Tagged: coastal flooding RSS

  • Jared Smith 10:40 am on December 2, 2009 Permalink
    Tags: coastal flooding, , ,   

    As messy as advertised, with the brunt yet to come 

    The flooding situation has been as messy as advertised this morning. NWS just reported that the high tide at Charleston Harbor this morning was 7.75 feet — well beyond the point where coastal flooding begins even without rain (typically 7 feet).

    Traffic into downtown Charleston is nearly impossible. The Crosstown is closed and it’s not likely to reopen for a little while. Stalled cars litter the streets-turned-rivers downtown. Josh Marthers at WCBD captures the flooding situation well. I also highly recommend watching traffic tweets and pictures (and there are some good ones) on Collecta.

    And as bad as this morning was, we haven’t seen the worst of it. This morning’s Day 1 Convective Outlook from the Storm Prediction Center continues the “slight risk” for severe weather in Charleston, and this could be upgraded to a “moderate risk” later today, especially if any sunshine peeks through and adds more fuel to the fire. The storm system which is expected to wreak havoc on us later this evening has already dropped several tornadoes in the Florida panhandle, and there is a good possibility we may see at least one or two tornadic cells later today in the Lowcountry. Straight-line damaging winds continue to be the primary threat from this system, though.

    There’s a good shot that we’ll have a tornado watch in effect by 3PM today. Keep an eye to Twitter as the day progresses with updates from NWS and SPC. We’ll announce watches and warnings there as they happen.

     

    • Jared Smith 1:36 pm on December 2, 2009 Permalink

      Not much has changed with the new Day 1 Outlook. Charleston is still listed as having an elevated risk of tornadoes and damaging winds. In the latest Hazardous Weather Outlook, NWS Charleston called this afternoon’s severe weather threat a “potentially dangerous situation” — something NWS does not say lightly. Here’s hoping for the best, but it does look like the ingredients are going to come together for a very rough late afternoon and evening. Some clearing was observed in Georgia — let’s just hope that doesn’t happen here.

    • Jared Smith 3:15 pm on December 2, 2009 Permalink

      Tornado Watch now in effect for a great deal of SC, including Charleston and surrounding areas, until 9 PM. More information forthcoming.

  • Jared Smith 2:17 am on December 2, 2009 Permalink
    Tags: coastal flooding, day 1, ,   

    Wednesday: Slight risk of severe weather, high probability of damaging winds 

    The Storm Prediction Center has just issued its Day 1 Convective Outlook, placing the Charleston area in a slight risk for severe weather. Currently, forecasters are pegging the severe event to take place in the late afternoon and into the evening hours. Primary threats are widespread damaging winds as well as the possibility of tornadoes, especially along the coastal regions.

    Currently, this is the thinking (or something like it) on Wednesday’s event:

    • 3AM – midday: Heavy rain with embedded thunderstorms associated with a warm front will soak the Lowcountry. The timing of the rain will line up with an already abnormally high tide at 7am. Enhanced with a brisk onshore flow, coastal areas including downtown Charleston could see potentially significant flooding. A Coastal Flood Warning goes into effect at 4am through 11am.
    • Midday – ~2-3 PM: Break in the action as the warm front lifts north, but before the cold front’s squall line reaches the coast. There’s a possibility that the sun may come out during this time; any sunshine could significantly destabilize the atmosphere further and thus enhance the intensity of severe weather.
    • 3 PM – Evening: Cold front makes its move on the Lowcountry. Squally thunderstorms with strong, damaging wind likely. Supercells also are a possibility; those storms can contain downbursts and tornadoes. Heavy rain also is expected, though the flood threat is not expected to be as pronounced in the evening. Activity will likely continue after sunset; be especially aware of rapidly changing conditions after dark because it will be much harder to see what’s happening.
    • Thursday: Conditions gradually abate themselves as the front moves through; rain tapers off through Thursday.

    The takeaway: The morning and afternoon commutes will likely be quite nasty. Allow extra time during your commute, and if you encounter a flooded area downtown in the morning, turn around! It takes relatively little water to stall out a vehicle. Streets such as Rutledge and Ashley Avenues, Jonathan Lucas, Bee Street, the Crosstown, East Bay Street, Market Street, and others could prove impassable. Have alternate routes ready to go. Other coastal communities, including Folly Beach and Isle of Palms, may also see significant flooding problems in the morning.

    Keep an eye here or to @chswx for updates throughout the day.

     

  • Jared Smith 11:18 am on December 1, 2009 Permalink
    Tags: coastal flooding,   

    Coastal flooding possible tomorrow AM; “widespread severe event” possible afterward 

    We’re watching with great interest a fairly good possibility for a widespread severe weather event Wednesday. A very strong low pressure system is coming together in the Gulf of Mexico and will push eastward during today and tomorrow. We’ll start feeling the effects of this low late tonight in Charleston, as strong onshore winds will begin to kick up the coastal waters, causing beach erosion and coastal flooding. NWS has the Charleston coast under a Coastal Flood Watch from late tonight through Wednesday morning, as it’s expected that heavy rain and wind will impact the area right at the time of high tide. Tides up to 7.8′ are currently expected in Charleston Harbor. This is a prime setup for a fairly significant downtown flooding event right at rush hour, as high tide is at 7:30am.

    Later Wednesday, this storm system will bring along with it a favorable setup for severe weather — a bit unusual for December, but certainly not unprecedented. The entire SC coastal area is in a “slight risk” of severe weather for Wednesday. Damaging winds, hail, and tornadoes cannot be ruled out. Plan accordingly for your Wednesday if you are traveling. We’ll keep an eye on things and update as the forecast becomes more clear.

     

    • Jared Smith 2:32 pm on December 1, 2009 Permalink

      From the latest area forecast discussion — things are looking ripe for a rough day:

      INGREDIENTS APPEAR TO BE COMING TOGETHER FOR A POTENTIALLY
      SIGNIFICANT SEVERE WEATHER EVENT. IF THE MODELS ARE CORRECT WITH
      THE TEMPERATURE AND BOUNDARY LAYER MOISTURE EVOLUTION…SURFACE
      BASED INSTABILITY OF AROUND 400-900 J/KG OF CAPE AND LI/S OF -2 TO
      -4C ACROSS THE ENTIRE FORECAST AREA…WITH NO CONVECTIVE INHIBITION
      WILL BE REALIZED. THIS COMBINED WITH STRONG MID-LEVEL QG FORCING…
      ENTRANCE REGION FORCING FROM A 130+ KT UPPER JET… MID- LEVEL
      LAPSE RATES STEEPENING TO BETWEEN 6.5 AND 7.0 C/KM ALONG WITH 0-6
      KM BULK SHEAR VALUES OF 65 TO 75 KT…WILL BE SUPPORTIVE OF
      ORGANIZED LINEAR CONVECTION WITH OCCASIONAL SUPERCELL STRUCTURES.
      WITH 850MB WINDS INCREASING TO AROUND 70 KT PROGGED BY BOTH THE GFS
      AND NAM…ENERGY HELICITY INDICES CLIMBING TO AROUND 1…AND 0-1
      KM HELICITY VALUES MAXING OUT IN THE 400-500 M2/S2…DAMAGING
      STRAIGHT LINE WINDS AND TORNADOES APPEAR TO BE THE PRIMARY SEVERE
      WEATHER THREATS WITH MARGINALLY SEVERE HAIL POSSIBLE AS WELL. THE
      SPC CONTINUES TO SHOW A SLIGHT RISK FOR THE REGION WEDNESDAY WITH
      30 PERCENT PROBABILITIES OF DAMAGING WINDS AND A LARGE HATCHED
      AREA FOR SIGNIFICANT SEVERE WEATHER ALONG MUCH OF COASTAL SOUTH
      CAROLINA AND GEORGIA. THE POTENTIAL IS CERTAINLY THERE FOR A FEW
      STRONG…LONG TRACK TORNADOES. WILL CONTINUE TO MENTION SEVERE
      WORDING IN THE ZONES AND FORECAST GRIDS FOR THE ENTIRE FORECAST
      AREA.

c
compose new post
j
next post/next comment
k
previous post/previous comment
r
reply
e
edit
o
show/hide comments
t
go to top
l
go to login
h
show/hide help
esc
cancel