FXUS62 KCHS 121051 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 551 AM EST Mon Jan 12 2026
.SYNOPSIS...
High pressure builds across the area through Tuesday, followed by a cold front Wednesday night. High pressure then returns heading into the weekend.
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.NEAR TERM /THROUGH TONIGHT/...
Near term guidance indicates that a ridge of high pressure will build over the forecast area today. The sfc pattern should yield light north-northeast winds through the day. As a result, llvl thicknesses will remain very cool, 1000-850mb thickness generally 1320m or less. Despite partly to mostly sunny conditions, temperatures should remain well below normal today, favoring values in the low 50s. In addition, dewpoints are expected to remain around 20 degrees through this afternoon, yielding RH values around 30 percent.
Broad high pressure will remain across the region tonight. Conditions through the night will feature light to calm winds, thin cloud cover, and dry conditions. Several hours of solid radiational cooling conditions should develop late tonight as cloud cover decreases. Low temperatures are expected to range in the mid to upper 20s inland to the low to mid 30s along the coast.
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.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Tuesday: Elongated surface high pressure will stretch from southeast Texas to Bermuda with temperatures warming to near 60 degrees. Most of the day Tuesday will be completely sunny with no clouds expected. The one exception to this is far southern GA late in the afternoon might start to have thickening cirrus. No precipitation is expected.
Wednesday: A rex block across the Western United States will be the primary feature in the upper level pattern which will drive a pattern change across the Eastern United States for the second half of the work week. The blocking pattern will allow for long wave trough amplification to occur across the Eastern United States with a seasonably strong wave diving south out of Manitoba. In front of this wave, a weak upper level low that was over Western Texas will open up and rapidly eject east. This remnant PV will move overhead Wednesday afternoon bringing a slight chance to chance of rain to the area. However it's unclear how much air mass modification will be able to occur due to the rapid weakening of the wave. PWATs will be around 0.20" Tuesday with substantial dry air in the low and mid levels of the atmosphere. Given the above, rainfall totals of only a few hundredths are expected at most.
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.LONG TERM /THURSDAY THROUGH SUNDAY/...
A pattern change will arrive across the region starting Thursday with much colder conditions forecast through the long term. Little if no precipitation is expected.
Thursday: A closed upper level low will be progressing east across the Ohio River Valley with a strong cold front crossing GA and SC in the afternoon. Behind the cold front, winds will turn from the northwest and be gusty. The core of the upper level low contains the strongest CAA in the low and mid levels of the atmosphere with the greatest static instability. GFS BUFR soundings show the 1.5 PV surface being depressed down to 650 mb with the tropospheric folding reaching as far south as coastal GA. What does this mean at the surface? This means wind gusts will be strongest underneath the core of the upper level low, or Thursday afternoon into early evening. A Lake Wind Advisory is likely with widespread wind gusts of 20 to 30 mph across the entire region.
Friday: Surface high pressure will rapidly approach the region from the west in the morning hours with lows Friday morning in the lower to mid 20s. This coupled with a fully mixed PBL, will allow for widespread teen apparent temperatures in the morning hours. Areas away from the immediate coast currently have a 40% to 80% chance of reaching Cold Weather Advisory criteria. High temperatures will be around or just shy of 50 degrees.
Saturday into Sunday: Surface high pressure from Friday will rapidly pull northeast with another strong cold front approaching the area. Ensemble guidance is in fairly good agreement with the cold front bringing low temperatures back into the 20s for most of the area with highs around 50 degrees. There is a rather wide IQR in this timeframe and taking a look at WPC cluster analysis reveals the variance comes from how the rex block modulates through this period. Either way, dry conditions are forecast with below normal temperatures.
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.AVIATION /12Z MONDAY THROUGH FRIDAY/...
12Z TAFs: VFR. North winds may continue to gusts into the teens around daybreak. Northeast winds are forecast to remain between 5-10 kts through the rest of the daylight hours today, then 3 kts or less this evening.
Extended Aviation Outlook: Tuesday: VFR with surface high pressure overhead. Winds out of the southwest and mostly less than 15 kt.
Wednesday: An upper level disturbance will move overhead with a chance of light rain at the terminals. Some guidance is indicating that MVFR conditions could occur, but at this point mostly VFR conditions are forecast given the amount of low level dry air in place.
Thursday: A cold front will cross the terminals with winds turning from the northwest 10 to 20 kt and gusts of 20 to 30 kt. Some MVFR cigs are possible with and behind the frontal passage.
Friday: VFR with surface high pressure overhead. Winds less than 10 kt.
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.MARINE...
Today and tonight: Gusty winds will gradually decrease across the Atlantic waters before dawn this morning. Ongoing Small Craft Advisories should end by 7 AM. The rest of the day and tonight, broad sfc high pressure will build across the marine zones. This pattern will generally support northeast winds between 10 to 15 kts. Wave heights should steadily decrease from 3-5 ft this morning to 2 to 3 ft by late tonight.
Tuesday: Northerly winds backing from the northwest 10 kt or less. Surface high pressure overhead.
Wednesday: Winds from the southwest 15 kt as surface high pressure moves away from the region. Seas 2 to 4 ft.
Thursday: A strong cold front will cross the waters Thursday afternoon with winds turning from the northwest and increasing in speed as lapse rates steepen. Winds will be sustained 25 to 30 kt with wind gusts of 30 to 35 kt. The latest run of the NBM has probabilities of wind gusts reaching gales around 40% to 60% for the SC/ GA nearshore waters and 60% to 80% for the offshore GA waters. Seas building 4 to 8 ft.
Friday: Surface high pressure will approach from the west with winds rapidly decreasing by sunrise Friday morning. Seas 4 to 8 ft decreasing 2 to 4 ft by the afternoon.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...Small Craft Advisory until 7 AM EST this morning for AMZ350-
352-354-374.
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NEAR TERM...NED SHORT TERM...Haines LONG TERM...Haines AVIATION...Haines/NED MARINE...Haines/NED