Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
831 FXUS62 KCAE 221918 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 318 PM EDT Sun Sep 22 2024 .SYNOPSIS... High pressure building over the SE US will keep warm conditions over the Southeast into the first half of the work week. Multiple shortwaves moving overhead bring at least daily slight chances for precipitation through much of the week. Confidence is low in the forecast beyond midweek as uncertainty remains high with the evolution of an upper trough moving toward the region and the potential for tropical development in the Gulf. && .NEAR TERM /THROUGH TONIGHT/... Key Message(s): - Upper ridge persists with above normal temperatures. - Isolated afternoon showers or storms over southeastern Midlands and CSRA. This afternoon: Hot temperatures persist underneath the upper ridge axis, with highs still on track to reach the low to middle 90s. Tonight: Weak surface trough may be able to trigger an isolated shower or storm across the eastern Midlands and CSRA early this evening, generally in an area with slightly higher pwat values. Any activity that develops would dissipate by 02z tonight, with dry conditions then expected the remainder of the night. Winds turning light overnight. Lows tonight remaining on the milder side, bottoming out generally around 70 degrees. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Key Message(s): - Upper ridge continues to bring above average temps. - Afternoon and evening precipitation is possible each day, mainly across the northern CWA Monday and western half Tuesday. Upper ridging is expected to be over the area as surface high pressure is filtered into the region from the Northeast to start the short term period. Meanwhile, an upper trough is forecast to continue developing over the Upper Midwest. All of these features slide eastward over the short term period. The ridge axis will continue across the region Monday, but begin to shift off the coast by Tuesday. Multiple shortwaves are forecast to ride around the periphery of the ridge as it passes overhead, bringing chances for precipitation to the northern half of the forecast area each afternoon and evening. Also, the upper trough is anticipated to dig southward and assist in developing a surface frontal boundary, resulting in southwest flow locally by Tuesday afternoon and Tuesday night. The southwest flow will likely lead to increased moisture to the region ahead of the frontal boundary, bringing slightly higher chances for precipitation on Tuesday. Due to the ridging, temperatures are expected to remain on the warm side, with highs in the mid 80s north to lower 90s south each day. Overnight lows remain above normal with lows near/around 70 degrees. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... Key Message(s): - Chances for precipitation increase in the long term despite forecast uncertainty regarding tropical development and eventual track. The uncertainty has decreased slightly regarding the increasing chances for precipition across the Southeast this upcoming week. However, the uncertainty remains pretty high regarding the development, strength and track of the potential tropical system. The NHC has increased the chance of development to 80 percent between days 3 and 7. The two main features causing uncertainty are the development and depth of the upper trough across the Central Plains/Mid MS River Valley Region during the early/mid week. The ECMWF/GFS/CMC indicate the trough over the Plains will cutoff, but depth and placement will make for an interesting interaction with the tropical system. So, confidence is increasing the some tropical system will develop in the Western Caribbean and Gulf of Mexico, but where it goes and how strong it gets is where the uncertainty comes in. The model ensembles continue to have a hard time placing a system that has yet to form. Regardless of what happens, daily chances for precipitation continue through the forecast period. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... Outside of KAGS, generally VFR conditions anticipated through the TAF period. KAGS may see usual mvfr/ifr visibilities overnight near the river. Skies mostly sunny this afternoon with satellite and visual observations showing the development of a few afternoon cu. Weak surface trough moving through the area, may combine with slightly better moisture and instability across the eastern Midlands and Central CSRA areas to develop an isolated shower during our peak heating hours this afternoon. Coverage would appear to remain rather limited based on latest models, and am inclined to keep mention of any activity out of any tafs due to the low confidence of a terminal being impacted. Conditions will remain vfr through the period at all taf locations except at KAGS. In that locations, the usual overnight development of mvfr/ifr visibilities will remain possible after 07z lasting through around 12z. Otherwise vfr at that location. Winds mostly out of the westerly around 5 to 6 knots through the afternoon, then light and variable overnight into Monday. EXTENDED AVIATION OUTLOOK...There are no significant concerns for restrictions at this time. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION...