Fred may be long-gone, but its tropical moisture continues to linger across the Lowcountry for another day, making for another round of stifling heat for Thursday. Temperatures will head into the low 90s; combine this with heinous dewpoints in the upper 70s, and that will yield heat indices around 105°. This is getting to the point where heat stroke becomes a real possibility, so be sure to take plenty of breaks in the shade and get plenty of hydration if you must be outside in the heat of the day.
Some will see relief through showers and thunderstorms. In fact, there is a small chance of storms once again in the morning if the High-Resolution Rapid Refresh model has anything to say about it, so we’ll want to watch that trend. Otherwise, we should see another round of scattered afternoon thunderstorms as the heating of the day kicks in and the seabreeze makes its trek. Once again, storm motions won’t be terribly fast, and with precipitable water values at or over 2”, flooding certainly cannot be ruled out in spots.
Fred continues to move northward across the western Carolinas this evening, bringing quite a ruckus including significant flash flooding in the NC mountains and several tornadoes. For our part of the Lowcountry, heavy rain has been the story. Heavy rainfall closed roads this morning in parts of downtown Charleston, while a stationary downpour within a rain band produced a radar-estimated 5-5.5” of rain across Ravenel and Hollywood.
As we get into Wednesday, Fred’s remnants will become long-gone, but its legacy of deep tropical moisture will remain. An airmass characterized by surface dewpoints in the upper 70s will linger, keeping things rather humid across the region. Heat indices look to top out in the low 100s despite the fact we may not even crack 90° tomorrow.
We may start the day with heavy downpours near the coast. High-resolution models have had a pretty consistent signal that lingering banding features from departing Fred may help kick off a few showers and thunderstorms during the morning hours, which might have impacts on the commute. Afterward, high pressure aloft will increasingly reassert itself, which indicates generally scattered showers and thunderstorms developing on the seabreeze in the afternoon. Storm motions will be slow and largely driven by the inland progression of the seabreeze, so pockets of very heavy rain cannot be discounted. Otherwise, though, there will indeed be a mix of sun and clouds, so it won’t be total gloom like we’ve seen the past day or two.
Get ready for periods of heavy rain tonight into Tuesday as Fred, which made landfall earlier near Cape San Blas, FL, continues its northward trek through Alabama and Georgia tonight into Tuesday. Deep tropical moisture will be the name of the game, and models show a feeder band-like feature off of the Atlantic coming up through the area early Tuesday morning. There’s a chance that the band could be moving through the area during the morning rush, so that’s certainly a trend to watch closely. We should see a lull followed by another renewed round of showers and thunderstorms as daytime heating takes hold. All in all, NWS is forecasting another 1-3” of rain (with locally higher amounts) before it’s all said and done Tuesday night.
Given the eastward nudge in Fred’s track over the last day, we’ll be keeping an additional eye out in case conditions become marginally favorable for severe weather closer to the Lowcountry. Right now, it looks like the bulk of the severe risk will stay to our west and northwest, cutting through Georgia into the Upstate. Still, shear profiles suggest that there could be a small window for severe storms late tonight into tomorrow. It may not be the worst idea to have your weather radios in the on and alerting position overnight, just to be safe. It’s important to note that this is not another Elsa: the center of circulation is much further to the west this go-around, and that in turn keeps the more favorable tornado parameters west.
Temperatures will predictably remain suppressed in the mid-80s given the prevalent cloud cover and rainfall. This remains a few degrees below normal for August.
Tuesday promises another day of isolated showers and storms along and ahead of the seabreeze as highs top out right around 90°. Humidity will make it feel a little closer to 99-100° as the seabreeze moves past during the afternoon. Otherwise, there’s not too much to write home about as ridging of high pressure aloft and at the surface persists.
We woke up to some fairly rude shower activity generally along and east of 17-A this morning as the front repositioned a little further north. Lift across the boundary within an enhanced corridor of moisture is keeping us in cloud cover and showers this morning. We could see another round of showers in the next couple hours lift out of Savannah into the metro area. Guidance continues to indicate a dry slot for at least a few hours late this morning into early afternoon, but then begins to advertise scattered showers (and maybe a thunderstorm near the coast) returning to the picture later this afternoon.
We could still see some peeks of sun throughout the day, but the best chances of that are going to be further inland, generally west of 17-A to the I-95 corridor. Closer to the coast, we’ll remain within a plume of higher precipitable water values and somewhat better forcing in proximity to the front, which will certainly make it tougher to get some sunshine through. Depending on the strength and timing of the high pressure wedge lifting out, this could make for another significantly cooler-than-normal day for much of the Charleston metro area.
By tonight, rain chances will spread further inland as the front begins to lift back to the north in response to a trough, currently found over the Midwest into the southern Plains, pushing eastward. This will increase rain chances markedly for tonight into Friday.
After a record cool day — Wednesday’s high of 77° breaks the record low maximum temperature of 80° set in 1969 — we’ll warm up by a few degrees for Thursday as more sunshine mixes in. Still, though, with high pressure wedging in from the north, we’ll stay cooler than normal once again.
The high pressure wedge will retreat a bit as Thursday goes on. This will allow for the seabreeze to help kick off a few showers and thunderstorms Thursday afternoon and evening, but we will still not have a ton of moisture to work with behind the front. Rain chances will steadily increase overnight Thursday into Friday as the front moves back north of us, increasing available moisture and instability.
A soggy pattern takes shape beginning Tuesday as a stalled front and an open pump of Gulf of Mexico moisture combine to produce widespread showers and thunderstorms. It won’t rain all of the time all day — will generally be on-and-off — but keep the rain gear handy regardless as when it does rain, it could rain pretty heavily. Some guidance is pointing to a particularly heavy slug of rain coming through starting tomorrow afternoon into the evening hours, which is certainly worth monitoring for the evening commute. Flooding is certainly a concern, and trends will be monitored appropriately, especially as high tide comes up at 5:06 PM.
Temperatures will be kept handily in check thanks to the rainfall. NWS has a high of 83° at best across the area. Depending on how “on” the rain ends up being, it’s conceivable we might not make it out of the 70s. Quite a contrast to last week, that’s for sure.
Stay abreast to forecast updates on Tuesday and throughout the week as we keep close watch on the potential for flooding rain.
Friday will be the hottest day of 2021 so far. Temperatures will soar into the upper 90s in the afternoon as deep westerly to northwesterly flow in the troposphere pins the seabreeze to the coast, keeping the cooler marine air at bay for much of the day. On the other hand, this will allow very humid air characterized by dewpoints approaching 80° to pool near the coast. When the seabreeze finally begins its inland trek in the mid-to-late afternoon, the highest heat indices will then be realized as this incredibly moist air moves across the much warmer air found over land. Given this potential, an Excessive Heat Watch is in effect for the Tri-County area. Ridging aloft will put the kibosh on any shower or thunderstorm activity, so don’t count on that to bring any relief, either.
If it’s at all humanly possible, avoid exertion in the heat of the day tomorrow. If you must be outdoors, get shade and hydration on a very regular basis. If you begin to feel ill, move into an air-conditioned area immediately. If you feel faint and your skin is hot to the touch, that’s quite possibly heat stroke — a 911-worthy medical emergency requiring swift treatment.
High heat will continue through Sunday, and heat advisories for heat indices approaching 110° are certainly possible. Please take it easy!
We’ll trade the persistent rain of the last few days for a real taste of summer beginning on Thursday. Temperatures will easily rise into the low 90s in the afternoon under mostly sunny skies as high pressure builds in aloft and at the surface. The humidity will make it feel closer to 105°, which is as hot as the heat index has been all summer. Take appropriate precautions: Plenty of water, plenty of shade, and most importantly, look before you lock. One hot car death is too many.
Today will continue to feature scattered showers and thunderstorms, especially this morning as slow-moving storms develop and move in from the west. Flooding will certainly be a concern wherever thunderstorms set up and rain for long periods. The next high tide will be at 12:07 PM.
It won’t rain all day, however; high-res models have this batch of storms eventually fizzling out by early this afternoon. Another round of storms could fire along the coast this evening, and this may drive additional heavy rain concerns before departing later tonight.
This will be our last day in the 80s until next week; the hottest temperatures of the season will begin Thursday and last into Sunday with highs well into the 90s and heat indices approaching 110°. (More on that later today.)
