Area Forecast Discussion
Issued by NWS Charleston, SC

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687 FXUS62 KCHS 201131 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 731 AM EDT Mon May 20 2019 .SYNOPSIS... High pressure will be the dominant weather feature this week. && .NEAR TERM /THROUGH TONIGHT/... Shortly after daybreak: Weak daybreak moisture convergence resulting in a few isolated showers from around Hilton Head Island south over the GA waters. Stratus was inland with some patchy fog adjacent to the CSRA and SC Midlands. Today: Overall the warm and dry pattern looks to remain intact with the mid level ridge axis forecast to only nudge a tad to the east by an advancing but quickly weakening short wave. It appears like it will remain too dry aloft along with poor mid level instability, resulting in only spotty/isolated convective rains along the SC sea breeze along and just inland from U.S. 17 in the mid afternoon afternoon hours. A narrow band of slightly higher 850-500MB layer RH should push into our far northwest zones late in the afternoon but with west winds in the boundary layer and well mixed lower levels/unimpressive surface dew points, only a few showers or isolated tstms seem possible in this region late day. We have POPs slight chance ranges at best today with a poor thermal updraft potential expected. Max temps will be similar to Sunday, lower 90s inland to upper 80s in the coastal corridor inland from the beaches and barrier islands. Tonight: A few spotty showers are possible early in the evening across SC zones and there is a slim chance the weak vort lobe aloft and slightly deeper moisture could result in a few late night showers across the Charleston Tri-County area as well. We have POPs mainly silent post sunset, maintaining persistence trends. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... Tuesday: The mid/upper lvl ridge will temporarily weaken as a front lingers just north of the area and subtle h5 shortwave activity traverses the area. Other than a few showers and/or isolated thunderstorm over the Tri-County area during peak heating, expect most areas to be dry and warm. In general, highs should peak in the low/mid 90s away from the coast. Temps should remain in the low/mid 80s near the coast. Overnight lows will be mild under little to no clouds. In general, lows should range in the upper 60s inland to around 70 closer to the coast. Wednesday and Thursday: Sfc high pressure will become centered along the Mid-Atlantic and Southeast coasts mid week while a large mid/upper lvl ridge of high pressure remains centered over the Southeast United States. Given the setup, warm and dry conditions will likely prevail through mid week. In general, highs should warm into the low/mid 90s inland while a more direct onshore wind limits temps in the upper 80s to around 90 east of the I-95 corridor. Temps should remain in the lower 80s along the immediate coast. Overnight lows should range in the upper 60s to around 70 degrees. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... Hot and dry conditions should prevail this weekend as deep layered high pressure remains across the region. Friday afternoon temps should top out in the mid/upper 90s away from the coast. However, warmest conditions should occur late weekend into early next week as the mid/upper lvl ridge makes a slight shift south, setting up a northwest downslope flow across the region. This includes warmer conditions along the beaches given the potential for a pinned seabreeze each day. In general, Saturday and Sunday afternoon highs should peak in the mid/upper 90s away from the coast and upper 80s along/near the beaches. Temps could reach 100 degrees well inland Saturday and Sunday, mainly along a corridor extending from Allendale/Hampton Counties in Southeast South Carolina to Tattnall County in Southeast Georgia. The combination of heat and sfc dewpts mixing out to the low/mid 60s suggests heat index values around 100 degrees, mainly along and west of the I-95 corridor. Overnight lows will likely be mild, generally in the low/mid 70s each night. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... VFR through 12Z Tuesday. Isolated SHRA/TSRA may develop on the sea breeze this afternoon, but this activity still looks too spotty for any TAF considerations. Extended Aviation Outlook: VFR conditions are expected at both CHS and SAV terminals through late week. && .MARINE... Persistence forecast continues through tonight with south- southwest flow mostly below 15 kt with seas 2 to 3 ft on average. The land/sea interface will continue to see typical warm season diurnal peaks during the afternoon and early evening hours, a few gusts to 20 kt are possible as the sea breeze pushes inland along the SC intra-coastal and adjacent Atlantic waters. Tuesday through Saturday: High pressure will remain the dominant weather feature across the coastal waters through late week, supporting winds/seas that remain below Small Craft Advisory levels. In general, south winds will prevail through Tuesday with wind speeds no higher than 10-15 kts. By Wednesday, winds should become more east/southeast around 15 kts or less, before returning to more of a south/southwest flow late week. Seas should range between 1-3 ft. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM...DPB LONG TERM...DPB AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.