Alert archive / Alabama / Mesoscale Discussions in 2017

Mesoscale Discussion 76

January 19, 201717 counties in Alabama; 12 counties in Florida; 4 counties in Georgia

The Storm Prediction Center issued this mesoscale discussion at Jan 19, 2017, 5:56 PM CST for 17 counties in Alabama; 12 counties in Florida; 4 counties in Georgia. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Jan 19, 2017, 5:56 PM CST (23:56 UTC)
Expired
Jan 19, 2017, 8:00 PM CST
In force
2 hr
Issued by
the Storm Prediction Center
Chance of a watch
20%
All 33 counties

Baldwin County, AL, Barbour County, AL, Butler County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Mobile County, AL, Monroe County, AL, Pike County, AL, Wilcox County, AL, Bay County, FL, Calhoun County, FL, Escambia County, FL, Franklin County, FL, Gulf County, FL, Holmes County, FL, Jackson County, FL, Liberty County, FL, Okaloosa County, FL, Santa Rosa County, FL, Walton County, FL, Washington County, FL, Clay County, GA, Early County, GA, Miller County, GA, Seminole County, GA

The radar

The Eglin Afb radar (KEVX), 38 km from the middle of the area, began a volume at 23:56 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

Tallahassee Rgnl, FL (KTLH), launched 12:00Z, 11.9 hours before the alert went out and 180 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, Tallahassee Rgnl, FL at 12:00Z on 2017-01-19Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 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, Tallahassee Rgnl, FL at 12:00Z on 2017-01-19The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 25 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
922 m above ground
0-6 km bulk shear
33 kt
0-1 km storm-relative helicity
25 m²/s²
0-3 km storm-relative helicity
1 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

262 
ACUS11 KWNS 192357
SWOMCD
SPC MCD 192356 
FLZ000-GAZ000-ALZ000-MSZ000-200200-

Mesoscale Discussion 0076
NWS Storm Prediction Center Norman OK
0556 PM CST Thu Jan 19 2017

Areas affected...Portions of southern Alabama and the Florida
panhandle

Concerning...Severe potential...Watch unlikely 

Valid 192356Z - 200200Z

Probability of Watch Issuance...20 percent

SUMMARY...Occasional strong wind gusts may accompany a band of
thunderstorms as it shifts eastward across portions of southern
Alabama and the Florida panhandle this evening. Watch issuance
currently is not expected.

DISCUSSION...Over the last two hours, the regional radar mosaic
indicates that a band of thunderstorms along the central Gulf Coast
has developed a leading stratiform region. This evolution is likely
in response to the arrival of strong west/southwesterly anvil-layer
flow, favoring downstream hydrometeor advection/seeding. In turn,
the overall strength of convection has trended downward, as modest
stabilization occurs ahead of the system. Nonetheless, occasional
weak embedded rotation within line segments may still materialize
this evening, as suggested by a fairly straight hodograph in KMOB
VAD wind profile data. These convective elements could encourage a
few strong wind gusts, as positive theta-e advection from the Gulf
of Mexico occurs ahead of the line. The tornado threat, while
non-zero, appears minimal, as surface pressure falls (and resultant
backed winds) remain displaced farther north.

..Picca/Edwards.. 01/19/2017

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

ATTN...WFO...TAE...BMX...MOB...LIX...

LAT...LON   30288858 32018785 32038685 31928541 31818494 31578477
            31338475 30848461 30418462 29648481 29668522 30218667
            30178782 30288858

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jan 19, 3:10 PM CSTMesoscale DiscussionSPCAutauga, Baldwin, Barbour, Bibb, Bullock, Butler and 29 more2 hr

Nearby

Mesoscale Discussions in Alabama, 2017Mesoscale Discussions in Florida, 2017Mesoscale Discussions in Georgia, 2017Every 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.