Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
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529 FXUS62 KCAE 280713 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 313 AM EDT Sun Apr 28 2024 .SYNOPSIS... Weak high pressure centered northeast of the region will remain in control through Monday along with a warming trend. A weak front is expected to bring a slight chance of showers and thunderstorms late Tuesday through Thursday, mainly northern and eastern areas. && .NEAR TERM /THROUGH TONIGHT/... Mostly cloudy skies across the region along with some patchy fog and stratus which have gradually developed over the past couple of hours. Through daybreak expect little change with some additional stratus and fog developing where the mid and upper clouds clear. Overnight lows will be in the mid to upper 50s. High pressure will remain northeast of the region today and tonight with a ridge of high pressure orienting east west across the SE US. Flow will be turning southeasterly today while continuing to advect moisture into the area. Although pwat values will be 1.2 inches or better there will be a considerable inversion aloft along with some dry air. This will leave a limited layer of moisture in the low levels so expect some cumulus to develop from mid morning through the afternoon however vertical development will be limited and no rain expected. This evening low clouds will begin to diminish with sunset with mid and high clouds lingering over the area through the night. High temperatures this afternoon will be in the upper 70s to low 80s with lows tonight in the mid 50s. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... Quiet weather is expected to continue on Monday, with high confidence in the forecast. Latest ensemble and operation guidance continues to show our pattern moderating downstream from the active central Plains. A series of shortwaves and low pressure systems are forecast to ride northeastward atop the ridge over the eastern US, with fronts slowly pushing the low-level ridge axis southward. In turn, our prevailing flow will shift from southeasterly to southwesterly on Monday. As a result, warm air advection is likely to be a bit more notable, with 850 hPa temps starting the day in the 12-14C range. This will allow highs to likely jump into the low and mid 80s, with more sunshine aiding the warming trend. Rain is unlikely as we`ll see subsidence under shortwave ridging, manifested in a strong inversion showing up in model soundings between 750-800 hPa. Overnight, look for dry conditions to continue, with lows in the upper 50s and lower 60s. A slow moving shortwave trough is forecast to approach the forecast area on Tuesday. Guidance has slowly trended towards a more organized trough and a slower progression of said trough on Tuesday. As a result, there is more forcing aloft for precipitation Tuesday afternoon. Big however, though. Guidance is split on the amount of moisture that will be in place ahead of this as the front and upper level support approaches Tues afternoon/evening. Amongst LREF guidance, GFS/GEFS are the most aggressive with rainfall chances, while the ECM/ECE members are least aggressive. The Canadian ens & operational model (and the early runs of the NAM) are somewhere in the middle, which seems like a reasonable spot to be in currently. The fly in the ointment is how much mixing we see by Tuesday afternoon, which could lower our dewpoints and yield lesser instability. I think the middle of the road is a good scenario here, with scattered showers or thunderstorms developing by the afternoon hours. Guidance (other than the ECM) is suggesting at least ~500 j/kg of CAPE developing for much of the area, which should yield the chance of thunderstorms. With weak shear, though, anything severe is unlikely. Highs will likely be in the mid to upper 80s across the area. Some showers could continue into Tuesday night, with lows in the low 60s. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... Confidence in the long term remains fairly high. Front should slowly push through the area on Wednesday, with all LREF members showing afternoon/evening rain chances persisting as the front won`t totally clear the region and moisture will remain in place ahead of it. Mid- level ridging will again build in by late week, with temperatures warming to near 90 Thur/Fri with subsidence aloft keeping us dry and sunny. By Saturday and Sunday, ensembles and operational models begin to show a more active pattern developing, with showers and thunderstorms possible again. So in general, the short and long term periods are fairly high confidence, especially with regards to above normal temperatures developing. Confidence is also high that our best chances of rain/storms will be Tues/Wed, & Sat/Sun. && .AVIATION /07Z SUNDAY THROUGH THURSDAY/... Mainly VFR conditions through the period with restrictions possible in stratus and fog through sunrise. Satellite imagery and surface obs show plenty of clouds across the region with some low clouds developing near the terminals. Expect this to remain variable through sunrise as clouds cross the area and disrupt the development of stratus and fog. ATTM have included mention of scattered clouds around 1.5 kft with TEMPO at AGS due to river impacts. A strong inversion will take until mid morning to mix out and allow remaining low clouds to dissipate then cumulus will begin developing from the mid morning through the afternoon hours. With an inversion aloft vertical growth will be limited and no rain is expected. Clouds will diminish with sunset as some drier air finally moves into the area. Winds through the period will be southeasterly at 8 knots or less. EXTENDED AVIATION OUTLOOK...Restrictions possible in early morning fog or stratus each morning. Slight chance of afternoon showers and thunderstorms Tuesday onward. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION...