SPC AC 261720

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1220 PM CDT Fri Jun 26 2020

   Valid 271200Z - 281200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS EASTERN OHIO TO
   THE MID-ATLANTIC AND SOUTHERN NEW ENGLAND COASTS...

   ...SUMMARY...
   Scattered afternoon thunderstorms may pose a risk for mainly
   damaging winds across much of New Jersey and Pennsylvania and
   portions of surrounding states on Saturday.

   ...Synopsis...
   A mid-level shortwave trough is forecast to move across parts of the
   Northeast during the day with a belt of stronger flow moving through
   the base of the trough.  A flattened mid-level ridge will remain
   over the southern High Plains.  Farther west, a mid-level trough
   will amplify over the Pacific Northwest during the period.  
   In the low levels, a very weak/ill-defined baroclinic zone is
   forecast to extend from the lower Great Lakes region
   west-southwestward across the Midwest/Ohio Valley states and then
   westward to the central High Plains.  In the West, a strengthening
   cold front will shift southeastward across northwestern portions of
   the country, reaching as far east as the northern High Plains
   overnight.

   ...Eastern Ohio to Long Island...
   Convection is expected to be ongoing Saturday morning and casting
   uncertainty regarding the magnitude of destabilization, especially
   in NY.  Yet, models indicate a belt of strong 700mb flow will
   overspread much of PA into NJ during peak heating with steep 0-3 km
   lapse rates.  Several clusters/bands of thunderstorms are forecast
   to develop by midday/early afternoon and move east into a
   destabilizing airmass over the Delaware River Valley.  It is over
   eastern PA, NJ, and perhaps as far north as the lower Hudson Valley
   that a greater concentration of strong to severe gusts (50-70 mph)
   may occur.  Because of the uncertainty at this time, will defer to
   later outlooks for a possible upgrade to 30-percent wind
   probabilities.  Farther south over the MD/VA vicinity, lower storm
   coverage is expected amidst weaker westerly flow.  However, ample
   heating and stronger storms possibly developing over the terrain and
   spreading east, may pose a risk for wind damage during the mid-late
   afternoon and early evening.

   ...Parts of Montana into southeastern Idaho...
   As a cold front shifts southeastward across the region ahead of the
   digging upper trough, daytime heating will yield weak
   destabilization -- hindered by a relatively dry low-level airmass. 
   Still, CAPE should be sufficient to foster isolated storm
   development by mid to late afternoon with a cluster of scattered
   storms possible during the evening across south-central MT.  A few
   of the stronger storms will probably pose a hail/wind threat.  The
   severe risk will likely diminish by late evening.

   ...Ohio and Mid Mississippi/lower Missouri Valleys...
   As several mid-level disturbances embedded in moderate westerly
   mid-level flow traverse this region, isolated to scattered
   thunderstorms are expected to develop in a destabilizing airmass --
   in the vicinity of a weak/diffuse baroclinic zone lying across the
   area.  Ample instability and modest deep-layer shear are expected to
   contribute to a few stronger storms capable of producing locally
   damaging winds and marginal hail.

   ...Central High Plains/central Plains...
   As weak disturbances aloft move out of the Rockies and across the
   High Plains, daytime heating/modest destabilization should result in
   isolated to widely scattered storm development -- initially near a
   lee trough, and then possibly spreading into Kansas with time.  Very
   steep low-level lapse rates will favor isolated severe gusts with
   the stronger downdrafts.

   ...Lower Mississippi Valley into the Southeast...
   A weak short-wave trough will cross the central Gulf Coast region
   and vicinity Saturday.  Afternoon heating/destabilization -- aided
   by a very moist low-level airmass -- will fuel development of
   scattered thunderstorms, though areas of potentially greater storm
   coverage remain difficult to narrow down at this time.  Still, with
   enhanced mid-level westerly flow atop the region, a few stronger
   storms/storm clusters -- capable of producing locally damaging winds
   and possibly marginal hail, can be expected, before weakening by
   early evening.

   ..Smith.. 06/26/2020

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