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SPC Activity Chart
Hazard Tue (03/19) Wed (03/20) Thu (03/21) Fri (03/22) Sat (03/23) Sun (03/24) Mon (03/25) Tue (03/26)
Severe No Severe Marginal Marginal No Area No Area No Area No Area No Area
Fire No Critical Elevated No Area No Area No Area No Area No Area No Area

Forecast Discussion - Convective Outlook

   SPC AC 190516

   Day 1 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1216 AM CDT Tue Mar 19 2024

   Valid 191200Z - 201200Z

   ...NO SEVERE THUNDERSTORM AREAS FORECAST...

   ...SUMMARY...
   Severe thunderstorms are not forecast across the contiguous United
   States through tonight.

   ...Synopsis...
   A mid-level low over AZ will slowly weaken and migrate eastward to 
   NM during the period.  A mid-level ridge will extend northward from
   northern CA into the Pacific Northwest.  Farther east, broad
   cyclonic mid-level flow will encompass the Upper Midwest
   southeastward through the East Coast.  Isolated to scattered
   thunderstorms are possible mainly during the afternoon and evening
   across the Desert Southwest/Four Corners.  Surface high pressure
   centered over the southern Great Plains into the Southeast will lead
   to offshore flow and tranquil conditions in those areas.

   ..Smith/Flournoy.. 03/19/2024

    

   NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 1300Z

        
   SPC AC 190448

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1148 PM CDT Mon Mar 18 2024

   Valid 201200Z - 211200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE WEDNESDAY
   AFTERNOON AND EVENING ACROSS PARTS OF THE TEXAS PANHANDLE AND
   ADJACENT WESTERN OKLAHOMA...AND WEDNESDAY NIGHT NEAR AND SOUTH OF
   THE TEXAS HILL COUNTRY INTO MIDDLE TEXAS COASTAL PLAIN...

   ...SUMMARY...
   One or two clusters of thunderstorms could develop across parts of
   the southern Great Plains late Wednesday afternoon through Wednesday
   night.  Some of this activity may pose at least some risk for severe
   hail and wind.

   ...Synopsis...
   Models continue to indicate that a less amplified, but still broadly
   confluent, split flow will evolve east of the Rockies into the
   western Atlantic through this period.  Within one branch,
   consolidating short wave perturbations emanating from the higher
   latitudes likely will continue digging to the southeast of the lower
   Great Lakes region, before turning eastward across the remainder of
   the Northeast late Wednesday through Wednesday night.  This may be
   accompanied by renewed surface cyclogenesis across portions of
   northern New England into the Canadian Maritimes, trailed by a
   reinforcing cold intrusion surging southeastward across much of the
   northern and middle Atlantic Seaboard, and more slowly southward
   across the lower Ohio into Tennessee Valleys, Ozark Plateau and
   central Great Plains through 12Z Thursday.

   Within a lower-latitude branch, the remnants of a perturbation
   emerging from the Southwest may slowly progress east of the Southern
   Rockies in the form of generally weak positively tilted troughing,
   but with perhaps a couple of still notable embedded smaller-scale
   impulses.  One of these, possibly still a fairly well-defined
   mid-level cyclonic vorticity center, may progress east-southeastward
   across the Texas Panhandle into western Oklahoma late Wednesday
   through Wednesday night.  A trailing perturbation may accelerate
   through stronger flow across the Southwestern international border
   area toward the Texas Big Bend, preceded by a more subtle impulse
   emanating from the subtropical eastern Pacific, which may reach
   Texas coastal areas by 12Z Thursday.  

   There is considerable spread evident in the model output concerning
   these developments, but models continue to indicate little in the
   way of substantive surface cyclogenesis, within broad surface
   troughing across the southern Great Plains.  And low-level moisture
   return off a modifying Gulf boundary layer likely will be limited in
   the wake of a prior intrusion of cool/dry air through much of the
   northern Gulf Basin.  Better low-level moistening may remain
   confined to the lower Rio Grande Valley and portions of the Texas
   coastal plain, beneath warm and capping elevated mixed-layer air.

   ...Texas Panhandle Vicinity...
   To the east of a weak surface low, surface dew points may only reach
   the mid 40s to around 50F by late Wednesday afternoon.  But it still
   appears that daytime heating will contribute to a modestly deep,
   well-mixed boundary layer, supportive of CAPE on the order of 500
   J/kg, as relatively cold mid-level air (-20 to -22C around 500 mb) 
   overspreads the region with the approaching cyclonic vorticity
   center.  Although lower/mid-tropospheric wind fields and shear may
   only become modest, at best, this environment could still support
   strong convection posing a risk for small to marginally severe hail
   and a few strong gusts, before convection becomes more widespread
   while spreading east-southeastward Wednesday evening.

   ...Southern Texas...
   A warm elevated mixed layer will likely contribute to strong
   inhibition through much of the period, but models suggest that a
   return of mid 60s F surface dew points by late Wednesday night may
   contribute to mixed-layer CAPE up to around 1000 J/kg.  Considerable
   uncertainty still exists concerning forcing for ascent to overcome
   the inhibition, but at least some model output suggests that a
   subtropical perturbation could support the initiation of storms by
   late Wednesday night, if not earlier.  If this occurs, strong
   deep-layer shear will provide potential for the evolution of
   supercells posing a risk for large hail and locally strong wind
   gusts.

   ..Kerr.. 03/19/2024

   WUUS02 PTSDY2 

   

        
   SPC AC 190729

   Day 3 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   0229 AM CDT Tue Mar 19 2024

   Valid 211200Z - 221200Z

   ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THURSDAY INTO
   THURSDAY EVENING ACORSS PARTS OF CENTRAL AND SOUTHEAST
   TEXAS...ADJACENT SOUTHWESTERN LOUISIANA...

   ...SUMMARY...
   Strong thunderstorms may impact parts of central and southeast Texas
   into adjacent portions of southwestern Louisiana on Thursday.  One
   or two organizing clusters could evolve, accompanied by at least
   some risk for severe hail and wind.

   ...Synopsis...
   It appears that split westerlies will continue to trend more zonal
   to the east of the Rockies during this period, in the wake of a
   deepening and occluding cyclone migrating northeastward across the
   Canadian Maritimes.  Models suggest that the leading edge of a
   significant cold intrusion trailing the cyclone will stall across
   the southern Mid Atlantic, and perhaps substantively begin to modify
   across the Tennessee Valley and Ozark Plateau into the lower Ohio
   and Missouri Valleys.  

   Across the Great Plains, some of this cold air may continue to nose
   southward toward the Texas South Plains, in the wake of mid-level
   troughing progressing east of the southern Rockies/northern Mexican
   Plateau toward the lower Mississippi Valley/northwestern Gulf of
   Mexico.  Although substantive spread is evident in the various model
   output concerning a couple of smaller-scale embedded perturbations,
   it appears that one mid-level cyclonic vorticity center will weaken
   while progressing east-southeast of the Texas Panhandle vicinity
   early the period.  A trailing perturbation may become better-defined
   while progressing east of the Permian Basin/Texas Bend through the
   upper Texas coast vicinity by late Thursday night.  Models suggest
   that this could support a developing surface low across the upper
   Texas coastal plain/northwestern Gulf coast vicinity, along the
   western flank of a developing frontal zone extending
   east-southeastward into the southeastern Gulf of Mexico.  However,
   it still appears that any cyclogenesis will be rather weak.

   ...Southeast Texas...
   Moderate boundary-layer CAPE developing beneath warm and capping
   elevated mixed-layer air may spread north-northwest of middle Texas
   coastal areas, toward the Interstate 35 corridor of central Texas
   during the day.  This may be aided by a corridor of stronger daytime
   heating, but much will depend on the extent of convective
   development which may be spreading east-northeastward into middle
   Texas coastal areas at the outset of the period, supported by
   forcing for ascent associated with a perturbation emanating from the
   subtropical eastern Pacific.

   There is some signal in the model output that this activity could
   grow upscale, supported by increasingly moist/unstable low-level
   inflow, while progressing across the coastal plain into the western
   Gulf of Mexico.  If this occurs, potential for renewed vigorous
   thunderstorm later in the day across parts of central into southeast
   Texas becomes more unclear.  Barring a substantive negative impact
   on further inland destabilization, forcing for ascent with the
   primary upstream  short wave may contribute to the initiation of
   scattered thunderstorm activity by late afternoon.  In the presence
   of strong deep-layer shear, supercells capable of producing large
   hail and locally damaging wind gusts will be possible.  Although
   low-level hodographs may be modest to weak, a tornado or two will
   probably also be possible.

   Into Thursday evening, convection may tend to consolidate and grow
   upscale into an organizing cluster near or just ahead of the
   developing surface low across upper Texas into southwestern
   Louisiana coastal areas. 

   It is possible that severe probabilities across at least parts of
   upper Texas coastal areas will need to be increased in later
   outlooks.  However, this may take a few cycles with much depending
   on sub-synoptic developments.

   ..Kerr.. 03/19/2024

   WUUS03 PTSDY3 

   NOTE: THE NEXT DAY 3 OUTLOOK IS SCHEDULED BY 0730Z