####018007003#### FXUS61 KPBZ 101833 AFDPBZ Area Forecast Discussion National Weather Service Pittsburgh PA 233 PM EDT Fri May 10 2024 .SYNOPSIS... Scattered showers give way to dry conditions overnight ahead of approaching low pressure that will return showers and thunderstorms for Saturday and lingering into Sunday. Temperatures will be below average this weekend. Warmer pattern returns next week with rain chances increasing again for Tuesday and Wednesday. && .NEAR TERM /THROUGH TONIGHT/... KEY MESSAGES: - Scattered showers tapering off this evening with areas of fog possible by sunrise. - Lows tonight 5-7 degrees below average. ------------------------------------------------------------------- Scattered showers continue this afternoon aided by an inverted surface trough extending out from low pressure across Delmarva and weak shortwave energy traversing an upper trough across the Northeast. Coverage has transitioned to more of a convective look as low and mid level drier air noted on water vapor satellite continues to advect with mid level flow backing more west of north through the afternoon. As the surface low pushes offshore, one last upper wave will dive through late this afternoon and help maintain the scattered showers owing to some shallow instability up to 200- 300 J/kg. No severe weather or flooding concerns are expected. Once forcing is lost tonight as dry air wins out and brief shortwave ridging builds, dry conditions will ensue. Light wind will flip southerly overnight as a southwesterly gradient establishes ahead of approaching low pressure. Low temperatures tonight will dip into the low 40s areawide which is a good 5 to 7 degrees below normal. With lingering low level moisture and light wind overnight, fog may form toward sunrise with hi res ensemble probabilities for < 1 mile up to 50-60% further south and east of Pittsburgh. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... KEY MESSAGES: - Warm front followed quickly by a cold front brings another shot of showers and thunderstorms. - Highs nearly 10 degrees below average. ------------------------------------------------------------------- Another upper wave dives southeast out of the Great Lakes Saturday as aforementioned low pressure tracks by to our north and its warm front reintroduces rain showers. Hi res ensemble timing is in good agreement on arrival of precipitation into eastern OH after 11am, PIT 2pm, and the ridges 3pm with even the earliest and latest timing only an hour to two on either side of the most likely. Overall totals with the warm advection driven precip should be light between 0.2-0.3". The cold front then arrives quickly after leaving us little time in the open warm sector. Southerly gradient flow will try to pull in warmer and more moist air but only have a short window to do so. Scattering of the cloud deck appears low probability, so this should help to keep instability in check ahead of the cold front. That said, hi res ensemble mean CAPE values range from 400-600 J/kg across the area with the 90th percentile closer to 900 J/kg (contingent on low probability clearing). Effective shear values should reach 20-25 knots and mostly southeasterly unidirectional. Combined with decent low and mid level lapse rates of 7-8 C/km, the environment may be able to support some gusty wind and small hail from the taller cores that manage to develop. Probability of exceeding 0.5"/hour rainfall rates are sub 30%. With clouds being dominant for most of the day and rain arriving by late morning, erred slightly below NBM for highs which should be just around either side of the 60 degree mark. Scattered showers may linger into the day on Sunday as the core of the 500 mb low gets closer overhead and the occluding surface low throws a weak trough across the area with lingering low level moisture. Additional rainfall totals look minimal and highest totals will be along the ridges with upslope enhancement. High pressure wins out by late afternoon with dry weather returning. && .LONG TERM /MONDAY THROUGH FRIDAY/... KEY MESSAGES: - Temperatures rebound into next week. - Showers and thunderstorms return Tuesday/Wednesday. ------------------------------------------------------------------- Upper ridging takes hold come Monday with surface high pressure establishing to our southeast. Uncertainty with the depth of an upper low well off to our north in Canada lends low confidence precipitation chances north of I-80. The most likely ensemble solution brings light rain there for the first half of the day, though a less likely solution with a weaker low would keep the rain further north. Pittsburgh and south should stay dry regardless. More widespread rain chances then arrive for Tuesday and Wednesday as low pressure ejects out of the Plains and high pressure breaks down. At this point, machine learning doesn't indicate any potential for severe weather. Ensemble total precipitation sits around a 30-60% chance of >0.5" by Wednesday night. Tuesday will be the coolest day of the week owing to plentiful cloud cover and precipitation. Much more ensemble spread is exhibited by the latter half of the week with a developing trough to our west, but a dry period to close out the week with rain returning for the weekend looks more likely than not. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... Light rain showers, increasing in coverage between 18z-22z, rising cig heights are expected through this evening. Intrusion of drier air as low pressure exits east will erode showers and cigs during the early evening hours, resulting in areawide VFR conditions. The combination of residual boundary layer moisture, some cig deck clearing, and light wind may promote fog formation during the pre-dawn hours Saturday morning. Highest probabilities are along the higher terrain east/southeast of KPIT where daytime showers will linger longest and drier air will be late on arrival (KMGW/KLBE/KDUJ). A cold front will approach from the NW at the end of the TAF period, producing a swath of light rain showers with low probability for thunder. .Outlook... Additional restrictions are likely in conjunction with the mentioned showers and low probability thunderstorms above. Scattered light rain showers will linger into Saturday night as the upper trough axis crosses. VFR returns Sunday and Monday under high pressure, before low pressure returns restriction and precipitation potential on Tuesday. && .PBZ WATCHES/WARNINGS/ADVISORIES... PA...None. OH...None. WV...None. && $$ SYNOPSIS...MLB NEAR TERM...MLB SHORT TERM...MLB LONG TERM...MLB AVIATION...Frazier ####018007130#### FXUS64 KAMA 101834 AFDAMA Area Forecast Discussion National Weather Service Amarillo TX 134 PM CDT Fri May 10 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM ... (This evening through Saturday night) Issued at 133 PM CDT Fri May 10 2024 A weather system centered over the desert SW has started to influence the southern plains. This has seen some low but more so mid level moisture move into the southern plains from the north. This moisture has slowly moved into the western panhandles which will allow for a low chance of light rain showers to even isolated thunderstorm to form this afternoon to evening. Accumulations of any rainfall during this time will be very low as the moisture is still not high. As the weather systems influence grows through today and tonight it will cause the winds to shift to a SE flow. The winds will strengthen some becoming gusty during the afternoon and evening hours. These winds will then drive in additional low level moisture across the panhandles. This will cause the chance for rain showers and thunderstorms to increase and cover the entire panhandles. As there will be more moisture in play moderate to even brief heavy rainfall may occur with these showers and thunderstorms increasing rainfall yields. Sunday will see the weather system finally move out of the desert SW and across the southern plains. In doing so it will draw additional moisture across the panhandles while increasing the instability and environmental dynamics. This will lead to even higher chance for rain showers and thunderstorms across the panhandles. It will also open up at least a low chance for strong to even severe thunderstorms. The central to eastern portions of the panhandles are currently the more favored area for this low chance of strong to severe thunderstorms to take place. The main threat from these powerful storms is going to be large hail and damaging winds. All this chat of rain and thunderstorms doesn't guarantee that any spot will receive any rain at all, it could be that one spot get multiple showers and thunderstorms while other will stay dry the whole time. So while the whole panhandles should average 0.5 to 1 in of rain some area will see higher some will see lower or nothing. This weekend will be on the cooler side as the ample moisture will have a high chance of causing fairly extensive clouds. This will help to suppress daytime heating bringing down the temperatures. This will further be compounded by the system itself moving cooler air across the southern plains. So below average highs in the 60s to 70s have a high chance of occurring for both Saturday and Sunday. SH && .LONG TERM ... (Sunday through next Thursday) Issued at 133 PM CDT Fri May 10 2024 Showers/storms will hopefully be ongoing intermittently through the weekend, creating a less than obvious thunderstorm outlook on Sunday. More vigorous upper level support should arrive to the region by Sunday afternoon-evening as a positively tilted trough ejects towards the Plains. Deep-layer moisture will remain in place by the time this system arrives, with high PWATs around or greater than 1.00" for much of the Panhandles. The question lies in how much instability can exist for afternoon convection, likely dependent on daytime heating and recovery from any overnight/ morning convection, along with if and where the cap can break to utilize any available fuel. As a sfc trough develops through the day, it may help to break the cap and initiate additional convection. Deep-layer shear would likely be favorable for some strong to possibly severe thunderstorms IF sufficient instability remains in place east of the sfc trough. Based on ensemble probabilities for CAPE >1000 J/kg (40-70%), the most favored areas for this low-end severe potential would reside across the eastern to central combined Panhandles. Regardless, any shower or storm on Sunday would likely provide beneficial rainfall, especially across eastern counties where model forecast soundings depict a saturated environment with tall, skinny CAPE profiles. Generally expect weekend rainfall totals in the 0.1-0.5" range, with localized higher localized totals in the 0.75-1.00" range or greater certainly plausible. As the system departs Sunday night, a weak cold front will swoop down and steal whatever moisture remains, although some lingering showers may persist into Monday morning. Monday will actually be warmer behind the front however, thanks to eroding cloud cover and increased sunshine. Sfc winds shift to south- southwesterly Tuesday as ridging aloft makes a temporary return. Expect highs in the mid to upper 70s Monday, warming into the 80s Tuesday. Rain and storms could return by midweek when ensembles agree another shortwave approaches the region. Details are still up in the air and although currently unimpressive, Wednesday could be a day to monitor for strong to severe storms, with rain chances persisting into Thursday. Harrel && .AVIATION... (18Z TAFS) Issued at 1129 AM CDT Fri May 10 2024 Rain showers and even isolated thunderstorms push into the western panhandles this afternoon and evening. While this is not expected to impact any terminal today there is a very small chance that KDHT can be impacted. Otherwise VFR conditions will prevail through the rest of today and early morning hours. By mid morning of Saturday rain showers and thunderstorms will spread across the panhandles and become more numerous. All terminals will have a chance for rain and thunderstorms through this time. Conditions have a high chance to become MVFR as low clouds settle across the panhandles starting during the mid morning impacting all terminals. While the chances are very low strong storms with hail and damaging winds cannot be fully ruled out. && .PRELIMINARY POINT TEMPS/POPS... Amarillo TX 51 69 52 72 / 10 60 70 80 Beaver OK 50 79 52 73 / 0 40 60 90 Boise City OK 47 67 47 72 / 20 80 70 80 Borger TX 53 76 54 77 / 10 60 70 90 Boys Ranch TX 51 70 52 77 / 20 70 80 70 Canyon TX 50 67 51 74 / 10 60 70 70 Clarendon TX 53 71 53 69 / 10 60 60 90 Dalhart TX 46 65 48 74 / 20 80 80 70 Guymon OK 48 73 50 74 / 10 60 70 90 Hereford TX 51 67 52 76 / 20 70 80 60 Lipscomb TX 52 78 54 72 / 0 30 70 90 Pampa TX 52 73 53 71 / 10 50 60 90 Shamrock TX 54 75 54 68 / 0 40 60 90 Wellington TX 55 75 54 68 / 0 40 60 90 && .AMA WATCHES/WARNINGS/ADVISORIES... TX...None. OK...None. && $$ SHORT TERM...98 LONG TERM....38 AVIATION...98