SPC AC 060555

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1255 AM CDT Mon May 06 2024

   Valid 061200Z - 071200Z

   ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
   WESTERN/CENTRAL/NORTHEAST OKLAHOMA INTO SOUTH-CENTRAL AND SOUTHEAST
   KANSAS...

   ...SUMMARY...
   Numerous severe thunderstorms are expected to develop and move
   eastward Monday afternoon through Monday night across parts of the
   southern/central Plains. Multiple intense, long-track tornadoes,
   very large to giant hail, and severe/damaging winds all appear
   likely.

   ...Synopsis...
   A potent shortwave trough is evident in water vapor imagery this
   evening within the Great Basin. This feature will continue eastward
   into the Four Corners by early this morning. An initial speed max is
   expected to eject into western Kansas. By late afternoon into the
   evening, another speed max will approach western Oklahoma. Deep
   low-level moisture is already being observed in the BRO 00Z
   sounding. Surface observations also show low 70s dewpoint as far
   north as the DFW Metroplex this evening. As the trough approaches,
   this moisture should stream northward. The overall synoptic setup
   indicates a severe weather outbreak occurring this afternoon and
   extending into the evening and parts of the overnight period.
   Multiple intense, long-track tornadoes are expected, especially in
   parts of southern Kansas into Oklahoma. Very-large hail of up 2-4
   inches can also be expected with intense supercells. Severe gusts
   may initially be isolated, but storm coverage should increase with
   time as well as the mode becoming more linear. As this occurs,
   severe gusts, some up to 80 mph, will become more common.

   ...Oklahoma into southern Kansas...
   Intense storms are expected across these areas by late afternoon.
   Storm coverage is likely to initially be greatest in south-central
   Kansas given the greater and earlier upper-level forcing. Isolated
   storms will still be possible along the dryline in western Oklahoma
   as strong heating in the Texas Panhandle should support dryline
   circulations that should at least locally erode inhibition. By the
   evening, greater forcing for ascent will arrive in western Oklahoma.
   Flow aloft will be nearly perpendicular to the dryline, which will
   favor a discrete storm mode. Even as the weak Pacific front
   overtakes the dryline, low-level forcing is not expected to be
   strong enough to promote substantial upscale growth, especially when
   coupled with continued strong shear across the boundary.

   Overall, there appears to be prolonged opportunity for discrete
   storms to form across western Oklahoma into parts of southern
   Kansas. While the environment during the afternoon will certainly
   support intense, long-track tornadoes, concern only grows by early
   evening. Discrete storms are expected to move eastward into an
   intensifying low-level jet core in central and eastern Oklahoma into
   southeast Kansas. Surface-based activity will likely persist into
   the evening and even parts of the overnight, given continued influx
   of moisture and weak capping. The time frame of greatest concern for
   intense tornadoes is from 03-06Z across central into northeast
   Oklahoma.

   This is a high-end environment. An upgrade to a tornado-driven High
   Risk was considered. There remains some lingering uncertainty with
   regard to the number of intense tornadoes that will occur. An
   increase in tornado probabilities will certainly be warranted should
   confidence in coverage and preferred corridors increase.

   ...Western Kansas into Nebraska...Iowa...Missouri...
   Convection will likely initiate in western Kansas into southwest
   Nebraska earlier than elsewhere given the timing of the upper-level
   forcing. Furthermore, a linear mode should more quickly become
   established due to the deep layer shear being oriented much more
   parallel to the initiating boundary than farther south. Buoyancy
   will generally decrease with northward extent. That being said,
   moisture will continue to push northward through the day and into
   the evening. Mid 60s F dewpoints could reach southeast Nebraska.
   Strong deep-layer and low-level shear will promote an organized line
   of convection capable of wind damage and QLCS tornadoes (some
   potentially strong). There is some potential for discrete storms to
   form ahead of the anticipated line. These storms would pose a
   greater threat for significant tornadoes. Large to very large hail
   will likely be more likely in western and central Kansas and
   coverage of very large hail will be conditional on how long a
   discrete mode is maintained.

   ...South Dakota...
   Richer low-level moisture (upper 50s to perhaps near 60 F dewpoints)
   will reach portions of central into northwest South Dakota. A narrow
   zone of instability is expected to develop by the afternoon between
   the cold and warm front. Large hail and severe  gusts will be the
   main threats, but low-level shear will be sufficient for a tornado
   or two.

   ...Edwards Plateau into Texas Rolling Plains...
   Storm coverage this far south should generally be much more isolated
   on account of weak and nebulous forcing. However, a strong enough
   dryline circulation could initiate convection within a strongly
   unstable and sheared environment. Should storms form, large hail and
   severe wind gusts would be possible.

   ..Wendt/Darrow.. 05/06/2024

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