The severe weather threat so far has yet to really materialize. Some strong storms flared earlier in the day, bringing some persistent heavy rain (at times dumping near a half-inch per hour according to radar estimations) across Colleton County into portions of Dorchester County. The storms have been on a weakening trend, though, as the expected instability has not yet yielded any major weather. RADAR indicates some storms packing heavy rain in Georgia, gradually moving NE, but the tornado threat has thankfully not borne itself out. As the sun goes down, so goes the threat for severe thunderstorms. After sunset, we’ll turn our attention to a swath of persistent heavy rain that has slowly been making its way across the Midlands. It will arrive overnight and stick with us through a lot of Tuesday. Thankfully, it’s been dry, which would mitigate any severe flooding, though we can’t rule out troubles downtown tomorrow morning.
Tagged: Severe Weather RSS
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Jared Smith
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Jared Smith
Tornado Watch until 10 PM for inland counties
The inland counties are under a tornado watch until 10 PM as a cold front advances against the seabreeze, creating a shear environment favorable for isolated tornado development in addition to large hail and damaging winds. But don’t take my word for it, here’s NWS in the latest Area Forecast Discussion:
ALREADY SEEING SEVERAL CLUSTERS OF STRONG TO SEVERE TSTMS
DEVELOPING ALONG THE LEDGE EDGE OF THE RAIN SHIELD IN CENTRAL
GEORGIA AS THEY ENCOUNTER THE WESTERN FRINGES OF THE INSTABILITY
AXIS THAT IS IN PLACE ACROSS EASTERN SOUTH CAROLINA INTO SOUTHEAST
GEORGIA. SEVERAL OF THESE CELLS HAVE ALREADY EXHIBITED SUPERCELLULAR
CHARACTERISTICS WITH OCCASIONAL MODEST GATE-TO-GATE SHEAR ZONES
NOTED. ATTM IT APPEARS THE RISK FOR SEVERE WEATHER WILL BE
GREATEST ALONG AND WEST OF A MONCKS CORNER-EARLY BRANCH-
STATESBORO-REIDSVILLE LINE. THE RISK MAY EXTEND FARTHER EAST TO
THE CHARLESTON AND SAVANNAH METRO AREAS DEPENDING ON HOW MESOSCALE
PROCESSES ALIGN LATER THIS EVENING…BUT THE INCOMING MARINE LAYER
IN THE WAKE OF THE SEA BREEZE SHOULD HELP SUPPRESS STRONG
CONVECTIVE UPDRAFTS FROM FORMING. WILL CONTINUE TO HIGHLIGHT LARGE
HAIL AND DAMAGING WINDS IN THE GRIDS AND TEXT PRODUCTS THIS
EVENING AWAY FROM THE COAST. WILL ALSO MENTION RAIN MAY BE HEAVY
AT TIMES AS INCREASING PWATS AND THE POTENTIAL FOR CONVECTIVE
TRAINING COULD LEAD TO SOME LOCALIZED FLOODING PROBLEMS.
FINALLY…THERE WILL ALSO BE A POTENTIAL FOR ISOLATED
TORNADOES…MAINLY WHERE MESOSCALE BOUNDARY INTERACTIONS SUCH AS
THE SEA BREEZE LOCALLY ENHANCE 0-1KM HELICITY VALUES.It’s worth noting that the coastal counties are not under a watch right now — that being said, there is always the possibility of a severe thunderstorm near (but not officially within) the watch area, so everyone in the Charleston metro area should keep an eye out this afternoon. Watch @chswx for any warnings or additional watches throughout the day.
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Jared Smith
Sunday severe threat
The storm system that’s put the Midwest, Alabama, Mississippi, Tennessee, and Kentucky under the severe weather gun over the past two days is pushing toward the coast today. While the atmospheric ingredients are certainly nowhere near what is needed for the widespread tornadic activity to our west, the potential remains for damaging winds, large hail, and perhaps isolated tornadoes over the Lowcountry.
Storms with occasionally heavy rain are trekking across the area this morning. Those will move aside by midday, allowing for a bit of clearing and heating to occur, which could fuel additional thunderstorm activity through this evening. High tide at Charleston Harbor is at 6:48 PM, so any heavy thunderstorms along the coast this evening might also cause some flooding trouble downtown.
Here’s what the Storm Prediction Center has to say:
…CAROLINAS…
AMPLE LOW LEVEL MOISTURE HAS RETURNED TO PARTS OF SC/NC TODAY WITH
DEWPOINTS IN THE MID 60S. WATER VAPOR LOOPS SUGGEST RAPID MID LEVEL
DRYING WILL OVERSPREAD THIS REGION TODAY…BRINGING STRONG HEATING
AND VEERING LOW LEVEL WINDS. SEVERAL MODEL SOLUTIONS SUGGEST THE
POTENTIAL FOR ISOLATED THUNDERSTORM DEVELOPMENT LATE THIS AFTERNOON
OVER EASTERN SC/NC…WITH STORMS TRACKING NORTHEASTWARD TOWARD THE
COAST AFTER DARK. IF THIS SCENARIO OCCURS…THERE WOULD BE A RISK
OF HAIL AND DAMAGING WINDS IN THE STRONGEST CELLS.And from NWS Charleston:
SEVERE THUNDERSTORMS…A STRONG STORM SYSTEM WITH A HISTORY OF
PRODUCING SEVERE WEATHER ACROSS THE SOUTHEASTERN UNITED STATES…
WILL CONTINUE TO MOVE EASTWARD TODAY. THE RISK OF SEVERE WEATHER
IS EXPECTED TO SHIFT INTO SOUTHEAST GEORGIA AND THE EASTERN
CAROLINAS TODAY AHEAD OF A COLD FRONT. WHILE ISOLATED
THUNDERSTORMS WITH LARGE HAIL AND DAMAGING WIND GUSTS ARE POSSIBLE
THROUGH LATE MORNING…THE BETTER CHANCES FOR SEVERE WEATHER WILL
BE FROM AROUND MIDDAY INTO THIS EVENING ACROSS THE REGION. IN
ADDITION TO LARGE HAIL OF 1 INCH OR GREATER AND DAMAGING WIND
GUSTS…THERE IS A POTENTIAL FOR ISOLATED TORNADOES.Follow @chswx on Twitter and you can receive watches, warnings, and other periodic forecasts to your cell phone simply by using Twitter’s built in SMS service. Watch @chswxextra for updates to this blog or additional background information as events unfold.
Of course, the most reliable source of weather information and warnings is a NOAA Weather Radio. You can pick these up at most grocery stores, RadioShack, etc. Ensure that your alarm is set to the “on” position so you can be immediately alerted to any severe thunderstorm or tornado warnings that may be issued.
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Jared Smith
Welcome to Spring: Slight risk of severe weather today
The Storm Prediction Center has the area in a slight risk for severe weather this afternoon. Dewpoints are headed well into the 60s across the area, and we’ve gotten more sunshine than first anticipated today, which will aid convection throughout the area. Current timing shows that the bulk of the activity is expected around and after midnight; an overnight severe threat currently cannot be ruled out and must be watched closely.
I’m currently seeing some isolated moderate showers move quickly northward over Moncks Corner, Lake Moultrie, and surrounding areas. A line of storms has kicked up in Georgia and is about to cross 95 into southern SC (Colleton, Beaufort, and Jasper counties). There’s also a cluster of thunderstorms moving eastward that might bring some rain/thunder to Summerville and North Charleston if it keeps it together.
Look for increasing winds tonight as high pressure is forced out by the cold front causing all this fun. A strong onshore flow is expected which may push tides near the 7′ mark, which is the threshold for shallow coastal flooding in beach communities and downtown Charleston.
Running conversation about today’s potential for rough storms is happening on Twitter at @chswxextra. Watch for any severe weather watches and warnings, as well as periodic conditions updates, on @chswx on Twitter and @chswx on Identi.ca.
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Jared Smith
Tough commute possible this afternoon
Heavy rain and thunderstorms — a few of which could reach severe limits — are a possibility this afternoon as a storm system pushes its way east through the area. While the best severe potential remains south of here (think Beaufort), there’s still a shot of some heavy rumbling up in Charleston. We’re not included in a watch or convective outlook yet, though that could change as the day rolls on.
Another concern is flooding. Localized totals of 3″ are forecasted. Right now, expect the heavier rains to start around noon and pick up throughout the afternoon. As with any heavy rain event, street flooding in the usual spots downtown cannot be ruled out, but a widespread flooding event is probably not so much in the cards, as tides will be receding throughout the afternoon. High tide is at 11:20 AM, followed by low tide at 5:46 PM.
Continue to watch this thread and @chswx for updates throughout the day.
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Jared Smith
Thanks to the steady rain, severe weather won’t be a worry this afternoon. The rain has been heavy at times, but rainfall totals haven’t been anything to write home about just yet. Still watching for a chance at some local flooding — particularly in the coastal areas — but the tide situation is on our side with that. Be careful if you have to travel today, as the rain and occasionally blustery wind will make things a bit difficult, particularly on the bridges.
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Jared Smith
Tornado Watch 803 CANCELLED as line of storms weakens
Tornado Watch 803 has been canceled as the energy needed to kick off additional severe weather has waned considerably; this is evident in the precipitation signature of the squall line pushing eastward. We may see rain with gusty winds — and you can never rule out a clap of thunder — but things have calmed considerably. The rain will be out of here by midday; enjoy one last day in the 70s before the temperatures plunge on Thursday.
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Jared Smith
Tornado Watch 803 until 10am; line of storms incoming
Look out for a rough morning ahead: The Storm Prediction Center issued Tornado Watch 803 around 6am out ahead of a very strong squall line that’s rifling through the Southeast. This line has a history of damaging winds and tornadoes cannot be ruled out. (Watch Wunderground radar in motion.) Additionally, the sun is starting to peek, which may add some instability before the line arrives.
As of this writing, it appears the line will start to be felt in the northwestern portions of Berkeley and Dorchester counties around 8:30am; it will spread quickly through the area shortly thereafter. The line is moving at speeds up to 55 MPH, so this will be a short-term event. Things should be clearing after 10am, when the Tornado Watch expires.
Watch @chswx on Twitter for the latest statements and any warnings that are issued.
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Jared Smith
Been watching RADAR. Heavy rain being reported in some areas but not seeing any thunderstorm reports within the line, which has not looked as impressive in the last hour. Wind fields and storm motions are still impressive, though, and anything that flares up has a shot at producing damaging winds (though the only warnings right now are in NE SC).
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Jared Smith
A weakening trend within the line is continuing. Precipitation is falling off noticeably, particularly over the portions of the Midlands and the inland Lowcountry that are still in the line. Still some stronger storms in Georgia that might hold up, but the trend is positive in terms of our severe weather threat. That being said, the watch continues — there’s still decent juice in the atmosphere — 64 degree dewpoints, for starters — that could still flare a storm.
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Jared Smith
This watch is now canceled. The weakening trend is enough for NWS to declare the severe weather threat moot. Still will see gusty winds but it looks like the major severe threat has ended.
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Jared Smith
Tornado watch canceled; threat ends
The Tornado Watch which has been with us for most of the afternoon — and stuck around a little longer than anticipated — has finally been dropped for the area.
We were very fortunate that the severe weather outbreak that had been predicted for this afternoon did not play out. One major factor was the lack of sunshine — because the clouds hung around, this kept a lid on the most explosive convection. Another factor was timing; storms did not begin to reintensify until they were largely offshore. We did notice the squall line falter and then pick up just before it pushed offshore, prompting a fairly long period where the Charleston area was warned for severe weather. After pushing offshore, very distinct rotations in the cells developed and are now moving ashore in the Grand Strand and into southeast North Carolina.
Flooding still persists throughout the region. Downtown streets, which have been turned to rivers twice in 12 hours, will need some time to clear out — the lowering tides will help. There’s also reports of standing water in Goose Creek, Moncks Corner, and North Charleston. If you encounter standing water, please do not attempt to cross — it’s hard to judge the depth of water during the day, and it’s nearly impossible at night.
Winds will remain strong through midday Thursday on the lakes; a Lake Wind Advisory continues for Lake Moultrie until noon. Small craft are also urged to use caution during the day Thursday. Gale warnings are still up until 5am for waters out 20 nm.
Here’s looking toward a much calmer and drier Thursday. We might see some rain peek back into the forecast Friday night; still tough to pin that one down, though.
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Jared Smith
Tornado Watch extended to 11 PM
NWS has extended Tornado Watch 789, previously scheduled to expire at 9 PM, to 11 PM. The main line of storms is about through Charleston now, but there seems to be some activity kicking up behind it — better safe than sorry. After these last few rounds of activity clear, I suspect the watch will be dropped, especially as the highest probability of tornadic activity has moved northeast into the Grand Strand and eastern North Carolina. Will continue to watch…
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Jared Smith
Tornado Watch 789 until 9 PM
It’s official, and about an hour before I thought: the Charleston area — and indeed, all of eastern SC — is now under a tornado watch. Primary threats cited in the watch discussion include damaging winds in excess of 70 MPH, half-inch sized hail, frequent and dangerous lightning, and of course tornadoes. The discussion in full:
Tornadoes…hail to 0.5 inch in diameter…thunderstorm wind
gusts to 70 mph…and dangerous lightning are possible in these
areas.The Tornado Watch area is approximately along and 80 statute
miles either side of a line from 55 miles west southwest of
Savannah Georgia to 45 miles east northeast of Orangeburg South
Carolina. For a complete depiction of the watch see the
associated watch outline update (wous64 kwns wou9).Remember…a Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.Other watch information…continue…ww 788…
Discussion…a mesolow/MCV in central GA will track newd along a
retreating warm front into central SC through the afternoon…and
ongoing pre-frontal storms will continue to spread newd over se GA
into srn SC. The moist and weakly unstable warm sector will surge
nwd across SC in advance of the low…while low-mid level vertical
shear will remain quite favorable for embedded supercells capable of
producing a few tornadoes and damaging winds.Storms in southern Georgia have been kicking up a lot of lightning this afternoon, and as I write this, there are two active tornado warnings there. This is definitely something to watch closely as the afternoon progresses and we get into that rush hour time.
For the record, the time of next high tide is around 7:30. That is expected to be a lower high tide, forecasted at 5.15 feet; however, any rapid rainfall on top of an already soaked Downtown could once again put streets underwater this evening. RADAR is not estimating the same rainfall rates out of the Georgia storms as we saw this morning; however, anything above half an inch per hour could prove problematic for an already overwhelmed drainage system.
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Jared Smith
New AFD, just released a few minutes ago:
WITH THE IMPRESSIVE DYNAMIC FORCING AND INCREASINGLY
FAVORABLE THERMODYNAMIC ENVIRONMENT SETTING UP OVER THE FORECAST
AREA…EXPECT AN ACTIVE EVENING WITH THE POTENTIAL FOR SIGNIFICANT
STRAIGHT LINE DAMAGING WINDS IN EXCESS OF 75 MPH AND STRONG LONG
TRACKED TORNADOES OF EF2 STRENGTH OR GREATER.Rain is going to start again shortly in Dorchester County, sliding up the coast and eastward. Going to begin to get very rough here in the next hour or so.
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Jared Smith 7:15 pm on April 25, 2010 Permalink
Looks like the chance of widespread severe weather is diminishing. We’re still not completely out of the woods yet but things are looking better. From the latest AFD:
A mesoscale discussion from around 6:30 indicated a watch coming soon along the SC coast; however, that’s yet to materialize. The threat may become so isolated that a watch issuance becomes unnecessary. (Fingers crossed there!)