U.S. Severe Weather Forecast (Previsión convectiva)

día tres

acus01 kwns 171303 
Storm Prediction Center ac 171302 

Day 1 convective outlook corr 1 
National Weather Service Storm Prediction Center Norman OK 
0702 am CST Tue Jan 17 2017 

Valid 171300z - 181200z 

..there is a marginal risk of severe thunderstorms southern Texas... 

Corrected for thunder line 

Isolated severe storms may develop across parts of southern Texas, 
mainly this evening into tonight. Large hail, locally damaging 
winds, and a brief tornado are possible. 

..southern Texas... 
A slow-moving cold front will become quasi-stationary across the 
coastal plain into the brush country today. Neutral mid-level height 
change is expected over the warm sector, downstream of a dampening 
shortwave trough ejecting from the Gulf of California towards the Texas 
Panhandle. However, an increase in low-level warm air advection will 
occur along and north of the front this evening, likely yielding 
scattered, mostly elevated storms across parts of central Texas. 
Farther east, weaker warm-air advection should still be sufficient 
for isolated storms forming across the coastal plain overnight. 

While low-level moisture should remain rich within the warm sector, 
relatively warm upper-level temperatures as sampled by 12z Corpus 
Christi and Brownsville soundings should limit total buoyancy. In 
conjunction with 35-45 kt effective shear and modest low-level 
hodographs, setup should favor weak, transient updraft rotation in a 
few cells embedded within a predominant cluster-type Mode. Isolated 
severe hail appears to be the main hazard, but locally damaging 
winds and a brief tornado may occur, considering the high quality 
low-level moisture. 

.Grams.. 01/17/2017 


Mesoscale Discussion

acus11 kwns 170037 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 170036 

Mesoscale discussion 0063 
National Weather Service Storm Prediction Center Norman OK 
0636 PM CST Mon Jan 16 2017 

Areas affected...central and northern lower Michigan 

Concerning...freezing rain 

Valid 170036z - 170630z 

Summary...precipitation rates are expected to slowly increase this 
evening as temperatures mostly remain below freezing. An initial mix 
of precipitation is expected to transition to mostly freezing rain 
by late tonight, with rates up to 0.05 inches per hour possible. 

Discussion...at 0030z, a shield of precipitation is slowly advancing 
northward across lower Michigan in advance of an upper trough and 
associated low pressure system moving out of the Central Plains. 
Substantial dry air in the lower half of the troposphere, evident on 
the 00z apx sounding, has limited precipitation rates thus far, but 
continued moistening will eventually lead to some increase in 
precipitation rates this evening as ascent continues within the 
warm-conveyor belt. 

An initial mix of precipitation types is expected early this 
evening, especially with northward extent, given a relatively weak 
warm nose and potential for some evaporative cooling of the column 
before saturation is achieved. Continued warm advection should 
result in a strengthening warm nose and erosion of the subfreezing 
layer near the surface, resulting in a transition to primarily 
freezing rain by later this evening. Surface temperatures will be 
somewhat marginal, especially across the southern part of the mesoscale discussion 
area, and a slow northward progression of the surface freezing line 
will occur as weak but persistent warm advection continues, with an 
eventual transition from freezing rain to rain possible from south 
to north during the overnight hours. 

.Dean.. 01/17/2017 

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


Latitude...Lon 43298610 43498644 44038644 44488615 44748606 45068565 
45028517 45008466 44758396 44478346 43958308 43588291 
43278323 43098373 43048427 43058512 43298610