U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 240600 
Storm Prediction Center ac 240559 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1259 am CDT sun Sep 24 2017 

Valid 241200z - 251200z 

..there is a marginal risk of severe thunderstorms across portions 
of Minnesota... 

A couple of strong storms -- and possibly a severe storm or two -- 
may occur during the afternoon across portions of Minnesota. 

A relatively stagnant, but high-amplitude flow field aloft is 
expected to continue today, with the western U.S. Trough making 
minimal eastward progress toward a Stalwart eastern U.S. Ridge. 

At the surface, a cold front is expected to make slow southeastward 
progress across the north central U.S. And Central Plains states, as 
a weak frontal low shifts quickly north-northeast across the plains 
toward Ontario through the period. 

In the western Atlantic, Hurricane Maria is expected to remain well 

..parts of central and northern Minnesota... 
As a weak surface low shifts northeast across Minnesota during the 
afternoon in conjunction with weak short-wave troughing, a small 
cluster of semi-organized storms may develop by mid afternoon, as 
modest destabilization -- hindered by weak lapse rates aloft -- 
develops. Despite the thermodynamic deficiency, favorably strong 
flow aloft and some veering with height -- especially near the 
surface low -- would suggest potential for one or two sustained/more 
intense updrafts to evolve. As such, will introduce 
low-probability/marginal risk area in parts of Minnesota for the 
afternoon hours. Expect storms to diminish by evening, as the low 
shifts into Canada and diurnal stabilization commences. 

.Goss/Gleason.. 09/24/2017 


Mesoscale Discussion

acus11 kwns 232256 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 232255 

Mesoscale discussion 1669 
National Weather Service Storm Prediction Center Norman OK 
0555 PM CDT Sat Sep 23 2017 

Areas affected...portions of southeastern nm and far West Texas 

Concerning...severe potential...watch unlikely 

Valid 232255z - 240100z 

Probability of watch issuance...5 percent 

Summary...a couple instances of large hail and strong/damaging winds 
may occur with isolated supercells over the next several hours. The 
overall severe threat is expected to remain very isolated, and watch 
issuance is not anticipated. 

Discussion...a couple supercells have developed late this afternoon 
within a modest low-level upslope flow regime across parts of 
southeastern nm and far West Texas. Winds strengthen to around 35-40 kt 
at mid levels as a highly amplified large-scale trough remains 
centered over the Great Basin. A veering wind profile per recent 
vwps from kmaf is also contributing to around 35-45 kt of effective 
bulk shear, which will allow for continued supercell structures 
through the evening. A narrow corridor of weak to moderate 
instability has developed across this region where some clearing has 
occurred. Given ongoing supercell structures and recent mrms mesh 
data, isolated large hail will continue to be a threat. Strong to 
locally damaging winds may also occur where low-level lapse rates 
have steepened due to diurnal heating. Both instability and shear 
weaken with eastward extent, and with the loss of diurnal heating 
that will occur later this evening, storms should eventually 
decrease in intensity. The ongoing threat for large hail and 
strong/damaging winds is expected to remain too isolated to warrant 
watch issuance. 

.Gleason/Edwards.. 09/23/2017 

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


Latitude...Lon 31010570 31880547 32730498 33590412 33770282 32930238 
31820227 30880244 29910268 29440348 29500409 29720467 
30500499 31010570