Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Sun Jan 15 2017 Valid 152000Z - 161200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF WEST-CENTRAL/NORTH-CENTRAL TX TO FAR SOUTHERN OK... ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE SOUTHERN PLAINS... ...SUMMARY... Scattered severe thunderstorms will be possible this afternoon and tonight across west-central to north-central Texas and southern Oklahoma. A few tornadoes, damaging winds, and large hail are anticipated. ...20Z Update... The severe threat across southwest into west TX is expected to continue increasing through the afternoon. The only change to the prior outlook across this area has been to account for the eastward movement of the cold front and line of pre-frontal convection. The northern extent of the appreciable severe risk remains confined by a shallow cold and stable airmass over the TX Panhandle into southwest OK. For more near-term meteorological details (through ~2130Z) on the developing severe risk across southwest TX, see Mesoscale Discussion 52. There is some concern that isolated showers and thunderstorms ongoing over parts of east TX in a warm air advection regime may become surface based this afternoon and evening. Low to mid 60s surface dewpoints across this region will continue to shift northward into the Metroplex over the next few hours as a warm front lifts northward. RAP/HRRR forecast soundings suggest that an isolated tornado threat may develop with pre-frontal warm sector convection as a low-level jet strengthens across central/north TX in the 00-03Z timeframe. Have accordingly made a minor adjustment to the 5% tornado probabilities in/around the Metroplex to account for this scenario. ..Gleason.. 01/15/2017 .PREV DISCUSSION... /ISSUED 1030 AM CST Sun Jan 15 2017/ ...Portions of Texas into southern Oklahoma... Mid/late morning water vapor satellite imagery shows an east/northeastward-moving upper low nearing the El Paso/far west TX vicinity. This low will continue northeastward and increasingly take on a negative tilt over the southern High Plains. Ahead of this system, 30-45 kt southerly low-level winds (1-3 km above ground level) will continue to transport a seasonally moist air mass northward, with lower 60s F surface dewpoints expected to reach parts of north-central/northeast TX late today, while some middle 60s F surface dewpoints will reach parts of south-central TX/Hill Country. Persistent low clouds and continued convection to the north of a warm front cast some uncertainty on the exact degree of destabilization later today, particularly with northward extent into north-central TX and far southern OK. Current thinking is that increasingly strong thunderstorms should develop by around mid-afternoon initially across southwest TX in vicinity of the Permian Basin and western Edwards Plateau. The most numerous storms through early evening should occur near the eastward-advancing front across west-central TX. However, sufficient low-level moisture and modest capping may allow for some front-preceding surface-based storms to develop late this afternoon/early evening across the Edwards Plateau/Hill Country vicinities toward the I-35 corridor of north-central Texas. Given that deep-layer/low-level shear will be increasing through early evening, both initial semi-discrete/line-embedded supercells will be possible ahead of an increasingly prominent linear mode near the cold front this evening. Bouts of large hail will be possible especially with initial development across west TX this afternoon, but damaging winds and isolated tornadoes should become the primary risks into this evening across a large part of west-central/north-central TX.Read more
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