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[SWDDY3]
USA Weather - Severe Weather Division
Day 3 Severe Weather Outlook
01:40 AM EDT Wednesday, May 19, 2004
Severe Weather Outlook for Friday,May 21st, 2004...
Outlook Valid 0500z Friday - 0500z Saturday>
National Synopsis
High pressure in the Gulf will all for WAA to engulf the mid section of the country. Low pressure will develop as a shortwave ejects out of the Rockies into the Upper Midwest by 18z. A new upper air system will bring some showers and storms to the Pacific Northwest as a wet pattern begins for that area.
Nebraska, Iowa, Southern Minnesota, Northeast Kansas, Central Illinois and Indiana
***A slight risk of thunderstorms has been placed for this area***
Current analysis indicates that severe convection is quite likely across this region on Friday. Shortwave will dive into the region by 18z ejecting a 500mb cool pool across portions of West Central IA. This coupled with the LLJ axis nosing in will provide a good environment for strong to severe storms. By 21z strong instability will be in place along with deep layer shear values to 50 knots. SBCAPE's to 4000+ J/kg coupled with LI's of -7 to -9° C will allow for a very unstable environment and a breeding ground for severe thunderstorms. By 00z a new shortwave will kick out into W South Dakota and help get the SFC low pressure area of 997mb on the move. New convection is expected in western portions of the slight risk area as an H7 dry slot will punch into the region. Due to SRH values, deep layer shear values, SR Inflow, and Boundary Layer Dewpoints; supercells with the and tornadoes could be possible in the region. A categorical upgrade is possible in later outlooks.
Mid Atlantic
***A slight risk of severe thunderstorms has been placed for this area***
MCS structure will continue to march eastward from Day 2 period and give the chance of some severe weather in the area. Strong instability suggests that storms could grow rather severe as they move into this region. Rather uni-directional wind fields makes for mainly a wind damage event in the region. Tornadic potential currently is very low. Some large hail will be possible with the strongest storms that sustain violent updrafts.
Mississippi, Alabama, and Georgia
Scattered Thunderstorms will contiue in the afternoon hours as strong instability and little CINH overtake the area. Diurnal heating along with pesky outflow boundarys will kcik up the 925mb mixing ratios and allow for convection to develop. Some storms could take on "pulse severe" characteristics. Main threats from thest storms will be heavy rainfall, dangerous lightning, very small hail, and brief wet microbursts.
TRIGONA/
ADAIR 
