Alert archive / Alabama / Mesoscale Discussions in 2012
Mesoscale Discussion 564
The Storm Prediction Center issued this mesoscale discussion at Apr 17, 2012, 1:34 PM CDT for 17 counties in Alabama. It was in force for 116 min.
The area
The outline as issued.
The facts
- Issued
- Apr 17, 2012, 1:34 PM CDT (18:34 UTC)
- Expired
- Apr 17, 2012, 3:30 PM CDT
- In force
- 116 min
- Issued by
- the Storm Prediction Center
Counties Autauga County, AL, Bibb County, AL, Chilton County, AL, Choctaw County, AL, Clay County, AL, Cleburne County, AL, Coosa County, AL, Dallas County, AL, Elmore County, AL, Hale County, AL, Marengo County, AL, Perry County, AL, Randolph County, AL, Shelby County, AL, Talladega County, AL, Tallapoosa County, AL, Wilcox County, AL
The radar
The Birmingham radar (KBMX), 51 km from the middle of the area, began a volume at 18:35 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
Birmingham, AL (KBMX), launched 12:00Z, 6.6 hours before the alert went out and 52 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
- 309 J/kg
- Mixed-layer CIN
- -34 J/kg
- Mixed-layer LCL
- 663 m above ground
- 0-6 km bulk shear
- 29 kt
- 0-1 km storm-relative helicity
- 28 m²/s²
- 0-3 km storm-relative helicity
- 78 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
599
ACUS11 KWNS 171835
SWOMCD
SPC MCD 171834
ALZ000-172030-
MESOSCALE DISCUSSION 0564
NWS STORM PREDICTION CENTER NORMAN OK
0134 PM CDT TUE APR 17 2012
AREAS AFFECTED...CNTRL AL
CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY
VALID 171834Z - 172030Z
A FEW STORMS COULD PRODUCE MARGINALLY SVR WIND GUSTS THIS AFTERNOON
ACROSS CNTRL AL. THE ISOLATED/SPORADIC/MARGINAL NATURE OF ANY SVR
THREAT IS EXPECTED TO PRECLUDE THE ISSUANCE OF A WW.
SFC MESOANALYSIS AROUND 18Z DEPICTS A STATIONARY FRONT EXTENDING
FROM 20 MILES SE OF MERIDIAN MS NEWD TO 35 MILES ENE OF ANNISTON AL.
LOW-LEVEL ASCENT ALONG THIS BOUNDARY IS BEING AUGMENTED BY
DIFFERENTIAL-HEATING INDUCED BAROCLINICITY OWING TO PERSISTENT
MID/HIGH-LEVEL CONVECTIVE CLOUD DEBRIS NORTHWEST OF THE SFC FRONT.
CONTINUED DESTABILIZATION NEAR AND SE OF THE FRONT IS SUPPORTING
MLCAPE VALUES OF 700-1000 J/KG PER MODIFIED 12Z BIRMINGHAM RAOB. AS
SUCH...SCATTERED CONVECTION WILL LIKELY DEEPEN THROUGH THE
AFTERNOON. AND...WITH BIRMINGHAM VWP DATA DEPICTING 25-40 KT OF SLY
TO SSWLY FLOW IN THE 4-7-KM AGL LAYER...DEEP-LAYER SHEAR INVOF THE
SFC BOUNDARY WILL BE SUFFICIENT FOR OCCASIONALLY ORGANIZED STORM
STRUCTURES INCLUDING MULTICELLS. STEEP LOW-LEVEL LAPSE RATES OWING
TO DIABATIC HEATING ON THE WARM SIDE OF THE FRONT/DIFFERENTIAL
HEATING ZONE WILL SUPPORT DCAPE VALUES IN EXCESS OF 800
J/KG...PROMOTING ENHANCED DOWNDRAFTS WITH A THREAT FOR A FEW
MARGINALLY SVR MICROBURSTS WITH THE STRONGEST STORMS. THE SLY
COMPONENT OF THE MID-LEVEL FLOW WILL HAVE A TENDENCY TO SUPPORT
STORM MOTIONS TOWARD THE COOL SIDE OF THE BOUNDARY...WHERE THE
NEAR-SFC STABLE LAYER WILL YIELD A DIMINISHING THREAT FOR STRONG
WIND GUSTS.
..COHEN.. 04/17/2012
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...BMX...MOB...
LAT...LON 31828839 32238838 32578801 33058734 33448658 33848565
33648537 33458535 33188539 32948561 32548614 31898724
31668801 31828839Nearby
Mesoscale Discussions in Alabama, 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.