SPC AC 020538

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1238 AM CDT Sun May 02 2021

   Valid 021200Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE LOWER
   MISSISSIPPI VALLEY AND CENTRAL GULF COAST...AND PARTS OF THE CENTRAL
   HIGH PLAINS...

   ...SUMMARY...
   Severe thunderstorms are possible today across much of the lower
   Mississippi Valley and central Gulf Coast.  A couple of tornadoes,
   damaging gusts, and marginally severe hail are possible with this
   activity.  Strong to severe thunderstorm development is also
   possible over the central High Plains, where large hail and severe
   gusts are the threats.

   ...Lower MS Valley...
   A mid-level low initially over northeast TX will move northeast and
   weaken into a deamplifying trough and reach the lower OH Valley by
   early Monday morning.  A destabilizing warm sector during the day to
   the south of a warm front, will facilitate a continuation of
   thunderstorm activity over the central Gulf Coast states during the
   day.  The aforementioned thunderstorm cluster, amidst strong
   southwesterly 500 mb flow, is expected to be ongoing early Sunday
   morning across LA and move east across MS into AL during the day.  A
   conditional risk for a few tornadoes, in addition to damaging gusts,
   will accompany the thunderstorms near the Gulf Coast and this threat
   could persist into the evening.  Farther northwest during the
   afternoon, gradual destabilization will likely occur over northern
   LA into AR and contribute to 250-1250 J/kg MLCAPE.  This separate
   area of potential concern is forecast in closer proximity to the
   mid-level wave, where a 40-kt LLJ is forecast to enlarge hodographs.
   It is possible a bi-modal tornado threat develops during the
   afternoon across both the Gulf Coast and lower MS Valley.  The loss
   of heating during the evening will likely result in storms weakening
   and a cessation of the severe risk by mid evening.

   ...Central High Plains...
   A southeastward-advancing cold front and dryline will intersect
   across east-central CO/west-central KS this afternoon. Upslope
   low-level flow will result in surface dewpoints as high as the low
   50s beneath steep midlevel lapse rates, resulting in 1000-2000 J/kg
   MLCAPE. Thunderstorms are expected to develop near the Front Range
   with additional storm activity expected to develop farther east over
   the central High Plains.  Effective shear 25-35 kt may support a few
   transient supercell structures and organized multicells initially
   capable of large hail.  The steep lapse rates will also favor severe
   gusts with the more intense convective cores.  As the cold front
   surges south/southeast during the evening, some upscale development
   is possible as convection shifts eastward into western KS. 

   More isolated convection is expected southward toward the Oklahoma
   Panhandle near a dryline.  A few storms could develop over the
   higher terrain of northeast NM and shift eastward across the OK
   Panhandle, producing hail and localized severe gusts. This activity
   will remain tied to the dryline and diurnally driven, with severe
   potential decreasing after sunset.

   ...Southern MN into central WI...
   A mid-level speed max initially over MN during the morning is
   forecast to quickly move east into Lower MI by early evening.  The
   northern periphery of a modestly moist warm sector will protrude
   north into parts of the Upper MS Valley.  Model guidance suggests
   dewpoints approaching 60 deg F during peak heating.  Although
   forcing will be rather weak and focused near the west-southwest to
   east-northeast frontal zone, a few strong storms could develop. 
   Isolated hail/wind may be a localized threat for a few hours during
   the late afternoon/early evening before this activity weakens.

   ..Smith/Lyons.. 05/02/2021

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z