Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 060918 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 418 AM EST Wed Dec 6 2023 .SYNOPSIS... Cooler weather in store for today and Thursday, with breezy winds this afternoon. Expect fair weather with a gradual warming trend Thursday through Saturday. The next chance of rain is expected this weekend with a return to cooler and drier weather behind a cold front on Monday. && .NEAR TERM /THROUGH TONIGHT/... Cold advection will lead to below normal temperatures today. Dry high pressure building into the region will allow for breezy winds through the day, diminishing quickly around sunset as the center of the high moves closer and the pressure gradient weakens. A Lake Wind Advisory should not be needed but gusts up to 20-25 mph are possible. Highs will be in the mid to upper 50s during the day. A strong downslope component to the winds will allow for diabatic heating which would typically point to highs on the warmer end of the guidance spectrum. With weaker winds tonight, we will see temperatures drop into the low 30s to upper 20s. There may be a quick drop in temperatures right around sunrise as the surface high is nearly overhead. This adds some uncertainty to the forecast with temperatures potentially dropping a few degrees cooler than expected. Roughly 25 percent of NBM members have lows in the mid 20s rather than low 30s to upper 20s which is the current forecast. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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Thursday and Thursday Night: High pressure will be centered over the forecast area before shifting offshore Thursday night. An upper level ridge to our west will translate eastward over the Carolinas with northwesterly 500mb flow Thursday becoming more zonal Thursday night. Air mass will remain quite dry with ensemble PWATs around 50 to 80 percent of normal on Thursday but as the surface high shifts offshore, some weak moisture advection may begin Thursday night as winds shift to the south. High temperatures should remain slightly below normal in the mid to upper 50s while lows Thursday night should be near normal in the mid to upper 30s. Friday and Friday night: Upper level ridge axis will shift east of the forecast area as an upper trough digs and deepens across the Plains states. Moisture advection becomes more significant Friday night with increasing deep southwesterly flow with PWATs rising to almost 1 inch by 12z Saturday. Significant dry air in the mid levels would prevent any precipitation from reaching the ground during this period. Temperatures should be warmer on Friday with southerly flow and increasing thicknesses with highs expected in the lower to mid 60s. Increasing clouds Friday night and southerly winds will limit radiational cooling and lows should also be warmer in the lower to mid 40s.
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The extended forecast period features a highly amplified 500mb pattern early in the period with active weather expected over the weekend. Despite some timing differences, global ensembles are in reasonable agreement showing a deep upper trough moving eastward through the MS/TN Valley over the weekend pushing a strong cold front through the forecast area on Sunday. There is increasing confidence in a potential high shear low CAPE convective event associated with this system and this will need to be monitored in the coming days. The upper trough takes on a negative tilt as it approaches the forecast area on Sunday. Strong, deep southwesterly flow will precede the upper trough and cold front on Saturday with strong moisture transport into the region Saturday night into Sunday with an 850mb jet around 50 knots crossing the forecast area on Sunday ahead of the cold front. PWATs rise to around 180-200 percent of normal on Sunday and ensembles showing some positive CAPE supporting the possibility of thunderstorms. Ultimately, timing of the front and available instability will determine the risk of severe weather but there is potential on Sunday. Behind the front, cool high pressure will build over the area into early next week. Temperatures during this period will start out above normal on Saturday and Sunday with highs in the upper 60s to lower 70s over the weekend then cooling below normal for Mon/Tue behind the front.
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&& .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... Gusty winds this afternoon but VFR conditions likely. Winds will remain up through the early morning as the pressure gradient strengthens. This will prevent fog even at AGS/OGB. Winds will increase around or shortly after 15Z with NW winds from 10 to 15 knots and gusts to around 20 knots through the afternoon. Gusts will quickly diminish through the evening and overnight. Expect light to calm winds by early Thursday morning. However the dry airmass will once again prevent fog. EXTENDED AVIATION OUTLOOK...The next chance for widespread restrictions will be Saturday night through Sunday as a strong low pressure system/cold front approaches from the west. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ is the U.S. government's official web portal to all federal, state and local government web resources and services.