Category Archives: Winter Weather

One more night of ice ahead

11:23 PM super-resolution radar reflectivity depicting periods of heavy rain -- likely freezing rain -- approaching the Lowcountry.

11:23 PM super-resolution radar reflectivity depicting periods of heavy rain — likely freezing rain — approaching the Lowcountry.

We’ll be through this winter storm soon enough, but we have one more round of potential freezing rain to contend with. The precipitation is crossing the Savannah River and adding to Augusta’s icing woes. Expect this precipitation to arrive in the next couple hours.

Elevated instability may allow for thunder to be heard — cloud-to-ground lightning strikes have been recorded for several hours in central Georgia in association with this batch of rain.

Low pressure will begin to move up the coast early Thursday morning; the resulting wind shift will bring the freezing line back toward the east. Between refreezing of any existing melt and any additional freezing rain, we could see additional ice accretion of up to .25″ in the inland counties that have absolutely been clobbered today. A trace of ice could be recorded almost to downtown Charleston; the peninsula itself should stay above freezing tonight, though.

The Ravenel Bridge is still closed, and may remain so for a little while into Thursday. (I have no inside information about bridge closings — I learn when the police announce it.) From what I’ve seen, long-term power outages are still very problematic in Dorchester and inland Berkeley counties — any additional ice accumulation won’t do much good for the linemen working their butts off to get power restored.

The good news is that things will begin to improve by the afternoon. Rain will leave and we’ll get warmer — 40s will feel like a heat wave comparatively. Temperatures will continue to rise into the weekend. Hang in there!

What’s changed since you went to sleep

5:30 AM winter radar mosaic and temperatures across the Southeast. Winter mask may not be exact. Use with caution.

5:30 AM winter radar mosaic and temperatures across the Southeast. Winter mask may not be exact. Use with caution.

There have been several key changes in the forecast this morning you’ll need to be aware of.

  • Ice Storm Warning extended to Charleston County and southern Berkeley County. Confidence is increasing that up to .25″ of ice will accumulate in inland portions of Charleston County, with a trace of ice expected downtown. Ice has closed the Ravenel, Limehouse, and Stono bridges as of 6am. Other bridges remain open but treat any bridge or overpass with extreme caution, especially if they are not treated.
  • There are numerous closings. The Citadel, College of Charleston, Trident Tech, and Charleston County Schools have all announced closures for today. The City of Charleston is on a delay until 10am as of right now.
  • Sub-freezing temperatures possible all day inland. We should head above freezing for several hours closer to the coast which will help melt things away — however, the freezing line will again push east so another period of freezing rain will be possible later tonight.

Continue to monitor local media for additional updates on closings. I’ll also be very interested to hear your reports!

Freezing rain advisory for coastal counties, Ice Storm Warning inland

The storm is on: Freezing rain advisories are up along the coast of the Lowcountry, with Ice Storm Warnings inland.

One round of precipitation — all liquid for us in the Tri-County — has departed. This first round dumped several inches of snow in eastern North Carolina. With winds coming out of the northeast and off of that snow-covered ground, there are some indications that perhaps things could get a little colder to the south and east than first thought. It’s a trend to watch carefully overnight.

The second wave of precipitation has arrived in Georgia. It, too, is falling as rain right now as the freezing line continues its southward march. This, too, will change over the next few hours as a crippling ice storm is forecast from Atlanta to Columbia with icing being felt perhaps as far north as Charlotte and Raleigh and as far east as Charleston.

We’ll certainly be dealing with very troublesome ice accretion in the northern sections of Dorchester and Berkeley counties, where ice accumulations could reach or even exceed .75″! Ice storm preparations should be complete in these areas at this point as the onset of precipitation will arrive around 4am. This could be a very disruptive event even in inland Berkeley and Dorchester with potential for power outages and tree damage. Here is the latest map from the NWS:

Ice accumulation forecast from the National Weather Service in Charleston, SC as of 10 PM February 11, 2014. Subject to change.

Ice accumulation forecast from the National Weather Service in Charleston, SC as of 10 PM February 11, 2014. Subject to change.

The forecast is much trickier near the coast, where the southern and eastern extent of the freezing line is still very much up in the air. I’m getting a lot of questions about the bridges tonight — the fact is, I just don’t know if they are going to close or not. Observations from the Don Holt helpfully tweeted by the National Weather Service in Charleston suggest that we could run into some problems, with road surface temperatures getting very close to the freezing mark already:

It behooves everyone to continue to monitor local media for updates from public safety officials and the National Weather Service. I’ll be updating on @chswx on Twitter and here on the blog as needed. You should also consider bookmarking chswx.us, a handy and very fast one-page site with just the essential weather info you need.

Stay tuned folks…looks like a busy day in store…

Evening winter storm forecast update

NWS has issued its evening forecast update — not many changes to write home about at this point:

  • The Ice Storm Warning is still on for inland Berkeley (Goose Creek, Moncks Corner, Jamestown, Lake Moultrie, Bonneau, St. Stephen, Cross) and Dorchester (Summerville, St. George, Ridgeville) counties and will go into effect at midnight Wednesday.
  • The Winter Storm Watch continues for Charleston County as well as portions of Berkeley County near the harbor (including Daniel Island). I suspect that by morning NWS will take action on some sort of upgrade to this watch (probably either to a Freezing Rain Advisory or to an Ice Storm Warning if guidance trends toward increased ice accumulation near the coast).

Here’s the watch/warning/advisory map — pretty busy, even for the coastal waters where we’ll see some hazardous conditions for small craft:

Watches, warnings, and advisories issued by the National Weather Service valid at 10:30 PM. Subject to change!

Watches, warnings, and advisories issued by the National Weather Service valid at 10:30 PM. Subject to change!

The latest guidance suite is coming in and continues to add confidence to the likely scenario being depicted in NWS and other media forecasts:

  • All liquid Tuesday before sundown. That much is pretty much a given. NWS is not discounting the potential for a little sleet mixing in with rain in northern Berkeley County Tuesday morning, but it will just be enough to be conversational at this point and not cause any major problems. People in the Ice Storm Warning should finish preparations for possible power outages and dangerous travel by sundown.
  • Transition to freezing rain complete for much of the Tri-County area by early Wednesday morning. Chances are good that we will escape freezing rain at the coast, along the barrier islands, and probably in downtown Charleston, but everywhere west of US 17 is going to be fair game for at least a little icing Wednesday morning. (My confidence in this scenario for Charleston County is still a little iffy — that freezing line is going to be very tough to pin down!) The current forecast (with plenty of support in guidance) is for any freezing rain to change back to rain in the coastal counties by around noon or so. Unfortunately, freezing rain will almost certainly hang around further inland (where the Ice Storm Warning is placed). It is here — roughly west of US 17-A — where the greatest risk of power outages and dangerous travel will exist.
  • Chance for a return to freezing rain/freezing drizzle late Wednesday into Thursday morning. As the low lifts out of the area, cold air will be drawn back in and we’ll have another chance at some freezing rain/drizzle before the moisture gets out of here by Thursday afternoon.

A few takeaways to be mindful of:

  • In the immediate Charleston metro, this will probably not be as crippling as the ice storm that hit late January. However, the exact details are still uncertain and a degree or two on either side of the current forecast could make big changes to impacts. Stay weather-aware. Charleston is under a Winter Storm Watch for a reason, after all.
  • Summerville/Goose Creek/North Charleston are in decent shape to see a tenth or two of an inch of accumulation, maybe enough for some tree and power line damage.
  • Greatest concern is for places such as Moncks Corner, St. George, Ridgeville, Cross, St. Stephen, Bonneau, and Jamestown (among other locations). The Ice Storm Warning is well-placed here — .25″+ of icing appears likely.

Everyone should continue to monitor the latest NWS forecasts for potential changes to impacts, watches, warnings, and advisories through Thursday!

Ice Storm Warning for inland Berkeley & Dorchester; Winter Storm Watch for Charleston County

Fairly big change with the 3PM update from the National Weather Service. NWS has extended the Winter Storm Watch into Charleston County as well as into southern Berkeley County (including Daniel Island) while upgrading inland Berkeley and Dorchester to an Ice Storm Warning.

Freezing rain chances are on the increase closer to the coast — the latest NWS forecast indicates a period of freezing rain overnight Tuesday into early Wednesday morning as far east as the airport. This could affect areas west of US 17 including West Ashley and Daniel Island as well as interior portions of Mt. Pleasant.

NWS ice accumulation forecast as of 3PM February 10. Subject to change.

NWS ice accumulation forecast as of 3PM February 10. Subject to change.

As it stands right now, it looks like a glaze of ice is in the cards from North Charleston west to Summerville/Goose Creek/Jamestown. West of 17-A, we will get into the more dangerous accumulations up to and exceeding .25″. As for downtown Charleston, Mt. Pleasant, and the barrier islands, NWS still keeps precipitation in liquid, non-freezing form. Let’s hope for the Ravenel’s sake it stays this way.

Preparations for the ice storm should be finished by tomorrow afternoon especially for those well inland. Power outages and dangerous travel will almost certainly be a concern for inland locations.

More updates later today…

Winter Storm Watch for inland counties including inland Berkeley and Dorchester

Overnight, the National Weather Service issued a Winter Storm Watch for much of its inland counties, including inland portions of Berkeley County and Dorchester County within the CHS Tri-County area. See the latest winter storm information from the NWS.

Map: Winter Storm Watches for much of SC including inland portions of the Tri-County area.

Map: Winter Storm Watches for much of SC including inland portions of the Tri-County area.

Here’s the 5am ice accumulation forecast update from the NWS:

5am ice accumulation forecast from the National Weather Service. Subject to much change.

5am ice accumulation forecast from the National Weather Service. Subject to much change.

Significant accumulating ice continues to be forecast especially west/NW of the US 17-A corridor in the Tri-County. This includes places like St. George, Moncks Corner, Jamestown, and Ridgeville. Places such as Summerville, Goose Creek, Huger should also stay on guard as those areas are right on the bubble.

Coastal communities, while not under a Winter Storm Watch as of this post, should monitor the system carefully. An eastward jog in the storm’s track could pull colder air closer to the coast increasing the freezing rain risk further east (a signal I have seen in the GFS model but not one the other models have really bit on). We’ll only be a few degrees north of 32 even toward the coast overnight Tuesday, so it’s something to watch.

Continue to monitor reliable weather sources as this storm approaches…

Winter storm could affect inland Tri-County Tuesday night into Wednesday

It’s increasingly looking like inland parts of the Tri-County — NOT the coastal communities — are facing another bout with accumulating ice Tuesday night into Wednesday. Here’s NWS Charleston’s first stab at an icing forecast:

NWS Charleston, SC forecast ice accumulation as of 3PM Feb 7. SUBJECT TO CHANGE!

NWS Charleston, SC forecast ice accumulation as of 3PM Feb 7. SUBJECT TO CHANGE! This map will not update automatically — the latest map can always be found here.

As it stands right now, the greatest icing threat will exist along and inland of a Walterboro-Summerville-Moncks Corner-Jamestown line. This is most certainly subject to change and could press further toward the coast as the details get fine-tuned. One complication is that we’ll be dealing with high pressure “wedging” into the area from the northeast. This causes a phenomenon called “cold air damming” in which cold air sinks between the Atlantic and the Appalachians; warm air often moves over the top of the wedge, causing clouds and precipitation which further cools things off and helps to strengthen the wedge. It is the subject of much hair-pulling for forecasters in the SE. From the NWS forecast discussion this evening:

SINCE MODELS TYPICALLY DO NOT HANDLE THE WEDGE ALL THAT 
WELL...THE POTENTIAL IS EVEN THERE FOR SOME FREEZING RAIN TO OCCUR 
CLOSER TO THE COAST. AT THIS TIME...IT APPEARS VERY POSSIBLE THAT 
OUR FAR INLAND COUNTIES COULD EXPERIENCE UP AROUND .25 INCHES OF 
FREEZING RAIN TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...WITH AMOUNTS 
DROPPING OFF FARTHER SOUTH AND EAST. PRECIPITATION SHOULD REMAIN IN 
THE FORM OF ALL RAIN ALONG THE IMMEDIATE SOUTHEAST SOUTH CAROLINA 
COAST AND ACROSS PORTIONS OF NORTH COASTAL GEORGIA BUT WILL NEED TO 
MONITOR LATER TRENDS CLOSELY.

This forecast is certainly complicated and will get plenty of fine-tuning in the next couple days. Stay tuned into reliable weather sources to make sure you are up to date with all the latest forecast information, especially if you live in Summerville, Moncks Corner, Goose Creek, North Charleston, or anywhere to the west and northwest of those communities as they stand to see the greatest potential impact from any freezing rain that falls.

What’s next?

9:30am radar showing precipitation ending in the Charleston area.

9:30am radar showing precipitation ending in the Charleston area.

Precipitation is coming to an end in the Charleston area after depositing up to 1/4″ of ice in many locations with a dusting of snow and sleet on top. Roads are treacherous with many bridges closed (including the Ravenel) due to icing. Travel is strongly discouraged today!

Now we turn our attention to bitter cold: We won’t get above freezing until later Thursday morning. Tonight is a drip-the-pipes night with temperatures expected to approach 20. Anything that melts today — which won’t be much — will almost certainly refreeze, potentially causing issues with black ice and more especially on secondary roads through Thursday morning. It’s not inconceivable that we could be dealing with residual ice through Friday as temperatures Thursday night are once again expected to drop below freezing.

Take cold weather precautions tonight — drip faucets, have pets indoors. Use extreme caution if heading out today or tomorrow (and try not to head out today if you can help it!)

Winter storm updates

A significant winter storm is affecting the Charleston area tonight with ice the current concern. Sleet will mix back in later before all precipitation turns to snow early Wednesday morning.

The National Weather Service has a Winter Storm Warning up for the entire Charleston area. This warning continues until 5PM Wednesday.

Bottom line: Icing will make travel extremely unsafe tonight. Unless you absolutely must head out, stay indoors until the storm passes.

Ice Storm Warning for Charleston County; Winter Storm Warning for Berkeley & Dorchester

An Ice Storm Warning has been issued for Charleston County, and a Winter Storm Warning has been issued for Berkeley and Dorchester counties. Warnings start at noon Tuesday and run until Wednesday at 5PM.

Ice accumulations everywhere will range from 1/4 – 3/4″ in spots. This will almost certainly cause issues with trees and power lines (not to mention the roads). Charleston County will see much more of a freezing rain event than anything else; we get into the wintry mix further inland, hence the Winter Storm Warning for Berkeley & Dorchester.

Timing per latest NWS forecast: Rain will change to freezing rain over the area after noon tomorrow; freezing rain will continue, heavy at times, overnight into early Wednesday morning. At that point, rain will change over to snow for all areas as the system departs. Snow is to taper off Wednesday, however we could deal with the after-effects for a couple days as ice melts and then refreezes at night.

Refer to local media for updates on closures. Will keep you advised here as more information from the NWS becomes available.