Area Forecast Discussion
Issued by NWS Amarillo, TX
Issued by NWS Amarillo, TX
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730 FXUS64 KAMA 020014 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 714 PM CDT Wed May 1 2024 ...New AVIATION... .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... (This evening through Thursday night) Issued at 410 PM CDT Wed May 1 2024 For the rest of this afternoon and tonight, refer to the above mesoscale update discussion for detailed information. Pops in the grids for tonight reflect the reasoning outlined in the mesoscale discussion. Semi-zonal to west southwest upper level flow is expected for Thursday and Thursday night. A very minor shortwave trof embedded in this flow is progged to zip eastward across the region during this time period, and could bring a few showers and thunderstorms to parts of the eastern OK and eastern TX Panhandles Thursday afternoon and night. NBM slight chance pops look reasonable and were accepted. 02 && .LONG TERM... (Friday through next Tuesday) Issued at 410 PM CDT Wed May 1 2024 For Friday through Sunday afternoon, a few minor upper level shortwave trofs embedded in the overall mean flow are forecast to move across the region and will bring a threat for showers and thunderstorms during this time frame. Based on the predicted track of these minor features, the southern Texas Panhandle may have the best chance of receiving precipitation, while the far northwestern zones may have the lowest chance. NBM pops reflect the above scenario and were utilized in the appropriate grids for Friday through Sunday. A much stronger upper level low pressure system is then slated to move across the central and northern Rockies and adjacent plains Monday into Tuesday. This suggested path offered by medium range models would prove to be more of a dry, windy, and warm scenario for our forecast area. Medium range models and associated ensemble members are in reasonable agreement with that idea and were accepted. That said, warmer temperatures along with breezy to windy conditions and dry weather are in the offing for Monday and Tuesday. 02 && .AVIATION... (00Z TAFS) Issued at 654 PM CDT Wed May 1 2024 For the 00Z TAFs, a cold front will move across the terminal sites late tonight into early Thursday morning with north winds in its wake. Some potential exists for a period of MVFR cloud development early Thursday morning at the TAF sites. Confidence is very low on whether or not any MVFR cigs form so have only included a sct deck at each site for this forecast cycle. The north winds will diminish Thursday afternoon. 02 && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 53 76 51 73 / 20 0 10 30 Beaver OK 51 75 46 77 / 30 10 10 30 Boise City OK 46 72 44 73 / 10 10 10 30 Borger TX 55 80 51 77 / 20 10 20 30 Boys Ranch TX 52 78 50 77 / 10 0 10 30 Canyon TX 52 77 51 74 / 20 0 10 20 Clarendon TX 56 77 53 72 / 50 10 20 30 Dalhart TX 46 74 44 73 / 10 10 10 30 Guymon OK 48 74 45 75 / 10 10 10 30 Hereford TX 51 78 51 75 / 10 0 10 20 Lipscomb TX 55 76 50 76 / 30 20 20 30 Pampa TX 53 76 51 72 / 20 10 20 30 Shamrock TX 57 76 53 73 / 60 20 20 30 Wellington TX 58 79 54 73 / 70 10 20 30 && .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...02 LONG TERM....02 AVIATION...02