Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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691 FXUS62 KCAE 072356 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 756 PM EDT Sun Jul 7 2024 .SYNOPSIS... Abundant moisture combined with an unstable air mass should support scattered to numerous showers and thunderstorms for each afternoon and evening through much of the next week. Above normal temperatures are expected again, with Heat Index values above 100 each day through next week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Key message(s) - Slow moving storms/potential for isolated flash flooding. Thunderstorms have been slow to develop this afternoon and evening, with the skies remaining largely benign until the past hour or so. Since, a cluster of thunderstorms has pushed into Burke and Richmond counties in GA. This has been pushing north/northeastward at a decent pace, which is good news considering this is the area of the FA that received the most rainfall yesterday. However, we aren`t out of the woods yet flash flood wise as this cluster should continue moving northward and interact with a larger, slow moving MCS pushing out of GSP`s area. This is the interaction that could yield our biggest threat of the day so far, as it could slow both complexes down a bit and lead to some training rainfall. The atmosphere is in a similar place to yesterday with skinny SBCAPE between 1500 and 2000 j/kg and PWs in excess of 2.25" across the FA. With weak atmospheric flow, this favors slow moving storms producing high rainfall totals in short periods of time. We will need to watch the areas that were impacted yesterday the closets, but this kind of setup tends to yield a potential for flash flooding regardless of how dry we have been. An isolated severe storm cannot be ruled out either. Similar to last night, storms should weaken into stratiform rain which may take several hours overnight and is honestly needed across the FA, so we will likely end up being fairly warm again tonight with lows expected in the mid 70s. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... Key Message(s): - Anomalously high atmospheric moisture - Scattered to numerous diurnal thunderstorms with isolated flash flood threat - High heat index readings possible again by Tuesday. Upper trough will continue over then central U.S., with western Atlantic ridge influencing our region. Will mention that there is a weak upper low on the western portions of the ridge, but it will continue to weaken and move southward through the period as the upper ridge begins to strengthen and push further west into Tuesday. Plenty of moisture will be over the area, with southwesterly winds aloft bringing Gulf moisture toward us, and low-level moisture coming inland off the Atlantic. Afternoon and evening convection appears likely as the sea-breeze moves inland each day, with other mesoscale boundaries from prior convection all being potential initialization points for convection too. High pwat values will lend to potential for periods of heavy rainfall in any slower storms. Severe threat is minimal, but can not rule out some gusty winds in stronger storms through the period. Temperatures should be a bit cooler Monday due to cloud cover with highs expected in the lower 90s, then a return to the middle 90s and higher heat index readings on Tuesday. Can not rule out the need for another Heat Advisory on Tuesday as latest guidance is showing some areas climbing above 108 degrees for periods Tuesday afternoon. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Key message(s): - Daily diurnal showers and thunderstorms - Heat indices exceeding 100 degrees - Isolated flash flooding threat Models still showing upper trough across the middle of the country, with our region under the influence of western Atlantic ridge. The upper trough will begin lifting on Thursday, with increasing upper ridging building back into our area by the weekend. Weak surface troughs, along with sea-breeze convection moving inland each afternoon, should aid in diurnal development of scattered to numerous convection pretty much each afternoon through the period. Heavy rainfall can be expected with any storms, especially with pwat readings still forecast above 2 inches each afternoon. High temperatures climb back into the low to middle 90s by mid-week. Heat indices are expected to exceed 100 degrees each day. Best chance to reach heat advisory criteria appears to be Wednesday, especially with dewpoints forecast in the upper 70s. Slightly lower dewpoints possible by the end of the week will bring lower heat index readings, but still expected at or above the century mark. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... VFR conditions through much of the TAF period with restrictions expected this evening into early tonight and possible around sunrise. Convection continues to develop and will be aided in the coming hours by and approaching boundary currently moving through the Upstate. Showers and thunderstorms are currently around all terminals except OGB and have a TEMPO to cover the cells as they move through the area. Expect thunderstorms to contain brief locally heavy rainfall and wind gusts around 25 knots. The convection will persist through midnight and possible into the early morning hours as boundaries collide and generate new cells. Restrictions also possible around sunrise as moisture will be trapped under an inversion however confidence is low as much will depend on debris cloudiness departing the area or not. With sunrise and heating cumulus will again begin developing and have once again included VCSH for all terminals from 19z through the end of the period for convection. EXTENDED AVIATION OUTLOOK...Restrictions possible in diurnally driven showers and thunderstorms each day as well as early morning fog and stratus. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$