South Carolina, one of 3 small areas under a slight risk of

[Stormsfury]

Severe thunderstorms today ... this morning, a pulse strong cell developed around 7:30 am and moved just south of Savannah, GA (McIntosh County) and showed the volitity of the atmosphere in the immediate area ... the sea breeze should help enhance convection today and has already developed numerous towers in my area at this early hour.

...CAROLINAS/TN VALLEY...

SATELLITE IMAGERY SUGGESTS STRONG DIURNAL HEATING WILL OCCUR FROM
ERN GA ACROSS COASTAL CAROLINAS WHERE BOUNDARY LAYER CONTINUES TO
SLOWLY MOISTEN. SBCAPES SHOULD EXCEED 2000 J/KG BENEATH MODERATE
MID-UPPER LEVEL FLOW WITH DEEP LAYER SHEAR ON THE ORDER OF 30KT BY
MID DAY. IT APPEARS THUNDERSTORMS MAY DEVELOP ALONG SEA BREEZE
EARLY IN PERIOD WITH INLAND FOCUS FOR CONVECTION BY MID DAY. LARGE
HAIL AND DAMAGING WINDS ARE POSSIBLE WITH MORE ORGANIZED ACTIVITY.

UPSTREAM ACROSS MS AND AL...CONSIDERABLE MID LEVEL CLOUDINESS IS
SPREADING EWD AHEAD OF WEAK UPPER SHORTWAVE TROUGH OVER THE CENTRAL
GULF COAST REGION. THIS WILL IMPEDE SFC HEATING AND RESULT IN ONLY
MARGINAL LOW-MID LEVEL LAPSE RATES...LIKELY ON THE ORDER OF 6-
6.5C/KM. IN THE ABSENCE OF STRONG FORCING AND ONLY MARGINAL
INSTABILITY IT APPEARS THE PROBABILITY FOR ORGANIZED SEVERE
THUNDERSTORMS IS LOW.

[Stormsfury]

I can attest to this, we had one doozy of a cell strike about 30 minutes ago. Incredible rainfalls, and lightning, along with hail the size of quarters.

BTW, here ... (I wasn't here ... thank goodness for the rain gauge) .. 1.55" in just 30 minutes.

...CAROLINAS...

STORMS HAVE ALREADY DEVELOPED ASSOCIATED WITH SEA BREEZE BOUNDARY
ALONG COASTAL AREAS. AIR MASS IS VERY UNSTABLE ACROSS CENTRAL AND
EASTERN SC AHEAD OF WEAK COLD FRONT DEVELOPING ALONG THE LEE SIDE
OF THE MOUNTAINS. DEEP SHEAR IS FORECAST TO INCREASE TO 40 KT
ACROSS THE CAROLINAS ENHANCING THE SEVERE POTENTIAL. MAIN THREATS
WITH THIS ACTIVITY WILL ALSO BE HAIL AND DAMAGING WINDS.

[therock1811]

Storms:
See my latest outlook for details.
Therock1811

[Stormsfury]

Winds weren't a big deal as the supporting updrafts didn't rapidly collapse upon itself ATT ... however, during the early afternoon, hail is ... which I can attest to, since I ran into 1" diameter hail earlier ...

However, later today, as the stronger cells may organize into bows and segments, damaging winds are possible ...

The maps look like about what SPC has as well ... ... works for me.

[Stormsfury]

Thundering again off towards my southwest as more storms slowly creep towards the northeast (and random directions due to light steering currents and other steering factors from seabreeze/outflow boundaries).

The ones that came through earlier have already weakened and dissipated.


http://weather.noaa.gov/radar/loop/DS.p ... kclx.shtml

[therock1811]

Looks like 12Z Cape there was 1989.23. This is in the "large" range. Also your SWEAT index was 176.84. That as I said in my outlook puts you in the slight risk category. But the K was only 17.60, so there is a slight potential for t-storms in general. LI was -4.55 & the LIFT computed using virtual temperature was at -5.33, meaning there is definitely some instability in the Charleston area.
Jeremy

[Stormsfury]

Very good analysis, Jeremy.

Right now, those storms have a very nice mammatus shield overspreading my area right now...unfortunately, I have no AAA batteries to take pictures of it with ... those storms are growing based on radar observations.

On SPC's make your own Composite Maps (RUC Model forecasts)
UVV at the 700-500mb level are running -9.
Best Cape is just offshore of CHS with 3000 j/kg, but the entire area is under 2000 j/kg ... suggesting quite unstable ...

With the earlier storm, the air here stabilized, as least temporarily ...
Right now, the storm is still hanging back to my west and south.

[ColdFront77]

I am aware of the CAPE, SWEAT Index, K-Index and the Lift Index... but these specific numbers are coming from some source that seem worth looking into.

I use one particular site, but the maps on it haven't working correctly for a particular severe weather parameter.

[therock1811]

Thanks, I'm learning. I would guess that before too long those 3000 j/kg might move onshore. Also the Jacksonville, FL area appears to be in a position for a slamming later this afternoon. CAPE there is around 1963.8 as of 12Z.

[ColdFront77]

The chance of rain for the Jacksonville area is only 20 percent this afternoon. I didn't think high CAPE's meant a good chance of thunderstorms every time.

[therock1811]

No but then with values that high there's a potential. I'll see what I can dig up.

[therock1811]

SWEAT index is 212.16, K index is 29.90 and the LI is between -4.64 and -5.36. All signs seem to point to development this afternoon.

[Stormsfury]

CAPE stands for Convective Available Potential Energy or just a measure of the stability of the atmosphere.

http://twister.sbs.ohio-state.edu/helpdocs/cape.html

[ColdFront77]

Yes, fun.


Jacksonville, Florida (3 hour RUC):

Lifted Index: -3.81 C Risk: Severe thunderstorms possible
Lifted Index @300 mb: -3.94 C
Lifted Index @700 mb: -0.40 C
Showalter Index: -0.59 C Risk: Thunderstorms probable
Total Totals Index: 47.47 C Risk: Scattered moderate thunderstorms
Vertical Totals Index: 25.19 C
Cross Totals Index: 22.28 C
K Index: 17.20 Risk: < 20 % chance of thunderstorms
Sweat Index: 204.38 Risk: None
Energy Index: -2.42 Risk: Severe Thunderstorms probable

[Stormsfury]

Severe Thunderstorm Warning in Dorchester County until 5:00 pm...

Doppler Radar indicated a severe thunderstorm capable of producing hail and damaging winds 3 miles east of St. George, SC, moving NE at 20 mph...Large hail was reported in St. George (near Pro-Storm's area)...

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHARLESTON, SC
430 PM EDT SUN MAY 25 2003

TIME(EDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....

0425 PM SAINT GEORGE SC .75 INCH HAIL
05/25/03 DORCHESTER HAIL REPORTED ON HIGHWAY
15.REPORTED BY LAW
ENFORCEMENT

Previous Storm earlier this afternoon

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE CHARLESTON, SC
405 PM EDT SUN MAY 25 2003

TIME(EDT) .....CITY LOCATION.....STATE ...EVENT/REMARKS...
....COUNTY LOCATION....

0230 PM NORTH CHARLESTON SC WIND DAMAGE
05/25/03 CHARLESTON SEVERAL TREES DOWN NEAR
INTERSECTION OF ASHLEY
PHOSPHATE AND FRONTAGE
ROAD. REPORTED BY LOCAL TV
STATION.