SPC May 19, 2017 0600 UTC Day 1 Convective Outlook

By Newsroom America Feeds at 19 May 2017

SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri May 19 2017 Valid 191200Z - 201200Z ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF SOUTHWEST OKLAHOMA INTO NORTHWEST TEXAS... ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE ENHANCED RISK AREA ACROSS PARTS OF THE SOUTHERN AND CENTRAL PLAINS EASTWARD INTO THE MID MISSISSIPPI VALLEY AND LOWER OHIO VALLEY... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS OUTSIDE OF THE SLIGHT RISK AREA ACROSS PARTS OF THE SOUTHERN AND CENTRAL PLAINS EASTWARD INTO THE MID MISSISSIPPI VALLEY AND LOWER OHIO VALLEY... ...SUMMARY... Severe thunderstorms associated with large hail and wind damage will be possible across parts of the southern Plains northeastward into the mid Mississippi Valley and lower Ohio Valley this afternoon and evening. The greatest chance for hail and a tornado threat appears to be across parts of southwestern Oklahoma into northwest Texas. Marginally severe thunderstorms may occur across parts of the central Appalachian Mountains and Mid-Atlantic this afternoon. ...Southern and Central Plains... An upper-level trough is forecast to move across the southern and central Rockies today as a 50 to 70 kt mid-level jet rounds the southeastern side of the trough. At the surface, a low is forecast to deepen across northwest Texas as a cold front moves slowly southward across west Texas into western Oklahoma. Much uncertainty exists concerning today's scenario due to the large amount of overturning that has taken place in the southern and central Plains. Several model solutions develop a cluster of thunderstorms this morning across west Texas along the front and move this cluster into western and central Oklahoma this afternoon. This could further hamper destabilization across the area concerning how today's scenario will play out. Further south, a moist and strongly unstable airmass remains across southern and central Texas. This airmass is expected to gradually advect northward into northwest Texas and southwest Oklahoma by afternoon. Some model solutions develop thunderstorms this afternoon along the northern edge of this strong instability in the vicinity of Wichita Falls and Lawton, Oklahoma. If this occurs, moderate deep-layer shear and steep mid-level lapse rates should support supercells with large hail. A tornado and isolated wind damage threat would also be possible especially as low-level flow increases during the late afternoon and early evening. Further to the northeast from the Ozarks northeastward into the lower Ohio Valley, a front is forecast to move southeastward across the region this afternoon. Thunderstorm development appears likely to take place along the front by mid afternoon with convection moving southeastward into the Ozarks and mid Mississippi Valley this evening. Surface dewpoints should remain in the mid to upper 60s F ahead of the front. Although areas of moderate instability appear likely to develop by afternoon, overturning from the previous day's linear MCS contributes to substantial uncertainty for today's scenario. NAM forecast soundings from Tulsa northeastward to Springfield and Indianapolis show 0-6 km shear in the 30 to 40 kt range suggesting supercells with large hail will be possible. However, cells may remain linear due to strong low-level convergence along the front. If multicell mode is favored, then wind damage could be the greatest threat late this afternoon into early evening. ...Ohio Valley/Central Appalachians and Mid-Atlantic... A low-amplitude upper-level ridge will be in place across the central Appalachian mountains today as a moist airmass remains located from the Ohio Valley eastward to the Mid-Atlantic. Widely spaced thunderstorms are forecast to develop this afternoon along an east to west gradient of instability from central Indiana eastward into northern Virginia. Forecast soundings along this corridor at 21Z generally show weak deep-layer shear profiles suggesting any severe threat will remain marginal. A few strong wind gusts would be the primary threat. ..Broyles/Mosier.. 05/19/2017 Read more



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