Area Forecast Discussion
Issued by NWS Amarillo, TX
Issued by NWS Amarillo, TX
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045 FXUS64 KAMA 191847 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 147 PM CDT Sun May 19 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE FOR THE SEVERE THUNDERSTORM POTENTIAL THIS AFTERNOON AND EVENING...Issued at 1:35 PM CDT Sun May 19 2024 Another conditional risk for severe thunderstorms is present today for northeastern portions of the Texas and Oklahoma Panhandles. The upper level ridge has flatten out over our area, and will allow for a shortwave surface trough to move in from the west this afternoon. Concerns about moisture quality and dryline placement are in place today, but if the right conditions are met a very unstable environment exists and will promote thunderstorms to become strongly severe. Mesoscale parameters... As of late this morning, a pocket of dry air has already moved into the southwestern quadrant of the CWA. Areas near Hereford, Vega, and even Amarillo have had their surface dewpoints plummet to the upper 30`s and some lower 40`s. Surrounding areas to the north and east have still retained moisture up to this point, so dewpoint temperatures reside in the upper 50`s and lower 60`s. Later this afternoon, a dryline should materialize with a west- to-east gradient and advance eastward. How quickly this occurs has been a point of contention, since many of the CAMs and 12Z guidance suggest the dryline should quickly mix east, and disallow storm from growing upscale in our area. However, the 12Z NAM products still favor a slower moving dryline and suggest storms will become severe in our CWA before they move into western Oklahoma and Kansas. Given that the current spread of dewpoint values are higher than most of the guidance, a slightly slower dryline progression is anticipated for today. This would permit storms to initiate in our two eastern stacks of counties (Beaver to Donley and eastward). Based off of model 0-6 km Theta-E moisture profiles, better quality moisture will be available in the mid to upper levels of the atmosphere. Though storm initiation seems more probable here than what the models convey, they may be slower to fully mature and become severe if subsidence still prevails aloft. Environment and hazards... Should the full potential of our mesoscale parameters be realized, a favorable environment exists for powerful severe thunderstorms. This is especially true for the far northeast Panhandles where the higher end instability and shear is placed. Based off of LAPS data and surface observation mesoanalysis, SBCAPE values range between 2,500- 3,500 J/kg, with MLCAPE ranging between 1,500-2,500 J/kg. Large inverted V model soundings show DCAPE around 1,600 J/kg. Steep lapse rates approaching 9 C/km, and 0-6 km bulk shear between 35-40 kts are also at play today. With wind direction generally veering with height, a discrete to semi- discrete storm mode is expected today. And provided such a large disparity between surface temperatures and dewpoints, LCL heights will be quite tall and high based storms are expected. The primary hazard today will be powerful straight winds up to 80 mph and dry microburst are possible. Large hail is also of concern today given the very unstable air and good bulk shear. However, the temperatures at the surface and aloft are quite warm for this time of year, so the freezing level is much higher for any storm that forms. Even so, 2 inch hailstones or larger cannot be ruled out. The tornado threat for today is also low considering the high LCLs and only modest low level shear. But if the triple point forms further south, and with higher terrain in place, a tornado or two is not impossible. Landspouts may also form today with any boundary convergence, but they will have the same limiting factors as a mesocyclonic tornado will have. In addition, 3CAPE and enhanced stretching potential values are below the recommended criteria for non-supercellular tornadoes. Rangel && .SHORT TERM ... (Today through Monday night) Issued at 308 AM CDT Sun May 19 2024 A mixed bag of potential is present today for the Panhandles as models see the ridge getting slightly flatten by a trough moving through to our north. This flattening will open the Panhandles up to deal with a short wave moving through on the southern end of the trough, which in turn will see the dry line retreat slightly west into our area. Most models expect it to set up in our far eastern counties this afternoon which could open those areas up to severe weather. As it stands, many models are showing the ingredients to make for all hazard type severe thunderstorms with MLCAPE sitting in the 2000 to 3000 J/kg range and 0 to 1 km shear pushing values above 30kts. However, these same models are also showing that usage of these ingredients is going to be very conditional with decent CIN present at the lower-levels. The presence of this CIN is mostly due to the lack of moisture at the low to mid level of the atmosphere. A quick look at model sounding continues to show that all of our moisture for the afternoon above the 500mb level, which in turn will make for very high based thunderstorms should we get anything at all. Added to this is the fact that shear starts to drop off greatly once you get past 3km, with most sounding showing only straight line speed shear present at the upper-levels. This will make it hard to keep anything high based sustains, which, at this time, is the more likely development given the expected LCL heights. In this case, the bigger threat for the day may actually come an isolated thunderstorm producing a severe wind gust rather than multiple supercells producing hail and/or tornadoes. Given this outlook, have chosen to keep POP reduced for the afternoon. As for rest of the Panhandles, confidence is high that the main threat for today will be the heat. As it stands, models are still expecting a lee-side low to be positioned in such a way that the Panhandles will see good downsloping southwesterly winds. The presence of these winds have a tendency to see temperatures increase even more than usual, which will likely result in afternoon highs in the mid to upper 90s across the Panhandles. This effect is further amplified in places like the Canadian River Valley and the Palo Duro Canyon, which could easily see temperatures in the triple digits this afternoon. The heat threat gets even worse for Monday, as most models look for a similar set up to be present under much drier conditions. Should this trend continue, then it is likely that places like the Palo Duro Canyon may need a Heat Advisory with canyon floor potentially reaching 105 by Monday evening. Scoleri && .LONG TERM ... (Tuesday through Saturday) Issued at 308 AM CDT Sun May 19 2024 A trough ejects from the desert SW into the plains on Tuesday becoming the dominate feature over the panhandles. This trough will break the spell of hot weather that baked the panhandles on Sunday and Monday. This will see the highs on Tuesday fall to the 80s and 90s. Winds are expected to shift to the west and remain gusty through the day. Then late on Tuesday to early on Wednesday a cold front associated with the trough will push through the panhandles. This will be a dry front so it will only shift the winds to the north and not cause any active weather. Cooler air will settle across the panhandles for Wednesday further reducing the temperatures to the 70s and 80s. Thursday and Friday the pattern continues to favor a shift to a zonal flow across the southern plains. This should help to push the cooler air out of the panhandles allowing the highs to warm back to the 80s and 90s. Winds during this time should follow a standard diurnal trend of gusty from the south during the day and weak during the night. If the winds become more southeasterly then moisture may be pushed into the panhandles leading to daytime rain showers and thunderstorms. The odds of this occurring do not look favorable at this time as any moisture that does move in is likely to be east in OK proper. By next weekend the pattern becomes hard to pin down making the forecast less confident. There are hints that a system may form during this time and bring active weather to the southern plains. Conversely there is a slightly smaller chance that a ridge will form instead bringing further dry and hot weather to the panhandles. Regardless of outcome it seem favorable that the pattern will shift for next weekend bringing a change in the weather compared to mid week. SH && .AVIATION... (18Z TAFS) Issued at 1258 PM CDT Sun May 19 2024 VFR conditions will prevail at all TAF sites over the next 24 hours. Only site anticipated to possibly have disruptions would be KGUY in the next 6 hours, if a storm manages to pop up in the area, but right now confidence is too low to mention in the TAF. Winds 15-20kts out of the west southwest through about 03z then becoming less than 10kts out of the west to northwest thereafter. Weber && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 59 98 63 89 / 0 0 0 0 Beaver OK 59 97 62 90 / 10 0 0 0 Boise City OK 54 94 57 85 / 0 0 0 0 Borger TX 60 102 65 93 / 0 0 0 0 Boys Ranch TX 55 99 61 91 / 0 0 0 0 Canyon TX 56 97 62 89 / 0 0 0 0 Clarendon TX 60 98 65 91 / 10 0 0 0 Dalhart TX 53 94 55 87 / 0 0 0 0 Guymon OK 54 97 58 88 / 0 0 0 0 Hereford TX 56 98 61 89 / 0 0 0 0 Lipscomb TX 60 98 65 92 / 10 0 0 0 Pampa TX 59 98 64 90 / 10 0 0 0 Shamrock TX 60 98 65 93 / 10 0 0 0 Wellington TX 62 100 67 94 / 10 0 0 0 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...None. OK...None. && $$ SHORT TERM...11 LONG TERM....98 AVIATION...89