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largetornado

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  1. largetornado

    2019 Short/Medium Range Severe Weather Thread

    Large part of the subforum under a marginal risk today. ...Ohio Valley/central Appalachians... Widely scattered thunderstorms are possible this afternoon, offering sporadic wind damage, with isolated severe (50+ kt) gusts and marginally severe hail possible. A narrow corridor of favorable return-flow moisture should advect northeastward through the warm sector just ahead of the front, with surface dew points in the mid 50s to low 60s F. This will offset modest midlevel lapse rates to yield a field of 500-1000 J/kg MLCAPE for a few hours this afternoon, with surface-based effective-inflow parcels at least briefly possible as far northeast as western NY. Low-level and deep-tropospheric speed shear should be favorable, though the prefrontal flow will be nearly unidirectional in vertical profile.
  2. largetornado

    April 11 Severe aspects

    Mesoscale Discussion 0304 NWS Storm Prediction Center Norman OK 0313 PM CDT Thu Apr 11 2019 Areas affected...Parts of northern and central Illinois Concerning...Severe potential...Watch unlikely Valid 112013Z - 112115Z Probability of Watch Issuance...20 percent SUMMARY...At least some increase in severe weather potential is expected with developing thunderstorm activity across parts of northern Illinois by the 4-6 PM CDT time frame. It is possible that this threat may remain low enough that a watch is not needed, but trends will be monitored. DISCUSSION...Near/just ahead of the lower/mid tropospheric cold front, forcing for ascent appears to be contributing to the ongoing increase in thunderstorm activity across northwestern Illinois into southwestern Wisconsin. This activity is largely rooted above a near-surface stable layer to the north of the surface warm front, with relatively warm mid-levels and weak mid/high level lapse rates allowing for only weak CAPE. The band of convection is expected to gradually spread eastward during the few hours, with southward development into the warm sector of the surface cyclone also possible by 21-23Z. Even within the warm sector, relatively low surface dew points across parts of eastern Missouri into west central Illinois are currently resulting in negligible boundary layer CAPE. However, modest low-level moisture (reflected by mid 50s+ surface dew points) appears to be returning northward/northwestward in a corridor to the east/northeast through north of Springfield, into the vicinity of the warm front. A combination of at least weak boundary-layer destabilization along the warm front, coupled with increasing lift ahead of the occluding surface cyclone triple point (and associated eastward advancing band of mid-level forcing for ascent), may allow for at least isolated boundary-layer based storm development. This seems most likely north/northeast of the Peoria vicinity, and may include one or two supercells accompanied by at least some risk for severe hail and localized strong surface gusts. Although low-level thermodynamic profiles appear rather marginal, given the synoptic environment, and large low-level hodographs near/beneath 50+ kt southerly 850 mb flow, an isolated tornado may not be out of the question. ..Kerr/Hart.. 04/11/2019
  3. largetornado

    April 11 Severe aspects

    FWIW, the HRRR is currently underdoing dew points in kansas by 3-4 degrees. Id probably add 2-3 degrees to the HRRR dewpoints for tomorrow.
  4. largetornado

    April 11 Severe aspects

    Can’t believe I’m taking a day off tomorrow. Warm sector has virtually no chance of activity and LCLs are around 850....
  5. largetornado

    April 11 Severe aspects

    Sounding from near Danville, IL. Directional shear not terrible, but could be better.
  6. largetornado

    April 11 Severe aspects

    18z nam and nam 3km both bring better moisture. I think question of warm sector activity comes down to sunshine. Right now, simulated IR is cloudy for most of the day.
  7. largetornado

    March 13th-14th Severe Weather

    Is it me or are these storms not moving east at all. Seems like the line has stalled and is just training. Would allow more time to destablize to the east...
  8. largetornado

    March 13th-14th Severe Weather

    Surprised by no upgrade to moderate.
  9. largetornado

    March 13th-14th Severe Weather

    Latest HRRR is handling the clearing well. Oddly, it doesnt destabilize much though. ~500 cape. Obviously enough for today, but I would have thought clearing would push to 750+
  10. largetornado

    March 13th-14th Severe Weather

    And the hail threat was “low.” Also concerned about sunshine along the Ohio river with a developing CU field
  11. largetornado

    March 13th-14th Severe Weather

    With 600-800 effective SRH, any cloud breaks and destabilization will greatly increase tor threat. Watch out for the sun.
  12. largetornado

    March 13th-14th Severe Weather

    80/50 Tornado watch for Indiana/Ky/Ohio
  13. largetornado

    March 13th-14th Severe Weather

    Currently, effective helicity is 350-400 in the tornado warned storm region. Forecast to hit 600-700. With 500 -1000 cape, thats more than enough.
  14. largetornado

    March 13th-14th Severe Weather

    Third storm just went tornado warned
  15. largetornado

    March 13th-14th Severe Weather

    First tornado warning of the day
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