Area Forecast Discussion
Issued by NWS Midland/Odessa, TX
Issued by NWS Midland/Odessa, TX
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017 FXUS64 KMAF 211848 AFDMAF Area Forecast Discussion National Weather Service Midland/Odessa TX 148 PM CDT Sat Sep 21 2024 ...New SHORT TERM, LONG TERM... .SHORT TERM... (This afternoon through Sunday night) Issued at 143 PM CDT Sat Sep 21 2024 An active afternoon and early evening is ahead for Southeast New Mexico and West Texas as a potent trough translates eastward from the Four Corners Region, developing an increasingly positive tilt through tonight. Ahead of this feature, ascent has started overspreading western areas, evidenced by scattered showers and isolated thunderstorms across Southeast New Mexico and the Upper Trans Pecos, which have been percolating since this morning. This activity is just a precursor to a round of strong to severe thunderstorms forecast this afternoon and evening as destabilization occurs and ascent continues increasing over the region. CAMs are in good agreement that storms will first initiate along a corridor from eastern New Mexico southward across Eddy and Lea Counties to the vicinity of the I-10/I-20 Split. Coverage will be isolated to scattered, with a 20-50% potential that locations see storms this afternoon and evening across much of the area, with the highest potential from Southeast New Mexico and the western Permian Basin south to the Davis Mountains. While not every storm will become severe, the most likely area for severe will be Southeast New Mexico, the northwestern Permian Basin, and Upper Trans Pecos where midlevel lapse rates of 7-8C/km and MLCAPE on the order of 1500-2000 g/kg will be realized during peak heating in an environment characterized by dewpoints in the 60s. Initiation may be delayed an hour or two given a weak cap over the area in the wake of the departing ridge, but it will be overcome by increased ascent and strengthening midlevel flow associated with the aforementioned trough. Severe hazards include large hail and damaging winds, though given veering hodographs and ample shear, a tornado cannot be ruled out. Storms that develop will move eastward through this evening, though will battle against a decrease in instability as well as a loss of insolation after sunset, thus are expected to weaken with a lingering wind threat possible through the evening. Storms will largely diminish after midnight, though lingering showers are possible over the northern Permian Basin ahead of an approaching cold front that will move into the region late tonight through Sunday morning. Lows tonight will trend cooler, with 60s to the west and 70s to the east, with a much cooler day on tap areawide on Sunday. The timing and location of the front will dictate temperatures, as well as potential cloud cover and precipitation, with another round of showers and thunderstorms expected Sunday associated with the front, mainly across the Permian Basin, Lower Trans Pecos, Stockton Plateau, and Big Bend. Have trended temperatures lower than the NBM solution given its propensity to mishandle fronts, especially as we get into the transitional fall season, with highs Sunday in the 70s and 80s for most, with 90s focused along portions of the river valleys, and upper 60s possible in northern Lea county. While the severe potential Sunday is substantially lower than today, a few storms may still become strong in the vicinity of the front, capable of mainly a damaging wind threat Sunday afternoon. Heading into Sunday night, rain chances gradually shift southward with the front, with lows ranging from the upper 40s across northern Lea county to the upper 60s and lower 70s along the Rio Grande. JP && .LONG TERM... (Monday through Friday) Issued at 143 PM CDT Sat Sep 21 2024 Upper air pattern evolution has come into better agreement with what the deterministic GFS and ICON models were showing yesterday, with a short wave trough embedded in larger scale troughing over the central CONUS, developing down from the Colorado Front Range into the Southern Great Plains. However, there is uncertainty regarding how this short wave will develop, with ECMWF, CMC, and ICON showing the short wave closing off into an upper low east of the Four Corners and meandering into Thursday and Friday, whereas the GFS shows the short wave remaining open, with a separate area of upper level spin over SW TX. LREF TLE-NH ensemble clusters depict an open short wave similar to the GFS. If the short wave closes off into an upper low that meanders over the area, we could see higher rain amounts, but if the short wave remains open and is east of the area by Wednesday, rain amounts shown in NBM might be too high. For now, this is looking more like a high PoP, low rain event, even for this time of year when rain chances are usually higher. NBM still depicts highest rainfall amounts by next Saturday near 1 inch over the eastern Permian Basin, with amounts close to 2 inches over the Western Low Rolling Plains. Grand Ensemble and ENS, GEFS, and GEPS ensembles are all in agreement that by next Saturday, highest rain totals will be farther north of the CWA. We will see whether this changes as this rainy pattern draws closer. Widespread severe weather is not anticipated with showers and storms this week as most instability and shear is forecast to be north and east of the area. However, proximity of the short wave and higher speed flow aloft will provide adequate CAPE and shear for afternoon and evening storms each day, with some of the stronger storms capable of producing heavy rain, gusty winds, and some hail. High temperatures Monday have trended down in the NBM compared to previous runs, below average with mostly 70s, 60s in higher elevations, and 80s and 90s limited to the Rio Grande basins. What the NBM is showing for highs over the Permian Basin may even end up being on the upper range of what actually occurs if conditions are mostly overcast and daytime heating is limited, while cold air advection and high pressure builds in behind Sunday`s cold front. Another cold front is forecast to drop down into the area Tuesday into Wednesday. Lift provided by the cold front and mid-level moisture and instability from the nearby upper disturbance over the Southern Great Plains again results in a chance of showers and storms, especially late Tuesday into Wednesday. High temperatures Tuesday will be warmer than Monday in advance of the next cold front, but highs will once again decrease Wednesday in cold air advection behind the second front. After this reinforcing shot of cooler temperatures, heights and thicknesses increase as ridging from the western CONUS builds east and allows temperatures to rise back to near normal by next Saturday and mostly in the 80s, with associated large scale subsidence reducing rain chances. With cooler temperatures and absence of 90s and above aside from near the Rio Grande, and 70s and 80s elsewhere, lows for most of the area fall into 50s and 60s each night. && .AVIATION... (18Z TAFS) Issued at 1240 PM CDT Sat Sep 21 2024 The primary concern this forecast period is low to medium (20-40%) potential for thunderstorms to impact western terminals this afternoon through early this evening. Have included TEMPO TS mention for CNM, HOB, and PEQ from roughly 20Z-02Z where confidence is highest for impacts including lightning, erratic gusty winds, and brief MVFR conditions in heavy rain and/or blowing dust. Significant uncertainty exists in impacts to the east, thus will monitor trends and amend as needed. Away from storms, elevated and gusty southeasterly winds will continue into tonight, with gusts to 20-25kt possible. A cold front moving into the region overnight through Sunday morning will veer winds to the northwest and north, with MVFR ceilings expected to develop into HOB and MAF near daybreak, persisting thereafter through the end of the period. Elsewhere, VFR with increasing clouds will prevail. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 73 84 58 75 / 10 60 70 20 Carlsbad 63 79 57 78 / 20 0 20 20 Dryden 73 91 66 80 / 0 20 70 30 Fort Stockton 71 89 60 75 / 20 30 60 40 Guadalupe Pass 61 77 53 72 / 10 0 10 30 Hobbs 66 73 52 77 / 40 20 20 20 Marfa 62 86 54 76 / 20 20 40 50 Midland Intl Airport 72 84 58 74 / 20 40 60 30 Odessa 72 85 58 75 / 30 40 60 30 Wink 71 86 60 78 / 30 20 40 40 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...None. NM...None. && $$ SHORT TERM...84 LONG TERM....94 AVIATION...84