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Area Forecast Discussion (AFD)

Issued by Charleston, SC (CHS)

FXUS62 KCHS 221415

Area Forecast Discussion
National Weather Service Charleston SC
1015 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


The mid and upper low that impacted the area the past few days 
is now off New Jersey and Delaware, and will continue to 
progress north-northeast this afternoon. As a result we'll 
experience small height rises aloft within an extremely dry 
northwest flow throughout the vertical. At the surface, a 
portion of high pressure from the Gulf of Mexico to the eastern 
Great Lakes will redevelop overhead and just offshore. These 
conditions will allow for full insolation, and with H8 temps 
climbing to 9-12C, it'll be a warmer day than this past weekend.
Late morning temps are already on average 3-6F warmer than 
Sunday, and since our previous forecast was already in line with
the H10-H8 thickness scheme, no changes in regards to max temps
this afternoon. This supports max temps within a couple of 
degrees either side of 80F, warmest near the Altamaha River. A 
weak sea breeze that develops will limit max temps near the 
coast to some 10F cooler.


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 southerly winds near the coast this afternoon 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.