U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 241951 
Storm Prediction Center ac 241950 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0250 PM CDT Sat Mar 24 2018 

Valid 242000z - 251200z 

..there is a marginal risk of severe thunderstorms late this 
afternoon and evening across parts of southeast Missouri and 
adjacent southern Illinois....western Kentucky/Tennessee and 
adjacent northeast Arkansas... 

..there is a marginal risk of severe thunderstorms across parts of 
northwest Texas... 

Isolated strong thunderstorm development is possible late this 
afternoon and evening near the confluence of the Mississippi and 
Ohio rivers, and later tonight (after 2 am cdt) across parts of the 
Texas Big Country, accompanied by some risk for severe weather. 

..20z outlook update... 
Latest visible imagery suggests early attempts at deepening 
convective development across parts of southeast Missouri into 
northeast Arkansas. This is within a clearing in low-level 
cloudiness, wrapping into the vicinity of a weakening southeastward 
migrating surface low center, and near the southwestern periphery of 
stronger mid-level forcing for large-scale ascent associated with a 
digging short wave trough. This mid-level forcing still appears 
likely to remain largely focused to the cool side of frontal zone 
extending east southeast of the low. However, there does appear a 
window of opportunity for continuing development of boundary layer 
based storm development into portions of western Kentucky and 
Tennessee by this evening. Low-level moistening and isolation are 
contributing to weak to modest destabilization within the warm 
sector, in the presence of 30-50 kt 850-500 mb flow. This 
environment is at least marginally conducive to organized severe 
storm development. While the signal still appears weak, at best, 
within latest model output concerning this potential, at least 
isolated strong to severe storm development does not appear out of 
the question, and the severe probabilities have been adjusted 

.Kerr.. 03/24/2018 

Previous discussion... /issued 1126 am CDT Sat Mar 24 2018/ 

..TX Big Country... 
There will be potential for isolated elevated storm development 
early Sunday as a surge of warm advection occurs to the north of the 
cold front that will stall and become quasi-stationary across the 
Edwards Plateau this afternoon. While the 12z NAM is likely too 
aggressive with the degree of MUCAPE given its typical bias in 
initial return flow scenarios, robust low-level moisture is 
prevalent south of the front. Guidance is consistent in depicting 
increasing 850 mb moisture overnight, although differences exist in 
amplitude and whether this will be sufficient for elevated storms to 
develop. Given ample speed shear through the potential cloud-bearing 
layer, it appears a conditional risk for severe hail is warranted. 

A few clusters of elevated storms are ongoing across the mid-MS to 
lower Ohio valleys, in advance of a shortwave trough over Iowa. Though 
the midlevel trough will dampen through tonight, warm advection 
downstream of this feature should Foster convection spreading 
southeast towards the southern Appalachians and South Atlantic 
coast. Weak ascent near the trailing cold front could support 
isolated thunderstorm development this evening across the Tennessee Valley 
and mid south. 

A few thunderstorms will remain possible along the or and northern 
California coasts, as well as the Sacramento Valley, as a deep midlevel 
trough moves inland this afternoon. Very isolated lightning may 
occur across western Montana in association with an ejecting/deamplifying 
trough today, and tonight with elevated convection across NE/South Dakota in a 
strengthening warm advection regime. In the latter two areas, 
however, the lightning threat appears to be too sparse to warrant 
outlook areas. 


Mesoscale Discussion

acus11 kwns 242027 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 242026 

Mesoscale discussion 0171 
National Weather Service Storm Prediction Center Norman OK 
0326 PM CDT Sat Mar 24 2018 

Areas affected...southeastern Missouri...far northeastern 
Arkansas...northwestern Tennessee...far western Kentucky...and far 
southern Illinois 

Concerning...severe potential...watch unlikely 

Valid 242026z - 242130z 

Probability of watch issuance...5 percent 

Summary...isolated convection continues to deepen and migrate 
southeastward across southeastern Missouri currently. This activity 
will pose an isolated hail/wind risk through about 02z or so. A ww 
issuance is not anticipated. 

Discussion...a deepening cumulus field over southeastern Missouri 
has evolved into a few isolated thunderstorms near/southeast of the 
Farmington, MO area over the past half hour. Radar imagery suggests 
that these cores have deepened beyond the freezing level, with some 
indication of small hail noted in the most dominant activity. These 
storms are in a weakly buoyant airmass (900-1300 j/kg mucape) 
boosted by low-70s f surface temperatures and near 60f dewpoints. 
Shear profiles are supportive of organization, however, with a 
general east-southeastward motion near/along the warm front expected 
over the next few hours. Dominant storms may produce hail 
approaching 1 inch in diameter through early evening and a few 
strong wind gusts may also occur. This threat will likely remain 
isolated enough to preclude a watch issuance, although storms should 
persist through sunset before weakening. 

.Cook/grams.. 03/24/2018 

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


Latitude...Lon 37899048 38059005 37848935 37278822 36558778 35778815 
35508884 35658952 35789019 36169074 36739094 37299089