So guidance will inherently struggle given this set of sensitive parameters. Regardless, there is a higher end potential for some training of stronger showers and multi-day accumulations that could yield the need for a flood watch over the next 48 hours. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Key message(s): - Continuing wet and cooler conditions expected through the end of the week. - Some offshore low pressure development possible for late week. The very slow moving pattern really will need change all that much as we move through the end of the week. The long wave trough however will become a bit more diffuse and weaker, along with a general weakening the lee ridging east of the Appalachians. While this will weaken isentropic lift some, surface heating will steadily push us back towards more diurnally driven convection Thursday-Saturday. PWAT`s will remain above average and there will be little on the synoptic scale to inhibit convection, so expecting widespread showers-storms to continue through this period. The most interesting feature of note in the longer term is possible offshore low pressure development along the residual frontal boundary. Most guidance now something forming underneath within the relatively weak synoptic low regime, so whatever does development could take some time to exit the area. Additionally, this low pressure system could greatly increase or decrease rainfall potential depending on how it interacts with larger scale moisture field, driving either additional moisture advection or drier air aloft. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... Periodic Restrictions Possible at this Morning Due to Rain.... Radar this morning shows showers with areas of embedded moderate rainfall moving through the region, mainly impacting AGS/DNL at this time. Expect on and off showers to continue through the day with probabilities highest at the Augusta area terminals. Brief visibility and/or ceiling restrictions are possible, but confidence is not high enough to warrant inclusion in the TAFs with this update. Guidance remains the most consistent in lowering ceilings to MVFR at AGS/DNL as well but generally thinking all terminals will see MVFR ceilings by this afternoon and continuing into tonight. Winds will remain generally out of a northeasterly direction. between 5 to 10 knots. EXTENDED AVIATION OUTLOOK...Periods of widespread restrictions and rain possible through the week. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$