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Area Forecast Discussion
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FXUS64 KEPZ 230854
AFDEPZ

Area Forecast Discussion
National Weather Service El Paso TX/Santa Teresa NM
254 AM MDT Wed Jun 23 2021

.SYNOPSIS...
The dominant area of high pressure will continue to shift across
the Southwest through the end of the week keeping high
temperatures in the upper 90s to around 100 degrees. Afternoon
storm chances will be focused across western areas today, then
shift to the mountains and perhaps eastern locations on Thursday.
Gusty outflow winds will still be the biggest threat from these
storms. Westerly flow will take over Friday and Saturday leading
to storm chances almost being completely shut down as drier air
pushes in. Big changes will arrive Saturday night into Sunday in
the form of a backdoor cold front, setting us up for what looks to
be a moist, cool, and hopefully rainy start to the new week. The
current forecast calls for high temperatures to be at least 15 to
20 degrees cooler than what we`ve been seeing for the past week.

&&

.DISCUSSION...
.SHORT TERM...Today and Tonight...
Isolated showers continue to affect the lowlands this morning. These
are the result of outflow boundaries intersecting each other. Gusty
winds have been occurring near them, and should be dissipating early
this morning.

The upper high slowly backtracks and expands towards NM today. This
will allow a plume of moisture to intrude into Arizona and western
New Mexico. Moisture parameters like precip water and surface
dewpoints increase during the day to 1.25"-1.5" and 50-60F,
respectively. The environment will be unstable too, MUCAPES to 500
j/kg and LI around -1 C are present. Therefore, chances for showers
and thunderstorm will be possible in southwestern NM, especially
over area mountains early this afternoon. This activity will grow
and move towards the adjacent lowland areas by mid-afternoon as
shown per multiple CAM members. The main hazard with any storm will
be gusty winds from outflow boundaries and blowing dust.

Now that the upper high will be right over us by this afternoon,
temperatures will be hotter with may locations in the lowlands
ranging between 100 to 104F. This is very close to advisory
criteria. However, the additional moisture in the area, and cloud
cover should keep us below criteria.

For tonight, we continue to have chances for precipitation mainly in
areas west of the Rio Grande. Some hi-res models are suggesting some
sort of MCS developing over northern Sonora and the NM Bootheel. The
GFS and the NAM are also indicating stronger instability early this
evening over northern Chihuahua, as well as higher PW content.
Therefore, there is chance for some storms near the International
Border. At the moment, it appears that the activity will remain
either in Mexico or SW NM. It does not appear that it will reach El
Paso. However, gusty west winds associated to the outflow boundaries
from these storms will be reaching the El Paso metro area. However,
my confidence is low that we will get any storms. Thus, kept the
POPs below 10%.

&&

.LONG TERM...Thursday through Next Wednesday...
The area of high pressure that has been so dominant across the
Borderland for the last week or more will shift to the east on
Thursday and weaken slightly. The remnants of the moisture plume
that will be pulled up on the backside of the high today will then
shift over our area on Thursday. However, westerly flow will
begin to take control of our weather and result in that plume
loosing its strength and mix out a fair amount of the associated
moisture. There should still be enough in place with PWs of
1-1.15" to lead to storms developing over the mountains and
possibly across eastern areas as the plume shifts to the east
during the day. Heading into Friday, that high pressure becomes
elongated across the International Border and into east Texas as
troughing digs down into the north-central Plains and a stout high
pressure takes shape over the Pacific Northwest. This will leave
our region in pure westerly flow at the surface and aloft.
Dewpoints are expected to fall into the low to mid 30s with PW
values tanking over the northern half of the area to less than
0.50". It`s looking like storm chances will almost be completely
shut down on Friday. If there is an isolated storm, it`ll more
than likely be across the Sacs or in far southeastern Hudpseth
County where the moisture content will remain slightly elevated.
There will be a small area of surface troughing overhead, so some
light westerly breezes will be possible during the afternoon
hours. Temperatures Thursday and Friday will be hot with values
topping out in the upper 90s to around 102 degrees across the
lowlands.

Saturday will be somewhat of a day of transition as the next big
play-maker for our weather will be setting its sights on the
Borderland. But first, during the day on Saturday, the
aforementioned trough across the Plains will continue digging
further to south/southwest, sending a secondary shortwave into the
Southwest. At the surface, dewpoints will remain in the low 30s
with PW values of 0.50-0.60" across the entire area as winds
remain out of the west ushering in drier air. It`s looking likely
that Saturday will be another dry and hot day across the region,
with highs once again topping out in the upper 90s to around 100
degrees. However, things will be about to drastically change as a
backdoor cold front barrels in late Saturday evening into the
overnight hours Sunday morning. The GFS has the front reaching the
NM/AZ border by daybreak on Sunday, while the ECMWF is a little
slower with the front`s push westward, holding off on it reaching
the western CWA border until mid-day Sunday to possibly even the
early afternoon. I`m siding more in favor with the GFS due to the
overall pattern aloft, but regardless of exactly which hour it
pushes in, this front is going to bring a lot of moisture into the
Borderland. Dewpoints will jump into the 50s to maybe even 60s in
far eastern areas with PW values reaching 1.25" by Sunday
afternoon. This moisture will stick around for at least the
following few days as easterly flow streams into the Borderland
thanks to the troughing in the Plains and a blocking high pressure
in the Great Basin area.

To take a step back and talk about Sunday`s rain chances, precip
will start to move into the Sacs and far eastern areas early
Sunday morning behind the leading edge of the front. As we go into
the afternoon hours, chances will spread across the CWA, with
convection potentially developing if you believe the slightly
more bullish GFS. Scattered activity will linger through the night
before more develops Monday afternoon. This same pattern
continues for Tuesday and Wednesday as well, with scattered rain
and storm chances persisting across most of the CWA each day. In
addition to the easterly pull of moisture, we`ll be in northerly
flow aloft in between the high and troughing, meaning that pieces
of energy will rotate around the high and bring batches of more
continental moisture in from the north as well. These pieces of
energy could provide the necessary lift to occasionally fire off
convection.

The ECMWF is more often than not the drier model of the group,
but even it is saying rain chances will continue for the entire
second half of the long term period. Not to get ahead of ourselves
because the finer details will continue to change over the coming
days, but both the GFS and ECMWF are spitting out rain totals of
1-2 inches in the mountains with most of the lowlands seeing
0.5-0.75" over a 3-4 day span. Now, if that`s not enough to get
you excited, let`s talk about temperatures. With this moisture,
rain, easterly winds, and cloud cover in place, this will
drastically lower temperatures across the Borderland. GFS MEX
guidance has temps in the lower 90s on Sunday, then in the mid to
upper 80s Monday and Tuesday. The ECMWF, which is typically a bit
too cool in these situations, is even putting lower 80s to upper
70s across the lowlands Monday and Tuesday. Needless to say, we`re
going to see a huge cool down across the area. If the forecast of
mid to upper 80s comes to fruition, those temps will be 10-12
degrees below normal for the end of June. Fun fact, our record
highs for Sunday through Wednesday are 113-114 degrees, so we`ll
(thankfully) be almost 25 degrees below the record high
temperatures for those days. We`ll have to keep an eye on if any
storms may become severe or any potential flooding issues as we
approach each day of this moist period. Even looking beyond the
forecast period, the overall pattern doesn`t seem to change too
much, meaning the moisture may be allowed to continue streaming
into the Borderland.

&&

.AVIATION...06Z TAF CYCLE
VFR conditions expected to prevail through forecast period, though
temporary reductions in VIS possible due to TSRA after 00Z
tomorrow could lead to MVFR. Some -SHRA/-TSRA continue over the
next couple of hours, although confidence is low regarding if they
will approach TAF sites. Thus, the VCSH for KDMN and KLRU, may
need to amend KELP due to a cell in far east EP. Skies beginning
SCT- BKN120-150 BKN- OVC200 due to decaying CB, clearing slightly
by 12Z to SCT- BKN200. Gusty outflow winds will also subside in
the next few hours, leaving most terminals 240-270 at 06-10KT
early Wed morning. Another round of CB and TSRA over area
mountains and SW NM after 18Z, with low confidence in VCTS
affecting TAF sites. TS outflow and blowing dust may reduce VIS to
3SM with gusts up to 40KT between 00-06Z tomorrow night.

&&

.FIRE WEATHER...
Upper high expands to the west today which will bring warmer
temperatures across the area through Friday. However, a plume of
moisture intrudes into Arizona and western New Mexico keeping
chances for storms in the forecast, especially for areas in western
NM. Anyway, near the surface we remain mostly dry with minimum
relative humidity in the 10 to 20% range. Therefore, any storm in
the area possess a risk for dry lightning and gusty and erratic
winds from outflow boundaries. Later this week we will be drying up
as the upper high blocks the moisture to our south, thus min RH
drops below 15% on Friday and Saturday. Although the eastern
portions may stay above 15%. Therefore, elevated fire weather
conditions will be possible due to dry weather and breezy winds in
the afternoon hours, especially over southwestern NM.

However, we are expecting humidity and rain chances to increase on
Saturday night through early next week. A backdoor cold front brings
a moist and cooler air mass to the region. The risk for fire weather
conditions improve as the environment moistens up; and we transition
from dry storms to periods of heavy rain with any storm.

Ventilation rates will be good to excellent through the period with
isolated areas with poor to fair conditions.

&&

.PRELIMINARY POINT TEMPS/POPS...
El Paso                103  77 101  78 /   0   0   0  10
Sierra Blanca           97  70  98  71 /   0   0  10  20
Las Cruces             102  71  99  71 /   0   0   0  10
Alamogordo             103  69  99  70 /   0   0  10  20
Cloudcroft              79  52  76  54 /  10  10  30  20
Truth or Consequences  101  70  98  71 /  10  10  10   0
Silver City             94  63  88  64 /  30  30  10   0
Deming                 101  72  98  70 /  10  10   0  10
Lordsburg               99  68  95  68 /  20  30   0   0
West El Paso Metro     103  78 100  78 /   0   0   0  20
Dell City              102  69 102  66 /   0  10  10  20
Fort Hancock           104  72 103  74 /   0   0   0  20
Loma Linda              96  70  96  71 /   0   0   0  20
Fabens                 103  73 102  76 /   0   0   0  10
Santa Teresa           101  72  99  74 /   0   0   0  20
White Sands HQ         102  74 100  75 /   0   0  10  20
Jornada Range          101  66  98  68 /   0   0   0  10
Hatch                  103  69 100  69 /   0   0   0   0
Columbus               101  71  98  72 /   0  10  10  20
Orogrande              101  71 100  72 /   0   0  10  10
Mayhill                 91  60  86  60 /  10  10  30  30
Mescalero               89  56  85  56 /  10   0  30  20
Timberon                88  53  84  54 /   0   0  20  20
Winston                 94  57  89  56 /  30  30  30   0
Hillsboro               99  67  94  66 /  20  20  10   0
Spaceport              101  62  98  64 /   0  10   0   0
Lake Roberts            95  52  89  52 /  30  30  10   0
Hurley                  96  64  91  63 /  20  30   0   0
Cliff                  101  56  95  57 /  20  30   0   0
Mule Creek              95  51  90  55 /  30  30   0   0
Faywood                 96  69  92  67 /  20  20   0   0
Animas                  99  69  95  68 /  30  30  10   0
Hachita                 99  70  95  68 /  20  30   0   0
Antelope Wells          97  65  95  67 /  30  30  20  10
Cloverdale              92  65  90  65 /  30  30  10   0

&&

.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...None.
TX...None.
&&

$$

32-Pegram/29-Crespo-Jones
National Weather Service Weather Forecast Office
