U.S. Severe Weather Forecast (Convective Outlook)

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Day Three

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acus02 kwns 200545 
swody2 
Storm Prediction Center ac 200544 


Day 2 convective outlook 
National Weather Service Storm Prediction Center Norman OK 
1244 am CDT Wed Jun 20 2018 


Valid 211200z - 221200z 


..there is a marginal risk of severe thunderstorms across the 
middle and lower Mississippi Valley...across central Montana...and 
over parts of the southern High Plains... 


... 
Scattered severe hail and wind is possible Thursday across parts of 
the middle and lower Mississippi Valley. Isolated hail is also 
possible across parts of the southern High Plains and northern 
rockies. 


... 
An upper low will travel southeastward across MO, with a belt of 
50-60 kt midlevel northwesterly winds moving from the Central Plains 
into the lower MS valley. At the surface, low pressure will develop 
toward the middle MS valley. A cold front will extend southwestward 
toward the arklatex by 00z, with a warm front extending east across 
the Ohio Valley. To the west, an upper high will be centered over AZ, 
with a low-amplitude shortwave flattening the ridge over the 
northern rockies where a cold front moving into Montana and Wyoming. 


..mid to lower MS valley... 
Cool air aloft with the upper trough and ample low-level moisture 
will lead to areas of 1000-2000 j/kg MUCAPE from Texas to Illinois. 
Complicating this forecast scenario will be widespread precipitation 
and clouds early in the day. However, a plume of heating and 
steepening low-level lapse rates is expected to develop mainly along 
and west of the MS river. Given cool temperatures aloft, an arc of 
diurnal re-development is expected. Hail and wind will be possible, 
and portions of the area may eventually be upgraded to a slight risk 
once predictability issues decrease in later outlooks. 


..central and southwest Montana and vicinity... 
Lift associated with the upper trough and cold front will lead to 
scattered storms during the afternoon. Steep lapse rates and 
lengthening hodographs will favor cells and/or small bows capable of 
large hail or damaging winds. 


..southern High Plains... 
Strong heating along with 50s f dewpoints will lead to a pocket of 
1500 j/kg MUCAPE by late afternoon. Weak southeasterly surface winds 
will lead to sufficient convergence for isolated afternoon storms 
mainly over northeast nm. Straight hodographs and northwest flow 
aloft will favor slow, southeastward-moving cells capable of 
marginally severe hail. 


..maximum risk by hazard... 
Tornado: 2% - marginal 
wind: 5% - marginal 
hail: 5% - marginal 


.Jewell.. 06/20/2018 


$$