SPC AC 140600

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Thu May 14 2020

   Valid 151200Z - 161200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
   THE NORTHEAST STATES AND FROM SOUTHWEST OK INTO THE TX EDWARDS
   PLATEAU...

   ...SUMMARY...
   Severe thunderstorms are possible across portions of the Northeast
   States Friday afternoon as well as over portions of the southern
   Plains and Ozark Plateau Friday afternoon into Friday night.

   ...Northeast States...
   A northern-stream shortwave trough is forecast to progress quickly
   eastward/southeastward across the Great Lakes into the Northeast
   States on Friday. Strong mid-level flow attendant to this system
   will spread eastward just ahead of it while an associated surface
   low and cold front also move across the Northeast. Temperatures and
   dewpoints ahead of this front are forecast to reach the mid 70s and
   upper 50s/low 60s, respectively, resulting in modest instability.
   Thunderstorm development is anticipated during the afternoon as the
   front interacts with this instability. Low to mid-level flow will
   strengthen over the region as the shortwave trough approaches,
   contributing to both moderate vertical shear and fast storm motions.
   Fast-moving bowing line segments, which may eventually amalgamate
   into a coherent convective line, will be the predominant storm mode.
   Damaging wind gusts from these bowing segments will be the primary
   severe hazard, although some isolated hail may occur, particularly
   with any more cellular/discrete storms. Additionally, moderate
   veering of the low-level wind profiles will support a low-probably
   tornado potential with both discrete development ahead of the line
   and line-embedded circulations.

   ...Southern/Central Plains into the Ozarks...
   Showers and thunderstorms are forecast to be ongoing from eastern OK
   into southwest MO/northwest AR early Friday morning, supported by
   warm-air advection across the front near the OK/KS border. Evolution
   of this complex of storms will have a large influence on severe
   potential downstream across the remainding portions of OK and AR as
   well as across northwest/north-central/northeast TX. Current
   expectation is for a well-developed cold pool to emanate from this
   activity and surge southward/southeastward. Given the steep
   mid-level lapse rates anticipate across the entire region, isolated
   damaging wind gusts and/or hail may occur with the storms that
   develop along this boundary as it moves southward/southeastward
   across eastern OK/western AR through the early afternoon.

   By the early to mid-afternoon, new storm development would likely
   occur along the western periphery of this cold pool as it encounters
   a moist and increasingly unstable air mass across from central OK
   southwestward into southwest OK and adjacent northwest TX.
   Intersection between this cold pool and the dryline is also
   possible, leading to a localized triple point and resulting higher
   severe potential. However, this overall scenario is dependent on the
   presence of this cold pool, which is still uncertain at this
   forecast range, particularly with western extent.

   The uncertainty of the above scenario is countered by the more
   certain dry line initiation from the central TX Panhandle southward
   into the Big Bend. Convergence along the dryline will be augmented
   by increasing large-scale forcing for ascent attendant to an
   approaching shortwave trough. Temperatures in the low/mid 80s,
   dewpoints in the mid 60s, and mid-level lapse rates over 8 deg C per
   km will result in strong to very strong instability (i.e. MLCAPE
   over 3000 J/kg). Vertical shear will be weak but updrafts capable of
   very large hail are still possible. A quick linear transition is
   anticipated, with one or more convective lines possible. Higher wind
   probabilities may be needed in later outlooks once the location and
   strength of these convective lines become more predictability.

   ...Central High Plains...
   Upslope flow and increased surface convergence near a deepening
   surface low are anticipated Friday afternoon across southeast
   WY/northeast CO. These surface features will combine with
   strengthening mid-level flow and lift associated with an approaching
   shortwave trough to support thunderstorm development. A few of these
   storms may be able to produce isolated strong wind gust and/or hail.

   ..Mosier.. 05/14/2020

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