U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 251948 
Storm Prediction Center ac 251947 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0247 PM CDT sun Jun 25 2017 

Valid 252000z - 261200z 

..there is an enhanced risk of severe thunderstorms across parts of 
eastern nm... 

..there is a slight risk of severe thunderstorms across much of nm 
into extreme southeast Colorado... 

..there is a marginal risk of severe thunderstorms from far West Texas 
to southeast Colorado... 

Severe thunderstorms with damaging wind and large hail are expected 
across parts of central and eastern New Mexico this afternoon and 
evening. Isolated severe storms are possible elsewhere from southern 
Colorado to southern New Mexico and far West Texas. 

..mid-afternoon update... 

Minor changes have been made to the 1630z outlook, namely to 
increase severe probabilities a bit over southeast Colorado. Strong 
boundary-layer heating has contributed to steepening surface-3km 
lapse rates over this region and the air mass is considerably more 
buoyant within southeasterly flow where dew points are holding in 
the mid 50s. A few thunderstorms have recently developed from south 
of lic to near laa and this trend should continue as satellite 
imagery depicts a thickening cu field across this region. Isolated 
severe thunderstorm threat appears somewhat higher than previous 
forecast depicted. Otherwise, severe threat appears to be increasing 
across the southern High Plains in line with earlier guidance. 

Reference mesoscale discussion #1148 for more information on this evolving severe 

.Darrow.. 06/25/2017 

Previous discussion... /issued 1131 am CDT sun Jun 25 2017/ 

..nm/southern Colorado/far West Texas... 
A very moist air mass exists across the region today within a 
Post-frontal upslope flow regime reinforced by prior convective 
outflows. In fact, 12z radiosonde observation-observed precipitable water values are 
in the upper 5-15% of daily climatological values. A gradual 
thinning of prevalent low-level clouds has begun to occur across 
eastern nm as of late morning per visible satellite imagery and this 
same general trend will continue through the afternoon. Storms 
should initially develop near mountains/higher terrain of 
south-central Colorado and interior nm this afternoon. Heating/orographic 
lift aside, such development should be aided by a ridge-peripheral 
weak mid-level disturbance moving east/southeastward from northern 
Arizona into nm per water vapor imagery. 

Steep lapse rates/moderate buoyancy in the presence of 30-40 kt 
effective shear (especially across east-Central/Northeast nm) will 
some support initial supercells capable of large hail. Storms should 
gradually congeal, grow upscale, and progress south-southeastward 
through late afternoon into evening across eastern nm and eventually 
toward parts of far west TX, with a corresponding increase in 
damaging wind potential. 

..coastal GA/Carolinas... 
A few stronger storms could occur this afternoon within a moist 
environment near/east of the cold front, but the potential for 
organized/sustained storms currently appears low. 


Mesoscale Discussion

acus11 kwns 252313 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 252312 

Mesoscale discussion 1149 
National Weather Service Storm Prediction Center Norman OK 
0612 PM CDT sun Jun 25 2017 

Areas affected...southeast Colorado...eastern nm...northwest Texas/OK 

Concerning...Severe Thunderstorm Watch 370... 

Valid 252312z - 260045z 

The severe weather threat for Severe Thunderstorm Watch 370 

Summary...large hail and damaging wind gusts remain possible across 
the entire watch area. Some very large hail (i.E. Greater than 2 
inches in diameter) and a tornado or two are also possible. Upscale 
growth into a convective line may eventually occur, enhancing the 
damaging wind threat. 

Discussion...regional radar imagery shows numerous severe 
thunderstorms currently ongoing across eastern nm. Primary threat 
with these thunderstorms is large hail. Some very large hail (i.E. 
Greater than 2 inches in diameter) is also possible, particularly as 
a result of storm/boundary interactions. Continued upslope flow 
regime coupled with dewpoints in the 60s, steep mid-level lapse 
rates, and moderate/strong bulk shear will favor continued 
strong/severe thunderstorm development across eastern nm. Primary 
threat for the next hour or two will remain large hail, although 
some damaging wind gusts are also possible. Eventually, some cold 
pool amalgamation/upscale growth is anticipated, with the 
northwesterly mean flow favoring southeastward propagation into 
east-central nm and the adjacent west-central portions of the Texas 
Panhandle. Northern extent of the eventual convective line will 
likely be demarcated by the southwestward progressing outflow 
boundary emanating from the discrete supercell that move through 
Baca County Colorado and is currently moving through Cimarron County OK. 
Very large hail and damaging wind gusts remain possible with this 
supercell as it tracks southward along a remnant outflow boundary. 
Boundary interactions may also contribute to increased tornado 
potential with this supercell as well as other storms across the 

.Mosier.. 06/25/2017 

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


Latitude...Lon 32910637 37850409 37840117 32910357 32910637