SPC May 18, 2017 0600 UTC Day 2 Convective Outlook

By Newsroom America Feeds at 18 May 02:09

SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1233 AM CDT Thu May 18 2017 Valid 191200Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM WESTERN NORTH TEXAS INTO SOUTHEAST KS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM CENTRAL TX INTO KS...EASTWARD TO THE MID-MS VALLEY... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM THE SOUTHERN AND CENTRAL PLAINS TO THE LOWER OH VALLEY...EASTWARD TO THE VA/NC COAST... ...SUMMARY... Severe thunderstorms are expected across the central and southern Plains into the middle Mississippi Valley Friday and Friday night. The most intense storms are expected from parts of north Texas through central Oklahoma and into southeast Kansas. Very large hail, damaging winds and a few tornadoes are all possible with these storms. Additional isolated strong storms are possible across parts of the lower Ohio Valley to the middle Atlantic coast. Hail and gusty winds could accompany any storms that develop in that region. ...Synopsis... The upper low/trough centered over the central/southern Rockies will eject northeast across the central and southern Plains on Friday. This will bring a band of strong southwesterly flow aloft across northern TX into the mid-MS Valley. Strong low-level south/southeasterly winds ahead of a surface low and dryline will maintain transport of rich boundary-layer moisture across the southern/central Plains vicinity. As the southern Plains surface low shifts northeast through the night, a warm front draped west to east from near the KS/NE state line into the mid-MS Valley will advance slowly northward through the period into southern IA, northern IL and central IN. Meanwhile, a surface dryline will surge eastward across OK and KS. These boundaries will be the focus for severe thunderstorm development through the period. Further east, A cold front located from southern OH into southern New England will track southward through the period. Thunderstorms, some potentially strong, may develop along/ahead of this boundary from the OH Valley into southeast VA/northeast NC in a moist and unstable environment. ...Southern/Central Plains to the Mid-MS Valley... A complicated scenario is unfolding across the region for Friday. A convective complex likely will be ongoing across parts of KS into MO/IL. This convection likely will be elevated but could still pose a hail threat given steep lapse rates and plenty of elevated instability. Additional morning convection is also possible across parts of TX into OK, though guidance varies on the extent and location of convection across this area. What guidance does agree on is that a very moist and unstable environment with very steep midlevel lapse rates and strong deep-layer shear will remain over the southern Plains. The position of the surface low will determine where the dryline and warm front are located and morning convection will impact where greatest destabilization in the vicinity of these boundaries occurs. At this time, it appears the most favorable boundary-layer conditions will exist from near the Red River vicinity of southwest OK/western North Texas into central OK along/ahead of the dryline. Discrete supercells capable of very large hail, damaging winds and perhaps a few tornadoes will be possible with these storms. The environment further to the north into southeast KS will be similar, though uncertainty is higher here given expected overnight convection on Thursday into Friday morning. Additional storms are expected to develop in the vicinity of the warm from north-central KS into northern MO. Capping concerns in this area, combined with likelihood of storms being elevated as they quickly move north of the front leads to greater uncertainty. However, very steep lapse rates and strong shear profiles will continue to support severe storms capable of very large hail. Heading into the overnight, one or more bowing complexes are expected to develop and track eastward across northern TX, OK, KS and MO. Further south into central TX, forcing will be weaker and convection will be more isolated. Still, the environment will support supercells, mainly capable of large hail, strong winds and perhaps a tornado. ...Lower Ohio Valley into Southeast VA/Northeast NC... Thunderstorms may develop in a moist and unstable environment ahead of a southward-sagging cold front. Upper forcing for ascent will be weak, as will deep-layer shear profiles. However, given steep lapse rates and moderate instability, brief, but strong storms are possible. Hail will be the main concern with these storms. ..Leitman.. 05/18/2017 Read more



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