SPC AC 111702

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1102 AM CST Tue Jan 11 2022

   Valid 121200Z - 131200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   The risk for thunderstorms appears negligible across much of the
   U.S. Wednesday through Wednesday night.

   ...Synopsis...
   Large-scale mid-level ridging appears likely to remain prominent
   within the mid-latitude westerlies across the eastern Pacific into
   the Canadian/U.S Rockies through this period.  Within this regime,
   and in advance of large-scale upstream troughing, a fairly
   significant short wave trough is forecast to translate northeastward
   toward the Pacific Northwest coast, to the south of building short
   wave ridging along the British Columbia coast into southeastern
   Alaska.

   The short wave trough is currently preceded by an elongated plume of
   moisture emanating from the subtropical Pacific, on
   south-southwesterly deep-layer mean flow.  This appears likely to
   persist into Wednesday, with an influx of moisture overspreading
   Pacific Northwest coastal areas into the Canadian Rockies, before
   the moisture return becomes cut off due to the progression of the
   trough.  However, despite this moistening, it appears that a
   relatively cool and stable low-level environment will be maintained
   (at least south of the Vancouver Island vicinity), as a  modest
   mid-level cold core (including 500 mb temps around -22 to  -24C)
   begins to spread inland late Wednesday night, resulting in
   negligible risk for thunderstorms.

   Downstream of the mid-level ridging, a couple of digging short wave
   perturbations are forecast to contribute to mid-level trough
   amplification across the Mississippi Valley through the Atlantic
   Seaboard.  Models indicate little phasing with a vigorous short wave
   trough digging across the Hudson Bay vicinity, around the
   western/southwestern periphery of a deep low center over northern
   Quebec; and it appears that Arctic air will become increasingly
   confined to eastern Canada, with substantive low-level warming
   across much of the eastern U.S.  However, while some moistening
   appears possible along weak developing surface troughing east of the
   south Atlantic coast late in the period, higher moisture content is
   forecast to remain confined along/south of a stalled, weakening
   frontal zone across the southwestern Atlantic, southern Florida
   Peninsula, southern Gulf of Mexico.

   ...Florida Peninsula...
   Beneath cool mid-level temperatures associated with the amplifying
   large-scale troughing, northeasterly to easterly post-frontal
   near-surface winds will continue to enhance low-level convergence
   and maintain sufficient boundary-layer moisture to contribute to
   thermodynamic profiles conducive to thunderstorm development along
   southern Atlantic coastal areas.  While one supporting mid-level
   perturbation may progress east of the Atlantic coast early in the
   period, a more substantive digging upstream impulse may approach
   this region Wednesday evening through Wednesday night.

   ..Kerr.. 01/11/2022

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