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Windspeed

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  1. Did not see a recent banter thread so thought I would just post here. This new video by Pecos Hank discussing super computer mesocyclone and tornado genesis with Dr. Leigh Orf is an absolute must watch:
  2. Windspeed

    Spring/Summer Banter Thread 2019

    This video by Pecos Hank discussing super computer mesocyclone and tornado genesis with Dr. Leigh Orf is an absolute must watch:
  3. Windspeed

    Hurricane Barry

    Even though 10m wind is only gusting SSE-->SE-->ESE between 40 and 55 kts, Barry's broad surface circulation extending a long distance east and northeast of the center will still pile ocean against the shape of the eastern LA and MS delta / coastline. As for the rotating precip on 248mi composite radar reflectivity south of the center fix, that is the tilted 700 to 500 mb level vortex. Chaining MCVs there can be deceiving on radar. A reminder of the much higher altitude of the radar beams at those distances from the array. As far as I can tell, the actual center is still pretty barren of convection and heavy precip. Whether a strong convective complex ever actually increases in coverage over the broad surface circulation, not just spitting out low level swirls, may never occur or precede the larger circulation moving inland tomorrow. However, the concerns here is how unstable / volatile that airmass boundary is right now feeding into the persistent complex from the SW and southern periphery. This system still has frontal characteristics of a surface boundary with continental vs unstable airmass. The low level convergence off the NW to N-Central Gulf modeled to follow the surface vort and continue throughout the weekend with periods of 1-3"/hr rates; hence the flooding threat into Mon across Louisiana. We certainly hope to avoid any "firehose" bands right over New Orleans.
  4. Windspeed

    Hurricane Barry

    For the exception of the UKMet (which continues to hold off the weakness longer, driving Barry into ETX and therefore models a much stronger hurricane), most of the 0z globals have trended weaker and east. Even the stronger intensity model guidance backed down, including the 0z HWRF, though oddly it continues intensifying Barry until it has crossed the Ponchartrain. Additionally the 0z ECMWF is noticeably closer to land on initial WNW track prior to northward turn into landfall. Obviously things can change quickly if a surface vort forms and ramps up in the short term; but with respect to location and intensity, the 0z consensus definitely leaned weaker and east.
  5. Windspeed

    Hurricane Barry

    Papin is cluing in on a possible location for the surface vort developing. As far as intensity modeling goes, until that develops, I would just try to take these HWRFs runs with much reluctance. The first two runs failed to simulate the strong convective feature overland along the hanging surface trough this morning. The same feature that caused flash flooding in New Orleans. Which that has/will hamper establishment of MCS development closer to the center of the 850-700 mb level vort. However, there has still been persistent convection with lightning data trying to converge into that suspicious area Papin is pointing out. Also the 12z HWRF did finally have that overland convective complex and yet still tries to rapidly stack a surface and mid level vortex a good distance SSE of the mouth of the Mississippi. If this disturbance is going to become a strong hurricane, tonight is critical for formation and vortex alignment to occur. Regardless, inland accumulation totals received a big head start / boost. Looking less likely LA avoids a flooding disaster no matter the eventual landfall strength of the TC.
  6. Windspeed

    Hurricane Barry

    I don't see anything yet that resembles a strong enough surface vort. Edit: vort, not cort.
  7. Windspeed

    Hurricane Barry

    The old surface boundary with the weak surface vort near the panhandle looks barren where convection on SAT and echoes on radar have dissipated pretty drastically since 0z. Deep convection and a lot of lightning data is converging on the axis around the 700 mb level vort that pushed further south. You can see this very clearly unfolding on IR. If a new surface vort forms there later today, things may get interesting relatively quickly.
  8. Windspeed

    Hurricane Barry

    So the 2nd run of the HWRF continues with a 24 hr period of rapid intensification on Friday like the 1st run. @ 0z Fri, Barry is still a 990 mb TS. By 0z Sat it is a 960 mb major hurricane and continues rapid deepening through landfall. Whatever it is sniffing out is hopefully wrong. It really gets the vortex aligned and stacked by Thursday morning. It doesn't seem to mind the northerly shear or has Barry's vort tucked just enough under the eastern periphery of the upper ridge over TX.
  9. Windspeed

    Hurricane Barry

    0z ECMWF shifting back west. Not so far west as the UKMET but right along the TX/LA state line.
  10. Windspeed

    Hurricane Barry

    GFS is crawling on 6 hr plots on a NNW track right up the Mississippi in central LA. This run is going to suck for New Orleans with respect to accum precip with strong backing low level southerly flow and convergence right off the Gulf over Lake Ponchartrain.
  11. Windspeed

    Hurricane Barry

    NWS New Orleans has updated its stage forecast to account for future TC impacts. Obviously this is fluid and could go up or down depending on how the official TC and precip forecast evolves.
  12. Windspeed

    Hurricane Barry

    It's not surprising to see one of the big three models show rapid intensification in one of its operational runs like the last 12z Ukie. If any single op by the ECMWF, GFS or UKMET globals manage to vertically stack the surface, 850 and 700 mb vorts faster, then the only limiting factors become northerly 15kt 400-200 mb flow and proximity of vortex to land. Obviously if we see convection become dominate along the mid level axis west of Tampa Bay and we have a new surface vortex form under that feature, then the threat of a much stronger TC increases significantly. This buys time for faster development and possible cyclogenesis at a slightly lower latitude. I would err on the side of caution in expecting this IRL however. A single op run showing much faster aligning vortexes needs to become a trend even if having a single modeled run presents a realistic possibility of how that scenario occurs. Regardless, we'll actually have real time observation if this is unfolding (or not) by 12z tomorrow as convection should really take off this evening and over night.
  13. Windspeed

    Hurricane Barry

    Higher CAPE values and strong low-level convergence off the Gulf into a NW tracking surface low. All the GFS op needed was a stronger surface vortex further off the coast versus the very weak disturbance that had been prevalent in previous runs. Regardless of eventual landfall intensity there would be significant impacts to already stressed tributaries that [mention=142]janetjanet998[/mention] alluded to earlier.
  14. Windspeed

    Hurricane Barry

    I am sure you meant Alicia since you mentioned 1983. In bringing back both blasts from the past, I may as well touch briefly on both. Anita in 1977 formed out of your prototypical tropical wave à la W.Africa/MDR/ITCZ corridor. It just gained latitude and crossed S.FL due to an upper trough/cutoff over that SE CONUS. As the cutoff lifted out and a strengthening ridge took over, the disturbance/wave axis closed off under an extremely favorable upper ridge in the E-Central GOM. The TC rapidly intensified to a Category 5, but the building ridge protected Texas and drove Anita on a WSW track into Mexico. OTOH, though also notable for its rapid intensification, Alicia developed out of a similar scenario that we are seeing unfold with our current invest 92L: A continental airmass stationary boundary with an attached MCS/mid level vort. The problems any system like this faces is proximity to land and developmental time over water. The keys to watch unfold will be 1) how broad is the surface vort max upon cyclogenesis, 2) how low in latitude that vortex forms and, lastly, 3) how strong does the ridge build in behind the Great Lakes/New England upper trough. GFS ens camp has remained broader and closer to land and therefore weaker. ECMWF has been further south and faster to develop a more defined vortex at onset of TC genesis out over water. If Euro scenario infolds IRL, then that would increase chance to have an Alicia like cyclone, though still not expected. A blend of both ensembles based on the past few days, if unchanged, would probably meet the criteria for a TC with enough time over water and enough upper support to reach a strong tropical storm to Category 1 intensity. Though running out of time to intensify further to something similar to Alicia. This of course *IF* the surface vortex that forms is not too broad.
  15. Windspeed

    2019 Atlantic Hurricane Season

    Even though we are still beyond 72 hrs from a trackable feature, if one does indeed resolve, there are already two different camps between the GFS vs ECMWF runs over the past few days. Though both models do have a sharp surface trough / low pressure system over the SE US & NE GOM, the ECMWF is more aggressive in southern advancement of that boundary and an attached 850-700 mb vortex. Cyclogenesis on the Euro is much further south out over the GOM, versus the GFS runs which keeps the feature either inland or in closer proximity to land. Granted we are still early into in these model runs and confidence should remain low for now. If given a scenario of better modeling agreement on the eventual placement of the surface trough, even with a disturbance positioned out over the GOM doesn't guarantee TC development. That being said, last night's 0z ECMWF was the most aggressive in development so far:
  16. Windspeed

    2019 Atlantic Hurricane Season

    A boundary is forecast to stall and linger over the north GOM next week. An MCS currently organizing over Kansas may push SSE with the boundary and move off the Panhandle coastline possibly developing a sharp surface trough / area of low pressure, which some of the globals are trying to close off into a tropical or sub tropical cyclone. At least something to watch for development towards the mid-to-late week timeframe.
  17. Windspeed

    2019 East & Central Pacific Season

    Though T#s have decreased and intensity has come down, still a formidable Cat 4 and looking quite good on SAT.
  18. The EPAC has finally taken off with its second named storm, Barbara reaching Major Hurricane status and Category 4 intensity.
  19. Windspeed

    2019 East & Central Pacific Season

    Barbara's eye finally cleared and became more stable after some old vortex convection dissipated. As such, ADT # responded upwards this afternoon, but has since leveled off to around 7.0. We're probably observing a high end 4 / borderline 5 now.
  20. Windspeed

    Tn Valley Severe Weather 2018-19

    Strong storms moved through TYS and MRX but most things have calmed down and seem rather tame at the moment.
  21. Windspeed

    Tn Valley Severe Weather 2018-19

    Tornado warning north of Knoxville. Rotation/strong winds moving towards Maynardville.
  22. Windspeed

    Tn Valley Severe Weather 2018-19

    The SPC did upgrade to a slight risk for much of the eastern TN Valley including an enhanced risk for the northeastern portion.
  23. Vanu began a westward drift and should avoid landfall as a strong cyclone. Globals show a westward motion for a few days before eventually getting sheared off. A weaker system may still get pulled via the low level flow into Pakistan/NW India so flooding rainfall may still be a concern in the coming week.
  24. Windspeed

    Tn Valley Severe Weather 2018-19

    Day 1 Outlook Graphic...
  25. Windspeed

    Tn Valley Severe Weather 2018-19

    SPC sticking with marginal for Tennessee and Ohio Valleys. Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0752 AM CDT Wed Jun 12 2019 Valid 121300Z - 131200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE OHIO/TENNESSEE VALLEYS INTO THE SOUTHEAST AND COASTAL CAROLINAS...MISSOURI/ARKANSAS VICINITY...AND WEST TEXAS... ...SUMMARY... Isolated strong to severe thunderstorms will be possible today across parts of the Ohio/Tennessee Valleys into the Southeast and coastal Carolinas, Missouri/Arkansas vicinity, and west Texas. Marginally severe hail and strong/gusty winds should be the main threats. ...Synopsis... For convective purposes, the mid/upper-level pattern will be dominated by a high-amplitude, synoptic-scale trough now located from northwestern ON across the upper Mississippi Valley, to the KS/MO border area and deep south TX. By 12Z, this trough should shift eastward to Lakes Superior and Michigan, IN, middle TN, AL, and the north-central Gulf. Several embedded/minor shortwaves will traverse the associated cyclonic-flow field through the period, contributing to relatively maximized potential convective coverage on the mesoscale. Farther west, a weak shortwave trough will move inland over parts of the Pacific Northwest and northern CA, contributing to locally gusty dry thunderstorms, as noted in the SPC fire-weather outlook. At the surface, 11Z analysis showed a wavy, quasistationary frontal zone from southern SC across central/southern GA, to near the LA coastline, and across deep south TX. This boundary should move little through the day, while becoming more diffuse west of central/eastern GA. Another cold front was drawn from Hudson Bay across northern ON, Lake Superior, to a low near CID, to another weak low near TUL, and finally, to yet another weak low near INK. This front will move eastward/southeastward through the period, reaching lower MI, southern MO, the Arklatex region, and portions of central/southwest TX by 00Z. By 12Z, the approach of the mid/upper trough will induce frontal-low formation over southeastern Lower MI. The cold front will extend from the MI low across eastern TN, southeastern MS, and south-central TX. ...Southeastern CONUS to Ohio Valley... Scattered thunderstorms should develop through this afternoon in an arc of favorable buoyancy and weak CINH, wrapping around the southern/western Appalachians, along and outside of the low-theta-e damming air mass. Isolated severe hail and damaging to marginally severe gusts are possible. The most favorable conditions at various levels for severe will be horizontally displaced from each other across this broad, arching area, but individual elements may contribute to at least marginal severe potential locally. Moisture quality and theta-e will be greatest over the FL/GA/Carolinas swath, while mid/upper flow, cooling aloft, and deep shear will increase northward/northwestward through the western Appalachians/Ohio Valley lobe. Warm and moist advection north of the frontal zone, across western GA and eastern portions of AL/KY, will contribute to destabilization through the afternoon, in tandem with diabatic heating, enabling a narrow corridor of 500-1500 J/kg MLCAPE to develop there. Despite modest midlevel lapse rates, pockets of 1500-2500 J/kg MLCAPE should develop this afternoon in the Southeast. Weak low-level flow is forecast area-wide, except for some hodograph enhancement possible above the surface late afternoon and evening near the Atlantic coastal areas of GA/Carolinas. An assortment of boundaries will focus convection, including the frontal zone, outflow, differential- heating areas, confluence lines in the warm sector, and sea breezes. ...Ozarks and vicinity... Airmass recovery following the morning clouds/convection should become favorable for the next round of thunderstorms -- this time including surface-based cells -- by mid/late afternoon. Seasonably cold, -16 to -18 deg C 500-mb temperatures will spread over this region this afternoon, near the mid/upper-level trough. When juxtaposed with residual boundary-layer moisture, afternoon surface diabatic heating and related strengthening of low/middle-level lapse rates, forecast soundings reasonably suggest around 500-1000 J/kg MLCAPE with little or no MLCINH and a well-mixed subcloud layer. Organization will be tempered by lack of more robust moisture and shear, with little directional shear and effective-shear magnitudes generally less than 30 kt. However, strong anvil-level flow will aid in ventilation aloft, and the most robust cells may offer marginally severe hail/gusts. With convective potential extending northward into much of IA, the northern bound of the marginal risk area is, in reality, much fuzzier than the graphical line indicates, but already low-end severe potential still appears to diminish with northward extent into lesser magnitudes of cloud-layer shear and low-level theta-e. ...TX Big Bend/Trans Pecos... Isolated thunderstorms may develop this afternoon over this region south of the cold front, especially near higher terrain where diabatic heating will erode MLCINH preferentially. Severe hail and strong to marginally severe gusts are possible from any sustained convection that can form, though convective coverage is in question. Low-level convergence will be maximized near the generally southward-moving surface low, and any associated convergence zone extending southward. The main uncertainty involves whether associated lift will be sufficient to form/maintain thunderstorms long enough to produce severe, in an environment characterized by steep low/middle-level lapse rates and adequate boundary-layer moisture. Surface dew points in the mid 50s to low 60s F contribute to potential MLCAPE 1500-2500 J/kg in modified model soundings. In areas south to southeast of the low where an easterly surface wind component will enhance directional shear, 35-45 kt effective-shear magnitudes may be found. Any severe threat in this region should be conditional and short-lived, decreasing markedly after dark. ..Edwards.. 06/12/2019
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