U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 040544 
Storm Prediction Center ac 040543 

Day 1 convective outlook corr 1 
National Weather Service Storm Prediction Center Norman OK 
1143 PM CST Sat Dec 03 2016 

Valid 041200z - 051200z 

..there is a marginal risk of severe thunderstorms across parts of far southeast 
Louisiana...far southern Mississippi...far southern Alabama and the 
western Florida Panhandle... 

Corrected for categorical outlook 

Thunderstorms with a marginal wind damage threat will be possible 
across parts of the central Gulf Coast on today. 

..central Gulf Coast... 
A low-amplitude upper-level ridge will move across the eastern U.S. 
Today as an upper-level trough moves into the Mississippi Valley. 
Between the two features...southwest middle-level flow will be present 
from the Ohio Valley southward to the central Gulf Coast. In the 
wake of the upper-level ridge...a 40 to 55 knots low-level jet will 
move across the central and eastern Gulf Coast states which will 
maintain moisture advection in the central Gulf Coast region today. 
Surface dewpoints should increase into the 60s fahrenheit across 
southern Mississippi...southern Alabama and the western Florida 
Panhandle. In response to surface heating...an axis of moderate 
instability may develop across the northern Gulf of Mexico extending 
to near the central Gulf Coast. Forecast soundings suggest that 
MLCAPE could peak near 1000 j/kg at Mobile Alabama and Pensacola Florida early 
this afternoon. 

In addition to the instability...strong deep-layer shear is forecast 
across the central Gulf Coast where forecast soundings show 0-6 km 
shear in the 45 to 55 knot range. This should be sufficient for 
storm rotation with the stronger cells embedded in a line segment 
moving eastward across the central Gulf Coast region. The latest 
version of the hrrr agrees with this scenario...moving a line of 
thunderstorms from southeast Louisiana at daybreak slowly eastward 
across the marginal risk area this morning into early afternoon. The 
current thinking is that this line will be associated with a 
marginal wind damage threat and that the potential for strong wind 
gusts will eventually affect the western Florida Panhandle by this 
afternoon. The marginal severe threat should gradually diminish 
after peak heating as the low-level jet weakens and moves 
northeastward away from the central Gulf Coast. 

.Broyles/Cook.. 12/04/2016 


Mesoscale Discussion

acus11 kwns 041144 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 041144 

Mesoscale discussion 1866 
National Weather Service Storm Prediction Center Norman OK 
0544 am CST sun Dec 04 2016 

Areas affected...southeast la...southern MS and Alabama 

Concerning...severe potential...watch unlikely 

Valid 041144z - 041345z 

Probability of watch issuance...5 percent 

Summary...a few strong storms may affect coastal regions of la...MS... 
and Alabama this morning...but the overall threat appears low. 

Discussion...a series of cells have congealed into a small mesoscale convective system 
across southeast la...which appears to be coincident with a warm 
front. Surface observations indicate a gradual warming trend along 
coastal MS and Alabama...but instability remains very weak as of 12z. This 
area of storms is expected to continue east/northeastward at around 
25 knots which would bring it into coastal Alabama by about 13z. This 
particular cell appears semi-organized with broad cyclonic rotation. 
Localized strong wind gusts will be possible south of the warm front 
if this feature holds together. A brief/weak tornado cannot be ruled 
out as well...conditional on upper 60s to near 70 dewpoints providing 
sufficient surface-based instability far enough inland. 

.Jewell/Edwards.. 12/04/2016 

..please see www.Spc.NOAA.Gov for graphic product... 


Latitude...Lon 29058992 29408950 29778917 29888887 30418848 30708795 
30658752 30408740 30208740 28988893 28898930 28928964