Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
387 FXUS62 KCAE 180544 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 144 AM EDT Sat May 18 2024 .SYNOPSIS... A few showers will be possible tonight with periods of showers and thunderstorms expected today and into Saturday night. Rich moisture across the region will keep rain chances likely lingering into Sunday. Cooler and drier air moves in for Monday and Tuesday with temperatures rebounding during the middle of next week as another ridge moves in from the west. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... 2am Update: Scattered showers have developed across the Central Midlands tonight but rainfall amounts have been very light. Additional showers are approaching the CSRA and could also bring some light rainfall amounts to our southern FA. The first significant round of showers and thunderstorms for today is currently moving into Alabama from Mississippi and should arrive in our CWA towards daybreak. Slight Chance to Chance PoPs gradually ramp up through 7am to account for this. Previous Discussion: Positively tilted upper trough continues to slowly progress through over the central/southern Plains toward the Mississippi River Valley this evening. Southwest flow aloft continues to usher in moisture with PWATs between 1.5" and 1.7" and dewpoints in the mid to upper 60s. PW values are expected to increase overnight to between 1.7" and 1.9", with a few locations closer to 2" across the CSRA/southern or eastern Midlands. Ongoing convection to our south is progged to remain out of the area tonight. However, weak short wave energy moving through the mid level flow is expected to generate scattered showers across the area amid increasing isentropic lift. The latest HRRR shows a reasonable solution, with perhaps a bit of a stronger area of showers and thunderstorms pushing through the CSRA around daybreak. Severe threat remains low though brief heavy rainfall is possible. Overcast skies and a well-mixed boundary layer keep overnight lows quite mild, only falling into the mid to upper 60s/near 70. Low dewpoint depressions may generate some reduced visibilities in and near shower activity. && .SHORT TERM /7 AM THIS MORNING THROUGH SUNDAY NIGHT/... Positively tilted trough will continue to slowly push eastward towards us and should be centered across the lower MS Valley by tomorrow morning. Strong flow at 500 hPa is expected to create strong shear profiles, and CAMs are generally showing some sort of MCS structure to our southwest, but how far north this gets and how fast it will be is in question. Generally, guidance has struggled with speed and placement of convective structures like this in recent weeks. So there is uncertainty about this, but confidence is high that an MCS of some sort will be in central GA at the start of this period. Ahead of this, rich moisture should favor some instability, and given the shear in the atmosphere, strong to marginally severe storms are again possible depending on the location of this convection. Thinking the best chance for this is in the southern FA, but timing and severity is hard to piece together right now. Think it`ll be approaching or through our FA by late morning, and if this happens, it opens the door for some afternoon sunshine and another round of thunderstorms in the central and northern FA. While the strongest shear will be to our east, robust instability is possible where we see sunshine tomorrow afternoon so we`ll need to watch for strong strong storms along an amorphous surface front across the northern part of SC. Highs should generally be in the mid 80s but upper 80s are possible for those that see more sunshine. Showers will probably hang around into Saturday night as the trough approaches with lows in the mid 60s expected. On Sunday, more showers and embedded thunderstorms are possible as the trough approaches and pushes over the region. Some uncertainty is present with where the surface low and resultant convergence develops, adding some overall uncertainty to rain coverage Sunday afternoon. But confidence is high that we`ll see scattered to numerous showers across much of the area, with highs in the upper 70s and low 80s. Showers should clear out on Sunday night as a back door front pushes through and pushes low PW air into the area. && .LONG TERM /MONDAY THROUGH FRIDAY/... Confidence continues to remain fairly high in the long term period. Cool and dry air is expected to remain in place on Monday, with highs well below normal near 80s. Modification quickly begins on Tuesday as high pressure shifts to our east and ridging aloft begins to build. This should carry highs back into the upper 80s and low 90s by Thursday. Another cold front is forecast to approach by the Thur/Fri timeframe, with the possibility of showers and thunderstorms in the afternoon in association with that. && .AVIATION /05Z SATURDAY THROUGH WEDNESDAY/... Ceilings Expected to Fall this Morning... Scattered showers have developed near CAE/CUB tonight but rainfall amounts have been very light and no restrictions are currently being reported. Additional showers are approaching the CSRA and could also bring some light rainfall to AGS/DNL and eventually OGB. While ceilings remain in VFR tonight, guidance remains bullish in dropping them to the IFR category prior to daybreak. Amended TAFs to reflect the ceilings falling by 09Z. An area of showers and isolated thunderstorms will approach the terminals towards daybreak, likely resulting in a temporary reduction in visibility. The ceilings should improve around midday with a return to VFR conditions in the afternoon. However, additional showers and thunderstorms will be possible across the region later today. Maintaining VCSH after 21Z due to low confidence in thunderstorm timing. EXTENDED AVIATION OUTLOOK...Periodic restrictions from showers and thunderstorms continue through Sunday night. Low ceilings are also possible Sunday morning. Conditions should improve on Monday. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$