U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 191942 
Storm Prediction Center ac 191940 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0140 PM CST Thu Jan 19 2017 

Valid 192000z - 201200z 

..there is a slight risk of severe thunderstorms late this 
afternoon and evening across parts of far southeastern 
Louisiana/Mississippi...southern Alabama and the western Florida 

..there is a marginal risk of severe thunderstorms across 
surrounding portions of the eastern Gulf states... 

An evolving cluster of thunderstorms may be accompanied by a risk 
for potentially damaging wind gusts, and perhaps a tornado or two, 
particularly across southeastern Alabama and portions of the western 
Florida Panhandle by late this evening. 

..20z outlook update... 
Based on latest observational data and model output, potentially 
cool/stable near surface air may remain entrenched near/just south 
of the higher terrain of northern Georgia into northeastern Alabama. 
However, increasing insolation and low-level moistening appear to be 
contributing to at least weak boundary layer destabilization to the 
south, ahead of slowly strengthening thunderstorm activity on the 
leading edge of convective outflow. This boundary has progressed 
into western Alabama/far southeastern Mississippi and Louisiana, and 
is expected to gradually advance eastward through early evening. 

Aided by strengthening large-scale ascent associated the lower/mid 
tropospheric warm advection, beneath increasingly difluent and 
divergent upper flow, the evolution of an intensifying and 
increasingly organized mesoscale convective system appears possible 
by early evening. Latest model guidance, including the rapid 
refresh and ECMWF, suggests that a 850-700 mb speed maximum (40-60+ 
kt) associated with this feature may develop inland across coastal 
areas, through southeastern Alabama, by 03-06z. It seems probable 
that this will be accompanied by the risk for potentially damaging 
surface gusts, which could continue into parts of west central and 
southwestern Georgia overnight. 

.Kerr.. 01/19/2017 

Previous discussion... /issued 1030 am CST Thu Jan 19 2017/ 

..portions of la/MS/al and the Florida Panhandle... 
While considerable cloud cover persists over much of 
central/northern portions of MS into al, modest 
moisture/destabilization could allow for a low-end isolated damaging 
wind and/or brief tornado risk through the afternoon/early evening. 

Farther south, a somewhat more focused severe risk may exist along 
the immediate Gulf Coast this afternoon into this evening, including 
parts of southeast Louisiana to far southern portions of MS/Alabama and 
the Florida Panhandle. While existing cloud cover and ongoing inland 
convection cast some uncertainty regarding the effective northward 
extent of appreciable destabilization inland, considerable mass 
response should occur in tandem with an amplifying upstream trough 
over the Southern Plains to arklatex. Accordingly, as gradual/modest 
destabilization occurs especially immediately near the coast, 
increasing forcing for ascent and strengthening deep-layer/low-level 
winds could support semi-organized storms modes near the coast later 
this afternoon into tonight. At least a localized damaging wind and 
a brief tornado threat will exist in these areas. 


Mesoscale Discussion

acus11 kwns 192110 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 192110 

Mesoscale discussion 0075 
National Weather Service 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... 


Latitude...Lon 33108532 32488494 31088522 30188576 28868934 29198986 
30808956 31628836 32368767 33248714 33378582 33108532