Webberweather53
Meteorologist
In light of the fact the Arctic April thread is being swamped with posts on this (mainly by @Myfrotho704_ @BufordWX, & myself), there's growing consensus on there being severe weather in some, way, shape or form for someone on this board next weekend, a high potential ceiling with this system, and given the threat begins within the next 5 days over Texas with the anticipation of forthcoming severe weather outlooks from the Storm Prediction Center (SPC), I think the creation of this thread is warranted. Details regarding the placement, breadth, and intensity of any severe weather are still yet to be ironed out, but most should keep a close eye on this over the coming week or so.
The synoptic-scale pattern features a cut-off upper level low emerging out of the southwestern US & southern Four Corners region with a retreating vortex over the Great Lakes & New England, a pattern we often associated w/ overrunning &/or winter storms in the southern US during Dec-Feb. The evolution of this pattern is still somewhat tenuous, but most models have trended towards the slower, aggressive, and more severe European solution, (with the GFS remaining a progressive outlier), and feature a strong area of low pressure forming over the southern Plains and Gulf coast states, which then rapidly lifts northward across the lower MS and Tennessee Valleys sometime on Easter Sunday &/or Monday. This should allow for sufficient boundary layer destabilization and a rapidly burgeoning warm sector, w/ strong moisture and warm air advection to overtake much of the deep south on Saturday, and especially Easter Sunday. In conjunction with strong instability that's hastened by Gulf of Mexico SSTs that are 1-2C (or more) above normal, an unusually (arguably record strong) strong 130-140 knot 200 hPa subtropical jet core that's being fueled by a CC Kelvin Wave over the Pacific should supply ample deep layer shear for organized convection, mainly in the form of supercells and/or multicellular clusters, with early hints at a primary threat of widespread, straight-line damaging winds & tornadoes, accompanied by an enhanced threat for hail over Texas on Saturday. In fact, the 12z EPS suite depicts a classic "double-barrel" or coupled jet structure with the thermally indirect left exit region and thermally right entrance region circulations superimposed onto one another over the lower MS and TN valleys on Easter Sunday, which favors very strong quasi-geostrophic forcing for ascent & rapid cyclogenesis over the southern US, further reinforcing the heightened potential for significant severe weather. As is often the case with strongly forced setups like this one, CAPE & storm mode are likely to be the biggest mesoscale wildcards that largely determine the overall character and evolution of this severe weather outbreak (i.e. less CAPE/linear storm mode >>> widespread wind damage/less tornadoes, more CAPE >>> large-scale tornado outbreak) & the warm, moist southwesterly flow off the Gulf into a relatively cooler air mass over the upper south (isentropic upglide) amidst potential ongoing convection ahead of the primary synoptic-scale forcing, is often a harbinger of substantial prefrontal convection that could significantly damper CAPE and limit the lateral extent of the warm sector. In the long run, this become a grave concern for areas well north of the Gulf Coast in addition to the potential for flash flooding. Regardless, it's also important to keep in mind, we're also near the relative climatological peak (mid-late April) for severe weather for many on this board, therefore severe weather outbreaks like this may potentially be, are somewhat commonplace at this time of the year and the large-scale ingredients tend to come together in larger quantities more frequently.
In summary/key takeaways:
a) A severe weather outbreak of some, way, shape, or form is becoming increasingly probable-likely somewhere over the southern US next weekend
b) Instability and deep layer shear should be more than sufficient to produce organized, intense moist convection over a large portion of the south, with primary threats of damaging winds & tornadoes
c) The overrunning nature of this setup increases the potential for widespread flash flooding, which will be a particular concern in areas near the periphery of the warm sector
d) A few synoptic and myriad of mesoscale details remain to be ironed out and will determine the timing, location, intensity, and breadth of this severe weather outbreak.
The synoptic-scale pattern features a cut-off upper level low emerging out of the southwestern US & southern Four Corners region with a retreating vortex over the Great Lakes & New England, a pattern we often associated w/ overrunning &/or winter storms in the southern US during Dec-Feb. The evolution of this pattern is still somewhat tenuous, but most models have trended towards the slower, aggressive, and more severe European solution, (with the GFS remaining a progressive outlier), and feature a strong area of low pressure forming over the southern Plains and Gulf coast states, which then rapidly lifts northward across the lower MS and Tennessee Valleys sometime on Easter Sunday &/or Monday. This should allow for sufficient boundary layer destabilization and a rapidly burgeoning warm sector, w/ strong moisture and warm air advection to overtake much of the deep south on Saturday, and especially Easter Sunday. In conjunction with strong instability that's hastened by Gulf of Mexico SSTs that are 1-2C (or more) above normal, an unusually (arguably record strong) strong 130-140 knot 200 hPa subtropical jet core that's being fueled by a CC Kelvin Wave over the Pacific should supply ample deep layer shear for organized convection, mainly in the form of supercells and/or multicellular clusters, with early hints at a primary threat of widespread, straight-line damaging winds & tornadoes, accompanied by an enhanced threat for hail over Texas on Saturday. In fact, the 12z EPS suite depicts a classic "double-barrel" or coupled jet structure with the thermally indirect left exit region and thermally right entrance region circulations superimposed onto one another over the lower MS and TN valleys on Easter Sunday, which favors very strong quasi-geostrophic forcing for ascent & rapid cyclogenesis over the southern US, further reinforcing the heightened potential for significant severe weather. As is often the case with strongly forced setups like this one, CAPE & storm mode are likely to be the biggest mesoscale wildcards that largely determine the overall character and evolution of this severe weather outbreak (i.e. less CAPE/linear storm mode >>> widespread wind damage/less tornadoes, more CAPE >>> large-scale tornado outbreak) & the warm, moist southwesterly flow off the Gulf into a relatively cooler air mass over the upper south (isentropic upglide) amidst potential ongoing convection ahead of the primary synoptic-scale forcing, is often a harbinger of substantial prefrontal convection that could significantly damper CAPE and limit the lateral extent of the warm sector. In the long run, this become a grave concern for areas well north of the Gulf Coast in addition to the potential for flash flooding. Regardless, it's also important to keep in mind, we're also near the relative climatological peak (mid-late April) for severe weather for many on this board, therefore severe weather outbreaks like this may potentially be, are somewhat commonplace at this time of the year and the large-scale ingredients tend to come together in larger quantities more frequently.
In summary/key takeaways:
a) A severe weather outbreak of some, way, shape, or form is becoming increasingly probable-likely somewhere over the southern US next weekend
b) Instability and deep layer shear should be more than sufficient to produce organized, intense moist convection over a large portion of the south, with primary threats of damaging winds & tornadoes
c) The overrunning nature of this setup increases the potential for widespread flash flooding, which will be a particular concern in areas near the periphery of the warm sector
d) A few synoptic and myriad of mesoscale details remain to be ironed out and will determine the timing, location, intensity, and breadth of this severe weather outbreak.
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