Preview of NWS' New Version of Forecast
This preview is not operational and should not be used for support decisions.

Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

FXUS62 KCHS 221009

Area Forecast Discussion
National Weather Service Charleston SC
609 AM EDT Mon Apr 22 2019

High pressure will prevail with dry weather through Thursday. A
storm system will then bring unsettled weather late in the


No changes for the sunrise update.

H5 Heights will rise today as the subtropical ridge over the
lower-mid Mississippi Valley builds east. H8 temperatures and
low-level thicknesses will respond accordingly with both
supporting highs in the upper 70s to lower 80s away from the
beaches under full insolation. A nebulous pressure pattern will
remain as broad, surface high pressure remains anchored over 
the region. This combined with a modest H9-H8 northwest flow 
will keep any weak sea breeze circulation that develops fairly 
close to beaches. The cooler Atlantic waters will still heavily 
influence the immediate coast and around around the Charleston
Harbor with most beach locations likely to only max out in the 
upper 60s to lower 70s.


Tonight: Another strong radiational night is likely as the
boundary decouples quickly after sunset and winds go calm
beneath clear skies. Lows will range from the lower-mid 50s 
inland to lower 60s at the beaches and Downtown Charleston. 

Tuesday: The mid-levels will consist of ridging over the Southeast 
in the morning. It is forecasted to dampen and move offshore 
overnight, allowing for semi-zonal flow over us. At the surface, the 
center of broad high pressure over the Southeast in the morning will 
start to move offshore in the evening and overnight. The high will 
bring our area dry weather and mostly sunny skies. South to 
southwest surface winds will help temperatures rise into the mid 
80s, except cooler at the beaches with the afternoon sea breeze. 
Lows will be mild, generally around 60 degrees.

Wednesday: Semi-zonal flow is forecasted in the mid-levels. At the 
surface, high pressure offshore will gradually move away from us. 
Meanwhile, a cold front will approach from the distant north while a 
storm system develops over the Southern Plains. Neither of these 
features will reach our area, so we can expect another dry day. 
Though, high clouds should increase with time. The air mass will 
continue to warm with southwest surface winds, leading to our 
highest temperatures so far this year. Highs may make a run for the 
90 degree mark in some locations, assuming the clouds don't get to 
thick too quick. This is a few degrees below the record highs for 
this date. Once again, relief in the form of cooler temperatures 
will be at the beaches. Likewise, overnight lows will remain mild.

Thursday: Mid-level ridging is forecasted to strengthen over the 
Southeast during the day. At the surface, high pressure will be 
offshore while a cold front continues to approach from the north. 
Additionally, a storm system will be developing over the Southern MS 
Valley. Despite the approach of these two features, the outer 
periphery of the high will continue to give our area dry weather. 
Continued southwest winds will allow daytime temperatures to make 
another run for the 90 degree mark in some locations, just a few 
degrees short of the records. Though, increasing clouds may limit 
how high temperatures get.


A storm system with its associated cold front is expected to move 
through the region on Friday, bringing showers and cooler 
temperatures. However, models disagree on the track and timing of 
the main features along with the main bands of rainfall.
Hence, we have chance POPs in the forecast. By the weekend the 
models continue to differ on whether it will be dry or if showers 
will persist. We opted to go with slight chance POPs to account for 



Extended Aviation Outlook: A storm system could bring flight 
restrictions on Friday.


Through Tonight: Fairly light winds this morning will give way
increasing south to southeast winds near the coast as a pinned,
weak sea breeze circulation tries to develop along the beaches.
Winds will remain 10 kt or less, but may be locally higher near
the beaches and Charleston Harbor with the sea breeze. South to
southwest winds 5 kt or less will prevail overnight. Seas will
average 1-2 ft nearshore waters with 2-3 ft over the Georgia
offshore leg.

Tuesday through Friday: High pressure will prevail over the 
Southeast Tuesday, trending offshore Tuesday night and 
continuing further offshore through Thursday. A weak pressure 
gradient will bring fairly good marine conditions through 
midweek along with a sea breeze each afternoon. By Friday a 
storm system may bring increased winds and seas. But at this 
time no Small Craft Advisories are expected.