Area Forecast Discussion
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Issued by NWS
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094 FXUS64 KLUB 201119 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 619 AM CDT Fri Sep 20 2024 ...New AVIATION... .SHORT TERM... (Today and tonight) Issued at 240 AM CDT Fri Sep 20 2024 Current water vapor imagery depicts the upper level ridge and dome of high pressure positioned over southwestern Texas. By this afternoon the upper level ridge is expected to track southeastward as the upper level low off the southern CA coast begins to track into the desert southwest region this afternoon. Moist southerly winds from the surface to H7 will help influence dewpoints once again in the upper 50s to mid 60s this afternoon. In addition, mid-level Pacific moisture wrapping around the center of the high pressure system will also creep into portions of the far southwestern Texas Panhandle this afternoon. Although instability remains rather weak, a few isolated showers will be possible across northwestern portions of the FA as a few perturbations in the flow aloft interact with the present moisture. Shower activity remains limited, with the best chance of areas seeing precipitation being confined to areas to the north and west of the FA where the better moisture looks to reside. A surface low well to our north, along with the incoming trough to our west will influence breezy southerly conditions today around 10 to 20 mph. These southerly winds in combination with similar thickness values compared to yesterday, and relatively clear skies will lead to temperatures in the 90s to lower 100s. Meanwhile, tonight will also be similar to previous in the 60s to near 70s which is still about 10 degrees above normal. && .LONG TERM... (Saturday through Thursday) Issued at 240 AM CDT Fri Sep 20 2024 Very fitting for the changing seasons this weekend is a welcome pattern change that promises cooler and wetter weather through the first half of next week. Saturday opens with a filling upper low in AZ that proceeds to minor out over the central plains by Sunday evening. Pressure falls in NM for much of the day on Saturday will tug unseasonably rich gulf moisture throughout eastern NM ahead of a dryline and approaching upper low. PWATs throughout the moist sector are progged between 130 and 200 percent of normal - highest just west of the TX/NM border. Models continue to keep the upper low on the slower side of earlier forecasts which favors dry conditions for all but our W-NW zones for much of the day. Even though the strongest upper divergence stays well to our north Saturday and Saturday night immediately downstream of the upper low, models agree nicely in an upper jet axis tracking from the western South Plains into the eastern TX Panhandle which (no coincidence) aligns nicely with their QPF distribution. NBM`s PoPs were tweaked to better fit this signal and heavy rain was inserted across our N-NW zones Saturday afternoon and evening where a longer residence time of lift and deep saturation could result in an inch of rain in some locales. Severe storm potential meanwhile should favor eastern NM with some of this bleeding over and into our western counties by Saturday evening as ascent ramps up. As earlier discussions cited, soundings still favor downbursts as the primary severe threat. As the upper low tracks over CO Saturday night into Sunday, a healthy cold front will drop into the TX Panhandle before sweeping across the CWA Sunday afternoon. Given the amount of CAA with this front, it wouldn`t be surprising to see FROPA speed up some in later forecasts. Following a lull in PoPs late Saturday night, good rain chances return Sunday afternoon - this time favoring all but our far W-NW zones which will reside west of an impressive moist axis. Heavy rain potential is again in the offing for Sunday, especially off the Caprock where PWATs flirt with 2 inches. Severe prospects are less than Saturday as deep convection should quickly become undercut and more anafrontal in nature which typically favors training along with some flooding potential in this case. Markedly drier north winds Sunday night and Monday within surface ridging will shove rain chances to our south until return flow ensues Monday night ahead of a trough diving south along the Continental Divide. Confidence is improving in another round of healthy PoPs for Tuesday thanks to rich moisture pooling over the area. The GFS and ECMWF diverge with this trough/low by Tuesday night, yet a generous field of saturated isentropic ascent is still favored in our area for most of Tue and Tue night. Left NBM`s PoPs intact but Tuesday`s high temps were nudged lower to account for thicker clouds and improved precip chances. Thereafter, confidence in the upper pattern craters as either ridging (ECMWF) or a nearby low (GFS) are over West TX. Until model clarity improves, left NBM`s low PoPs and moderating temps in check for Wed and Thu. && .AVIATION... (12Z TAFS) Issued at 617 AM CDT Fri Sep 20 2024 Southerly winds are expected to become breezy this afternoon before diminishing after sunset. VFR conditions are expected to prevail. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...12 LONG TERM....93 AVIATION...12