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DISCUSSIONS PRÉVISIONS du 10 au 16 juil. 2023


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Effectivement, les conditions sont pas mal propices. Au niveau de la formation des cellules, le NAM 3 km et le HRRR s’entendent assez bien sur une ligne fin pm qui balaye tout le sud-ouest. 

Edited by Blizzard
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La ligne d'orages semble passer après le peak des indices mais quand même j'ai jamais vu un setup comme ça au Québec. Si une cellule pop devant le front elle sera très violente.

Je me garde toujours une petite gêne et je parle rarement des orages sur le forum mais 2 bons setup en 2 jours, fallait en parler.

Edited by dave20
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il y a 17 minutes, Snoreau a dit :

Laval-Montréal-Longueuil. + ou - 3,5 millions de personnes dans la zone

Je souhaite pas ça. C'est une chose une tornade dans un champ inhabité, pas dans une zone de 3,5 millions de personnes...

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Discussion sur la situation du côté américain: 

   Mesoscale Discussion 1517
   NWS Storm Prediction Center Norman OK
   1058 AM CDT Thu Jul 13 2023

   Areas affected...Portions of NY...VT...and far northern PA

   Concerning...Severe potential...Watch likely 

   Valid 131558Z - 131800Z

   Probability of Watch Issuance...95 percent

   SUMMARY...The threat for damaging winds, hail, and perhaps a couple
   of tornadoes will increase this afternoon. Watch issuance is likely.
   Parts of this area will be upgraded to Enhanced Risk (for severe
   wind gusts) with the 1630Z Day 1 Convective Outlook.

   DISCUSSION...Airmass destabilization is rapidly occurring across NY
   and vicinity as ample daytime heating has already warmed surface
   temperatures mostly into upper 70s and 80s. A rather moist low-level
   airmass is also present based on recent surface dewpoint
   observations and area 12Z soundings. Further heating of this moist
   airmass will likely lead to the development of around 1500-2000 J/kg
   MLCAPE along/ahead of a cold front. This front, coupled with
   large-scale ascent associated with a shortwave trough ejecting
   across the Northeast and southern Quebec, will likely foster robust
   thunderstorm development within the next couple of hours as parcels
   reach their LFCs.

   Recent VWPs from KENX and KCXX show a veering and strengthening wind
   profile with height through mid levels, with around 30-35 kt of
   deep-layer shear. This should provide sufficient updraft
   organization to support a mix of cellular and linear modes.
   Convection developing along the cold front is already beginning to
   show signs of deepening in far western NY. This trend should
   continue over the next couple of hours as the front moves eastward
   across NY. As low-level lapse rates become steep, scattered to
   numerous damaging downdraft winds will be a concern with any
   clusters/lines that can become established. Convection that remains
   at least semi-discrete will pose a threat for hail. The presence of
   a seasonably strong (25-35+ kt) southerly low-level jet across much
   of NY and vicinity will also provide sufficient 0-1 km SRH to
   support some threat for a couple of tornadoes, both with supercells
   and line-embedded vorticies. Recent (12Z) high-resolution guidance
   suggests that a mainly linear mode should dominate. Given the
   increased potential for scattered to numerous damaging/severe winds
   this afternoon, parts of central/eastern NY and VT will be upgraded
   to Enhanced Risk with the 1630Z Day 1 Convective Outlook.

   ..Gleason/Bunting.. 07/13/2023

mcd1517.png

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13 minutes ago, math423 said:

Je me demande si nous ne serons pas plutôt en mode ligne de grains au final que supercellule.

Je crois qu'au Nord d'Ottawa s'étirant vers le Nord et Nord-Est de Montréal sera le "spot" pour des cellules discrètes donc potentiellement supercellulaires. Mais dépassé Montréal vers l'Est (Montérégie/Estrie) je crois bien que la dominante deviendra linéaire.

Edited by tornado_master
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2 hours ago, Antoine said:

Encore du temps potentiellement violent demain, avec une certaine probabilité de tornade..

 

image.thumb.png.8309f9971603e6bc232e5f444e70edd0.png

Pas très courant de voir ça mais même cette nuit/demain matin il y aurait un certain risque d'Ottawa vers Montréal

day1probotlk_0100_torn.gif

Edited by tornado_master
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il y a 53 minutes, tornado_master a dit :

Pas très courant de voir ça mais même cette nuit/demain matin il y aurait un certain risque d'Ottawa vers Montréal

day1probotlk_0100_torn.gif

Effectivement, le NAM 3km 00Z voit des orages assez costauds dans la grande région de Montréal demain matin.
image.thumb.png.0498aacb0e148a7ca713cdf49a966f80.png

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En effet, dans ses plus récentes prévisions du 06z, le NAM entrevois maintenant un petit centre dépressionnnaire sur Montréal vers midi/15h. Le potentiel de rotation est bien présent tout juste au Nord-est de Montréal en fin de matinée/début pm surtout si il y a présence d'éclaircies.

NAM_221_2023071606_F12_HLCY_1000_M_ABOVE_GROUND_0_M_ABOVE_GROUND.png

NAM_221_2023071606_F12_EHI_3000_M.png

Edited by tornado_master
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L'Anti-biorage n'a pas d'effet avec ce genre de set-up... Lol  Le phénomène est peux être même inversé ! :lol:

Un bultin spécial est sortie ce matin à E C  et il tonne déjà ici

Edited by Pooram
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