Severe Storms Possible in Oklahoma Thursday (5-11-23)
As of 12Z, several elements are moving into place to support severe thunderstorms on the southern Great Plains later this afternoon and this evening. Key players include a vigorous shortwave trough, rich boundary layer moisture, and an advancing dryline. As the shortwave trough, currently emerging from New Mexico, advances east, a surface low will deepen slightly and translate from SE CO into the OK panhandle in conjunction with the upper-level disturbance.
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The evolving surface low will pull a dryline currently located from near Dalhart to just east of Lubbock into west-central Oklahoma, which will serve as the initiating boundary for storms. Rich low-level moisture is present ahead of this boundary, particularly across central/southern TX, and should be advected northward into Oklahoma with persistent southerly flow. By 00Z, surface dewpoints should be in the mid-60s across central Oklahoma near the initiating boundary, supportive of moderate instability (SBCAPE 2500-3500j/kg) and limited convective inhibition.
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Such a setup is synoptically favorable for severe storms on the southern Plains, but there are several mitigating factors in this case that need to be monitored.
First, ongoing deep moist convection is generating extensive cloud cover in the warm sector. Should this persist, both moisture return and near-surface heating could be adversely impacted, reducing the likelihood of convective initiation. High-resolution guidance weakens this convection through 15Z but given its location on the nose of the low-level warm/moist advection and the unstable environment already in place, I’m not entirely confident this weakening will take place as prescribed. The shortwave trough will provide only glancing forcing for ascent in Oklahoma, especially with southward extent, making solar heating a key driver of convective initiation.
Second, mid-level lapse rates are not forecast to be impressive for a southern Plains severe weather event, generally ≤ 7C/km. Though yesterday evening’s soundings sampled an area of very steep H7-H5 lapse rates in the Texas panhandle and eastern New Mexico, these are expected to deteriorate during the day today. Moderate instability should still evolve if ample heating and rich low-level moisture materialize.
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Despite these potential drawbacks, and if ongoing convection does weaken with time, a favorable environment should evolve for supercells in central Oklahoma this evening. Moderate instability will be co-located with ≥ 40kts of deep layer shear, oriented orthogonally to the initiating boundary. Low-level shear will also increase with time, particularly as 850mb flow increases somewhat after 00Z east of I-35, and should be supportive of tornadoes with any organized supercells in this vicinity late in the evening.
In summary, severe thunderstorms are possible in a broad arc from west-central Kansas into southern Oklahoma ahead of a sharp dryline. Numerous thunderstorms will likely form in Kansas where synoptic support is most robust, with increasingly sparse storm coverage further south. A more focused corridor of significant severe weather potential could become established after 22Z in central Oklahoma, where the overlap of moderate instability, adequate forcing for ascent, and favorable deep layer shear appear most favorable. In this region, large damaging hail (perhaps > 2” in diameter), tornadoes, and damaging winds will be possible with storms that form and can become organized.
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21Z (4PM CDT) Update – Severe Potential Shifts South
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Earlier convection across southwestern Oklahoma persisted into the early afternoon, appreciably impeding diurnal heating and moisture return. As a result, air across northern Oklahoma and southern Kansas is only weakly unstable, and limited severe weather is anticipated in this region. South of I-40, a strongly unstable and sheared airmass has developed. The morning convection left behind a diffuse outflow boundary in the vicinity of the Red River, which should serve as a focus for severe weather this evening. Low level flow is strongly backed in this corridor with favorable hodograph presentations. Very large hail, damaging winds, and tornadoes remain possible, particularly within the orange shaded area, where the greatest coverage and intensity of storms is forecast.
More Forecasts
A Tornado Outbreak is Possible on Monday in Oklahoma & Kansas
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As of this evening, a broad corridor of conditional significant severe weather potential appears likely to evolve across Kansas, Oklahoma, and perhaps extreme northern Texas tomorrow afternoon and evening. If storms are able to form along the dry line between 3pm and 8pm, the ambient environment will be supportive of strong tornadoes, giant hail, and eventually upscale growth with an attendant damaging wind threat.
People in areas at risk for severe weather should monitor trusted sources tomorrow for additional information.
Synoptic Storm Expected Early Next Week (12-18-23)
Synopsis: A large low pressure system will bring active weather to much of the eastern seaboard, with a focus in New England, late this weekend into early next week. As the low moves northward from its current position in the northern Gulf of Mexico, a favorable upper-level pattern evolution should allow the system to deepen rapidly to near 980mb at 40°N. Rapid pressure falls should result in a large mass response/impressive low-level jet evolution, increasing the risk for damaging wind gusts and drawing a large plume of moisture northward. Near the surface low, a 10-18 hour period of steady to heavy rain can be expected, with a shorter window of potentially damaging winds along the NewEngland coast during the day on Monday.
Severe Storms in New England Thursday (7/27)
Thunderstorms are expected to develop across southern New Hampshire, the Hudson Valley, and perhaps northeast Pennsylvania, and move southeast with time through a favorable environment. Damaging winds, flash flooding, and tornadoes will all be possible with the most intense storms. A particularly favorable environment for tornadoes could evolve across northern MA/southern NH during the afternoon, where strong low-level shear will be co-located with substantial instability.
Strong Storms & Flooding Possible Friday (7-14)
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In a deeply moist and unstable airmass, subtle disturbances aloft should trigger waves of thunderstorms across New England and New York on Friday. A focused corridor of severe thunderstorm potential could emerge across portions of downstate NY and southern New England.