Alert archive / Florida / Mesoscale Discussions in 2012

Mesoscale Discussion 451

April 5, 2012Miami-Dade County, Monroe County, Florida

The Storm Prediction Center issued this mesoscale discussion at Apr 5, 2012, 2:10 AM EDT for Miami-Dade County, Monroe County, Florida. It was in force for 3 hr.

The area

The outline as issued.

The facts

Issued: Apr 5, 2012, 2:10 AM EDT (06:10 UTC)
Expired: Apr 5, 2012, 4:45 AM EDT
In force: 3 hr
Issued by: the Storm Prediction Center

Counties Miami-Dade County, FL, Monroe County, FL

The radar

The Key West radar (KBYX), 64 km from the middle of the area, began a volume at 06:14 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

Key West, FL (KEYW), launched 00:00Z, 6.2 hours before the alert went out and 68 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1247 J/kg
Mixed-layer CIN: -67 J/kg
Mixed-layer LCL: 1172 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 62 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 2.8

Open this sounding in Storm Lab

The text

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

550 
ACUS11 KWNS 050611
SWOMCD
SPC MCD 050610
FLZ000-050845-

MESOSCALE DISCUSSION 0451
NWS STORM PREDICTION CENTER NORMAN OK
0110 AM CDT THU APR 05 2012

AREAS AFFECTED...FL KEYS...EVERGLADES NATIONAL PARK...SRN MIAMI-DADE
COUNTY.

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 050610Z - 050845Z

POTENTIAL EXISTS FOR SPORADIC STG-SVR GUSTS...AS LINE OF TSTMS MOVES
EWD ACROSS REGION THROUGH ABOUT 09Z.

ALTHOUGH EARLIER MCS OVER NERN GULF HAS DISSIPATED...ANOTHER
ORGANIZED/QUASI-LINEAR CONVECTIVE SYSTEM HAS FORMED FARTHER S.  AT
530Z...STRONGEST PART OF THIS MCS WAS LOCATED FROM ABOUT 40 SSW
SANIBEL ISLAND SSWWD BETWEEN DRY TORTUGAS AND MARQUESAS KEYS...TO
NWRN COAST OF CUBA W OF HAVANA.  OUTFLOW FROM EARLIER COMPLEX
INTERSECTED NEWER ONE ABOUT 45 SSW APF...AND STILL WAS MOVING SEWD
ABOUT 20-25 KT.  NEWER COMPLEX WAS MOVING EWD 20-30 KT...BUT SHOULD
ACCELERATE SOMEWHAT AS COLD POOL BECOMES MORE MATURE.  AIR MASS OVER
LOWER-MIDDLE KEYS AND WRN FL BAY REGION IS THERMODYNAMICALLY
FAVORABLE...WITH SFC DEW POINTS LOW-70S F AND 2-KM DEEP MOIST LAYER
CONTRIBUTING TO MLCAPE 1500-2500 J/KG.  15-25 KT BOUNDARY-LAYER
SELYS...EVIDENT IN SFC OBS AND VWP...WILL CONTRIBUTE TO 30-35 KT
STORM-RELATIVE INFLOW...BASED ON EXPECTED MOTION VECTOR FOR MOST OF
MCS.  ALTHOUGH LOW-LEVELS ARE VERY MOIST...PRECIP LOADING AND
ACCELERATIONS RELATED TO EMBEDDED MESOCIRCULATIONS MAY ENHANCE GUST
POTENTIAL LOCALLY.

SVR THREAT SHOULD LESSEN WITH NWD EXTENT FROM GULF COASTAL AREAS OF
EVERGLADES NATIONAL PARK WHERE EARLIER OUTFLOW ARRIVES BEFORE NEWER
MCS...STABILIZING BOUNDARY LAYER.  SVR THREAT ALSO MAY DIMINISH WITH
EWD EXTENT ACROSS INLAND AREAS OF EVERGLADES...TOWARD TMB-HST
CORRIDOR.  IN THAT REGION...ACTIVITY MOVES OVER
NOCTURNALLY/DIABATICALLY STABILIZED BOUNDARY LAYER WITH SFC TEMPS
MID 60S TO NEAR 70 F AND SLIGHTLY LOWER DEW POINTS THAN FARTHER SW.
MODIFIED MFL RAOB AND RUC FCST SOUNDINGS SUGGEST INCREASING SBCINH
WITH EWD EXTENT...THOUGH STABLE LAYER IS SHALLOW ENOUGH THAT
ISOLATED STG GUSTS STILL MAY PENETRATE TO SFC.

..EDWARDS.. 04/05/2012

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

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

LAT...LON   25828146 25838119 25768093 25648052 25468018 25138038
            24898062 24758094 24648131 24548173 24538201 24538217
            24618215 24628207 24598203 24598194 24628172 24738160
            24808148 24788130 24818114 24888101 25018102 25138103
            25138111 25218117 25358114 25538121 25708132 25828146

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 4, 10:03 PM EDT	Mesoscale Discussion	SPC	Charlotte, Collier, DeSoto, Hillsborough, Lee, Manatee and 2 more	57 min
Apr 5, 10:14 AM EDT	Severe Thunderstorm Watch	SPC	Escambia, Okaloosa, Santa Rosa	8 hr
Apr 5, 2:12 PM EDT	Mesoscale Discussion	SPC	Calhoun, Gadsden, Holmes, Jackson, Liberty, Okaloosa and 3 more	93 min
Apr 5, 2:58 PM EDT	Severe Thunderstorm Watch	SPC	Bay, Calhoun, Franklin, Gadsden, Gulf, Holmes and 6 more	6 hr
Apr 5, 4:49 PM EDT	Mesoscale Discussion	SPC	Calhoun, Escambia, Gadsden, Holmes, Jackson, Leon and 5 more	86 min

Nearby

Mesoscale Discussions in Florida, 2012 Every 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.