SPC AC 061726

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1226 PM CDT Tue Jun 06 2017

   Valid 071200Z - 081200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE FL PENINSULA...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE SOUTHERN/CENTRAL HIGH PLAINS...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
   OF THE NORTHERN ROCKIES...

   ...SUMMARY...
   A few severe thunderstorms will be possible across portions of the
   Florida Peninsula, the southern/central High Plains, and the
   northern Rockies Wednesday into Wednesday night.

   ...Synopsis...
   General cyclonic mid-level flow will persist across the eastern US
   Wednesday, as a positively tilted trough continues to shear along an
   axis from the central Appalachians to the Canadian Maritimes.
   Farther south, a weaker impulse will continue to slowly advance east
   across the central/eastern Gulf Coast. Across the central US and
   Intermountain West, broad ridging will remain in place, although
   several weak/subtle impulses will likely crest the ridge and drop
   southeast across portions of the High Plains. Meanwhile, a rather
   amplified trough will approach the Pacific Northwest coast overnight
   Wednesday.

   ...Portions of the Florida Peninsula...
   The persistence of the large-scale pattern over the eastern US will
   maintain a west/southwesterly sub-tropical jet over parts of Florida
   on Wednesday. Embedded within this jet, weak perturbations will
   likely foster waves of convection moving onshore the Florida
   Peninsula through the day. As such, broad shields of precipitation
   will temper boundary-layer destabilization, limiting the severe
   threat some. Nonetheless, with a broad corridor of southwesterly
   850mb winds around 30-40kt, adequate low-level flow/shear may be
   conducive to a few rotating updrafts, capable of locally damaging
   winds and perhaps a tornado on Wednesday.

   ...Portions of the southern/central High Plains...
   Similar to the previous day, modest north/northwesterly mid-level
   flow will continue along the northeastern periphery of a ridge
   centered over parts of the Rockies. Broad southeasterly, upslope
   flow will likely maintain/transport surface dew points in the 50s to
   near 60 over the southern/central High Plains. In turn, as
   convection develops off higher terrain and slowly spreads southeast,
   it will encounter an environment generally characterized by a
   well-mixed boundary layer and MLCAPE values around 1000-1500 J/kg.
   Effective shear values around 25-30 kt may yield temporary/transient
   organization of cells, promoting a few instances of large hail.
   Gusty/locally damaging winds will also be possible, with ample
   sub-cloud evaporation expected.

   ...Portions of the northern Rockies...
   Mid-level heights will slowly fall late in the period, as a ridge
   builds east and a trough approaches the Pacific Northwest.
   Southwesterly flow aloft will gradually increase through the period,
   in response to the approaching trough. While such an influence does
   appear to be rather late in the period (casting some doubt on the
   potential for severe storms), convection organizing along higher
   terrain late will exist within an environment characterized by steep
   low-level lapse rates and adequate mixed-layer CAPE. In turn, any
   stronger cells that evolve northeastward may be capable of strong,
   gusty winds and perhaps marginally severe hail.

   ..Picca.. 06/06/2017

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