U.S. Severe Weather Forecast (Convective Outlook)

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swody1 
Storm Prediction Center ac 301427 


Day 1 convective outlook resent 1 
National Weather Service Storm Prediction Center Norman OK 
0927 am CDT Thu Mar 30 2017 


Valid 301300z - 311200z 


..there is an enhanced risk of severe thunderstorms lower Ohio 
Valley... 


..there is a slight risk of severe thunderstorms Midwest to central 
Gulf Coast to southern Appalachians... 


..there is a marginal risk of severe thunderstorms surrounding the 
slight risk... 


..there is a marginal risk of severe thunderstorms Great Basin... 


... 
scattered severe storms are most likely from the Midwest to the deep 
south with damaging winds, a few tornadoes, and hail possible from 
midday to evening. 


..Midwest to the central Gulf Coast and southern Appalachians... 
Ongoing convection from southern MS to an mesoscale convective system over the northwest 
Gulf along with scattered showers and storms over the mid-MS valley 
and Midwest renders low confidence in the potential for robust 
destabilization across the warm sector. 12z raobs sampled meager 
MUCAPE north of the central Gulf Coast where rich boundary-layer 
moisture is confined to this region. Given the degree of moisture 
farther north along with extensive cloud cover slowing diurnal 
destabilization, peak MLCAPE will likely remain weak below 1000 j/kg 
during the late afternoon. 


As a surface cyclone becomes centered over central Illinois and attendant 
cold front arcs southward across the MS valley, scattered storm 
development should occur around midday. Deep-layer winds will be 
strong, but meridional. Both the rap/NAM soundings depict 
veer-back-veer profiles and small low-level hodographs with modest 
srh. This type of setup should Foster splitting cells, 
conglomerating into clusters and short-line segments, with the 
primary severe threats being hail and damaging wind. A few tornadoes 
may occur, but the likelihood of several tornadic storms appears too 
low to warrant a broad area of enhanced probabilities. 


From the central Gulf Coast to southern Appalachians, the ongoing 
mesoscale convective system in the northwest Gulf casts considerable uncertainty in diurnal 
convective development to its immediate north. However, as a 
mid-level speed Max ejects across the region tonight, isolated to 
scattered storms should form and/or storms that initially formed 
along the cold front over MS may be sustained. While instability 
will be nocturnally waning, deep-layer shear will be adequate for 
all severe hazards with coverage expected to warrant category 1-2 
risks. 


..Great Basin... 
A band of showers and isolated storms is expected to form along a 
strong cold front attendant to an amplifying shortwave trough. 
Although buoyancy will be scant, well-mixed thermodynamic profiles 
ahead of the front should support downward momentum transport of 
robust flow aloft and may yield isolated severe wind gusts. 


.Grams/dial.. 03/30/2017 


$$ 

Mesoscale Discussion


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sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 301610 
alz000-msz000-301715- 


Mesoscale discussion 0377 
National Weather Service Storm Prediction Center Norman OK 
1110 am CDT Thu Mar 30 2017 


Areas affected...coastal MS and Alabama 


Concerning...severe potential...watch unlikely 


Valid 301610z - 301715z 


Probability of watch issuance...20 percent 


Summary...while wind damage is perhaps possible on a localized and 
intermittent basis, the expected coverage and magnitude of this 
possible risk will likely preclude a Severe Thunderstorm Watch. 


Discussion...visible satellite imagery shows a cumulus field over 
the coastal counties of MS east into the Florida Panhandle and surface 
observations show temperatures have warmed into the upper 70s with 
dewpoints near 70 degrees f. 500-mb upper air analysis this morning 
shows the leading edge of more appreciable height falls (30-60 M per 
12 hours) have overspread the coastal plain of MS/al. Background 
upward vertical motion associated with mid- to upper-level forcing 
for ascent and 50+ kt flow at 500-mb are aiding in the maintenance 
of the squall line over coastal MS southward to the mouth of the MS 
river. A 25-kt gust was measured at kasd at 1451z in association 
with the squall line. 


Analysis of the kmob VAD data shows speed shear in the lowest 5-km 
but the unidirectional southerly flow will probably prove 
unfavorable for isolated 50-60 mph gusts and resultant widespread 
wind damage given the north-south orientation of the convective 
line. Nonetheless, the mature trailing stratiform convective line 
will likely continue to move east across coastal MS/Alabama during the 
next several hours. Localized/intermittent wind damage is possible, 
but the weakness in mid-level lapse rates and aforementioned 
concerns on the flow geometry imply the need for a Severe 
Thunderstorm Watch is low. 


.Smith/guyer.. 03/30/2017 


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


Attention...WFO...mob...lix... 


Latitude...Lon 30168918 30678923 30838764 30358745 30168918