U.S. Severe Weather Forecast (Previsión convectiva)

día tres

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Storm Prediction Center ac 251953 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0253 PM CDT Sat Mar 25 2017 

Valid 252000z - 261200z 

..there is a slight risk of severe thunderstorms for portions of 
the central Gulf Coast... 

..there is a marginal risk of severe thunderstorms from the central 
Gulf Coast to the middle Mississippi Valley... 

Isolated strong to locally severe thunderstorms may occur through 
the early evening hours across the central Gulf Coast states 
northward into the middle Mississippi River valley. 

Only notable change with this update is the focusing of slight risk 
/ higher damaging-wind probabilities closer to the Gulf Coast, where 
more substantial moisture and greater resultant buoyancy exist ahead 
of a line of strong to occasionally severe storms. Through the 
evening hours, stronger low/mid-level flow should depart to the 
northeast, favoring a gradual weakening trend. 

Farther west, strong to briefly severe thunderstorms may continue to 
develop along pre-frontal confluence over central Mississippi and 
vicinity. For more information, reference mesoscale discussion 331. 

.Picca.. 03/25/2017 

Previous discussion... /issued 1130 am CDT Sat Mar 25 2017/ 

..Gulf Coast/lower MS River Valley/mid-south... 
Well ahead of the synoptic cold front, the outflow-focused remnants 
of last night's convection continue to decelerate while slowly 
progressing into western al, while otherwise stalling along coastal 
la. It appears the strongest/most organized convection will remain 
semi-focused this afternoon across southeast la and possibly 
near-coastal portions of MS/Alabama into the Florida Panhandle. 
Low/mid-tropospheric winds should continue to gradually weaken 
during the day, but some additional heating/destabilization will 
nonetheless support some stronger mostly linear storms capable of 
locally damaging winds and possibly a tornado. 

Otherwise, a few stronger storms could redevelop this afternoon 
across the mid-south/lower MS River Valley vicinity near/just ahead 
of the synoptic front within a modestly unstable environment. 
However, semi-prevalent cloud cover and weakening mass convergence 
should limit any such risk. 

..middle MS River Valley... 
The slow-moving closed/cold cyclone will continue to drift 
east-northeastward today from the Ozarks toward central/southern Illinois 
by tonight. Immediately ahead of this nearly stacked low, locally 
stronger heating (60s f surface temperatures) and moderately steep 
lapse rates, as noted between 850mb-650mb in the 12z observed 
sounding from Springfield MO, could support some stronger updrafts 
this afternoon. Marginally severe and gusty winds could occur, and 
sufficient low-level moisture/ambient vorticity could allow for a 
few funnels. 


Mesoscale Discussion

acus11 kwns 251834 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 251834 

Mesoscale discussion 0331 
National Weather Service Storm Prediction Center Norman OK 
0134 PM CDT Sat Mar 25 2017 

Areas affected...central through north central Mississippi 

Concerning...severe potential...watch unlikely 

Valid 251834z - 252030z 

Probability of watch issuance...20 percent 

Summary...storms will pose some risk for a few instances of hail and 
strong to locally damaging wind gusts this afternoon. A ww issuance 
will probably not be necessary unless more storms begin to show 
signs of further intensification and organization. 

Discussion...a small cluster of thunderstorms which appears to have 
initiated within pre-frontal confluence zone and in association with 
a northeastward-ejecting vorticity maximum has intensified over west 
central MS. Destabilization of the boundary layer has occurred, and 
objective analysis is indicating MLCAPE from 500 to 800 j/kg. 
However, the instability corridor is relatively narrow due to 
widespread clouds and convective precipitation attending a squall 
line just downstream. The cluster of storms will develop northeast 
into northern MS next couple hours where effective bulk shear from 
30-40 kt is sufficient for updraft rotation. However tendency will 
be for mid level winds and deep-layer vertical shear to gradually 
weaken as the upper trough advances east. The narrow instability 
corridor and weakening winds aloft suggest the severe threat will 
likely remain relatively confined in space and time. In the 
meantime, the stronger storms will remain capable of a few instances 
of large hail and damaging wind. 

.Dial/guyer.. 03/25/2017 

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


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