2018 Short to Medium Range Severe Thread

[Hoosier]

Current model timing would suggest a threat could begin in the sub on Monday evening.  How much of a severe threat there would be overnight into Tuesday morning is questionable, as instability would obviously be entirely advective driven then, but the system has healthy dynamics to work with. 

[Indystorm]

As of Sat, morning SPC has brought the slight risk farther north into IL and the bottom quarter of IN based on model trends even though the enhanced is still farther south.  Will have to see how this low develops as things progress.

[Hoosier]

   Day 2 Convective Outlook  
   NWS Storm Prediction Center Norman OK
   1258 AM CDT Sun Nov 04 2018

   Valid 051200Z - 061200Z

   ...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM THE LOWER
   MISSISSIPPI VALLEY INTO A PORTION OF THE TENNESSEE VALLEY...

   ...SUMMARY...
   Numerous severe storms with potential for damaging wind and
   tornadoes are expected Monday evening into the overnight from a
   portion of the lower Mississippi Valley into the Tennessee and Ohio
   Valleys.

   ...Lower Mississippi into the Tennessee and Ohio Valleys...

   Only minor adjustments have been made to previous outlook, and
   guidance remains generally consistent. Potential still exists for
   significant severe weather to transpire Monday evening and night,
   mainly from the lower MS Valley into the Tennessee Valley regions.
   Primary zone of cyclogenesis should commence Monday evening over the
   lower MS Valley (northern AR or southern MO) in response to forcing
   for ascent in exit region of a progressive, intense upper jet streak
   located within base of an amplifying shortwave trough. The cyclone
   will deepen as it lifts northeast into the OH Valley Monday night
   with trailing cold front advancing through the TN and lower MS
   valley regions. 

   Latest observations indicate surface winds over the western Gulf
   have shifted to southerly, and this air continues to modify with
   dewpoints already in the low 60s F. Cold front now moving through
   east TX as of early Sunday morning will stall along the Gulf coast,
   allowing the Gulf boundary layer to modify further through Monday.
   Gulf moisture with mid to upper 60s F dewpoints will advect rapidly
   northward through the warm sector along a strengthening low level
   jet, contributing to destabilization with 500-1500 J/kg MLCAPE by
   Monday night, but mid level lapse rates will remain somewhat
   marginal. Mixed storm modes including a squall line and supercells
   are likely to develop along and just ahead of advancing cold front
   by late Monday afternoon, initially over the lower MS Valley, then
   continuing east into the TN and OH Valleys overnight. Impressive
   wind profiles with large 0-1 km hodographs and intense mid-upper jet
   should foster organized storms including embedded bowing segments
   and supercells with low-level mesocyclones capable of mainly
   damaging wind and tornadoes, though some hail will also be possible.
   A moderate risk upgrade might be warranted for a portion of this
   region in later outlooks.

   ...MAXIMUM RISK BY HAZARD...
   Tornado:  10% SIG - Enhanced
   Wind:     30% SIG - Enhanced
   Hail:     15%     - Slight

   ..Dial.. 11/04/2018

 

[Hoosier]

Thread for today's severe weather

 

[largetornado]

FWIW, there may be the *potential* for some severe around 12/27. GFS has been fairly consistent and the EURO has a similar low as well.  

Obviously pretty far out still but the D7/8 period looks somewhat intriguing. 

SPC D4-8 Outlook. 

Quote

  ...DISCUSSION...
   High-PW air mass will be shunted off the Atlantic coast during the
   day2 period. Current medium-range model guidance suggest numerous
   fast-moving short waves will traverse the CONUS such that
   moisture/instability will struggle to return north until Christmas
   day when a significant moisture surge is expected across the western
   Gulf basin into TX. This moisture surge will be induced by a
   significant trough that will progress across the southwestern
   US/southern Rockies region. While models agree broadly that
   destabilization should occur across the southern Plains, timing of
   the ejecting trough may greatly influence potential severe threat
   with this feature. Will not introduce severe probs at this time but
   organized convection may ultimately evolve during the day7/8 time
   frame.

 

[CheeselandSkies]

Just a very narrow/weak ribbon of CAPE depicted ahead of the front and wrapping back into the triple point (on the 12Z, too). Need systems like that in A/M/J 2019 after a couple weeks of Gulf priming. Still will monitor, if the last couple years have taught me anything it's to not sleep on out of season chase opportunities in N. IL.

Still, that system as currently depicted verbatim is representative of the S. WI weather hole of the last several years. Severe misses to the south, big snow misses to the north (or, as in the case of the late November system, snow missed to the south, too).