Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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408 FXUS62 KCAE 151016 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 616 AM EDT Mon Jul 15 2024 .SYNOPSIS... Scattered diurnally driven showers and thunderstorms remain possible today with heat index values up to 108. Increasing chances of showers and thunderstorms will be over the region Tuesday through next weekend with temperatures slowly falling from midweek onward. && .NEAR TERM /THROUGH TONIGHT/... Key Message(s): - Heat index values of 105-110 this afternoon, resulting in a Heat Advisory for eastern Midlands. - Isolated showers and thunderstorms expected in the afternoon to evening. An upper ridge over the region continues today and tonight; however, it begins to flatten somewhat overnight. Nonetheless, the main story today will once again be the heat as southwesterly flow persists today and the airmass hasn`t changed all that much from Sunday. Afternoon highs are forecast to be around 100 across the forecast area. Some westerly flow at 850 and 700 mb layers, will likely lead to some drier dew points getting filtered into the region from the west. Most guidance keeps dew points in the upper 60s to around 70 this afternoon, which would result in heat indices in the 105-108 range, with the highest values for the eastern Midlands, generally east of I-26. Thus, have issued a Heat Advisory in this part of the forecast area from 11 AM to 8 PM today. That said, there is some uncertainty in how low the dewpoints drop this afternoon. Some of the latest guidance is showing values as low as the mid 60s. If this does happen, we likely will not hit the 108 Heat Advisory threshold. Regardless, it will feel hot once again today. Overnight, we remain warm and muggy with lows in the mid 70s. Similar to Sunday, isolated to widely scattered showers and thunderstorms are expected to develop again this afternoon and into the evening. Forecast soundings show there isn`t much in the way of shear, as one might expect in mid July, so the severe threat is minimal today. That said, some gusty winds may occur near thunderstorms due to some elevated DCAPE forecast for the afternoon. && .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... Key Message(s): - Increasing chances of mainly afternoon and evening convection each day - High temperatures in the upper 90s to around 100 degrees with the potential for a Heat Advisory Tuesday The synoptic scale change will continue Tuesday and Wednesday with noticeable changes occurring over the forecast area. Change will be slow to occur Tuesday as the upper level troughing begins to dig into the Upper MS Valley and western Great Lakes. By Wednesday a well defined upper trough axis will stretch from the central Great Lakes through OK with a surface cold front extending into northern KY. As this occurs the Bermuda high offshore will continue pushing moisture into the SE US with pwat values slightly over 2 inches each day. Model soundings continue to indicate at moderate to strongly unstable atmosphere however with the upper trough well west of the area a trigger mechanism will still be lacking. Winds through the mid and upper level will also be weak with generally under 20s knots and little divergence aloft. With the increasing convergence at the surface continue to expect increasing coverage of showers and thunderstorms Tuesday and Wednesday however with the weak steering flow there is potential for locally heavy rainfall and possible hydro related issues with training cells. Some areas which have been dry for an extended period may also experience higher than normal runoff. Temperatures will be in the upper 90s to around 100 Tuesday and with the increasing clouds and potential for showers and thunderstorms Wednesday most locations will be in the mid 90s. On Tuesday the combination of heat and humidity will push heat index values into the 105 to 108 degree range. Will continue to monitor the need for a heat advisory. Overnight lows each night will be in the low to mid 70s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Key Message(s): - Gradual cooling trend continues Thursday and Friday - Showers and thunderstorms expected each day The upper level pattern through the long term will continue to become increasingly amplified which allows the trough to dig further into the SE US and linger over the eastern US. The Bermuda high will remain in place so moisture will continue moving onshore with the frontal boundary gradually moving southward Thursday then stalling across the region while becoming more diffuse Friday through Sunday. With the upper troughing over the region expect short waves to rotate through the area and when combined with the surface convergence produce high chance to likely pops each day. With the upper troughing and clouds over the region high temperatures will also continue to lower a few degrees with afternoon highs in the low to mid 90s Thursday and the mid 80s to around 90 Friday through Sunday. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... VFR conditions generally expected through the TAF period. Some periodic fog remains possible through 13z this morning. Otherwise, VFR conditions are anticipated through the TAF period. Isolated to widely scattered showers and thunderstorms are expected to develop this afternoon and evening, but confidence is too low that the terminals will be affected to include in the TAF at this time. Winds are expected to remain light (<10 kts) through the day and generally be out of the southwest. EXTENDED AVIATION OUTLOOK...Typical summertime afternoon showers and thunderstorms may cause periodic restrictions each day with abundant moisture causing possible, brief early morning restrictions around sunrise. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening for SCZ016-022-027>029-031-037-038-041-135>137. GA...None. && $$