Monthly Archives: February 2014

Great weekend ahead

All yesterday’s cold front did was knock us from the 80s to the upper 60s — and as far as cold fronts go this winter, that’s A-OK. Great weekend ahead with passing clouds (but plenty of sunshine) and temperatures still slightly above normal in the afternoons.

Unfortunately, winter continues to rage on and we could see our next Arctic blast by mid-week. More details on that later today or tomorrow. In the meantime…get out and enjoy!

Severe Thunderstorm Watch until 2PM

6:50 AM radar composite and Severe Thunderstorm Watch outline. Subject to change. Image: GREarth

6:50 AM radar composite and Severe Thunderstorm Watch outline. Subject to change. Image: GREarth

The National Weather Service has issued a Severe Thunderstorm Watch including the Charleston Tri-County area until 2PM ahead of a potent cold front and its associated squall line. The primary concern is for damaging straight-line winds. While far less likely, an isolated tornado along the leading edge of the line cannot be totally ruled out.

Expect the squall line to begin to affect the western parts of the area late this morning (around 11am); it will make its push to the coast by 1pm. The line will be clear of the area by the evening rush and should not affect the commute.

Inland locations affected by the recent ice storm will be particularly susceptible to additional damage to weakened trees. It won’t even necessarily take a gust that meets severe criteria (58 MPH) to cause problems. Stay indoors as storms approach.

Make sure you are able to reliably receive warnings today and take action if needed.

Friday thunderstorms

At 1:30am, a squall line stretching from New Orleans to Cleveland, OH associated with the trailing cold front from a particularly strong storm system moving into the Great Lakes was steadily moving east at around 30 MPH. The line was roughly 350 miles to the west of Charleston. Tornado and severe thunderstorm watches stretch from Louisiana to Lake Erie and as far east as bordering the upstate of South Carolina.

This line will make steady progress overnight, taking aim on the Charleston Tri-County area during the late morning hours and getting through the metro area in the 1-3 PM timeframe. The line is expected to be steadily weakening as it approaches the coast, becoming further removed from the best upper-air dynamics (and then eventually running into the stable marine layer that often weakens approaching storms). That being said, we’ll have a little destabilization time and some strong to severe wind gusts can’t be ruled out as the line moves through. Also note: A severe weather watch is not out of the question.

People who were hit hardest by the ice storm need to watch this one! Further damage to trees weakened by the ice storm may occur even in thunderstorms that don’t reach severe wind criteria (58 MPH winds) which would normally trigger a warning from NWS.

The line and its associated cold front will get through before the evening rush. High pressure will build in behind it, setting us up for a bit more seasonable of a Saturday (though upper 60s still aren’t too shabby for this time of year!)

Last of the 80s tomorrow

After tying the record high of 83 (first set in 1956) today, we could get close to tomorrow’s record of 82 inland. Closer to the coast, we’ll stay firmly in the 70s. (Beaches may yet be cooler thanks to very chilly water temperatures.) A slightly more southerly wind will draw in some cooler air from the ocean and perhaps keep temperatures down a notch over today — time will tell. Sensible weather will remain generally tranquil with perhaps some passing clouds; coastal areas could contend with some sea fog coming ashore at times.

Friday looks to be a different story; a cold front with showers and potentially some gusty thunderstorms associated with it looks timed to get through during the early-to-mid-afternoon hours. That will keep max temperatures down into the mid-70s before the front gets through. A few storms could produce some strong winds but widespread severe weather is not looking likely. Will update if that changes.

Spring preview continues

We’ll be sticking with mostly dry weather (small chance of showers after midnight for inland locations) and the 70s (locally cooler at the coast thanks to the seabreeze and possible sea fog development) for the next few days. Our next strong front comes along on Friday; this front will likely be accompanied by showers and thunderstorms out ahead of it. Interestingly, the Storm Prediction Center has a large 30% severe risk cut out from roughly the GA/SC border up north through the Mid-Atlantic states — something to watch as the forecast is fine-tuned.

Brewvival folks, take note: Guidance generally agrees the front clears the area late Friday/early Saturday, but the degree to which the front makes it offshore is still in some question. Thus, some lingering showers appear possible Saturday morning, so I’ll need to keep some rain chances around in the early going. At any rate, as things stand right now the major mud event from last year does not look to be in the cards this time, but we’ll need to watch the timing of things carefully. More updates as time goes on.

Unfortunately, the longer-range modeling tends to agree that this spring preview will be ending around the start of March as the pattern shifts back to what we’ve seen for much of January and February: A strong ridge around Alaska, bringing dry and warm weather to the West, and a trough in the East, transporting blasts of Arctic air and routing storm systems through. (April can’t come soon enough.)

For now, though, enjoy the warmth — it is such a nice change from what we’ve dealt with over the last couple months!

Saturday #chswx: Windy but clearing

Surface temperatures, radar, and winds around ~1600ft off the surface. As temperatures rise, these winds will be able to mix down and cause some strong wind gusts.

Surface temperatures, radar, and winds around ~1600ft off the surface valid 10:30am February 15. As temperatures rise, these winds will be able to mix down and cause some strong wind gusts.

The rain and the cold front are gone! In the front’s wake, we have a Wind Advisory through 5PM; gusts to 40 MPH will be possible. This could mean additional limbs or perhaps even a tree or two down in the areas most affected by the past week’s ice storm as well as tricky driving conditions on the bridge (don’t worry, it won’t be closed).

Despite the wind behind the cold front, we’ll still get to near 60 today with decreasing clouds to kick off what should be a nice weekend.

12:36 super-resolution radar image from the NWS radar site in Early Branch, SC. Showers on the way! Image: GR2Analyst

12:36 super-resolution radar image from the NWS radar site in Early Branch, SC. Showers on the way! Image: GR2Analyst

Expect the onset of rain in the Charleston area around 2am or so based on current radar trends. About a quarter of an inch of rain is expected through Saturday morning. Rain will be gone by 10am with clearing to follow — we’ll salvage a decent afternoon with temperatures in the low 60s and plenty of sun. Wind advisories are up for the Tri-County area along with the risk of gales in the coastal waters — gusts upward of 35-40 MPH may complicate ice storm recovery efforts in Berkeley & Dorchester counties.

4.1 earthquake near Edgefield, SC this evening

Many felt a shallow 4.1 magnitude earthquake about 7 miles from Edgefield, SC around 10:23 PM. Reports of the quake have been felt as far south as Claxton, GA and Hilton Head Island according to the National Weather Service and USGS:

Reports of shaking associated with the 4.1 earthquake near Edgefield as received by USGS as of midnight Feb 15.

Reports of shaking associated with the 4.1 earthquake near Edgefield as received by USGS as of midnight Feb 15. Click the image for the latest reports.

While I did not personally feel the quake, many of you stepped up immediately to make a report. The first report I got was from St. George:

Then the reports rolled in from all over:

Fortunately, there are no reports of major damage, though a few pictures have circulated of cracks in floors and drywall in the Upstate. Rumors that the quake damaged a water tower in Augusta, GA are inaccurate as the water tower was conducting a scheduled release from its overflow valve:

We are no strangers to earthquakes here in Charleston with the Summerville fault kicking off occasional tremors (this is the 13th earthquake in the past year for SC). However, quakes centered in the central Savannah River area (CSRA for short) are exceedingly rare:

To learn more about the Charleston area’s earthquake history, I highly recommend scearthquakes.com, which has a lot of information about the catastrophic 1886 quake and the seismic zone near Summerville. The USGS has also compiled many useful links about SC earthquakes as well.

If you felt tonight’s quake, please take a moment and report it to USGS — this helps their data collection immensely, especially in an area that doesn’t feel a lot of quakes.

Black ice a concern tonight; “Ravalanche” continues

There’s a chance that we may encounter some black ice in the area tonight, especially the further inland you go. Temperatures are expected to drop right around freezing for several hours tonight, so any wet spots on the roads could re-freeze (especially on bridges and overpasses). I don’t believe this will be as major of an issue for folks near downtown or on the barrier islands (aside from untreated overpasses).

Tomorrow morning’s commute will be hamstrung at least for a short time as the Ravenel Bridge will go into an unprecedented third day of closure. SCDOT will reassess in the morning according to a Mt. Pleasant Town Council member:

Any lingering ice on the bridge should melt away fairly quickly by afternoon. Temperatures will rebound quickly tomorrow and we’ll end up well into the 50s with quite a bit of sun — heat wave! This will help the situation well inland where ice may still be found on some surfaces. Friday night into Saturday morning is looking a little rainy but we should salvage a decent Saturday afternoon. Sunday looks excellent.

Ice storm tapering off; only uphill from here

Regional radar composite (winter-masked) with surface pressure analysis (via RAP model) and temperature observations valid 7:10 AM.

Regional radar composite (winter-masked) with surface pressure analysis (via RAP model) and temperature observations valid 7:10 AM.

The risk for precipitation continues to taper off as a surface low is moving quickly up the Eastern Seaboard this morning, taking the deepest moisture with it. At the same time, an upper-level trough of low pressure is pushing eastward; this feature may stir up a little extra precipitation over the area through early afternoon.

Temperatures are holding above freezing at the stations that are reporting and it appears additional ice was less of an issue than first feared overnight. However, the Ice Storm Warning was extended until noon for inland Berkeley and Dorchester counties due to the continued risk of falling ice and tree limbs; similarly, the Ice Storm Warning continues until 10am closer to the coast for the risk of falling ice. The Ravenel Bridge is still closed; ice has been observed falling off the cables.

After the upper-level system clears out, clouds will thin and we should actually see a little sun and perhaps lower 40s.