937 FXUS64 KEPZ 242034 AFDEPZ Area Forecast Discussion National Weather Service El Paso TX/Santa Teresa NM 234 PM MDT Sat Jul 24 2021 .SYNOPSIS... Low forming over Arizona, combined with persistent high over east Texas, will produce moist southerly flow across the area through Monday. This should lead to continued scattered thunderstorms and some local flooding. By Tuesday and Wednesday the upper high shifts north over the central Plains, bringing a slightly drier east flow to the Borderland, resulting in mostly isolated thunderstorms. The upper high settles back down in the southern Plains Thursday and Friday, bringing back a southerly flow and perhaps a slight uptick again in thunderstorms. Temperatures will remain seasonable to slightly below normal. && .DISCUSSION... .SHORT TERM...Tonight and Sunday... Upper low pressure system continues its slow westward retrograde today. 24-hour precipitation analysis shows the majority of rainfall occurred along the Rio Grande valley and south-central New Mexico yesterday, with much of southwest New Mexico staying dry. Current thinking is that this rain coverage will more-or-less "flip-flop" today with better chances west of the Continental Divide and AZ/NM state line. This forecast is backed up by latest CAMs, which focuses rain coverage over the Gila Region and NM Bootheel this evening, with more scattered showers and thunderstorms moving northward out of Chihuahua and into far west Texas tonight. Moisture parameters become even more favorable for heavy rains today, as surface westerlies pull in a fetch of Pacific moisture over much of southwest New Mexico this morning. Dewpoints will remain in the lower 60's along the Continental Divide, with above normal precipitable water values near 1.5". Instability and shear parameters remain very marginal and not conducive for severe weather. Much like yesterday, the marginal instability and lack of effective layer wind shear suggests the primary threat will be heavy rains and flooding, with only small hail and a few gusty winds possible. Scattered to numerous thunderstorms should begin to develop after the noontime hour today, with a focus along the AZ/NM state line. Latest HRRR runs also suggest good thunderstorm coverage along the International Boundary later in the evening, possibly reaching El Paso by sunset. Including CHC PoPs for all locations tomorrow afternoon with DEF PoPs and higher QPF west of the Continental Divide. These storms will be very efficient rain producers, with a few storms likely producing rain rates in excess of 3" per hour. Leaving current Flash Flood Watch in place, which will go through 6 AM Sunday morning. Confidence is still too low to extend the Watch across the Rio Grande Valley, but localized flooding is very much possible there as well. Heavy rains will quickly cause low water crossings, arroyos, and other low lying areas to become impassable. Today will be another good day to pay attention to the weather conditions and know where flood prone areas are located. Increased cloud cover and rain showers will keep much of southwest NM well below normal in terms of high temperatures, although we should still see a few 90-degree readings east of the Rio Grande. && .LONG TERM...Sunday night through Saturday... This period starts with the upper low over the northern Baja and the upper high over eastern/central Texas. Resultant southerly flow will continue with layered moisture and scattered thunderstorms. Moisture slightly deeper west (PWs ~1.3 west to ~1.1 east) so POPs and flood potential a bit higher. This pattern will continue Monday though slightly lower PWs will reduce flood potential somewhat. The upper high shifts north over the central Plains Tuesday and Wednesday as the upper low drifts well offshore. This will result in and easterly flow which will entrain some drier continental air. PWs will fall to around .8 to 1.1 inches and dewpoints drop a bit, so thunderstorms should become more isolated. Models...mainly GFS/ECMWF...show upper high elongating northwest over the central Rockies down to the lower Mississippi Valley on Thursday and Friday, with the aid of an inverted trough approaching southern Arizona. This will increase moisture again (PWs back to around 1.0 to 1.2 inches). This pattern should favor the western zones again as moisture slightly higher and closer to the dynamics of the inverted trough. && .AVIATION...18Z TAF CYCLE... VFR skies with FEW-SCT BCMG BKN-OVC100. Winds will be light, generally AOB 10 kts, favoring mainly 220-250. As the afternoon continues, thunderstorm chances will increase with present trends showing DMN the most likely to see storms first then TCS. ELP and LRU are more likely to see storms after 00z. These trends will be monitored closely. MVFR and IFR are possible within any storm. && .FIRE WEATHER... After today, a largely typical monsoon pattern will persist through the period. Moisture will gradually decrease while temperatures warm a few degrees. This will cause a decrease in min RH values with values in the mid to upper 20s tomorrow to near 20 by Wednesday. Thunderstorm chances will focus over the mountains with only isolated storms in the lowlands. Winds, outside of thunderstorms, will top out 10 to 15 MPH each afternoon. Vent rates will vary across fire zones, ranging generally fair to very good. Moisture may begin to increase again mid to late next week. && .PRELIMINARY POINT TEMPS/POPS... El Paso 66 92 72 95 / 50 10 20 10 Sierra Blanca 64 87 68 90 / 50 20 20 20 Las Cruces 61 89 68 94 / 40 10 20 20 Alamogordo 61 90 68 94 / 30 30 20 30 Cloudcroft 51 69 52 70 / 40 50 20 50 Truth or Consequences 63 88 68 92 / 40 30 20 30 Silver City 63 79 60 84 / 50 50 30 30 Deming 65 89 66 94 / 30 20 30 20 Lordsburg 70 84 66 91 / 50 40 30 20 West El Paso Metro 66 92 72 96 / 50 10 20 20 Dell City 62 94 70 95 / 40 10 20 10 Fort Hancock 65 94 72 97 / 60 10 20 20 Loma Linda 61 85 67 88 / 50 10 20 20 Fabens 65 92 71 96 / 50 10 20 10 Santa Teresa 64 90 70 94 / 50 10 20 10 White Sands HQ 64 89 70 93 / 40 20 20 20 Jornada Range 61 88 68 92 / 40 20 20 20 Hatch 64 89 68 94 / 30 20 20 20 Columbus 66 89 67 93 / 40 20 40 20 Orogrande 64 90 69 94 / 30 20 20 20 Mayhill 55 79 59 80 / 30 50 20 40 Mescalero 54 78 59 80 / 40 60 20 50 Timberon 54 77 58 79 / 30 40 20 40 Winston 59 80 60 82 / 50 50 30 40 Hillsboro 62 85 64 88 / 40 30 30 30 Spaceport 61 87 67 92 / 30 20 20 20 Lake Roberts 59 79 59 83 / 60 50 30 40 Hurley 64 82 62 87 / 50 40 30 30 Cliff 66 85 63 88 / 60 40 30 30 Mule Creek 61 79 60 85 / 70 50 30 30 Faywood 63 83 63 88 / 40 30 30 30 Animas 68 84 65 90 / 60 40 30 30 Hachita 65 85 65 91 / 50 30 30 30 Antelope Wells 64 85 64 91 / 60 50 40 40 Cloverdale 63 79 62 84 / 70 60 30 40 && .EPZ WATCHES/WARNINGS/ADVISORIES... NM...Flash Flood Watch through late tonight for NMZ401>408. TX...None. && $$ 34-Brown/17-Hefner