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Tallis Rockwell

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About Tallis Rockwell

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  • Four Letter Airport Code For Weather Obs (Such as KDCA)
  • Location:
    Houston TX

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  1. Tallis Rockwell

    Hurricane Barry

    I don't know why but something tells me that this unlikely...
  2. Tallis Rockwell

    Severe storms and flash flooding for May 7-13

    Enhanced with sig tor probs for day 2 Well-defined upper low off the southern CA coast is forecast to eject across the lower CO River basin into the southern Rockies by early evening Tuesday. Leading edge of large-scale forcing for ascent is expected to spread into the High Plains of NM/west TX shortly after peak heating. At the same time, a much weaker, but notable disturbance will eject across Mexico into deep south TX. This low-latitude feature should induce a coastal boundary and low-level warm advection will increase in response. It appears a substantial amount of convection will evolve across south TX into the middle/upper TX coastal region. This should temporarily slow northward advance of low-level moisture across east TX into eastern OK. Even so, adequate boundary-layer moisture should remain undisturbed across the southern High Plains where lower 60s surface dew points should hold east of a well-defined dry line, south of a synoptic front. While the synoptic front should contribute to convective development from the northern TX Panhandle to southeast KS, primary concern for organized severe will focus along the dryline near the TX/NM border. Strong surface heating is forecast by 18z across eastern NM where temperatures should easily soar into the 80s by early-mid afternoon. As a result, CINH should weaken by 21z and scattered supercells should easily develop within a strongly sheared environment. Forecast soundings for this region exhibit profiles that strongly favor supercells. Very large hail, in excess of 2", and tornadoes can be expected with this activity. Thunderstorm clusters should translate along/north of the synoptic front across the northern TX Panhandle into northwest OK/south-central KS during the overnight hours.
  3. Large-scale pattern will become seasonally favorable for organized severe during the upcoming medium-range period. Severe thunderstorms, including large hail, damaging winds, and tornadoes are expected across a substantial portion of the CONUS during the day4-6 time frame. Latest model guidance continues to suggest a pronounced upper trough will eject across the lower CO River Valley into the southern Rockies during the day4 period...central/southern Plains day5...and Midwest day6. Southern extent of dominant surface anticyclone should stall across KS and an extensive moist warm sector is expected to eventually materialize across the southern Plains/lower MS Valley into MO ahead of this ejecting short wave. While it seems likely that organized severe will spread from TX to the Midwest ahead of this feature, it's not entirely clear of the convective evolution each day. Day3 TX short wave will likely induce a substantial amount of precipitation that could/should disrupt northward advance of highest PW air mass to higher latitudes. Initially, most robust convection will be confined to the High Plains where steep lapse rates will contribute greatly to buoyancy. If the short wave timing is accurate, a more substantial severe event could unfold day5 across the Plains. GFS/Canadian are more aggressive with surface low development across KS than the ECMWF which is weaker with the surface low Wednesday. Mid-level speed max will eject into the Midwest Thursday along with an attendant severe threat . Seems like a repeat of 2015
  4. Tallis Rockwell

    Severe weather event for April 24-25

    Funnel cloud and damage confirmed. BRYAN, Texas — An apparent tornado touched down in Bryan Wednesday afternoon. Some homes are damaged in the 6900 block of Coyote Run Road, according to KBTX. It’s not clear if anyone was injured. Emergency crews are headed to the area near FM 1179 and Highway 6. Brazos County remains under a tornado warning. Check back for more on this developing story.
  5. Tallis Rockwell

    Severe weather event for April 24-25

    That happens.
  6. On Wednesday, the models move the upper-level trough into the southern Plains and have a moist airmass in place from the Texas Coastal Plains northeastward into the mid Mississippi Valley. Thunderstorm development will be possible ahead of a front across the eastern third of Texas northeastward into the Arklatex. Deep-layer shear is forecast to be strong enough across south-central and southeast Texas for a severe threat Wednesday afternoon and evening. The models are in good enough agreement that a severe threat areas has been added across this area on Day 5. A good synoptic set up but without a clear picture on the mesoscale ingredients this could be nothing
  7. Tallis Rockwell

    Cyclones from 4/10-4/13

    A blizzard, a very high fire weather risk, and a probable significant weather event all in one week.
  8. Tallis Rockwell

    April 10-12 Great Plains Storm

    I have added that as a discussion point for the topic so feel free to jump in.
  9. Tallis Rockwell

    Cyclones from 4/10-4/13

    Should have just put April...
  10. Tallis Rockwell

    Cyclones from 4/10-4/13

    ...DISCUSSION... By day 4 (Thursday), somewhat greater moisture will be advected northward ahead of the surface low with dewpoints in the 50s F. It still appears likely that a band of storms will develop along the trailing cold front as this boundary intercepts the destabilizing boundary layer across the middle MS, OH and TN Valleys. Despite an expected marginal thermodynamic environment, some risk for damaging wind will exist given strength of low-mid level winds and strong vertical shear supportive of a few embedded meso-vortices and bowing structures. Have introduced a 15% probability to account for this possibility. Day 5 (Friday) The upper trough will continue east northeast with associated deep cyclone moving from the Great Lakes into southeast Canada. Storms may continue along the front and warm conveyor belt in the high shear/low CAPE environment. Some severe probabilities might eventually be needed from the Mid Atlantic into the Carolinas if confidence increases that the thermodynamic environment will become sufficient for severe storms. Day 6 (Saturday) General model consensus is that rich low-level moisture with near 70 F dewpoints will advect northward into the warm sector over the lower MS Valley in advance of a southern-stream shortwave trough. This environment may become favorable for a more significant severe event by later Saturday from southeast TX to the lower MS Valley, then continuing into the Gulf Coast states Sunday (day 7). If models continue to demonstrate consistency in this scenario, a categorical risk area will need to be introduced in later updates. Saturday looks to be the climax but the GFS puts the surface low in an unfavorable place while the ECMWF has a more favorable surface profile EDIT: Another one mentioned significant snow fall taking place in the Ohio valley and the implications of that for their already bad flooding situation.
  11. Tallis Rockwell

    Severe Weather April 3rd - 8th 2019

    The slight risk for Saturday is larger then France...
  12. Tallis Rockwell

    Severe storms 3-9/12

    Instability is going to make or break this event. Lift and shear is forecast to be more then favorable. I think GFS is underestimating the CAPE.
  13. Tallis Rockwell

    Severe potential for 2/23-2/27

    Please don't let this day be represent of the year.
  14. Tallis Rockwell

    Severe potential for 2/23-2/27

    It is official .THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF NORTHERN MISSISSIPPI...SOUTHWEST TENNESSEE AND FAR NORTHWEST ALABAMA... ...SUMMARY... Scattered severe thunderstorms are expected to develop today from the Arklatex region and lower to mid Mississippi Valley eastward into the Tennessee and Ohio Valleys. Tornadoes, wind damage and isolated large hail will be possible across much of the area. ...Significant tornado and wind damage event expected across parts of the lower to mid Mississippi and Tennessee Valleys today... ...Arklatex/Lower to Mid Mississippi Valley/Tennessee and Ohio Valleys... A well organized negatively-tilted upper-level trough will move across the southern Plains today as a 90 to 100 kt mid-level jet moves through the base of the trough. At the surface, a low will gradually deepen and move northeastward across the central Plains into the lower Missouri Valley. A surface trough is forecast to extend southward into the lower Mississippi Valley with a moist airmass located across the region. Surface dewpoints in the upper 60s and lower 70s F will overspread northern Louisiana, southeast Arkansas and most of Mississippi by midday. At the start of the period, a cluster of thunderstorms should be ongoing from northern Mississippi into western and middle Tennessee. The stronger storms embedded in the cluster may have an isolated severe threat. This activity is forecast to move northeastward away the moderate risk area allowing for the moist sector to warm up late this morning. In response, a corridor of moderate instability is expected to be in place by midday from northeast Louisiana into far southeast Arkansas and western Tennessee. As large-scale ascent increases ahead of the southern Plains upper-level trough, thunderstorms are forecast to develop during the morning along the surface trough in the Arklatex with this convection moving northeastward into southeastern Arkansas by midday. More isolated thunderstorms will be possible across the moist sector from northern Louisiana into north-central Mississippi. During the early to mid afternoon, convective coverage should increase with scattered thunderstorms moving east-northeastward across the Enhanced and Moderate Risk areas. RAP forecast soundings across the Moderate Risk area from north-central Mississippi into southwest Tennessee at 21Z show moderate instability and impressive kinematic profiles. MLCAPE is forecast to be from 1000 to 1200 J/kg with 0-6 km shear in the 50 to 55 kt range. This will support supercell formation with cells that remain discrete. In addition, hodographs are long and looped with 0-3 km storm relative helicity values in the 350 to 450 m2/s2 range. This low-level shear environment will be favorable for tornadoes. A potential for long-track significant tornadoes will exist across the Moderate Risk area from late this morning through much of the afternoon. Wind damage and isolated large hail will also be possible with supercells. A squall-line is also expected to develop and move across the Enhanced and Moderate risk areas during the late afternoon and early evening. Wind damage, isolated large hail and a few tornadoes will also be possible with the stronger thunderstorms embedded in the line. This squall-line with wind damage potential should move across middle Tennessee and north-central Alabama during the evening. Further north across the Ohio Valley, scattered thunderstorms are forecast to move northeastward into western Kentucky and southern Indiana during the afternoon. Forecast soundings at 21Z for Paducah show MLCAPE near 800 J/kg with 0-6 km shear of 65 kt. This combined with strong low-level shear will be sufficient for severe storms capable of producing tornadoes and wind damage. Most of the severe convection should remain south of the Ohio River. Due to the weaker instability in the Ohio Valley, severe coverage is expected to be less. ..Broyles/Bentley.. 02/23/2019
  15. Tallis Rockwell

    Severe potential for 2/23-2/27

    ZCZC SPCSWOD48 ALL ACUS48 KWNS 180956 SPC AC 180956 Day 4-8 Convective Outlook NWS Storm Prediction Center Norman OK 0356 AM CST Mon Feb 18 2019 Valid 211200Z - 261200Z ...DISCUSSION... Models continue to indicate that blocking will remain prominent within the mid-latitude westerlies across the northeastern Pacific through this period. Downstream, it appears that flow may transition to a broadly confluent regime across the Pacific coast, Rockies, and Plains, and a less amplified regime in general across the southern tier of the U.S., by late next weekend into early next week. As this takes place, one more vigorous short wave impulse is forecast accelerate east-northeastward out of the Southwest. There appears increasing consensus, within and among the various model output, that this feature will provide support for strong surface cyclogenesis to the lee of the southern Rockies by this weekend. Guidance generally indicates that the cyclone center will rapidly migrate from the Texas/Oklahoma Panhandle region into the Great Lakes on Saturday. This probably will include intensifying lower/mid tropospheric flow (to 50-70 kt in the 850-500 mb layer) across an evolving warm sector boundary layer that will become at least weakly unstable, across lower portions of the southern Plains through the mid to lower Mississippi Valley region. This environment may become conducive to the evolution of an organized mesoscale convective system, and perhaps discrete supercell development ahead of it, accompanied by the risk for damaging wind gusts and tornadoes. It remains unclear whether destabilization eastward and southeastward, toward the Mid Atlantic and Southeast, on Sunday will remain sufficient to support an appreciable continuing severe weather threat. ..Kerr.. 02/18/2019