textproduct: El Paso

KEY MESSAGES

Updated at 1220 AM MDT Tue Sep 22 2026

- The risk of heavy rainfall and medium to higher-end flooding impacts is increasing, especially for south-central New Mexico, especially Tuesday evening into Wednesday morning.

- This is all due to a back door cold front interacting with an upper level trough pulling in deep subtropical moisture form the Pacific.

- The focus for heavy rainfall will shift east later Wednesday into Thursday, but will become more localized. Additional scattered showers and thunderstorms are expected through Friday in southwestern New Mexico.

- Quieter weather will prevail for the weekend, with showers and thunderstorms returning late Monday.

DISCUSSION

Issued at 1141 PM MDT Mon Sep 21 2026

The threat for higher-end flooding is increasing, especially for south-central New Mexico. The overall forecast pattern and is more or less locked in, now it is down to specific details like which specific arroyo and stream basins see the most rainfall.

Our upper level low over California is slowly weakening as it drifts into Nevada, while 200 mb streamline analysis shows broad upper level diffluence over the Sierra Madres near the junction of Sonora, Chihuahua, and Sinaloa. Convection in this region was fairly concentrated this evening, but water vapor imagery shows some signs of a tight upper level low taking shape, as expected. This system will weaken into a shortwave trough as it rolls northwards up the Sierra Madres Tuesday, aided by broadening upper level diffluence across Chihuahua and New Mexico and a strengthening subtropical jet streak in SE Arizona.

Meanwhile, at the surface, the back door cold front has topped the Sacramento and Guadalupe Mountains. Mesonet obs show steady east winds with a few gusts around 20-25 mph in parts of Alamogordo, and the upper range of WSMR. The Dell City West Texas Mesonet station also has an east wind along with PX Well RAWS. Expect some low stratus and fog to develop along the east slopes of the Sacramentos as cooler/moisture air seeps in closer to dawn, lagging behind the initial wind shift. A few spots could see brief dense fog.

By Sunrise, some sparse showers may be on-going in SW New Mexico, and the back door front tries to reach the Arizona state line by mid-morning. Thunderstorms look to initiate tomorrow afternoon along the higher terrain, but also near the cold front in SW New Mexico. Outflow looks to push the front back to the east a bit, falling in line with a surface and low level trough that develops ahead of the approaching shortwave trough from the south. By evening, the surface front and low level trough will become the focus for intense moisture convergence. This is where the heaviest rain will focus, with several waves of showers and embedded thunderstorms training across the broader region. Unfortunately, there is still some uncertainty into where exactly this region sets up. Notably, a few high res models have a sharp eastern cutoff to the significant precip Tuesday night, with some producing 2-3 inches of rain in parts of south-central New Mexico, and scant amounts over El Paso.

The most likely scenario broadly produces 2-3 inches of rain from the east slopes of the Black Range to the San Andres Mountain, and south across much of Luna and Dona Ana County, tapering off into western El Paso County. The worst-case scenario type model runs (e.g., the 00Z HRRR with its hopefully-outlier cataclysmic totals east of the Black Range, appear to the result of repeated training of the max precip rates over the same area with very little variation. The more likely scenario would see isolated pockets of 3 to 5 inches within the broader 2-3 inch area.

That said, the greatest probabilities when looking at various exceedance levels (1 inch, 2 inch, 3 inch) focus on western Sierra County and northern Dona Ana County. All the long-run arroyos coming off the Black Range towards the Rio Grande are at risk of seeing higher-end flooding. This same area has broadly seen 2-3 inches of rain over the past 7 days, including portions of the Black Range crest, but mainly east of the Lake Valley/Highway 27 corridor all the way into the northern end of the Jornada del Muerto. That extra saturation will enhance runoff.

A fair amount of the heavier rain will likely fall into basins that feed in south of Caballo Dam (everything south of Percha Creek), which will likely bring significant rises in the Rio Grande. Thankfully, water levels have dried back up through most of the Rio Grande south of Caballo, but we may still come close to bankfull in the reaches from Percha Dam south through Selden Canyon, down to around Leasburg.

Heavy rainfall is likely to be ongoing Wednesday morning, impacting the morning commute, especially if El Paso ends up back in the heaviest rain axis. The shortwave trough will move north into the Gila region by midday Wednesday, with a trailing vort lobe curling down towards El Paso and west of the Big Bend. The heaviest rain will lift northeast as it does so, with the intensity moderating a bit. Much of southwestern New Mexico could see a significant dry period Wednesday afternoon. Meanwhile, the focus for rain will shift east.

The trough will linger over Hudspeth County heading into Wednesday Night and Thursday, but the overall QPF amounts look to pale in comparison to what central areas are looking to get Tue Night/Wed AM. Kept the Flood Watch as is, though the eastern extension of it looks questionable.

An additional upper low that develops from the lifting west coast trough looks to move up towards the Four Corners by Friday morning. Additional rounds of more widely scattered showers and thunderstorms look likely Thursday night into Friday, especially in the Gila Region, but may avoid the most hard-hit areas from Tue/Wed.

A lull for the weekend looks to be followed by increasing showers and thunderstorms late Monday. Tropical systems in the Eastern Pacific will need to be monitored for the middle of next week, but it looks like the moisture will stay at bay through Tuesday, and there is considerable uncertainty beyond that, and enough to focus on in the near term.

AVIATION

(12Z TAFS) Issued at 527 AM MDT Tue Sep 22 2026

Light rain showers expected to persist through the morning out in western NM where KDMN and KTCS could see some light showers but showers shift to thunderstorms around noon. Thereafter, all TAF sites have a chance for showers and thunderstorms today, but looks like KELP may have less of a chance to see the bulk of the storms today. Thunderstorms will be heavy rain producers. Looks like early this evening TAF sites could see some lowered cloud bases which could drift into MVFR category, potentially even lower CIGs possible.

FIRE WEATHER

Issued at 613 AM MDT Tue Sep 22 2026

Today and especially tonight will be the start of the big rain event we've been messaging. Heavy rainfall from thunderstorms will continue into Wednesday but will start tapering off Thursday and even into Friday.

Min RHs today will be 30-40% in the lowlands and 50-70% in the mountains but Wednesday and Thursday min RHs increase to 60-80% in the lowlands and 80-100% in the mountains. Scattered to numerous storms expected Tuesday through much of Thursday where flash flooding will be the primary concern across the area. 20 foot winds will be somewhat breezier today 10-15 mph out of the southeast. Light winds Wednesday persisting into the weekend with speeds generally around 5-10 mph.

PRELIMINARY POINT TEMPS/POPS

El Paso 65 76 62 80 / 80 90 70 60 Sierra Blanca 60 79 57 79 / 40 80 70 60 Las Cruces 60 71 57 77 / 90 100 70 50 Alamogordo 60 75 58 78 / 70 90 80 80 Cloudcroft 46 55 45 58 / 70 90 80 90 Truth or Consequences 59 68 57 75 / 100 100 80 70 Silver City 55 66 53 73 / 90 90 50 60 Deming 59 72 56 79 / 90 90 60 40 Lordsburg 61 72 57 79 / 60 70 30 40 West El Paso Metro 64 75 62 80 / 80 90 70 50 Dell City 64 81 60 80 / 40 80 80 80 Fort Hancock 68 85 64 86 / 60 70 70 60 Loma Linda 59 72 56 75 / 70 80 80 70 Fabens 66 80 63 83 / 70 80 70 60 Santa Teresa 62 74 60 79 / 90 90 70 50 White Sands HQ 62 73 60 79 / 90 90 80 70 Jornada Range 60 72 57 77 / 100 100 80 70 Hatch 61 73 59 79 / 100 100 80 60 Columbus 63 75 60 81 / 90 90 50 20 Orogrande 62 74 60 77 / 80 90 80 80 Mayhill 53 66 52 70 / 80 90 80 90 Mescalero 52 66 50 69 / 70 90 70 90 Timberon 49 64 47 66 / 70 90 80 90 Winston 54 61 51 69 / 100 100 60 80 Hillsboro 57 68 56 75 / 100 100 80 70 Spaceport 59 69 56 76 / 100 100 90 70 Lake Roberts 53 64 50 73 / 100 90 60 60 Hurley 56 68 53 74 / 90 90 60 60 Cliff 61 72 57 80 / 80 80 50 40 Mule Creek 57 68 55 76 / 60 60 50 40 Faywood 58 67 56 73 / 100 90 70 60 Animas 62 74 59 80 / 60 60 40 20 Hachita 60 73 57 79 / 80 80 40 20 Antelope Wells 61 75 59 80 / 80 60 40 10 Cloverdale 58 73 56 78 / 70 50 30 20

EPZ WATCHES/WARNINGS/ADVISORIES

TX...Flood Watch from noon MDT today through Wednesday evening for Eastern/Central El Paso County-Northern Hudspeth Highlands/Hueco Mountains-Rio Grande Valley of Eastern El Paso/Western Hudspeth Counties-Rio Grande Valley of Eastern Hudspeth County-Salt Basin-Southern Hudspeth Highlands- Western El Paso County.

NM...Flood Watch from noon MDT today through Wednesday evening for Central Grant County/Silver City Area-East Central Tularosa Basin/Alamogordo-East Slopes Sacramento Mountains Below 7500 Feet-Eastern Black Range Foothills-Lowlands of the Bootheel-Northern Dona Ana County-Otero Mesa-Sacramento Mountains Above 7500 Feet-Sierra County Lakes-Southeast Tularosa Basin-Southern Dona Ana County/Mesilla Valley- Southern Gila Foothills/Mimbres Valley-Southern Gila Region Highlands/Black Range-Southwest Desert/Lower Gila River Valley-Southwest Desert/Mimbres Basin-Uplands of the Bootheel-Upper Gila River Valley-West Central Tularosa Basin/White Sands-West Slopes Sacramento Mountains Below 7500 Feet.