U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 251941 
Storm Prediction Center ac 251940 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
0140 PM CST Wednesday Nov 25 2015 

Valid 252000z - 261200z 

..no severe thunderstorm areas forecast... 

severe weather is not expected through tonight. 

No change has been made to the previous forecast. 

.Smith.. 11/25/2015 

Previous discussion... /issued 1024 am CST Wednesday Nov 25 2015/ 


A middle-level low over northwestern Nevada will progress into Utah while remaining 
loosely phased with a polar-branch short-wave trough moving across 
central Canada. At the surface...a cold front presently from the 
upper MS valley through Central High plains into northern inter-mountain 
region will advance eastward into the upper Great Lakes and southward into the 
southern High Plains. 

..cntrl/Southern Plains late tonight/early Thursday... 

A southwesterly low level jet will be maintained through the forecast period from the 
Southern Plains to middle-MS valley...enhancing poleward fluxes of heat and 
moisture ahead of the cold front. Considerable capping observed in 
the 12z radiosonde observation data suggests that a prolonged period of 
moistening/ascent --occurring largely through warm air advection and isentropic 
upglide-- will be necessary to condition the environment for thunderstorm 
development. This notion is consistent with latest model guidance 
which indicates an increasing probability for elevated thunderstorms toward 
12z Thursday from the eastern Texas Panhandle into central Kansas. The presence of 
only a weakly buoyant air mass will preclude any severe weather 

Elsewhere...sporadic lightning may accompany deeper convective 
elements forming over southern nm/far western Texas this evening. 
However...areal thunderstorm coverage appears too marginal to warrant 
inclusion of a general thunderstorm area. 


Mesoscale Discussion

acus11 kwns 211627 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 211626 

Mesoscale discussion 1992 
National Weather Service Storm Prediction Center Norman OK 
1026 am CST Sat Nov 21 2015 

Areas affected...portions of central Indiana 

Concerning...heavy snow 

Valid 211626z - 211830z 

Summary...observational trends suggest that the southern extent of a 
heavy snow band becoming established from northern Illinois to Southern Lower 
Michigan...is also extending into parts of central Indiana. Snowfall rates 
around 1 inch per hour will be possible with this activity into the 
afternoon hours. 

Discussion...the risk for heavy snow addressed in recently issued 
mesoscale discussion 1991 is extending southward into parts of central 
Indiana. Wet-bulb cooling within the boundary layer is encouraging 
the recent phase-change to...and maintenance of...snow. This is in 
association with a shield of precipitation advancing east-northeastward across 
the lower Great Lakes region. Surface observations at the 
Lafayette/purdue University ASOS indicate heavy snow...with a recent 
amdar sounding near Indianapolis suggesting deep near-/sub-freezing 
temperatures favoring efficient snow aggregation. These factors 
suggest that the heavy snow risk...with rates of 1 inch per 
hour...is extending southward into central Indiana. Present indications are 
that heavy snow will last into the afternoon hours....enhanced by 
ample 700-mb frontogenesis...and eventually maintained by 
deformation-zone related ascent. 

.Cohen.. 11/21/2015 

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


Latitude...Lon 40738724 41038614 41168508 41028478 40698507 40258604 
39728670 39638729 39928749 40338749 40738724