SPC May 12, 2019 1630 UTC Day 1 Convective Outlook

SPC 1630Z Day 1 Outlook
Day 1 Outlook Image

Day 1 Convective Outlook NWS Storm Prediction Center Norman OK
1122 AM CDT Sun May 12 2019 Valid 121630Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS SOUTHEAST STATES
AND TRANS-PECOS OF TX... ...SUMMARY...
Scattered damaging winds are expected across portions of the
Southeast States through early evening. A couple of storms producing
large hail are anticipated over the Trans-Pecos of Texas from 2 to 8
PM CDT. ...Southeast States...
Primary changes are to adjust probabilities to reflect ongoing
convection and expected placement of upstream frontal boundaries
during the late afternoon. MCS over the Apalachicola Valley is poorly simulated by most morning
CAM guidance, except for the HRW-ARW. Area VWPs sample a belt of
40-50 kt flow from 4-6 km AGL and the air mass downstream of this
MCS continues to slowly destabilize with surface temperatures
warming through the 70s into the upper 70s to mid 80s. It is
plausible this MCS may persist with strong gusts producing wind
damage. Downstream convective development should also occur along a
residual outflow boundary across south-central GA as differential
heating increases. Modified 12Z Charleston sounding suggests that
the air mass near the South Atlantic Coast south of the outflow
boundary would support MLCAPE to around 2000 J/kg. While low-level
hodographs will be modest, deep-layer shear should be sufficient for
a few organized multicell clusters/line segments with damaging winds
as the primary hazard. Farther north and west, there is some signal for convective
development along the cold front from central AL northeast into the
southern Appalachians and a separate corridor across southern VA
where convergence near that portion of the front will be strongest.
Destabilization across both regions will be limited by extensive
cloud cover ahead of the front, rendering relatively low confidence
in both severe storm coverage and intensity. Will generally maintain
MRGL risk probabilities for the late afternoon to mid-evening
threat. ...Trans-Pecos and Permian Basin...
Upper 40s to mid 50s surface dew points are prevalent and will
contribute to MLCAPE reaching 500-750 J/kg at peak heating. Weak
upslope flow downstream of an eastward-drifting closed upper low
over Sonora should foster isolated to scattered storm development
across southern NM and the Trans-Pecos during mid/late afternoon.
While low-level winds will be weak, an elongated hodograph with
adequate speed shear through the cloud-bearing layer should foster a
couple discrete cells with mid-level updraft rotation. These
slow-moving supercells may remain relatively longer-lived with
severe hail as the primary hazard. ..Grams/Wendt.. 05/12/2019 

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