SPC AC 020551

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1251 AM CDT Sat Jul 02 2022

   Valid 021200Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE
   NORTHERN HIGH PLAINS AND FROM THE MIDDLE ATLANTIC INTO SOUTHERN NEW
   ENGLAND...

   ...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.

   ...Synopsis...

   Large-scale pattern will not change appreciably over the next 36hr
   as upper ridging holds across lower latitudes into the northern High
   Plains, with broad troughing expected over the northeastern states.
   This flow regime will ensure seasonally strong flow aloft will
   extend from the Pacific Northwest-northern High Plains-northern
   Middle Atlantic. Several weak disturbances will traverse this flow
   field, though height changes will prove negligible through the
   period, especially where buoyancy is expected to support robust
   updrafts. Even so, several areas will likely experience
   isolated-scattered severe thunderstorm activity, namely: 1) interior
   Pacific Northwest, 2) northern/central High Plains, 3) middle
   Atlantic into southern New England, and 4) along a trailing boundary
   draped from KY into KS. The most concentrated corridors for severe
   will likely be across the northern High Plains and from northern VA
   into southern New England. In both cases severe wind gusts should be
   the primary severe threat, though hail can not be ruled out.

   ...Northern/Central High Plains...

   Latest satellite imagery and 00z model guidance suggest a weak
   short-wave trough over ID will top the ridge over eastern MT around
   peak heating. This feature is expected to aid convection across the
   northern High Plains where easterly low-level component maintains
   buoyancy within a very steep lapse-rate environment. Scattered
   strong/severe thunderstorms should develop then propagate southeast
   during the late afternoon/evening hours, as weak LLJ develops across
   western NE into southeast MT after sunset. Supercells are possible
   in this regime, but wind/hail are the primary risks as convection
   spreads downstream ahead of the weak short wave.

   ...Middle Atlantic to Southern New England...

   Modest westerly mid-level flow will extend as far south as the PA/MD
   border during the day as upper trough shifts east into QC. The
   trough will encourage a surface boundary to advance into southern
   New England, arcing southwest into the central Appalachians by 18z.
   This boundary should be the primary focus for potentially robust
   updrafts, within a sheared environment that favors organized
   multicell updrafts, and perhaps a few supercells. Strong surface
   heating ahead of the wind shift will contribute to steep low-level
   lapse rates, and this should aid potentially severe downdrafts with
   the strongest activity.

   ...KY-KS...

   Latest radar imagery depicts a small cluster of convection migrating
   across the central High Plains into southwest KS. A weak mid-level
   disturbance should progress downstream and likely aid convection
   along a front draped across KS/MO. Strong daytime heating in the
   wake of this feature should contribute to additional convective
   development later in the afternoon, possibly focused along
   aforementioned early-day convective outflow. Other isolated storms
   should also develop along the slow-moving front into the lower OH
   Valley.

   ...Pacific Northwest...

   Strong 500mb speed max is forecast to translate through the base of
   an offshore trough into southeast OR during the late evening. This
   feature will likely contribute to robust convection across interior
   OR, which will spread northeast as the exit region of this jet
   translates into the northern Rockies.

   ..Darrow/Squitieri.. 07/02/2022

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