SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0228 AM CDT Mon Mar 09 2020 Valid 111200Z - 121200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS WEDNESDAY ACROSS THE OZARK PLATEAU VICINITY... ...SUMMARY... Strong thunderstorms may impact portions of the Ozark Plateau vicinity Wednesday, accompanied by at least some risk for severe weather. ...Synopsis... The transition to a less progressive regime characterized by increasing blocking appears likely to continue across the eastern Pacific. As this occurs, little, if any, eastward progression of the mid-level troughing and embedded closed low near and southwest of the southern California coast is forecast, and the closed low may actually shift southward some, away from the coast during this period. Broad downstream ridging may generally be maintained across much of the Gulf coast region. This may include rising heights across parts of the Mid South, in the wake of one short wave trough within a much more progressive branch of westerlies across southern Canada and the northern tier of the United States. However, a more vigorous perturbation is forecast to dig across the central international border area, and to the east of the northern Rockies, and this could lead to some suppression of the crest of the southern branch ridging, across the central Plains by late Wednesday night. Models indicate that this impulse will be accompanied by a southeastward migrating cyclone across the Canadian Prairies, and broad deepening surface troughing across the northern Plains/upper Mississippi Valley, south-southwestward through the south central Plains by 12Z Thursday. As all this occurs, instability supportive of areas of widely scattered to scattered thunderstorm activity will largely be confined to the southern tier of the United States. East of the Rockies, this is expected to generally remain along and south of a weakening frontal zone, initially extending across the southern Mid Atlantic coast into the Ozark Plateau and south central Plains. With low-level flow above the surface maintaining a substantial westerly component, little further moisture influx is expected off the Gulf of Mexico. But lower to mid 60sF surface dew points inland may contribute to weak to moderate boundary layer destabilization across parts of west central and northern Texas into the Ozark Plateau, and perhaps eastward through northern portions of the eastern Gulf states. ...Ozark Plateau vicinity... Models suggest that forcing for ascent near the southern periphery of the lead northern branch short wave trough may be contributing to a sustained, evolving cluster of thunderstorms across parts of northeastern Oklahoma at the outset of the period. This convection is expected to be aided by inflow of most unstable CAPE on the order of 500-1000 J/kg, on the nose of a 30-40 kt 850 jet accompanying a 50+ kt 500 mb speed maximum, contributing to an environment at least marginally conducive to severe hail and wind. It appears that this activity could continue east-southeastward along the frontal zone across the Ozark Plateau into portions of the Mid South during the day Wednesday. How long and how far remain unclear, as aforementioned large-scale pattern developments result in weakening forcing for this activity at some point. There are discrepancies within the various model output concerning this. The latest NAM, for example, suggests that a continuation of vigorous convection east-southeastward across parts of northern/central Alabama and Georgia might not be out of the question by late Wednesday evening. This will need to be monitored for possible adjustments in later outlooks for this time period. ..Kerr.. 03/09/2020
from SPC Convective Outlooks http://bit.ly/1CYpnJx
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