Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
083 FXUS62 KCAE 200920 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 520 AM EDT Thu Jun 20 2024 .SYNOPSIS... High pressure along with dry weather and near normal temperatures are expected through today. Unsettled conditions are possible tomorrow and into the weekend as moisture moves in from the Atlantic. Well above normal temperatures are expected by Sunday into early next week. && .NEAR TERM /THROUGH TONIGHT/... There is little change in the overall large scale pattern today as upper ridging and high pressure continue to dominate the weather. Expect another day of warm and dry weather conditions as PWATs struggle to exceed 1 inch. Scattered cumulus are likely to develop later today along with periodically gusty winds out of the east. Any cumulus should dissipate quickly with the loss of daytime heating, giving way to mainly clear skies tonight. Clouds may increase towards daybreak as an area of low pressure, Invest 92L, approaches the Georgia and Florida coasts but rain is not expected until after daybreak. Temperatures will be similar to previous days with highs around 90 degrees and lows in the mid to upper 60s. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... An area of low pressure east of the Bahamas, Invest 92L, is expected to move south of the region Friday. The NHC Tropical Weather Outlook gives it a low (30%) chance for further development in the next 48 hours. The expectation is that this disturbance will remain disorganized, but infuse more moisture into the region to support a chance of showers and thunderstorms on Friday afternoon, mainly south of the I- 20 corridor. The moisture increase will be significant, with PW values exceeding 1.5" and approaching 1.8" by late Friday afternoon across the Southeast Midlands and CSRA. Additionally, temperatures will be warmer than Thursday by a few degrees, with highs in the low to mid 90s as a potent upper ridge and broad surface high pressure situate over the TN Valley. The increased moisture will also lead to more cloud cover and warmer overnight lows, mainly in the upper 60s to around 70. A warming trend really kicks into gear on Saturday, with highs reaching the middle 90s to perhaps the upper 90s for a few locations. Changes in the wind field, with more southerly flow in the lower levels, will reinforce moisture availability and dewpoints are expected to creep into the upper 60s to low 70s possible across the southeast Midlands. However, this will be countered by northerly flow aloft, as a mid and upper level low sets up off the coast of NC. With PW values around 1.5"-1.7", daytime heating should trigger isolated diurnally-driven convection across the area. Storms should wind down with sunset, and overnight lows will be mild again, only in the low 70s. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... The main story in the extended forecast remains the heat. While moisture will remain intact across the area with PW around 100-120% of normal, its effect on apparent temperatures will be more impactful than the increased risk for showers and thunderstorms. Upper ridging will build across the southern tier of the CONUS and remain in control into early next week. GEFS mean 850mb temperatures are forecast to be 18-22C through the middle of next week, giving us temperatures of 8-12 degrees above normal at the surface. There has been little change in the overall high temperature forecast from the NBM or the spread through at least Monday, though it should be noted that the deterministic NBM highs on Monday seem to be at the 25th percentile. The spread on Tuesday is wider, likely due to the uncertainty regarding any convection which may interfere with peak heating potential. Potent low level moisture (dew points in the upper 60s and low 70s) is thought to yield max heat indices of 98F- 103F across the region, especially for Sunday through Tuesday. Its also worth mentioning warm overnight lows, in the low to mid 70s. There remains uncertainty for Tuesday and Wednesday as the pattern shifts with a couple of disturbances moving through the region. Ensemble PW means differ between the GEFS and the ECENS, with the EC quite a bit drier than the consistently wet GEFS. Didn`t deviate from the blend at this juncture since there is too much uncertainty. Overall though, it does look like we`ll be entering into a more active and summer-like pattern at temperatures remain well above normal. More information on the potential for moderate to major heat risk late in the forecast period can be found at wpc.ncep.noaa.gov/heatrisk. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... VFR conditions continue at the terminals early this morning with just a few passing clouds. Light easterly winds should increase after daybreak and may be gusty at times, especially this afternoon. Dry conditions are likely to continue at all terminals with scattered cumulus developing this afternoon and dissipating after sunset. Winds should gradually diminish tonight under clear skies though cloudiness may begin to approach the terminals from the east towards the end of the current TAF period. EXTENDED AVIATION OUTLOOK...Brief restrictions possible in isolated to scattered afternoon and evening thunderstorms Friday through Sunday. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$