Area Forecast Discussion
Issued by NWS Midland/Odessa, TX
Issued by NWS Midland/Odessa, TX
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956 FXUS64 KMAF 281715 AFDMAF Area Forecast Discussion National Weather Service Midland/Odessa TX 1215 PM CDT Tue May 28 2024 ...New AVIATION... .SHORT TERM... (Today through Wednesday afternoon) Issued at 340 AM CDT Tue May 28 2024 For those that have been keeping an eye on the thunderstorm potential this afternoon, to summarize the thinking here is that it is surely going to be conditional at best. There`s a lot of moving parts going into this forecast, so we`re going to break it down by ingredient: low-level moisture (and thus instability), storm forcing, and shear. 1) Moisture/instability: Current surface observations show that the dryline has retreated back into New Mexico and up against our western high terrain. Dewpoints for those now east of the dryline are largely in the upper 50s/low 60s. While still worth-while, this isn`t as high it otherwise could be, due in part to convection across south-central Texas last evening that has prevented truly rich Gulf moisture to advect into the area with 65-70+ dewpoints still hung up east of our area. This issue is exaggerated by the modest westerlies aloft that will likely mix the dryline to the central Permian Basin by the early afternoon. All of this to say that the picture we`re looking at now is quite different than it did 24 or even 12 hours ago and storms appear to be focused further east than previously thought. Still, steep mid-level lapse rates make up for the somewhat less rich low level moisture and around 3000 J/kg is still anticipated along/east of the dryline. This is still plenty to get intense storms should they form... 2) Forcing: We already talked about the positioning of the dryline and how storm activity will be largely nudged eastward than previous thinking. Another potential factor at play will be morning convection in the vicinity of the Red River/north Texas which is primed to shoot outflow across Texas. The impact of this boundary varies greatly from CAM to CAM with the NAM nest being most aggressive, bringing the outflow through a bulk of the Permian Basin during the early afternoon. While this outflow will largely serve to temporarily serve to wash out instability as it moves through, it could also serve as a forcing mechanism to get storms going in the CAPE-rich environment south of it, especially if/when it interacts with the dryline. The most interesting scenario here is from the NAM nest which brings such a strong outflow in early enough that enough destabilization occurs behind it though some capping is introduced. While this is a more extreme scenario, there is still consensus across the HREF that some outflow could nose into our northeastern counties in the mid-late afternoon. The dryline itself could also be a focal point for storms, primarily where local convergence is highest. Storm forcing and achieving convective initiation remains the greatest point of uncertainty for this forecast. 3) Wind shear (and ultimately storm-mode): With south-southeasterly flow ahead of the dryline beneath modest westerlies aloft, bulk environmental shear is generally 30-40kts, enough to get a splitting supercell or two (especially across the classic region of Pecos County where a local maxima in low-level shear is present). The previously discussed outflow set to move into the Basin at some point this afternoon will also enhance low level directional shear with easterly surface winds and with an early outflow arrival depicted by the NAM and enough destabilization occurs to break the cap behind this boundary, things could get interesting. Still, the general idea will be perhaps a few discrete storms to fire off the boundary (especially across Pecos County or the southeastern Permian Basin), likely growing upscale and departing east of our area by 03z this evening. Needles to say, the forecast remains quite volatile and somewhat uncertain but it is best to be prepared for storms should they occur. Generally large hail and damaging winds are the main threats but an isolated tornado cannot be ruled out. Another sneaky hazard today will be the heat, especially for the Davis Mountains into the Big Bend where it`ll be quite hot with Heat Advisories in effect for this afternoon. If you have made it this far, congratulations...now we can talk a little bit about Wednesday. The large outflow boundary serving to stifle much confidence in this afternoon`s setup (plus the outflow from any storms that form in our area today) will likely pull good moisture well into our western zones by Wednesday morning. Between stratus fills in and likely sticking around for the Permian Basin and some subsidence from a weak ridge moving overhead should create stable enough conditions to limit a bulk of the shower/storm activity. A few storms off the elevated heat sources in the Davis Mountains and Pecos County are still quite possible. Overall, NBM seems way too overzealous with PoPs for this period, so have undercut them by blending in the HREF. Temperatures on Wednesday will be appreciably cooler in the Permian Basin due to the cloud cover (with highs only in 80s!) while it remains hot along/south of the Pecos, especially south of Hwy 90. -Munyan && .LONG TERM... (Wednesday night through Monday) Issued at 340 AM CDT Tue May 28 2024 Wednesday night, convection will be tapering off to the east under messy zonal flow aloft. A 35+kt LLJ will provide 35-45kts of deep layer shear to keep convection ongoing for a few hours during the evening before things stabilize w/loss of daytime heating. The dryline will bank up against the higher terrain, and rich Gulf moisture will keep overnight minimums well above normal. Thursday, temperatures rebound to 6-8F above normal, with a slight chance of convection along/east of the dryline as it mixes east during the afternoon, and into the evening hours. Forecast soundings depict dry subcloud layers and mid-level laps rates 7-8 C/km or better, all w/30-40 kts of deep-layer shear, so the severe threat continues. Friday, models bring a boundary in from the northeast, backing surface flow to the east Friday and Saturday. This will yield the coolest couple of days in the extended, w/highs only 3-5F above normal. Upslope flow will aid in afternoon/evening convection along/east of the dryline, especially Saturday as long- range models bring a modest shortwave through the region. Sunday and Monday, models begin developing an upper ridge south of the border, resulting in drier conditions and the return of widespread triple digits to West Texas and Southeast New Mexico. This looks suspiciously like the summertime ridge, and given that it`ll be the beginning of June, the timing is about right. Latest cluster analysis points in the same direction. Unfortunately, this will bring an end to any appreciable chances of rain outside orographic diurnal development in the Davis Mountains each day, and the long hot summer begins. Stay tuned... && .AVIATION... (18Z TAFS) Issued at 1213 PM CDT Tue May 28 2024 S winds expected before winds back to SE and then E following passage of an outflow boundary generated by storm complex NE of the area. This boundary moves SW from 22Z to 06Z Wednesday. Gusty/erratic winds with storms that form along and behind boundary may complicate wind field, with MVFR and IFR VIS in storms, VFR outside of storms. VFR conditions become MVFR at MAF as lower CIGs develop from 00Z-10Z. MVFR CIGs also likely at HOB and possibly CNM Wednesday morning. VFR CIGs expected for terminals along and SW of Pecos River. && .FIRE WEATHER... Issued at 340 AM CDT Tue May 28 2024 Elevated fire weather conditions are expected through next week, mainly over the higher terrain west of the Pecos on the west side of a developing dryline each day. Critical minimum relative humidities will coincide with increased 20-ft winds each afternoon. ERCs remain above the 95th percentile in these areas. However, fuel density and limited opportunities for fire starts remain low. The one exception will be Saturday afternoon, when the dryline will be far enough west that lightning starts will be possible in the Sacramento Foothills, Guadalupes, and areas directly south to the Presidio Valley. && .PRELIMINARY POINT TEMPS/POPS... Big Spring 65 84 68 92 / 30 20 20 20 Carlsbad 65 93 65 100 / 10 10 10 10 Dryden 71 94 72 96 / 30 20 10 20 Fort Stockton 69 96 70 100 / 20 20 10 20 Guadalupe Pass 63 88 64 90 / 0 10 0 0 Hobbs 62 86 65 97 / 20 10 10 10 Marfa 57 94 56 94 / 20 10 10 10 Midland Intl Airport 65 87 68 95 / 30 20 10 20 Odessa 67 88 70 97 / 20 20 10 20 Wink 68 94 70 102 / 20 10 10 10 && .MAF WATCHES/WARNINGS/ADVISORIES... TX...Heat Advisory until 8 PM CDT this evening for Central Brewster County-Chisos Basin-Davis Mountains-Davis Mountains Foothills-Lower Brewster County. NM...None. && $$ SHORT TERM...16 LONG TERM....44 AVIATION...94