U.S. Severe Weather Forecast (Convective Outlook)

Day Three

acus01 kwns 191615 
Storm Prediction Center ac 191613 

Day 1 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1013 am CST Friday Dec 19 2014 

Valid 191630z - 201200z 

..no severe thunderstorm areas forecast... 

isolated thunderstorms will remain possible into this evening across 
parts of the western and central Gulf Coast states. 

..wrn/central Gulf Coast... 
Low-amplitude shortwave trough over East Texas will rapidly progress east/NE 
towards the southern Appalachians through early Sat. With only modest 
low-level warm air advection atop a near-surface stable layer and the reinforcement 
of static stability with a broad stratiform rainfall 
shield...quasi-stationary front across the northwest/N-cntrl Gulf should 
remain offshore except near the mouth of the MS river as a weak 
cyclone moves along the frontal zone. 

Thunderstorm coverage has already substantially diminished compared to 
earlier this morning. Given the modest large-scale ascent and dearth 
of elevated buoyancy/instability sampled in 12z lch/shv/lix 
radiosonde observations...prospects for inland thunderstorm activity appear rather limited. 
Renewed thunderstorm development will remain possible along the offshore 
frontal zone...with the northern periphery of scant buoyancy supporting a 
risk for sporadic lightning strikes over parts of the coastal plain. 

.Grams/corfidi/Gleason.. 12/19/2014 

Mesoscale Discussion

acus11 kwns 170924 
sels mesoscale discussion 
Storm Prediction Center mesoscale discussion 170924 

Mesoscale discussion 1980 
National Weather Service Storm Prediction Center Norman OK 
0324 am CST Wednesday Dec 17 2014 

Areas affected...portions of coastal Southern California 

Concerning...severe potential...watch unlikely 

Valid 170924z - 171130z 

Probability of watch issuance...5 percent 

Summary...limited risk for a marginally damaging wind gust or two -- 
or possibly a brief/weak tornado -- is evident over coastal portions 
of Ventura/Los Angeles/Orange counties in Southern California early this morning. 
Ww issuance will not be required. 

Discussion...latest radar and lightning data depict a small cluster 
of thunderstorms crossing The Channel islands area and adjacent 
coastal Southern California at this time...coincident with a middle-level cyclonic 
circulation center moving east-southeastward across this area per WV loop. 

Despite surface dewpoints only in the low 50s...relatively steep 
lapse rates through the lower and middle troposphere are 
contributing to marginal cape /a few hundred j/kg per objective 
analyses/...thus fueling updrafts which are extending through the 
mixed-phase /-20 c/ layer. 

While area vwps depict relatively modest /20 to 30 knots/ swlys through 
500 mb...backed/sely low-level winds ahead of the storms seem to be 
aiding in occasional weak/short-lived low-level circulations in 
stronger cells -- as observed by kvtx /Ventura/ WSR-88D. Given the 
sustained/weakly rotating storms...a very isolated/low-end severe 
risk may spread onshore over the next couple of hours. With that 
said...any risk for strong winds and/or a brief/weak tornado should 
remain well below thresholds required to consider ww issuance. 

.Goss/Thompson.. 12/17/2014 

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


Latitude...Lon 33831966 34421979 34531953 34431907 34101833 33781773 
33401780 33231830 33171948 33391973 33831966