Area Forecast Discussion
Issued by NWS Amarillo, TX
Issued by NWS Amarillo, TX
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855 FXUS64 KAMA 011851 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 151 PM CDT Wed May 1 2024 ...New MESOSCALE UPDATE... .MESOSCALE UPDATE FOR THE SEVERE THUNDERSTORM POTENTIAL THIS AFTERNOON AND EVENING... Issued at 126 PM CDT Wed May 1 2024 We are watching the potential for severe storms to fire up in the far eastern Panhandles later this afternoon and evening. An elongated upper level trough at 500 mb is moving east off of the Rocky Mountain range today and will promote storms to form along a surface dryline as the height gradient tightens and upper level vorticity increases. Near term mesoscale features will be paramount to determine if storms will be able form in the CWA today, where they will be, and what hazards could be present. 11 AM and onward, mesoscale parameters... A weak surface boundary has moved through the northwest Panhandles and will diminish it`s flow by the afternoon. A NE/SW dryline is setting up with the sharpest gradient expected to develop by 4 PM east of Amarillo, perhaps between the eastern half of the CWA and the eastern two stacks of counties, (Beaver to Donley and eastward). Current CAM guidance suggest that the cap will be broken today and storms will generate along the dryline around the 4 PM hour. Some contingencies are still active, as low level cloud coverage is still present in the eastern two stacks. A large scale outflow boundary has also been detected moving west across western Oklahoma from overnight convection in that area on the previous day. These conditions may allow stable air to settle into the setup area which may prevent storms from becoming severe or even stop any storm from forming. Short term model guidance still shows clouds clearing between 1 and 2 PM, (according to the latest 15Z and 16Z guidance). Satellite imagery also shows some areas of clearing, but the process seems slow, and overcast conditions remain in effect for most portions of the far east. CAM guidance also has a history of not handling these outflow boundaries very well, since it`s a smaller mesoscale feature that can be difficult to forecast. Nevertheless, Satellite imagery and surface observations hint at the boundary progression weakening and slowing down. If this outcome of clearing skies and a dispersing outflow boundary come to fruition, then storms have a better chance to meet convective temperatures and break the cap this afternoon. Otherwise, if any of the two preventatives pan out, (cloud coverage lingers or stable air moves in), then expect minimal chances for any storm to reach severe limits. Currently, the CAMs and other near term models have no issues convecting today. However, there are still small discrepancies concerning coverage and potential severity. Environment and hazards... Concerning the threat area today in the eastern Panhandles, SBCAPE and MUCAPE should reach values around 3,000 J/kg, with an area of even higher values >3,500 J/kg in the southeast Texas Panhandle. Strong lapse rates should be approaching 8 C/km, and effective bulk shear could range between 30 - 40 kts. Continuing from the surface and viewing upward with height, backed surface winds from the southeast will veer well with height creating curved but not very long or robust hodographs. LCLs will be lower in the southeast Texas Panhandle compared to places further north. Perhaps looking at values to range between 1,000 - 2,000 m overall. FZL levels will reach around 11,000 ft for the area and -20C levels should only be about 10,000 ft higher. Despite relatively modest bulk shear vectors, based off of the other parameters mentioned very large hail is possible with any storm that can become severe. Hail up to the size of teacups (3.00 in) is possible. Impressive DCAPE values may also be present between 1,000 - 1,500 J/kg. Given this, strong outflow winds will be possible even up to 70 mph. Low level wind shear and 0- 1 km SRH are not overly impressive, but the low level jet should kick in by the evening hours as shown by model forecast 850 mb winds. By then, LLWS parameters will increase providing a short window for a tornado threat. Any discrete storm that can sustain itself through the evening hours will have that capability, though the threat is not high considering the parameters will marginally hit the criteria. Thunderstorms will initiate in an isolated manner, and a discrete storm mode is expected until the late evening. Afterwards, storms in the southeast Texas Panhandle should congeal into a multicellular cluster by the nightfall. Areas under these storm cells can anticipate heavy rainfall, as overall storm motion should be slower today given the steady and leisurely progression of the dryline as it moves east during the day and then retreats west during the nighttime hours. Rangel && .SHORT TERM ... (Today through Thursday night) Issued at 308 AM CDT Wed May 1 2024 Summary: Wednesday brings yet another setup - at least the third in the past three weeks - where critical fire weather conditions are expected in the western Panhandles and severe thunderstorms may occur in the east. In contrast to the past two weeks, remaining uncertainty about severe thunderstorms does not focus on if they will develop but where, with the late afternoon location of the dryline the primary forecast question. Very large hail and damaging winds look to be the primary risks but a tornado or two would be possible as well. Details: 07z WV satellite shows west-southwesterly flow aloft over the Panhandles and Four Corners. A larger than expected area of convection is seen over OK ahead of a shortwave. At the surface, dewpoints in the 50s and 60s are surging north-northwestward with the dryline making its usual nocturnal retreat to the west - dewpoints west of this feature are generally around 20. Today, lee surface troughing should continue to our west, with downslope winds continuing our trend of highs in the mid 80s to lower 90s. Additionally, expect the western Panhandles to see RH values drop into the single digits, particularly the far west central TX Panhandle, where overnight recovery looks to be poor. This should lead to critical fire weather conditions but, given lack of a notable LLTR and modest mid-level winds, highly aggressive fire behavior is not favored. In the east, expect moist advection to continue, allowing dewpoints to remain in the 60s in many locations. Dryline should mix eastward this afternoon with most non-NAM/GFS guidance suggesting the eastern two columns of the TX Panhandle and Beaver County will remain in the moist sector as peak heating is achieved, with the NAM farther west with the moist sector and the GFS suggesting the dryline will mix just east of our CWA. Progged MLCAPE values are around 3000 J/kg with weaker capping than our previous two nearly weekly similar type risks. Given this and the overachieving convection Tuesday night, am fairly confident some storms will develop with some chance of this occurring east of the forecast area entirely given the GFS solution. Given progged 0-6km bulk shear of around 40 knots and the orthogonal orientation of shear with the dryline, initial discrete supercells are favored. Given favored rotating updrafts and steep mid-level lapse rates of 8 C/km, very large hail to 3 inches in diameter looks to be the primary hazard, followed by damaging winds. Hodographs suggest a bit more near surface helicity compared to previous runs, so there will be a risk for a tornado or two as well. Thursday, welcome cold front pushes south through the CWA, leading to highs mainly in the 70s. Appreciable moisture with this frontal passage looks to largely remain to our west, so have attempted to limit mentions of rain, particularly after noon Thursday. Ferguson && .LONG TERM ... (Friday through Tuesday) Issued at 308 AM CDT Wed May 1 2024 Friday through Sunday...Models are trending towards a better chance for precipitation as we head into the weekend. Friday could see some early morning showers/storms due to the frontal boundary stalled over portions of the FA and an embedded shortwave moving through the Panhandles. Highs on Friday are a bit of a challenge as cloud cover will be an issue for most of the day limiting the heating, but there is the potential for southwest flow to kick in, at least for the southwest Panhandles and push temperatures back into the low to mid 80s with some clearing late in the afternoon. Some guidance suggest that the front will remain well to the south and while we`ll be on the cool side at the surface due to the front, we will still have deep layer moisture and a fairly shallow inversion aloft. Saturated soundings to the top of the inversion early to mid Friday morning as well as a shortwave moving through, suggests the potential for elevated storms capable of producing large hail. Another shortwave with a cold front associated is expected to move across the northern Panhandles Friday night and again is expected to ignite another round of storms late Friday night into Saturday morning. Given the elevated nature of these storms, large hail will be the main threat. With PWAT`s around an inch, these storms will have the potential for heavy rain as well. A break during the day Saturday with the front through, but as we move into Saturday evening we can expect another shortwave out of the southwest flow to bring even more chances of storms to the Panhandles. There is a a question as to how far that front on Saturday will push south, and if it does take a further south track then the storms will most likely be more in the Lubbock area. By Sunday afternoon, most of the activity will be out of the area or to the east. Highs on Saturday look to be in the low to mid 70s, given the cold front, and on Sunday we can expect mid 70s to lower 80s. We`ll have to keep an eye on Monday as the next upper trough is expected to move across the Panhandles, with a potentially strong stacked jet associated. If the pattern holds, it will likely support wind highlights, and would typically be a good Fire Weather setup, however we still have to evaluate just how much moisture the Panhandles will receive over the weekend, to see if there will be any Fire Weather concerns. But highs on Monday are expected to be in the 80s. Tuesday`s highs are suggested to be in the 80s via NBM, however if the system pushes through as expected, there is a bit of a pullback on the temps for Tuesday and more likely we`ll see 70s to maybe some isolated areas reaching 80. Weber && .AVIATION... (18Z TAFS) Issued at 1243 PM CDT Wed May 1 2024 For the 18Z TAFs, any thunderstorms that develop later this afternoon and evening should remain east of the terminal sites at this time based on the latest numerical model guidance. A cold front will move through the region late tonight and Thursday morning with gusty north winds in its wake. Some concern exists for MVFR cloud development in the post frontal airmass, with KGUY the most likely location to see this occur, and have added a low end MVFR cig early Thursday morning. Did include a sct MVFR deck of clouds at KDHT and KAMA where confidence is lower at this time. 02 && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 54 78 50 73 / 20 0 10 30 Beaver OK 52 77 46 77 / 20 10 10 20 Boise City OK 48 73 43 73 / 10 0 10 30 Borger TX 55 80 51 77 / 20 10 10 30 Boys Ranch TX 53 81 49 76 / 10 0 10 30 Canyon TX 53 79 49 74 / 20 0 10 20 Clarendon TX 57 80 53 71 / 40 10 10 30 Dalhart TX 48 75 42 72 / 10 0 10 30 Guymon OK 50 75 44 74 / 10 0 10 30 Hereford TX 52 80 50 76 / 10 0 10 20 Lipscomb TX 56 77 49 76 / 20 20 10 30 Pampa TX 55 77 50 73 / 20 10 10 30 Shamrock TX 58 79 53 73 / 40 20 10 30 Wellington TX 58 81 54 74 / 50 20 10 40 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...Red Flag Warning until 9 PM CDT this evening for TXZ001-002-006- 007-011-012-016. OK...Red Flag Warning until 9 PM CDT this evening for OKZ001. && $$ SHORT TERM...77 LONG TERM....89 AVIATION...02