Sunrise 6:32 AM   Sunset 8:09 PM Moonrise 1:42 AM   Moonset 11:57 AM

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FXUS62 KCAE 010734 AFDCAE

Area Forecast Discussion National Weather Service Columbia SC 334 AM EDT Wed May 1 2024

SYNOPSIS
Dry and warm conditions expected Wednesday and Thursday as surface high pressure and upper level ridging build back into the area. Rain chances start to increase Friday as moisture steadily increases as southwesterly low level flow strengthens.
Showers- storms are then likely over the weekend as a series of weak disturbances push across the area and moisture continues to build.

NEAR TERM /THROUGH TONIGHT/
The upper level trough is moving east of the area early this morning. There remains enough lift for a few isolated showers mainly in the east Midlands mainly before dawn. Water vapor imagery is showing dry air aloft spreading into the area from the west. With shallow low-level moisture remaining and near calm winds, expect areas of fog to develop toward morning, possibly dense in some areas, especially the southern Midlands and CSRA where model fog probabilities are higher. Will monitor for possible advisory at some point. Surface and upper ridge will be building in from the west this afternoon, the focus for any showers should be mainly in the coastal plain where the surface trough will be located as suggested by CAMS. So after the fog lifts, expect clearing skies. Temperatures should be warm, with guidance consistent in the low to mid 80s. Clear tonight, perhaps some patchy fog toward morning with lows around 60.

SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
A quiet short term period is expected as deep ridging will build across the SE CONUS. As the ridge axis starts settles overhead, the dry northwesterly flow from 850-250mb will weaken and turn more westerly, with the associated surface high pressure center shifting offshore. Despite losing the downslope component flow, PWAT's overall will not increase much, but with the surface high pressure center shifting east, easterly low level flow will develop below 850mb. Dew points will tick up a bit compared to Wednesday thanks to the onshore flow and clear skies will help temps climb into the upper 80's.

Offshore high pressure will strengthen further into Friday as ridging continues to build aloft. Temps will again climb into the upper 80's but steadily increasing PWAT's will yield some mid-level cloud cover by the afternoon. Surface winds will turn out of the south as the surface high strengthens. GEFS and EC guidance suggests some showers pushing into the region by late Friday as some weak troughs ride through the main ridge axis to our northwest. Precip chances remain low however until overnight Friday and into Saturday morning, as PWAT's climb back above 1.5".



LONG TERM /SATURDAY THROUGH TUESDAY/
Broad ridging over the SE CONUS will begin to weaken Saturday while PWAT's continue to increase with southerly component low level advection strengthening. Troughing to our northwest will flatten the ridge and provide the impetus for some shower-storm activity each day through long term period; none of the mid- level shortwaves will correspond with a strong enough low-level boundary to scour out entrenched moisture. GEFS and EC ensemble members clearly show this elevated period of moisture, with mean PWAT's up around 1.5-1.75" Saturday-Tuesday. So while PoPs are relatively high each day, the severe potential will remain limited over the weekend; CSU probs only show marginal risks for Saturday and Monday. This is primarily due to mediocre low- mid level lapse rates and a lack of height falls which only yield ~500 J/kg ML CAPE each afternoon over the weekend. From a shear perspective, as the ridge axis weakens, mid- level flow aloft will also weaken resulting in 0-6km shear of less than 15-20 knots. Increasing surface heating and steepening lapse rates in general are expected by Monday and Tuesday however; GEFS > 1000 J/kg ML CAPE is > 50% both days. But shear will remain fairly both days. So, showers and storms probable Saturday through Monday afternoons with increasing severe potential for Monday as instability ramps up.

AVIATION /06Z WEDNESDAY THROUGH SUNDAY/
LIFR/IFR conditions expected early this morning as fog and stratus develops across the region.

Upper level trough moving east of the area early this morning.
Satellite showing some clearing upstream to the west behind the trough. This clearing aloft will spread across the region overnight. With low level moisture in place and near calm winds, expect widespread fog/stratus to develop. Confidence is relatively high with satellite guidance suggesting a high probability of restrictions along with the latest lamp/HRRR. Low clouds and fog should lift by 14z-15z with scattered cumulus.
Winds will shift to northwest to north behind the trough less than 10 knots.

EXTENDED AVIATION OUTLOOK...Some late night/early morning fog/ stratus possible. Increasing moisture, some upper energy, and a surface boundary expected to provide a chance of showers and thunderstorms, and associated restrictions, Fri thru Sun.

CAE WATCHES/WARNINGS/ADVISORIES
SC...None.
GA...None.

Pimlico
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Wed -- 02:35 AM EDT     Moonrise
Wed -- 05:29 AM EDT     1.86 feet High Tide
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Wed -- 07:27 AM EDT     Last Quarter
Wed -- 12:34 PM EDT     0.61 feet Low Tide
Wed -- 12:55 PM EDT     Moonset
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Jamestown Bridge
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Wed -- 02:07 AM EDT     0.22 feet Low Tide
Wed -- 02:34 AM EDT     Moonrise
Wed -- 06:27 AM EDT     1.21 feet High Tide
Wed -- 06:30 AM EDT     Sunrise
Wed -- 07:27 AM EDT     Last Quarter
Wed -- 12:54 PM EDT     Moonset
Wed -- 03:09 PM EDT     0.20 feet Low Tide
Wed -- 06:55 PM EDT     1.03 feet High Tide
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Jamestown Bridge, Santee River, South Carolina, Tide feet

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