Area Forecast Discussion
Issued by NWS
Issued by NWS
269 FXUS64 KLUB 181134 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 634 AM CDT Mon Aug 18 2025 ...New AVIATION... .KEY MESSAGES... Issued at 1232 AM CDT Sun Aug 17 2025 - Scattered thunderstorms are forecast across the Caprock and Rolling Plains today. - A few storms may be severe and capable of producing damaging wind gusts in addition localized flash flooding today. - Storm chances will continue Tuesday through early Thursday morning. && .SHORT TERM... (Today and tonight) Issued at 1232 AM CDT Mon Aug 18 2025 In the mid/upper-levels, a well-defined, subtropical ridge continues to retrograde into the southern Rocky Mountains, with the 250 mb and 500 mb circulations beginning to align, as per recent trends in water-vapor imagery. The 18/00Z objectively analyzed UA charts also showed that the ridge is beginning to amplify once again, with the 250 mb anticyclone rotating over northern Chihuahua and the TX Big Bend region. The mid-level tranche of the ridge remains rather broad and stretched out across the Lower 48, with another circulation identified over the southeastern U.S. that is much weaker and forcing the alignment of the aforementioned anticyclonic vortex over the southern Rocky Mountains. Farther west, broadly cyclonic flow persists over the Great Basin and western U.S. interior, with a 40 kt jet streak observed at 250 mb by the 18/00Z RAOB at WFO ABQ that weakens and veers west-northwestward over W TX, as observed by the AMA and MAF RAOBs. The semi-progressive troughing is otherwise displaced over the 49th parallel, with an intense shortwave trough continuing to dig into the Pacific Northwest. The superposition of these synoptic-scale features has, as predicted, cause the monsoon to deflect into a southwest-to-northeast-oriented manner over W TX tonight. However, at this point, the advection of additional moisture associated with the monsoon has been effectively terminated following the strong, northeasterly component to the high-level flow (i.e., 30 kt over central Mexico, as per the 18/00Z UA charts) along the base of the amplifying ridge. The monsoon will continue to gradually decay over the next 24 hours, with convectively-augmented vorticity lobes embedded within the decaying fetch maintaining thunderstorm chances area-wide as 250 mb flow intensifies Monday. At the surface, the gradient wind field has been contaminated by the scattered storms Sunday afternoon and evening, particularly across the southern South and Rolling Plains. Outside of the contaminated wind field, winds prevail out of the south, as a surface trough bisects the CWA and extends poleward across the TX PH, connecting with a lee cyclone rotating in southeastern CO. The airmass is very moist, with 70-72 degree dewpoints observed by multiple mesonets across portions of the Caprock and Rolling Plains in congruence with the footprint of heavy rainfall that occurred Sunday. Elsewhere, dewpoints were hovering in the lower-middle 60s. Surface winds will become veered towards the southwest once again before the pre-dawn hours Monday as the lee cyclone in southeastern CO dissipates. Winds are then expected to back towards the south-southeast as daily cyclogenesis regimes persists in the west-central Great Plains. High temperatures will also be a couple of degrees hotter Monday beneath the amplifying ridge, with highs rising into the middle-upper 90s; and the hottest temperatures will be in the Rolling Plains. Scattered storms are expected to develop across portions of the CWA once again Monday afternoon, as the right-exit region of the 250 mb jet streak arcing around the apex of the amplifying ridge noses into W TX atop an uncapped airmass. Despite 250 mb flow increasing to around 30-35 kt, flow throughout the rest of the steering layer will be anemic as the monsoon decays. However, unlike Sunday, the mean convective storm motion will have a southward component to it due to the contribution of the strengthening high-level flow, although the bulk of the storms will still generate strong enough cold pools for to propagate along outflow boundaries. With little change to the barotropic state of the airmass, the reservoir of PWATs, which are and will be slightly above seasonal norms, will facilitate a localized risk of flash flooding. Strong to perhaps a few severe-caliber gusts in excess of 60 mph will be possible with storms Monday from the excessive water-loading in updrafts. The potential for storms will wane after 19/05Z; however, elevated showers may persist into the early morning hours Tuesday. Sincavage && .LONG TERM... (Tuesday through Sunday) Issued at 1232 AM CDT Mon Aug 18 2025 The subtropical ridge will continue to amplify over the southern Rocky Mountains Tuesday, with the mid- and high-level, anticyclonic vortex becoming aligned over the Four Corners region. Farther north, the intense, positively-tilted shortwave trough will begin to emerge over the Pacific Northwest, resulting in an ageostrophic response that will allow the 250 mb jet streak branching over the Great Basin to strengthen to near 80 kt. This will orient the steering flow over the CWA to the north, while also intensifying throughout the 500-200 mb layer. A wavy surface troughing pattern will be present across the southern High Plains, with the respective surface trough connecting to a lee cyclone in NW KS; and this cyclone should be embedded along a southward-moving, synoptic cold front spawned from a leading shortwave trough ejecting into the Upper Midwest. A few storms may develop in the pre-frontal airmass Tuesday afternoon, but it remains unclear how much coverage there will be, as the airmass may be convectively-overturned, perhaps substantially, from the rounds of storms Monday. The forecast becomes a bit murky with respect to the timing of the synoptic cold front, which may be convectively-reinforced and accelerate its forward momentum southward towards W TX. Recent initializations of the NAM have caught onto this, and the NAM does particularly well with handling faster anafrontal movements relative to other suites of NWP guidance. NBM PoPs appear to have a better reflection of this as well, with the highest PoPs delineated late Tuesday night into early Wednesday morning. Large-scale forcing for ascent will increase via the leading edge of the intense 250 mb jet streak arcing around the apex of the 598 dam subtropical ridge, contributing to 20 kt of flow throughout the steering layer. There is the potential for convection to become semi-organized along the cold front as it progresses southward, and ultimately, the timing of its passage will dictate the spatial extent of PoPs that follow heading into Wednesday evening. It is still too soon to know the exact mesoscale evolution of storms late Tuesday into Wednesday morning, but prospects for at least a few swaths of locally heavy rainfall appear possible. Thereafter, increasingly confluent flow aloft as the subtropical ridge expands will stifle storm chances through the weekend, with high temperatures near seasonal norms. Sincavage && .AVIATION... (12Z TAFS) Issued at 634 AM CDT Mon Aug 18 2025 VFR. Scattered afternoon TS remain on the table with higher probabilities at LBB and PVW than CDS. Expect light winds outside of TS. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...09 LONG TERM....09 AVIATION...93