Alert archive / Florida / Mesoscale Discussions in 2012
Mesoscale Discussion 1817
The Storm Prediction Center issued this mesoscale discussion at Aug 26, 2012, 10:44 PM EDT for 10 counties in Florida. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 26, 2012, 10:44 PM EDT (02:44 UTC)
- Expired
- Aug 27, 2012, 12:45 AM EDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 60%
Counties Broward County, FL, Charlotte County, FL, Collier County, FL, DeSoto County, FL, Glades County, FL, Hendry County, FL, Martin County, FL, Miami-Dade County, FL, Monroe County, FL, Palm Beach County, FL
The radar
The Miami radar (KAMX), 122 km from the middle of the area, began a volume at 02:44 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 watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Miami, FL (KMFL), launched 00:00Z, 2.7 hours before the alert went out and 115 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.
- Mixed-layer CAPE
- 2399 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 528 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- 30 m²/s²
- 0-3 km storm-relative helicity
- 81 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 1.5
The text
As transmitted, in the capitals the NWS used until 2016.
118
ACUS11 KWNS 270244
SWOMCD
SPC MCD 270244
FLZ000-270445-
MESOSCALE DISCUSSION 1817
NWS STORM PREDICTION CENTER NORMAN OK
0944 PM CDT SUN AUG 26 2012
AREAS AFFECTED...SRN FLORIDA
CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE
VALID 270244Z - 270445Z
PROBABILITY OF WATCH ISSUANCE...60 PERCENT
SUMMARY...IT IS NOT YET CERTAIN THAT A TORNADO WATCH WILL BE NEEDED
THIS EVENING/OVERNIGHT...BUT TRENDS ARE BEING MONITORED FOR A
CONTINUED INCREASE IN SEVERE POTENTIAL THAT COULD POSSIBLY REQUIRE
ONE.
DISCUSSION...WITH TROPICAL STORM ISAAC TAKING A GRADUAL TURN TO THE
NORTHWEST AS IT PROGRESSES WEST OF THE LOWER KEYS INTO THE
SOUTHEASTERN GULF OF MEXICO...LOW-LEVEL FLOW FIELDS HAVE VEERED
SOME...TO A MORE SOUTHERLY COMPONENT...ACROSS SOUTHERN
FLORIDA...WITH SOME STRENGTHENING TO 50+ KT IN THE LOWEST 1-2 KM
EVIDENT IN VAD WIND PROFILER DATA. THIS HAS COINCIDED WITH
INTENSIFICATION OF CONVECTIVE BANDS...AS REFLECTED BY
EXPANDING/COOLING CLOUD TOPS AND INCREASING CLOUD TO GROUND
LIGHTNING...ON THE OUTER PERIPHERY OF ISAAC...ACROSS COASTAL AREAS
NEAR/NORTH OF MIAMI...INTO THE INTERIOR SOUTH CENTRAL PENINSULA.
ALTHOUGH LATEST OBJECTIVE ANALYSES SUGGEST THAT APPRECIABLE BOUNDARY
LAYER INSTABILITY REMAINS CONFINED TO THE MORE IMMEDIATE SOUTHEAST
COASTAL AREAS...POTENTIAL APPEARS TO EXIST FOR THE INLAND ADVECTION
OF A MORE MOIST/DEEPER BOUNDARY LAYER OVERNIGHT...AS LOW-LEVEL WINDS
CONTINUE TO VEER TO THE SOUTH. IF THIS OCCURS...IN THE PRESENCE OF
CONTINUING STRONG LOW-LEVEL SHEAR...IT MAY NOT BE OUT OF THE
QUESTION THAT THE POTENTIAL COULD INCREASE FOR THE DEVELOPMENT OF
SUPERCELLS CAPABLE OF PRODUCING TORNADOES.
..KERR/CORFIDI.. 08/27/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...MFL...MLB...TBW...
LAT...LON 27158244 27358161 27138024 26478007 25618016 25488045
25498112 26048177 26468190 27158244SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 26, 11:24 PM EDT | Tornado Watch | SPC | Brevard, Broward, Charlotte, Collier, DeSoto, Glades and 17 more | 12 hr |
| Aug 27, 3:44 AM EDT | Mesoscale Discussion | SPC | Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 16 more | 2 hr |
| Aug 27, 7:26 AM EDT | Mesoscale Discussion | SPC | Brevard, Citrus, Dixie, Gilchrist, Hernando, Indian River and 13 more | 3 hr |
| Aug 27, 7:55 AM EDT | Mesoscale Discussion | SPC | Broward, Charlotte, Collier, DeSoto, Glades, Hardee and 16 more | 95 min |
| Aug 27, 11:54 AM EDT | Mesoscale Discussion | SPC | Indian River, Lake, Marion, Orange, Osceola, Saint Lucie and 3 more | 2 hr |
| Aug 27, 2:28 PM EDT | Mesoscale Discussion | SPC | Citrus, DeSoto, Hardee, Hernando, Highlands, Hillsborough and 6 more | 92 min |
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.