033 FXUS64 KAMA 241142 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 642 AM CDT Sun May 24 2020 .AVIATION...12z TAF Cycle... VFR conditions are expected for at least first half of TAF period. However, scattered thunderstorms are expected to develop by mid afternoon today, and the eastern most terminals have a chance to see impacts, with KAMA most favored through early evening. Heavy rain, large hail and strong outflow winds will be possible with the storm activity. A cold front will move into the KDHT/KGUY terminals later this morning, but should stall and possibly retreat by late morning. The front is expected to push on through the terminals Sunday night and should bring with it north winds, MVFR/IFR cigs (LIFR possible), and scattered showers (a few thunderstorms can't be ruled out). Otherwise, winds will be out of the south and southeast at 10 to 20 knots. Some low level wind shear is possible at KGUY and KAMA this morning up until about 13z. Ward && .PREV DISCUSSION... /Issued 317 AM CDT Sun May 24 2020/ SHORT TERM...Today through Monday. Mid level low pressure centered over southern MT with south extending trough axis has not moved much over the last 6 to 12 hours. This has helped maintain broad cyclonic flow over the Rocky Mountains and adjacent plains. An embedded shortwave was noted on mid level water vapor imagery, along with several departing mesoscale convective systems (one moving through central SD/NE and another moving into eastern OK and north TX). A cold front (augmented by storm outflow) is now moving through northwest KS and northeast CO. As of 07z, temperatures across the Panhandles were in the mid 60s with dew points in the upper 40s to low 50s. Mid 50s dew points were noted in the far southern CWA and into LUBs area. Low 60s dew points were noted in southwest OK and south across the Red River. Moreover, some recovery of moisture will be needed for this forecast to work out (and this is expected based on the current pattern). For today, shortwave trough over AZ will round the base of Great Basin trough, with PVA overspreading sharpening dryline by mid afternoon. The cold front is expected to stall in the northwest Panhandles and possibly retreat by early afternoon. The 250mb trough axis is progged to take on some negative tilt through the morning which should encourage low level moisture advection and help sharpen the dryline in the west central Panhandles. Convective initiation will likely occur as the shortwave dynamics sync up with moisture convergence along the dryline by 20z-21z. Low to mid 60s dew points east of the dryline beneath steep lapse rates will support strong instability (similar to yesterday). MLCAPE values of 2500 to 3500 J/kg are possible. The big difference from yesterday is increased column moisture (PWATs around 1.0 inch) and increased forcing with stronger shortwave and some weak 250mb jet dynamics. Shear is still unimpressive, with only 20 to 30 knots of effective deep layer shear. There is decent veering of winds in the lowest 4km, but wind speeds are almost uniform at around 20 to 30 knots up to 8km (closer to 40 knots at anvil layer). Thus, storms will take on mostly multicell modes and may grow upscale into linear segments given stronger forcing with shortwave. Like yesterday, large to very large hail up to baseball size will be possible with the strongest storms due to updraft velocity alone. Very strong downburst winds up to 70 mph are also possible with DCAPE values over 1500 J/kg. A tornado is unlikely given weak shear and LCLs around 1 to 2 km, but can't be ruled out with boundary interactions or storm mergers. Localized flooding is possible given moisture and storm motion being fairly slow (mean wind only around 20 knots). Storms will be pushing out of the area by 9 PM or so. Some models show an "onion sounding" which has been connected to wake low development. This along with some heat bursts along anvil edges can't be ruled out. The cold front is expected to move through most of the Panhandles Sunday night. There is some model discrepancy with precipitation or thunderstorms forming along and behind the front, with the EC being most aggressive. However, there may be room to decrease precipitation chances if the latest trends with NAM and GFS continue showing much drier air in wake of front and 500mb low forming further south. Ward LONG TERM...Tuesday through Saturday Night. Upper low looks to cut off from the main flow and meander to our southeast over Texas Tuesday through Saturday. Resulting surface low over north Texas, combined with persistent surface high over the Upper Midwest, should lead to northerly or northeasterly surface winds across the Panhandles through much of the extended. Additionally, a good deal of mid level moisture is progged to wrap around the upper low, leading to at least partly cloudy conditions every afternoon. The result should be below average temperatures through Saturday. Given the influence of bias correction in the NBM and the notable pattern shift ahead, have nudged afternoon highs downward just a bit. As for precipitation, with multiple embedded vorticity maxima rotating around the upper low and the aforementioned moisture being present, have maintained multiple mentions for showers, especially across our eastern zones. Progged MUCAPE remains modest to very modest depending on the period, so have limited thunder mentions to a slight chance. Ferguson AVIATION...06Z TAFs. VFR conditions expected for most of the TAF period. However, scattered thunderstorms are expected to develop by mid afternoon Sunday, and all terminals stand a decent chance to see impacts, with KAMA most favored through early evening. Included a PROB30 at all sites to indicate best timing. Heavy rain, hail and strong outflow winds will be possible with storm activity. A cold front will move into the KDHT/KGUY terminals later this morning, but should stall and possibly retreat before arriving at KAMA. The front is expected to push on through the terminals Sunday night and may bring with it north winds, lower cigs (MVFR likely, IFR possible), and scattered showers. Otherwise, winds will be out of the south and southeast at 10 to 20 knots. Some low level wind shear is possible favoring KGUY this morning before 12z. Ward && .AMA Watches/Warnings/Advisories... TX...None. OK...None. && $$ 7/77