SPC AC 011718

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1218 PM CDT Fri Jul 01 2022

   Valid 021200Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE
   MID-ATLANTIC TO THE NORTHEAST...AND ACROSS PORTIONS OF THE NORTHERN
   PLAINS...

   ...SUMMARY...
   Isolated to scattered severe thunderstorms capable of producing
   damaging winds and hail are expected Saturday across parts of the
   Northeast and Mid-Atlantic, as well as across parts of the northern
   Plains. Isolated severe thunderstorms may also develop across parts
   of the interior Pacific Northwest.

   ...Northeast into the Mid-Atlantic and Mid Mississippi Valley...

   A belt of stronger mid/upper westerly flow will overspread the
   region as an upper trough pivots eastward across the Great Lakes and
   New England. At the surface, a cold front is forecast to develop
   east/southeast across the Northeast and Mid-Atlantic. The front will
   extend westward into the Ohio and Mid-Mississippi Valleys, sagging
   southward across these areas through the end of the period. 

   Ahead of the front, a seasonally moist airmass will be in place,
   with mid/upper 60s F dewpoints common. While midlevel lapse rates
   will remain modest, heating into the 80s F will support 1000-2000
   J/kg MLCAPE. Deep-layer flow will remain mostly unidirectional,
   though increasing speeds with height will support 35-45 kt effective
   shear magnitudes across the Mid-Atlantic and southern New England.
   As a result, organized supercells and bowing clusters are possible.
   Steep low-level lapse rates and high PW values, combined with rather
   weak low-level shear will favor damaging gust potential. Modest
   lapse rates and somewhat warm temperatures aloft will limit the
   large hail potential, but any organized/sustained supercell could
   produce marginally severe hail. 

   Deep-layer flow will become weaker with westward extent along the
   front into the Ohio and Mid-Mississippi Valleys. However, surface
   dewpoints into the low 70s will support MLCAPE values as high as
   2000-3000 J/kg amid modest effective shear (20-30 kt). Widely
   scattered thunderstorm clusters along/ahead of the cold front could
   produce sporadic strong gusts through the early evening.

   ...Northern Plains...

   An upper ridge will be oriented across western WY/MT on Saturday.
   Northwesterly mid/upper flow will increase modestly over the region
   as several shortwave impulses cresting the ridge migrate
   east/southeast into the northern Plains. Southeasterly low-level
   flow will maintain modest boundary-layer moisture along/east of the
   surface lee trough extending southward from eastern MT toward
   WY/SD/NE border vicinity. Strong heating and steep midlevel lapse
   rates will support MLCAPE around 1500-2500 J/kg. Flow will generally
   be weak from the surface to around 600 mb before increasing to
   around 30-50 kt above 500 mb. However, vertically veering profiles
   will result in effective shear magnitudes around 35-45 kt,
   supporting organized convection. 

   Weak large-scale ascent and some warming between 850-700 mb may
   ultimately limit convective coverage. However, most forecast
   guidance is consistent in at least widely scattered supercells
   develop, with some propensity toward upscale development during the
   evening as a southerly low-level jet increases. Any cells that
   develop will have the potential for producing damaging gusts and
   large hail. If upscale development occurs, an accompanying increase
   in damaging wind potential is expected into parts of SD.

   ...Oregon/Northern Rockies Vicinity...

   The upper ridge axis initially oriented near ID/western MT will
   slide eastward as an upper low and associated trough develop
   south/east along the Pacific Coast. Increasing southwesterly flow
   and large-scale ascent ahead of the coastal trough will overspread
   the interior Pacific Northwest/northern Rockies vicinity. Low-level
   moisture will remain limited, though sufficient midlevel moisture
   and steep midlevel lapse rates will support modest destabilization
   (around 500-1000 J/kg MLCAPE). High-based cells capable of strong
   outflow winds and marginal hail will be possible as storms quickly
   progress northeast during the afternoon/early evening.

   ..Leitman.. 07/01/2022

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   NOTE: THE NEXT DAY 2 OUTLOOK IS SCHEDULED BY 0600Z