SPC AC 160600

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0100 AM CDT Mon May 16 2022

   Valid 161200Z - 171200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE MID-ATLANTIC AND NORTHEAST...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
   THE SOUTHERN HIGH PLAINS...

   ...SUMMARY...
   Scattered to numerous severe storms are expected Monday from central
   New York/western New England southward into the Carolinas. Damaging
   winds, hail, and a few tornadoes will be possible through about 00Z.
   In addition, scattered severe storms are expected to move from
   eastern New Mexico into the Texas Panhandle with a threat for large
   hail and severe wind gusts.

   ...Synopsis...
   A mid-level trough will move from the Great Lakes to the
   Mid-Atlantic during the day today. A 55 to 60 knot mid-level jet
   will round the base of this trough and overspread portions of the
   Mid-Atlantic during the afternoon/evening hours as the trough
   becomes negatively tilted. A surface low will develop along the
   frontal boundary and deepen through the day as it lifts northeast
   from western Pennsylvania into central New York. 

   Farther west, a ridge centered over the Rockies will deamplify
   through the day as several weak shortwave impulses eject from the
   broad trough over the eastern Pacific. The strongest of these
   mid-level impulses will move from southern California at 12Z this
   morning to the central Rockies by late this evening. 

   ...Mid-Atlantic into the Northeast...
   Storms should be ongoing at the beginning of the period along and
   ahead of the surface front from eastern Ohio into eastern Kentucky.
   Initially, instability will be limited due to the cool temperatures
   and meager moisture (mid-upper 50s dewpoints). However, expect storm
   intensity to increase by late morning as the boundary layer warms.
   The greatest instability is expected across eastern New York, and
   east of the Appalachian crests across the Mid-Atlantic where low 60s
   dewpoints are already in place this morning and are expected to
   increase further by early afternoon as the surface low deepens and
   brings a higher theta-e airmass poleward. 

   The line of storms will likely be fractured across western
   Pennsylvania and western New York during the morning, but it is
   expected to congeal into a squall line by mid-day as storms reach
   this reservoir of greater instability. In addition,
   lower-tropospheric flow is forecast to strengthen gradually through
   the day which should also aid in storm organization. 

   Strong instability and moderate lower tropospheric flow combined
   with the strong forcing should support widespread damaging winds
   along this squall line. However, modest lapse rates (6 to 6.5 in the
   low and mid levels) and DCAPE (300-500 J/kg) may preclude the
   potential for significant (65 kt) winds. 

   Moderately strong ascent atop an uncapped warm sector will likely be
   sufficient for some warm sector storm development ahead of the
   squall line. Moderate effective shear would support supercell storm
   mode from this activity with primary threats of large hail and
   damaging winds.

   ...Carolinas to the Gulf Coast....
   A relative minima in low-level instability is forecast across the
   Carolinas into Georgia this afternoon as dewpoints mix into the low
   60s ahead of the cold front. Some isolated storms remain possible
   with a marginal threat for large hail and damaging wind. The greater
   storm coverage is expected along the Gulf Coast where dewpoints
   should remain in the upper 60s to near 70, yielding moderate to
   strong instability. Mid-level flow will remain quite weak across
   this region, but may be sufficient for some multicell clusters. The
   weak shear and inconsistent storm coverage from 00Z CAM guidance
   precludes the need for a slight risk across this region. 

   ...Central and Southern High Plains...
   Low-level moist advection is occurring across the southern High
   Plains this morning with 50 degree dewpoints to the TX/New Mexico
   border. This will continue as lee cyclogenesis strengthens through
   the day. As a result, low to mid 50s dewpoints are expected near the
   dryline in eastern New Mexico by mid day. Mid-level height falls
   will overspread the southern and central High Plains by mid day and
   scattered storms are expected to develop along the dryline from
   eastern Colorado into eastern New Mexico by early to mid-afternoon.
   Shear will be sufficient for at least some storm organization and
   potentially supercells early. However, forecast soundings are very
   supportive for strong downburst winds and relatively quick cold pool
   development, with upscale growth anticipated. This is supported by
   the majority of 00Z CAM guidance which shows at least a broken line
   of storms moving out of eastern New Mexico and into the Texas
   Panhandle. Instability will increase with eastward extent which
   could allow the threat to persist into the early overnight hours.
   Have ended the marginal delineation in western Oklahoma where storms
   are expected to be around 05-06Z which is approximately when storms
   are expected to weaken. 

   ...Portions of the Northern Rockies...
   Storms are expected to form over the Continental Divide this
   afternoon as a weak shortwave traverses the region. A few sustained
   storms are possible given the weak instability and moderate
   effective shear. Marginally large hail and a damaging wind gust or
   two will be the primary threats from this activity.

   ..Bentley/Dean.. 05/16/2022

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