SPC AC 021944

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0244 PM CDT Thu Jul 02 2020

   Valid 022000Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
   EVENING ACROSS WESTERN PORTIONS OF THE DAKOTAS...NEBRASKA AND
   KANSAS...

   ...SUMMARY...
   Scattered clusters of strong thunderstorms will continue to
   gradually develop late this afternoon and evening, mainly across the
   higher plains and southeastern portions of the plains into the lower
   Mississippi Valley.  Some of these may pose a risk for severe hail
   and wind.

   ...20Z Outlook Update...
   Categorical and probabilistic lines have been adjusted in an attempt
   to account for the gradual progression of synoptic and sub-synoptic
   features, and trends concerning ongoing destabilization which will
   impact convective potential through the remainder of the period. 
   This includes the eastward progression of the sea-breeze across the
   Florida Peninsula, the westward propagation of outflow across
   western/southern Mississippi, the southeastward propagation of
   outflow across eastern Oklahoma, and the ongoing initiation of
   storms across a number of areas.

   For details concerning the severe weather potential, please refer to
   the 1630Z Outlook discussion appended below and the latest SPC
   Mesoscale Discussions (including recently issued SPC Mesoscale
   Discussions 1077-1080.

   ..Kerr.. 07/02/2020

   .PREV DISCUSSION... /ISSUED 1118 AM CDT Thu Jul 02 2020/

   ...Dakotas and northwest NE...
   Morning water vapor imagery shows broad southwesterly flow aloft
   across northern High Plains.  One subtle shortwave trough is
   currently moving across central WY, and will begin affecting the
   western Dakotas by mid-afternoon.  Strong heating is occurring in
   this region, with dewpoints now in the 60s from the Black Hills
   southward.  This will yield an axis of very unstable air (MLCAPE
   over 3000 J/kg) and foster the development of scattered
   thunderstorms.  Activity will develop first over the Black Hills,
   then extend northward and southward through the late afternoon. 
   Supercells capable of large hail and damaging winds will be the
   initial concern, but a gradual transition to bowing structures and a
   more dominant wind threat will occur during the evening.

   ...Northeast CO/southwest NE/northwest KS...
   Forcing weakens with southward extent, with more uncertainty of
   details when/where convective initiation occurs over northeast CO
   and northwest KS. However, a consensus of 12z CAM solutions show a
   cluster of thunderstorms moving across this region late this
   afternoon and evening.  Forecast soundings show steep mid level
   lapse rates, large CAPE, and sufficient mid/upper level flow to
   support organized storms.  Large hail and damaging winds will be
   possible.  Shear decreases sufficiently over southwest KS to suggest
   that those storms that form will be less-organized, this will leave
   that area in MRGL risk.

   ...Eastern OK into AR...
   A cluster of ongoing thunderstorms and an associated outflow
   boundary is currently over southeast KS moving into northeast OK. 
   This activity is deep within the upper ridge, where winds aloft are
   weak and mid-level temperatures are warm.  Nevertheless, abundant
   low-level moisture and large CAPE values are present ahead of the
   southward-moving system.  This may lead to a few intense storms
   capable of gusty/damaging winds this afternoon and early evening.

   ...New England into northeast NY...
   No changes have been made to the outlook in this region. 
   Considerable low-level moisture and moderate CAPE are forecast
   across portions of New England and NY this afternoon, with scattered
   thunderstorms spreading southward from Quebec into the region. 
   Lapse rates are not particularly steep, and low-level winds are
   weak.  Nevertheless, a few strong/severe storms may affect this
   area, with occasional hail and gusty/damaging winds possible.

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   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 0100Z