SPC Mar 7, 2018 0830 UTC Day 3 Severe Thunderstorm Outlook

By Newsroom America Feeds at 7 Mar 2018

SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0147 AM CST Wed Mar 07 2018 Valid 091200Z - 101200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorms are possible Friday night in the vicinity of the Ozark Plateau, and across the northwestern Gulf of Mexico. At the present time, the risk for severe storms appears negligible (i.e., less than 5 percent). ...Discussion... Models indicate that the blocking upper ridge will remain prominent in the vicinity of Newfoundland and Labrador through this period. However, the center of the broad and deep closed low, initially to the east of the lower Great Lakes, is forecast to elongate and shift eastward toward the Canadian Maritimes, where renewed surface cyclogenesis may take place in response to forcing associated with an impulse pivoting around the low. As this occurs, it appears that cyclonic mid/upper flow east of the Mississippi Valley through the western Atlantic may lose some amplitude Friday through Friday night. Upstream, within the belts of westerlies emanating from the mid-latitude and subtropical Pacific, several short wave perturbations may progress through and to the east of the axis of larger scale ridging across the West. Guidance generally suggests that these may progress east of the Rockies into the High Plains by late Friday night. Perhaps in advance of the southernmost of these features, a modest surface cyclone may migrate southeastward out of the Texas/Oklahoma Panhandle vicinity into the Red River Valley. Most of these developments, however, remain points of considerable uncertainty due to sizable differences among the various models. This spread results in some uncertainty concerning the extent and placement of potential convective development. In general, though, thunderstorms seem most probable to initiate Friday night across parts of the western Gulf of Mexico, and late Friday night across parts of eastern Oklahoma into the Ozark Plateau. ...Central Plains/Ozark Plateau vicinity... Models indicate that lower/mid tropospheric lapse rates may steepen considerably through the period in response to differential thermal advection across southern portions of the central Plains toward the Ozark Plateau. This is expected to coincide with a fairly rapid, but perhaps still somewhat modest, moisture return off the Gulf of Mexico. By late Friday night, mid 60s F+ surface dew points may spread into Texas coastal areas, with lower 60s through much of central Texas and mid 50s+ north of the Red River into eastern Oklahoma. As the leading edge of the better moisture return begins to encounter weaker inhibition, and perhaps stronger forcing for ascent associated with warm advection along a 30-40 kt southwesterly 850 mb jet, most guidance indicates at least scattered thunderstorm development late Friday night across central/eastern Oklahoma into the Ozark Plateau. It might not be out of the question that hail could accompany strongest storms. Low severe probabilities could be introduced in later outlooks for this time period, once model discrepancies become better resolved. ...Northwest Gulf of Mexico... Perhaps in response to weak low/mid-level warm advection, and/or forcing associated with an impulse in the subtropical stream, models generally indicate that there will be an increase in thunderstorm development over the destabilizing Gulf of Mexico Friday night. Due to the variability among the models, it remains unclear as to the extent to which immediate Gulf coastal areas are impacted. ..Kerr.. 03/07/2018 Read more



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