Current Severe weather and Day 3

[Allexpert Mike]

Since NEMAS is having technical difficulties right now I just made products (MSA and SWODY 3) here they are. When NEMAS comes back up i'll be posting along with other great forecasters in the SWO.


MSA------------------

A surface Low in Minnesota is extending a cold front down through the Plains and as the front approaches we see a MCS moving eastward into Southern Illinois and Kentucky. Latest RUC data shows s/w energy along this front to continue and as we head through the evening hours we expect more severe cells and clusters to develop. Low-level lapse rates are conditionally unstable with lapse rates of 5-6C/KM. Strong low-level jet streak over the threaten area is increasing the LLJ to around 40KTS. This is leading to strong waa and we can see the strong waa increasing the instability with TT index ranging from 55-60dC. Deep layer shear is strong and sufficient with deep layer shear to 45KTS along with BRN shear values around 75m^2/s^2. Low-level shear is very strong with 0-1km helicity values ranging from 300-350m^2/s^2. Strong diffluent flow aloft to 60KTS along with vertical shear profiles shows that super cells are possible. Strong low-level storm inflow to around 25KTS shows potential for some isolated tornadoes in these super cells that will form. 9-11km storm relative winds show the potential for HP super cells. With intense water loading will see CAPE values decrease but the threat is there for rain wrapped tornadoes, which prove to be the most deadly. Will keep you updated through the afternoon-evening on this severe situation. Main threats are for damaging winds and large hail up to 2.0", tornadoes are also a threat.




---------SWODY 3------------

Synopsis-

Were watching two areas of concern for severe potential. One area will be with a strong surface Low currently over the Northern High Plains, which will ride the northern stream into Eastern Canada dragging a cold front through the Eastern US. This front will stall in the Middle Atlantic with split flow pattern allowing for wind fields to be weak in the upper levels and as a result nothing will push this front out. Also strong upper level ridging off the Southern half of the Eastern US will also aid in the front stalling. Back West another strong low pressure system in Southwestern Canada will get organized and move eastward extending a cold front down through the Plains, which will lead to another threat for some severe weather.

Plains-

As the front drops down strong s/w energy along the frontal boundary will increase the precipitation in intensity along with the strong UVV's. UVV's will be strong due to the strong low-level speed convergence along the front and also the moderate PVA with the H5 s/w's. A surface wave of low pressure will develop and ride along the stationary frontal boundary (the front stalled out in Middle Atlantic and Southeast). Strong LLJ structure will lead to strong waa and isentropic lifting increasing thermodynamic instability and dynamic lifting. Low-level jet streak ahead of the front will increase the flow in spots up to 50KTS. Strongest deep layer shear will be behind the front not being to much help for severe weather, however strong mid-level jet streak will increase deep layer shear to around 40KTS. Adding to the strong instability will be the TT index ranging from 50-55dC, and also to add model soundings show at 12z areas that will be in the threat will see the K-index increase to the mid-upper 30's. SBCAPE values will be rather high with values ranging from 1500-2500j/kg. Strong directional and unidirectional shear teaming up with strong lifting between -3 to -6C we could see threat for some strong rotating updrafts leading to a threat for some large hail and tornadoes. Damaging winds will also be a threat in the stronger cells.

Southeastern US/MS Valley-

As the front sags down southward will see our threat for severe weather enter the picture. Strong LLJ structure will feature wind speeds of 30-40KTS. WAA and GOM advection will be strong with the help from strong surface-low-level ridging off the Southeastern coast throwing back a return flow of moisture. Very weak MLJ structure with more of a southerly mid level flow shows us that training won't be a problem. Deep layer shear will be strong with high BRN shear values. Cap will be very weak with a slight contrast between LCL and LFC showing us convection will really fire up in the afternoon hours. Strong instability with the help from the strong waa will be evident with TT index ranging from 45-50dC. Model sounding show SWEAT around 350 with the K-index rising to the mid 30's during the afternoon hours. Cloud cover will dominate all day preventing diurnal heating, which will keep instability down, but nonetheless instability will still be strong. With weak wind fields aloft the tornadic threat will be low, however latest guidance shows the entrance region of a strong upper level jet streak trying to make it into the MS valley so will continue to watch that as it may bring more of a tornadic threat given the strong directional and deep layer shear profiles. Super cells will be common given vertical shear profiles along with strong upper level jet diffluence.