Jan 1, 2017 0700 UTC Day 2 Convective Outlook
Updated: Sun Jan 1 06:25:03 UTC 2017 (20170101 0700Z Day 2 shapefile | 20170101 0700Z Day 2 KML)
Probabilistic to Categorical Outlook Conversion Table
Categorical Graphic
20170101 0700 UTC Day 2 Outlook Graphic
Day 2 Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
ENHANCED 96,788 7,633,635 New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...Metairie, LA...
SLIGHT 80,851 7,390,205 Birmingham, AL...Montgomery, AL...Shreveport, LA...Huntsville, AL...Beaumont, TX...
MARGINAL 150,672 21,544,259 Houston, TX...Memphis, TN...Nashville, TN...Atlanta, GA...Columbus, GA...
Probabilistic Graphic
20170101 0700 UTC Day Probabilitic Graphic
Probability of severe weather within 25 miles of a point.
Hatched Area: 10% or greater probability of significant severe within 25 miles of a point.
Day 2 Prob. Risk Area (sq. mi.) Area Pop. Some Larger Population Centers in Risk Area
30 % 96,612 7,624,202 New Orleans, LA...Baton Rouge, LA...Mobile, AL...Jackson, MS...Metairie, LA...
15 % 80,269 7,507,026 Birmingham, AL...Montgomery, AL...Shreveport, LA...Huntsville, AL...Beaumont, TX...
5 % 148,615 21,278,430 Houston, TX...Memphis, TN...Nashville, TN...Atlanta, GA...Columbus, GA...
   SPC AC 010625

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1225 AM CST Sun Jan 01 2017

   Valid 021200Z - 031200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS MONDAY INTO
   MONDAY EVENING ACROSS PARTS OF EASTERN LOUISIANA...CENTRAL AND
   SOUTHERN MISSISSIPPI...AND MUCH OF WESTERN ALABAMA...

   ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SURROUNDING
   AREAS OF THE WESTERN AND CENTRAL GULF STATES...

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS ADJACENT
   PORTIONS OF THE MID SOUTH AND LOWER OHIO/TENNESSEE VALLEYS...

   ...SUMMARY...
   Severe thunderstorms are expected Monday across much of the western
   through central Gulf states into portions of the Mid South,
   accompanied by the risk for potentially damaging wind gusts and a
   few tornadoes.

   ...Synopsis...
   Ridging to the east of a blocking mid/upper high, centered near the
   Gulf of Alaska, appears likely to expand eastward and southeastward
   through portions of the western Canadian provinces and portions of
   the Pacific Northwest during this period.  As this occurs,
   downstream troughing over the northwestern U.S. may undergo
   considerable deformation, with at least one significant short wave
   impulse forecast to emerge from it, and accelerate east
   northeastward toward the upper Great Lakes region.

   In lower latitudes, subtropical ridging is forecast to elongate east
   to west, with the center of highest heights shifting from the
   Caribbean into the vicinity of the Mexican Gulf Coast.  On the
   northern periphery of this feature, into larger-scale ridging over
   the southeastern U.S., it still appears that a significant remnant
   short wave impulse, emerging from the Southwest, will weaken as it
   accelerates east northeast of the southern Plains.  However, the
   extent to which this occurs prior to reaching the southern
   Appalachians/south Atlantic coast region, remains unclear.

   Associated with/in response to these developments, models indicate a
   significant low-level cold intrusion will nose southward to the lee
   of the northern Rockies on Monday.  Primary surface cyclogenesis may
   commence across parts of the Upper Midwest/Great Lakes region, well
   removed from the Gulf Coast region, where a substantive return flow
   of moisture is expected to be ongoing.  However, guidance remains
   suggestive that a fairly significant secondary surface low may
   accompany the southern mid-level impulse, eastward/northeastward out
   of Texas.

   ...lower Plains to Appalachians...
   Substantive low/mid-level moisture return, and at least weak
   destabilization, appears possible as far north as the middle
   Mississippi/Ohio Valleys and southern portions of the Great Lakes
   region.  However, much of this may occur above a residual
   cool/stable near surface layer with little appreciable severe
   weather potential currently evident.  Richer low-level moistening,
   and significant boundary layer destabilization, probably will remain
   confined to portions of the western and central Gulf States, with
   return to areas farther north impeded, at least in part, by
   convective development associated with the short wave emerging from
   the southern Plains, and downstream warm advection.

   Guidance continues to indicate that thermodynamic profiles across
   much of the western into central Gulf Coast states, perhaps areas as
   far north as the Mid South, will become characterized by modestly
   steep lower/mid-level lapse rates and CAPE of 500-1000+ J/kg. 
   Higher CAPE is expected to be focused across central and southern
   portions of Louisiana and Mississippi into Alabama, where surface
   dew points likely will reach or exceed the mid 60s F.

   Due to lingering variability among the model output, among other
   issues, the potential convective evolution Monday into Monday night
   remains unclear.  However, given the magnitude of the potential
   instability, the environment should be conducive to severe storm
   development.  Models are suggestive that southern short wave impulse
   will be accompanied by considerable strengthening of lower/mid
   tropospheric wind fields, including southerly 40-50 kt flow around
   850 mb, veering to west/southwesterly at 50-70 kt around 700 mb. 
   This should provide more than sufficient low-level and deep layer
   shear for organized severe convection, including supercells.

   Furthermore, guidance now seems suggestive that forcing for ascent
   may remain sufficient to maintain vigorous storm development through
   the day Monday, into at least Monday evening, spreading across much
   of Louisiana and Mississippi into Alabama. This will partially be
   driven by low/mid-level warm advection, which may support or
   maintain a progressive organized mesoscale convective system with
   potential for damaging surface gusts.  Sizable clockwise curved
   low-level hodographs appear likely to support a risk for tornadoes
   as well, particularly in discrete cells preceding any evolving
   convective system.  A strong tornado or two may not be out of the
   question.

   ..Kerr.. 01/01/2017

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