Area Forecast Discussion
Issued by NWS
Issued by NWS
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200 FXUS64 KLUB 150757 AFDLUB Area Forecast Discussion National Weather Service Lubbock TX 257 AM CDT Sun Sep 15 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (Today and tonight) Issued at 254 AM CDT Sun Sep 15 2024 The mid/upper-level pattern remains similar to yesterday as a Rex Block continues to meander over the eastern U.S., while an amplifying, positively-tilted trough digs into the Pacific Northwest which has maintained the belt of broadly cyclonic flow over the Intermountain West. A shortwave ridge was evident on water-vapor imagery this early-morning over West Texas as the synoptic pattern is slow to progresses and the Rex Block keeps the amplified, subtropical ridge centered over central Mexico. Farther west, a vorticity lobe was also evident on the water-vapor bands over the southern Great Basin, with its center now rotating over LAS; and this feature will continue to rotate eastward and emerge over the Four Corners later this afternoon. Large-scale subsidence was not as pronounced as in prior days, as observed by the 15/00Z RAOBs from WFOs AMA and MAF last evening, and geopotential height tendencies were neutral to slightly-positive based on the objectively analyzed upper air map data and current water-vapory imagery. The cirrus shield generated by the upper-level outflow channel from the weakening tropical storm offshore Sinaloa have since advected east of the CWA given the superposition anticyclonically-curved, 250 mb jet streak over the State of Texas. At the surface, a weak, lee cyclone was analyzed across the Raton Mesa, with a quasi-stationary front branching eastward into the OK PH and bending southeastward across western Oklahoma as per recent mesonet and METAR data. The dryline is very diffuse and the circulation continues to disperse owing to the loss of large-scale, geostrophic deformation aloft, and has since translated west of the TX/NM state line. A surface trough also extends southward from the aforementioned lee cyclone, and is anchored to the west of the Mescalero Escarpment. Moist, southerly flow remains intact with the highest dewpoints analyzed in the Rolling Plains (i.e., upper 60s) while lowering into the 50s across the Caprock Escarpment and temperatures were much cooler than this time yesterday. The influx of moisture/higher dewpoints should result in slightly cooler temperatures, with highs ranging in the lower-middle 90s area-wide. Emergence of the vorticity lobe over the Four Corners this afternoon will generate diurnally-driven convection along the southern Rocky Mountains, and the inflection point of the shortwave ridge moving over the region and the broadly cyclonic flow to the west will govern a more-southwesterly component to the steering flow today. Isolated convection may propagate into the extreme southwestern TX PH this afternoon with an expectation for the dryline circulation to disperse entirely, leaving only the surface trough west of the edge of the Mescalero Escarpment to serve as one of two foci for convergence in the low-levels. The northwest-to-southeast-oriented, quasi-stationary front, which will be located near or to the northeast of the extreme southeastern TX PH, will serve as another focus for low-level convergence for the initiation of storms this afternoon. Therefore, very low PoPs (i.e., 10-percent) were reintroduced across the far southern TX PH for the late-afternoon and early-evening hours. At least isolated convection should clip and/or form in portions of the northern zones late this afternoon especially as surface flow backs to the southeast as cyclogenesis persists near the Raton Mesa and southeastern Colorado. The severe weather threat is low; however, given LCLs above 700 mb, a rogue, strong wind gust or two cannot be ruled out. The potential for storms will once again wane near and after sunset, followed by cool temperatures and a light, southeasterly wind heading into Monday morning. Sincavage && .LONG TERM... (Monday through Saturday) Issued at 254 AM CDT Sun Sep 15 2024 The extended forecast will feature slightly above normal temperatures in the upper 80s to mid 90s through the week with increased precipitation chances. Monday, the upper low will come barreling over southern California and into Nevada. Weak upper ridging will still persist over the forecast area with the bulk of precipitation chances kept to our west. With the approaching upper trough axis comes height falls and the development of strong lee troughing leading to breezy southerly surface winds. By Tuesday, the upper low will eject northeastward towards Montana as the 500mb jet axis is shoved eastward. The right entrance region of the 40-50 knot jet will clip the northwestern zones Tuesday evening and provide dynamical lift for convection. With the forward progression of the ridging, southwesterly winds aloft will open the door for mid-level moisture advection. Storms are likely to fire along the higher terrain in New Mexico Tuesday afternoon and push east-northeast. The aforementioned jet placement and modest shear will help to keep convection alive past sunset as it approaches and enters West Texas late Tuesday evening. The increasing low level jet will also help to maintain showers and storms through the overnight hours as they push eastward. Buoyancy parameters are relatively weak with less than 1000 J/kg of MUCAPE. A storm or two may become strong to marginally severe, especially earlier on in the evening as storms enter the western zones. Another upper low will come barreling south along the coast of California Wednesday, with continued southwesterly flow aloft and increased mid-level moisture. Additionally, the dryline will sharpen Wednesday and be draped across the far southwest Texas Panhandle and into the South Plains. Dewpoints will be in the 60s east of the dryline with a slight chance for evening showers and thunderstorms near and east of the I-27 corridor. The trough axis out west will continue to meander east with the jet skirting West Texas on Thursday. The dryline will retreat Wednesday night to eastern New Mexico and become the focal area for storm development Thursday afternoon. Southerly surface winds and increased low level moisture across much of the area will give way to better instability parameters for convection. Additionally, the low level jet ramping up will help in storm maintenance through the late evening hours. By Friday, the upper trough will continue to swing east before ejecting northeast by Saturday night into Sunday. Model output has inconsistencies in the timing and strength of the trough axis, which could be the difference in the cold front timing and depth of the cooler air mass. However, precipitation chances look possible through the end of the week and into the weekend. && .AVIATION... (06Z TAFS) Issued at 1224 AM CDT Sun Sep 15 2024 VFR prevails for the TAF period. Low chances for -TSRA will be possible at KCDS this afternoon but confidence in coverage is too low to include in this TAF cycle. && .LUB WATCHES/WARNINGS/ADVISORIES... None. && $$ SHORT TERM...09 LONG TERM....11 AVIATION...09