SPC AC 022000

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0300 PM CDT Sun Aug 02 2020

   Valid 022000Z - 031200Z

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
   THE NORTHEAST AND CENTRAL/SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   A few tornadoes, damaging winds, and marginally severe hail will
   remain possible across the Northeast through mid-evening. Scattered
   large hail and severe wind gusts may also occur from southeast
   Wyoming to east-central New Mexico through the early evening.

   ...20Z Update...
   The main change with this update was to combine the two Slight Risk
   areas across the Northeast for consistency with recently issued
   Tornado Watch 410. Recent visible satellite imagery shows clearing
   across much of central/eastern NY and PA, where surface temperatures
   have generally warmed into the mid to upper 80s. Plentiful low-level
   moisture is also present across this region, with surface dewpoints
   ranging from the mid 60s to mid 70s (greater with southward extent
   into the Mid-Atlantic). Wind profiles from recent VWPs across this
   area show veering/strengthening through both low and mid levels. An
   18Z special sounding from ALB also sampled this favorable wind
   profile for severe storms, with around 50 kt of effective bulk shear
   present.

   Primary uncertainty remains overall storm coverage across the warm
   sector through the evening, as the more pronounced large-scale
   forcing for ascent associated with a northeastward-ejecting
   shortwave trough may remain displaced primarily in southern
   Ontario/Quebec. Regardless, potential for isolated to widely
   scattered storm development across the warm sector remains apparent.
   Damaging winds and isolated tornadoes remain the primary threats,
   although some hail may also occur with the more robust storms.

   A small eastward expansion has been made to the Slight Risk for
   large hail and severe wind gusts across the central/southern High
   Plains based on latest short-term observational and model trends.
   See Mesoscale Discussion 1379 and Severe Thunderstorm Watch 411 for
   more information on the near-term severe threat across this region.

   ..Gleason.. 08/02/2020

   .PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 02 2020/

   ...Northeast...
   Earlier small cluster of storms over northern NJ, located along a
   warm front, has weakened as it moved into southeast NY. Expect some
   increase in coverage/intensity in this general area through
   afternoon as the storms move in tandem with the warm front. Forecast
   soundings and high-resolution guidance depict favorable deep- and
   low-level shear profiles and primarily a cellular nature to storms
   this afternoon, supporting the potential for supercells exhibiting
   low-level rotation and a risk for a few tornadoes. Strong wind gusts
   and isolated severe hail will also be possible.  

   Farther north, large-scale ascent associated with perturbations
   ahead of the upper-level trough should support a second location
   with a more concentrated severe risk this afternoon/early evening. 
   MLCAPE of around 1000 J/kg and favorable supercell wind profiles
   will support a risk for all severe hazards.

   In between the Slight Risks anticipated storm coverage should be
   lower, however a conditional risk for all severe hazards will exist
   with any more isolated storms.

   ...Southeast WY to New Mexico...
   Generally north-northwesterly mid-level flow will persist between 
   a strong anticyclone over the Lower CO Valley and a broad trough
   from the Upper Great Lakes to the northwest Gulf. The best
   CAPE/shear space should exist along the Front Range from southeast
   WY along the I-25 corridor in CO/northeast NM as weak low-level
   easterlies sustain a feed of low to mid 50s surface dew points. The
   Slight Risk has been expanded north along the Front Range where
   latest high-res guidance and forecast soundings suggest scattered
   severe storms capable of large hail/damaging gusts. Scattered to
   widespread storms with a severe hail/wind risk are also expected to
   develop over northeast New Mexico this afternoon and evening.

   ...Florida...
   The current track of Tropical Storm Isaias is such that the risk for
   low-level rotation with bands of thunderstorms should remain
   offshore through 12z Monday.

   CLICK TO GET WUUS01 PTSDY1 PRODUCT

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