199 FXUS64 KAMA 250542 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 1242 AM CDT Sat May 25 2019 .UPDATE...Shower and thunderstorm activity has greatly diminished across the far southern Texas Panhandle, with no further development expected during the overnight hours. As a result, have updated PoP grids to greatly reduce or zero out the forecast until mid morning. The most pressing concern this morning will be an increase in moisture advection due to return flow, with fog and low stratus clouds being monitored. The latest GOES-East fog product is already showing signs of low stratus develop across portions of the western and central Panhandles as skies have cleared. Latest surface observations are also showing that locations like Dalhart and Guymon have visibilities dropping to about 5 and 8 miles respectively. Beyond those immediate concerns, the expectation for severe thunderstorms remains for Saturday with updates to the grids expected after the full suite of 00Z models have been evaluated. Bieda && .AVIATION...06Z TAFs...MVFR, to possibly IFR, conditions are expected to develop at the TAF sites due to fog and low stratus. These conditions are expected to persist through about sunrise. Afterwards, the dryline is expected to sharpen across eastern New Mexico and allow for more thunderstorms, some of which could severe, to develop this afternoon. All severe thunderstorm hazards are in play with these storms. Conditions should start to improve at KDHT AFT 26/03Z, and at KGUY and KAMA AFT 26/06Z (or beyond the TAF period). Bieda && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 82 61 77 59 85 / 40 40 60 50 10 Beaver OK 81 60 80 61 86 / 50 50 60 50 10 Boise City OK 82 53 78 53 81 / 20 20 50 40 5 Borger TX 86 62 80 60 87 / 40 40 70 50 10 Boys Ranch TX 84 59 80 58 86 / 40 20 70 50 5 Canyon TX 84 60 78 59 86 / 40 30 70 50 5 Clarendon TX 82 62 77 61 86 / 50 50 60 50 10 Dalhart TX 84 53 78 53 83 / 50 20 60 50 5 Guymon OK 83 58 78 57 85 / 40 40 70 40 5 Hereford TX 83 60 79 59 86 / 40 20 60 50 5 Lipscomb TX 82 62 80 62 84 / 50 50 60 50 10 Pampa TX 82 61 77 60 84 / 40 40 70 50 10 Shamrock TX 82 63 78 62 84 / 40 50 50 50 10 Wellington TX 83 64 80 63 86 / 40 50 40 50 10 && .PREV DISCUSSION... /Issued 644 PM CDT Fri May 24 2019/ AVIATION... For the 00z TAFs... Outflow boundary emanating from thunderstorms from Lubbock to Childress can be seen in KAMA 88D data, currently near a line from Hereford to Boys Ranch to Dumas. Outflow has brought cooler air which has reduced instability with its passage. Chances for evening thunderstorms have gone down as well. VFR conditions expected to prevail at all terminals through this evening and overnight. MVFR ceilings expected to move into southeast part of forecast area around sunrise, reaching AMA around 15z Saturday, and not reaching northern terminals. Ceilings at AMA expected to lift into VFR range early- to mid- afternoon. Threat for afternoon and evening thunderstorms exists at all terminals Saturday with very unstable airmass in place ahead of dryline. Cockrell PREV DISCUSSION... /Issued 159 PM CDT Fri May 24 2019/ SHORT TERM...Tonight and Saturday... Nearly stationary frontal boundary has stalled across the far southeastern Texas panhandle, ranging from near Lubbock to Canadian at 18Z. This boundary once again will serve as a focus for thunderstorm development this afternoon and evening. 18Z special sounding shows the cap very much in place to the north of the boundary, which should help limit some development to the north of US60. However, any storm which is able to be lifted above the mixed layer aloft will be able to accelerate upward, given the steep mid level lapse rates above 700mb. Once again this afternoon and evening, along the front, severe storms are possible, with large hail and damaging winds the primary hazards. However, near the front, there will be sufficient wind shear for supercells to form, and the potential for tornadoes. For Saturday, we will play another game. Supercells once again possible during the afternoon and evening hours as the boundary will be reinforced from the north, with a dryline to the west. Supercell thunderstorms once again possible Saturday afternoon. Additionally, there will be the potential for locally heavy rainfall, with some cells producing up to 1-3 inches in localized areas. Fox LONG TERM...Saturday Night through Thursday night... The focus of this discussion will be the weekend, as we look to finally have a little break as we move into the work week. But we'll be watching the end of the work week for more active weather. Saturday night through Sunday night...Surface high remains strong over the southeastern CONUS providing moist low level south to southeast flow over the Panhandles. This will keep the dryline at bay along the western TX/Easter NM state line area. Weak lee surface low's will develop and try to push the dryline east, but return flow from the southeast will be too strong. Upper level trof still poised to be over the western CONUS with a closed low to track south over the southern NV tip by Sunday night. This will help drive moisture to our mid levels. PWAT values will still be in the 1.25"- 1.75" range Saturday night into Sunday night. Moderate to heavy rain can be expected with all storms. Typical diurnal heating should help to drive the storms to become surface based along the dryline and progress eastward Saturday and Sunday. Given the ample low level moisture and the steep mid level lapse rates (7-8.5C/km), ML CAPE values look to be in the 2000-3500 J/kg range on Saturday, and 1000-2500 J/kg on Sunday. Large hail (baseball, possibly larger) and damaging winds (70mph) will be the primary threats, but tornadoes can't be ruled out as well. Additionally, the tornado threat will increase in the evening hours both days due to the strengthening low level jet. Side note to watch, with the aforementioned lee low, we do have a high-res CAM that suggests that a weak cold front could sag into the OK Panhandle and fire off severe convection, but keeps everywhere south of the storms (the TX Panhandle) capped, and doesn't trigger any convection. This will need to be watched, as there is potential for thunderstorms to not occur as well. Monday through Wednesday...Upper level low will eject to the northeast out of the southern NV area, and actually looks to be able to suppress the upper level ridge that's been in place over the eastern CONUS. This will latch on to a large scale cold airmass across the northern states, leading toward a more zonal upper level flow across the central and eastern CONUS. What does that mean? Well, a stronger lee low will develop on Monday and will likely push east pulling in drier air and shifting the dryline east of the Panhandles, removing the thunderstorm threat to the area. In addition, breezy to windy conditions are expected to occur across the central and western Panhandles. Currently don't think we will see Wind Highlights, but still something to keep an eye on. Just depends on how strong the winds aloft are able to mix down. Tuesday another lee low develops, and looks to be weaker, but will help keep the dryline east of the OK/TX state line. Winds will be breezy but not as strong as they were Monday. Cold front expected to move through on Tuesday night and highs on Wednesday could be in the mid to upper 70s. Thursday and Thursday night...While the Panhandles will still be in a more zonal flow, a weak amplitude upper level trof will move over the western CONUS. Surface flow will start to back from the southeast again, and that will retreat the dryline back to the west. For now Instability will again increase, and there will be a chance of storms, but right now it's hard to say if they will have severe, potential. Mid level lapse rates are only 5-6C/km, and CAPE values are less than 1000 J/kg. SRH values not too impressive less than 200m2/s2 in the 0-3km range and around 50m2/s2 in the 0-1km range. Still possible to get storms. Weber AVIATION...18Z TAFS... Low clouds have more or less burned off, with a few areas of scattered lower clouds and/or fog across the southern Texas Panhandle. Clear skies now at KAMA, with VFR conditions expected to last for another two to three hours in the south. For KDHT and KGUY, VFR conditions are expected to continue for the bulk...if not all...of the upcoming TAF cycle. Thunderstorms are once again the main issue today, with a few showers remaining to the east and southeast of all three terminals. However, the stationary front to the southeast which is helping to keep the showers/storms going...will very slowly drift northward, keeping KAMA in the target area for additional thunderstorms to fire this afternoon and evening. Like last night, once sunset occurs, the low level jet will begin to strengthen, and may cause a few areas of LLWS on approach and takeoff. Fox && .AMA Watches/Warnings/Advisories... TX...Flood Watch until 7 AM CDT this morning for the following zones: Collingsworth...Donley...Hemphill...Wheeler. OK...None. && $$ 98/36