Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 829

May 18, 20126 counties in Florida

The Storm Prediction Center issued this mesoscale discussion at May 18, 2012, 1:03 PM EDT for 6 counties in Florida. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued
May 18, 2012, 1:03 PM EDT (17:03 UTC)
Expired
May 18, 2012, 2:30 PM EDT
In force
87 min
Issued by
the Storm Prediction Center
Chance of a watch
20%

Counties Broward County, FL, Collier County, FL, Hendry County, FL, Miami-Dade County, FL, Monroe County, FL, Palm Beach County, FL

The radar

The Miami radar (KAMX), 85 km from the middle of the area, began a volume at 17:05 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Miami, FL (KMFL), launched 12:00Z, 5.1 hours before the alert went out and 79 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Miami, FL at 12:00Z on 2012-05-18Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1355 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Miami, FL at 12:00Z on 2012-05-18The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 16 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1355 J/kg
Mixed-layer CIN
0 J/kg
Mixed-layer LCL
572 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
16 m²/s²
0-3 km storm-relative helicity
71 m²/s²
Significant tornado parameter
0.1
Supercell composite
0.5

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

086 
ACUS11 KWNS 181703
SWOMCD
SPC MCD 181703 
FLZ000-181830-

MESOSCALE DISCUSSION 0829
NWS STORM PREDICTION CENTER NORMAN OK
1203 PM CDT FRI MAY 18 2012

AREAS AFFECTED...S FL

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 181703Z - 181830Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...ISOLATED SVR THUNDERSTORMS ARE POSSIBLE ACROSS S FL THIS
AFTERNOON. WW DOES NOT APPEAR NECESSARY ATTM.

DISCUSSION...MID-DAY SURFACE OBSERVATIONS SHOW TEMPERATURES WARMING
INTO THE 80S ACROSS S FL. THIS HEATING IS AIDING IN STRENGTHENING
LOW-LEVEL CONVERGENCE AND BOUNDARY LAYER DESTABILIZATION. AS A
RESULT...VIS SATELLITE IMAGERY SHOWS DEEPENING CUMULUS...WHICH
SHOULD LEAD TO SCATTERED THUNDERSTORM DEVELOPMENT DURING THE NEXT
FEW HRS. MODIFIED 12Z MFL RAOB FOR A SURFACE TEMPERATURE IN THE
MID/UPR 80S AND DEWPOINT IN THE LOW 70S YIELDS MLCAPE VALUES NEAR
2500 J/KG. THE STRONG BUOYANCY COMBINED WITH VEERING WIND PROFILES
CHARACTERIZED BY WEAK SPEEDS /PER AMX VWP/ WILL SUPPORT MULTICELL
THUNDERSTORM CLUSTERS POSING A THREAT FOR ISOLATED DAMAGING WIND
GUSTS AND PERHAPS MARGINALLY SVR HAIL.

..GARNER/WEISS.. 05/18/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MFL...KEY...

LAT...LON   26618141 26808081 26738000 25298035 25208114 26098165
            26618141

Nearby

Mesoscale Discussions in Florida, 2012Every mesoscale discussion in 2012

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.