AFD_CHS

FXUS62 KCHS 150640 AFDCHS

Area Forecast Discussion National Weather Service Charleston SC 140 AM EST Sun Feb 15 2026

.WHAT HAS CHANGED...

The Aviation section has been updated to reflect the 06Z TAF issuance. Added key message 2 to highlight the potential for strong to severe thunderstorms this afternoon and evening.

.KEY MESSAGES...

- 1) A storm system will move across the region today into

tonight, bringing widespread rain.

- 2) A squall line of strong to severe thunderstorms is expected

to impact portions of southeast Georgia and South Carolina Lowcountry and adjacent Atlantic waters this afternoon and evening.

.DISCUSSION...

KEY MESSAGE 1: A storm system will move across the region today into tonight, bringing widespread rain.

Satellite water vapor shows a potent closed mid-level low over the TX/LA, tracking east. Short term guidance indicates that the low will travel east generally over the I-20 corridor across the Deep South, then continuing east pushing offshore as an amplified shortwave over the mouth of the Savannah River between 3-6Z Monday. HREF 0Z indicates that a band of 1.4" PW will remain ahead of the H5 low as it reaches the forecast area this afternoon. GFS1deg indicates that a wide field of H5 Q-vector convergence will reach SE GA and the SC Lowcountry just after 18Z this afternoon then pushing offshore by 6Z Monday. The combination of synoptic scale forcing and deep moisture should support widespread rain showers this afternoon into this evening. Rainfall late this morning into the mid-day hours should be concentrated near the warm front lifting across the region. However, the strongest and most focused forcing will likely be associated with the cold front that is timed to reach the forecast area from the west by 21Z. NAM12 indicates a solid band of 925-700mb frontogenesis will push across SE GA and portions of the SC Lowcountry late this afternoon into this evening. Guidance remains in good agreement of a general 0.5" to 0.75" of rainfall today into tonight, with some higher amounts associated with thunderstorms.

KEY MESSAGE 2: A squall line of strong to severe thunderstorms is expected to impact portions of southeast Georgia and South Carolina Lowcountry and adjacent Atlantic waters this afternoon and evening.

Early this morning, a squall line was located over the lower Mississippi River Valley, pushing east. This lines has been highlighted with a Tornado Watch, along with several Severe Thunderstorm and Tornado Warnings. The squall line will likely remain intact as HREF indicates that 0-1 km SRH should range between 200-300 M2/S2 along and ahead of the line. Instability is forecast to remain below 500 J/kg, with the highest values expected across SE GA. Recent runs of the HRRR indicates that the northern section of the squall line will push across SE GA and southern portion of the SC Lowcountry this afternoon, 2-6 PM. These storms may bring a risk of severe wind gusts, impacting trees and power lines. SPC Day1 has expanded the Slight Risk 1 to 2 counties north of the Altamaha River, with a Marginal Risk just north of the Savannah River. It is possible that portion of the CWA, especially SE GA, could see a Severe Thunderstorm or Tornado Watch today. These storms will push offshore late this afternoon, possibly producing wind gusts within the Special Marine Warning criteria.

.AVIATION /06Z SUNDAY THROUGH THURSDAY/...

VFR conditions will prevail at CHS/JZI/SAV terminals until the showers and thunderstorms arrive this afternoon. However, light to moderate showers should begin to develop around noon as a warm front lifts north across the area, followed by increasing chances of moderate showers in the 20-24Z timeframe. Once the warm front passes, gusty south winds should develop across the terminals. Wind gusts between 20-25 kts should remain until the cold front arrives this afternoon. The risk for thunderstorms should increase late this afternoon, perhaps embedded in a swath of precipitation associated with an arriving cold front from the west. Thunderstorms will be highlighted with TEMPOs between 20-24Z at KSAV and 22-02Z at KCHS/KJZI. After the convective line, cloud bases are forecast to lower to at least IFR as the core of the low tracks over the terminals this evening.

Extended Aviation Outlook: The potential for flight restrictions will remain late tonight as an area of low pressure moves across the region.

.MARINE...

A low pressure system will be approaching the area from the west throughout the day, resulting in breezy southerly winds building during the morning hours, with scattered showers also being possible. Hiked up the start time of the Small Craft Advisory for all zones outside the nearshore Charleston waters given the anticipated earlier arrival of winds greater than 25 knots, and also did include the Charleston Harbor in an SCA for this afternoon and evening. 6 foot waves will likely remain 10+NM offshore, with 3 to 4 foot waves expected along the shore and highest waves (8+ ft) expected 60 NM out. Later this afternoon and into the evening hours, there is a low end chance (level 2 out of 5) for strong thunderstorms that may require Marine Weather Statements or potentially even a Special Marine Warning from Savannah southwards, so remain aware of that possibility later this afternoon. Will likely see winds dip below SCA criteria this evening/overnight, but a resurgence in winds is expected Monday morning as explained below.

The low pressure system will traverse the local waters this evening and into the overnight hours, continuing chances for scattered showers and thunderstorms with winds swinging around to become out of the north by Monday morning. A surge of cold air pushes in from the north after sunrise, which looks to reinvigorate the winds back to above SCA criteria Monday morning. Spatial extent of these winds remains uncertain, which is why the Charleston Harbor and the nearshore waters from Savannah to Altamaha Sound, GA did not get their SCA extended to account for these winds.

Winds decrease into the evening hours on Monday as a surface high pressure builds across the region through Tuesday. Overnight into Wednesday, the surface high pressure moves eastwards into the Atlantic and a surface low pressure moves into the central CONUS. This will create a pinched surface pressure gradient resulting in periods of breezy winds Wednesday and Thursday, with potential for SCA winds currently looking to remain in the offshore South Carolina waters.

.CHS WATCHES/WARNINGS/ADVISORIES...

GA...None. SC...None. MARINE...Small Craft Advisory from 1 PM this afternoon to 7 PM EST this

evening for AMZ330. Small Craft Advisory from 1 PM this afternoon to 1 PM EST Monday for AMZ350. Small Craft Advisory from 10 AM this morning to 1 PM EST Monday for AMZ352-374. Small Craft Advisory from 10 AM this morning to 9 PM EST this evening for AMZ354.

APT/NED