Separ, New Mexico Weather Forecast Discussion

902
FXUS64 KEPZ 271914
AFDEPZ
Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
114 PM MDT Sat Sep 27 2025
...New DISCUSSION, AVIATION...
.KEY MESSAGES...
Updated at 1221 PM MDT Sat Sep 27 2025
- Widely scattered thunderstorms this afternoon and evening will
   mainly be focused over SW New Mexico, west of the Rio Grande.
- More widespread showers and embedded thunderstorms will develop
   across much of the area late tonight into Sunday morning.
- Showers are expected to lift north towards the Sacramento
   Mountains and Hudspeth County by mid-morning Sunday. Stronger
   thunderstorms may then redevelop in their wake across south-
   central New Mexico and Far West Texas Sunday afternoon.
   Isolated severe thunderstorms will also be possible, but it all
   hinges on whether or not we can see some partial clearing
   Sunday. Localized flooding will also be possible, where
   thunderstorms track over the same area repeatedly.
- Showers and isolated thunder will continue Sunday night into
   Monday, with stronger thunderstorms possible in the Sacramento
   Mountains again Monday afternoon.
- A more prolonged dry spell looks to set up on Tuesday and
   through the week ahead. Some chilly spots could develop at
   night in typically colder valleys.
&&
.DISCUSSION...
Issued at 1221 PM MDT Sat Sep 27 2025
Very difficult/low-confidence forecast for today and tonight.
Water vapor imagery shows out cutoff upper low over the lower
Colorado Basin, with several vort lobes noted across southern
Arizona. Dry slotting is pushing into SW New Mexico, and that`s
helping to clear out leftover cirrus and convective debris that
was abundant this morning. The NAM and GFS both indicate most of
SW New Mexico will destabilize, despite weak capping at 600 mb
associated with the dry slot. SBCAPE values of 800-1200 J/Kg look
to be common west of the Rio Grande in NM by mid-afternoon.
However, model fields also suggest we`re in an area of neutral
vorticity advection as the shortwave trough that helped keep last
night`s light rain and cloud cover going has moved northeast of
the area. Higher aloft, 200mb streamlines suggest a weakly
confluent pattern over SW New Mexico, with diffluent flow having
shifted to eastern New Mexico. Both the NAM and GFS suggest a weak
shortwave trough will approach from the southwest between 21-24Z.
With the drier air aloft, it`s difficult to see anything
reflected in water vapor imagery. But the models suggest this will
be coming from central Sonora, and there is a stubborn
thunderstorm stuck on the coast near San Carlos. All across the
Sierra Madres and into the Gila Region, just ragged cu has
developed so far.
The NAM and GFS both indicate a weak surface/low-level
convergence zone forming along the Rio Grande later this afternoon
and overnight, which could provide a focus for convection later
on.
The 12Z HREF was all over the place, especially later tonight. But
the HRRR from 12Z and subsequent runs have shown some consistency
with convection developing over the Bootheel, Gila, and the Casas
Grandes Valley of NW Chihuahua after 21-22Z, and very little
convection to the east, except maybe an isolated pop-up along the
eastern slopes of the Sacramento Mountains. The SW New Mexico
storms move NE to NNE and diminish before sunset, and before
reaching the Rio Grande. However, most HREF members show
scattered convection lifting into south-central New Mexico and far
west Texas later tonight, generally after midnight, and lasting
into the morning hours Sunday. The NAM and GFS suggest low level
moisture will increase during this time frame, with the NAM also
indicating strengthening convergence in the 850-700 mb layer as SE
flow just aloft delivers additional moisture. The GFS also
indicates as vort lobe slowly moving into SW New Mexico during the
late night hours as well. This all favors the scattered overnight
convection solution.
So, bottom line... expect widely scattered convection in SW New
Mexico this afternoon, diminishing towards sunset and sputtering
as it tries to move east of a TCS-DMN line. An isolated
thunderstorm can`t be ruled out over the Sacramento Mountains,
favoring the east slopes, with little convection this afternoon
elsewhere. Additional scattered showers and isolated thunderstorms
will develop over Mexico and lift into the area overnight into
Sunday morning.
On Sunday, the upper low will weaken into an open trough as it
finally kicks out to the northeast, reaching the Four Corners by
Monday morning. Showers and thunderstorms will be ongoing at
daybreak Sunday. They`ll mostly lift north and east of El Paso and
Las Cruces by mid-morning, but we might not completely dry out
CWA-wide before additional scattered convection fires up to our
south and lifts N to NNE across the area. Showers and
thunderstorms may be off and on all day and into the
overnight, until additional dry air aloft moves in from the west
on Monday. The Sacramento Mountains, and to a lesser extent, the
Black Range, could still fire up additional thunderstorms Monday
afternoon as the trough swings through.
Some training of cells could result in localized flash flooding,
with deeper convection that develops later Sunday into Sunday
night. Otherwise, the Sacramento Mountains will see the highest
rainfall amounts late tonight through Monday morning, with some
areas getting over 1 inch, but mostly spread out over a long
duration, outside of training cells later Sunday.
Increased deep layer (0-6km) shear around 30-40 knots could help
organize convection and lead to a few severe thunderstorms Sunday,
assuming deeper convection does materialize. Lower-level shear
also looks to be enhanced over parts of southern Otero and
Hudspeth Counties Sunday afternoon, as low level SE flow
increases. These areas may have a tougher time getting rid of the
morning showers and destabilizing, but this will need to be
watched closely.
Tuesday onwards looks dry as monsoonal moisture even deep into
Mexico begins to scour out for the season. With drier conditions
and light winds expected, we`ll start to see our usual overnight
low cold spots develop in valleys embedded in the Gila Region and
Sacramento Mountains, and a few desert locales like the Jornada
Range as well.
&&
.AVIATION...
(18Z TAFS)
Issued at 1221 PM MDT Sat Sep 27 2025
VFR conditions will prevail through the afternoon hours. Scattered
thunderstorms are expected to develop in SW New Mexico after 20Z,
possibly impacting DMN after 21Z. Thunderstorms will struggle to
approach LRU and points east through the early evening hours.
However, more widespread showers and thunderstorms are expected to
develop across the area late tonight into Sunday morning,
generally after 06Z. Most of this overnight convection will be
moderate rain showers with more scattered embedded thunderstorms,
with not much risk of strong winds or hail.
&&
.FIRE WEATHER...
Issued at 522 AM MDT Sat Sep 27 2025
Approaching upper low will bring increasing chances for showers
and thunderstorms through Sunday. Coverage will increase on
Sunday, leading to an enhanced risk of burn scar flash flooding.
Minimum RH will remain well above critical thresholds through the
weekend. Drier air will filter in as the low ejects eastward on
Monday, allowing for a reduction in RH of around 5 to 15 percent
compared to Sunday afternoon`s readings. A warming and drying
trend will take hold through the end of the work week but will
continue to stay above 20 percent. Light winds will prevail
throughout the forecast period with the exception of thunderstorm
outflows.
&&
.PRELIMINARY POINT TEMPS/POPS...
El Paso                  65  80  63  82 /  50  60  60  20
Sierra Blanca            59  73  55  74 /  40  60  60  40
Las Cruces               60  76  58  78 /  50  60  60  30
Alamogordo               59  76  57  78 /  70  70  70  30
Cloudcroft               49  55  43  56 /  70  80  70  50
Truth or Consequences    58  75  56  76 /  50  50  60  30
Silver City              53  73  52  73 /  50  40  40  30
Deming                   59  80  58  81 /  50  40  50  20
Lordsburg                59  78  58  79 /  50  20  20  10
West El Paso Metro       65  78  63  79 /  50  60  60  20
Dell City                61  74  58  78 /  40  70  50  20
Fort Hancock             65  81  62  81 /  50  60  50  40
Loma Linda               58  70  55  71 /  50  60  60  30
Fabens                   64  79  61  80 /  50  60  60  20
Santa Teresa             62  78  60  78 /  40  60  60  20
White Sands HQ           62  76  60  77 /  50  70  70  40
Jornada Range            60  75  57  76 /  50  60  70  40
Hatch                    60  79  58  78 /  50  60  60  30
Columbus                 61  81  61  81 /  60  40  40  10
Orogrande                60  74  57  76 /  50  60  70  30
Mayhill                  51  63  48  66 /  60  80  60  50
Mescalero                53  67  48  68 /  70  80  70  50
Timberon                 51  62  47  64 /  60  80  60  50
Winston                  48  69  47  69 /  50  50  50  30
Hillsboro                54  75  53  75 /  50  50  60  30
Spaceport                58  75  55  76 /  50  60  70  30
Lake Roberts             48  73  48  73 /  40  40  40  40
Hurley                   53  74  53  75 /  50  40  40  30
Cliff                    55  79  55  80 /  40  20  20  20
Mule Creek               52  75  51  76 /  30  20  10  10
Faywood                  55  73  55  73 /  50  50  50  30
Animas                   58  80  58  81 /  50  20  10  10
Hachita                  58  78  58  78 /  50  30  30  10
Antelope Wells           56  80  57  80 /  50  20  20  10
Cloverdale               55  75  53  76 /  40  10  10  10
&&
.EPZ WATCHES/WARNINGS/ADVISORIES...
TX...None.
NM...None.
&&
$$
FORECASTER...25-Hardiman

NWS EPZ Office Area Forecast Discussion