Alert archive / Alabama / Mesoscale Discussions in 2017

Mesoscale Discussion 75

January 19, 20174 states

The Storm Prediction Center issued this mesoscale discussion at Jan 19, 2017, 3:10 PM CST for 4 states. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jan 19, 2017, 3:10 PM CST (21:10 UTC)
Expired: Jan 19, 2017, 5:15 PM CST
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 50 counties

Autauga County, AL, Baldwin County, AL, Barbour County, AL, Bibb County, AL, Bullock County, AL, Butler County, AL, Chambers County, AL, Chilton County, AL, Clarke County, AL, Clay County, AL, Coffee County, AL, Conecuh County, AL, Coosa County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Dallas County, AL, Elmore County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Lee County, AL, Lowndes County, AL, Macon County, AL, Mobile County, AL, Monroe County, AL, Montgomery County, AL, Perry County, AL, Pike County, AL, Russell County, AL, Shelby County, AL, Tallapoosa County, AL, Washington County, AL, Wilcox County, AL, Escambia County, FL, Holmes County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Plaquemines Parish, LA, Saint Bernard Parish, LA, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Perry County, MS, Stone County, MS

The radar

The Ft Rucker radar (KEOX), 149 km from the middle of the area, began a volume at 21:09 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, 9.2 hours before the alert went out and 176 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 877 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 69 m²/s²
0-3 km storm-relative helicity: 57 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted.

976 
ACUS11 KWNS 192110
SWOMCD
SPC MCD 192110 
GAZ000-FLZ000-ALZ000-MSZ000-LAZ000-192315-

Mesoscale Discussion 0075
NWS Storm Prediction Center Norman OK
0310 PM CST Thu Jan 19 2017

Areas affected...Southeast Louisiana...southeast
Mississippi...central and southern Alabama...and western portions of
the Florida Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 192110Z - 192315Z

Probability of Watch Issuance...20 percent

SUMMARY...Some gradual increase in severe weather risk is indicated
across the discussion area, with a severe storm or two possibly
evolving over the next 1-2 hours.  In the short term however, watch
issuance is not expected.

DISCUSSION...Latest radar loop shows a somewhat disorganized band of
storms extending from north central Alabama southwest to
southeastern Mississippi, and then southward across far southeast
Louisiana.  A few stronger updrafts exist within the line, but any
risk for damaging winds remains minimal at this time.  Meanwhile,
occasional/more isolated showers continue ahead of the main band,
with some low-level rotation evident at times per area WSR-88D
velocity data.  A brief tornado is not out of the question in the
short term, though risk remains low.

Over the next few hours, modest additional destabilization of the
moist boundary layer should occur, with broken cloud cover
permitting some heating.  As ascent (as implied in water vapor
imagery) shifts across the slowly destabilizing airmass, some uptick
in storm intensity -- both within the main band and with isolated
cells farther east -- appears possible.  While corresponding risk
for locally gusty winds and/or a brief tornado or two may likewise
increase, threat does not at this time appear likely to become
sufficient to warrant watch issuance.

..Goss/Guyer.. 01/19/2017

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...FFC...TAE...BMX...MOB...JAN...LIX...

LAT...LON   33108532 32488494 31088522 30188576 28868934 29198986
            30808956 31628836 32368767 33248714 33378582 33108532

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jan 19, 5:56 PM CST	Mesoscale Discussion	SPC	Baldwin, Barbour, Butler, Clarke, Coffee, Conecuh and 11 more	2 hr
Jan 18, 6:06 PM CST	Mesoscale Discussion	SPC	Catahoula, Franklin, Grant, LaSalle, Tensas	114 min
Jan 18, 11:56 PM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Catahoula, Concordia, Evangeline and 5 more	2 hr
Jan 19, 6:28 AM CST	Mesoscale Discussion	SPC	Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberville and 9 more	2 hr

Nearby

Mesoscale Discussions in Alabama, 2017 Mesoscale Discussions in Mississippi, 2017 Mesoscale Discussions in Florida, 2017 Every mesoscale discussion in 2017

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.