Area Forecast Discussion
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000
FXUS64 KEPZ 192131
AFDEPZ

Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
331 PM MDT Sat Aug 19 2017

.SYNOPSIS...
Numerous showers and thunderstorms with heavy rain that could
result in flash flooding...will develop across borderland later
today end especially overnight. Activity will be widespread and
will continue into early Monday...as the healthy dose of Monsoon
driven moisture persists over the region for the next couple of
days. A flash flood watch remains in effect. Rain chances fall
back somewhat later Monday and Tuesday...before possibly ramping
back up by mid week as a cool front approaches from the northeast.
Highs Sunday and Monday will run at least a few degrees below
normal.

&&

.DISCUSSION...
Latest W/V imagery continues to depict UL low pressure off the
southern CA coast...and a broad area of high pressure aloft over
the NW Gulf of Mexico and far SE TX. An upper level disturbance
remains evident over NW Mexico...with attendant circulation center
over NW Sonora. Mutual circulation between the so cal cut off low
and that around the Gulf of Mexico upr high...continues to drive
a healthy stream of deep Monsoon moisture over the borderland.
Trends from area soundings from last few releases reveal top down
moistening of the atmosphere...with the 12Z EPZ PWAT already back
above 1 inch. Visible imagery nicely reveals convective banding
already over southern NM/far W TX.

Flow will carry embedded short wave northward across far eastern
AZ through Sunday...with associated NE quadrant lift/diffluence
expected to focus storm development over our area during this
time. Storms should focus first over the southern and western
deserts this evening as the wave approaches from the south...then
over all areas during the pre dawn hours on Sunday...as the asscd
low aloft tracks over SE AZ. Heavy rain/flash flooding threat
will continue into Sunday evening...as the embedded low remains
forecast to be a slow mover north. Widespread 1-2 inch amounts
expected overnight with isolated higher amounts possible...particularly
with outflow/storm regeneration from slow moving activity in
general. In this type of synoptic setup...only weak outlfow
strengths are required for regeneration. While just over 3 inches
is in our forecast over Sacs for total event rainfall...local
amounts up to 4 inches will be possible anywhere in our CWFA. Far
west TX should get in on the action as well...however as of this
writing...for tonight it appears bulk of precipitation should fall
early this evening and pick up again after midnight. PWAT`s over
0.75"...up to 1.5" and in some instances over 1.7" are forecast
over SW NM and far W TX through Monday.  For the southern
bootheel uplands early Monday morning...while not specified in the
grids I wouldn`t rule out the possibility of some shallow ground
fog.

By Monday morning...this disturbance should be sufficiently north
of our area such that its influence is less of a concern for
prolonging the wideapread flash flooding threat. However with the
cut off Ca Low...a negatively tilted shortwave rotating around
this feature may touch off an additional round storms during the
afternoon hours on Monday. As such have included small hail in the
grids for storms. While damaging wing gusts are not included in
Monday`s fcst, I wouldn`t rule out this possibility with a few
storms Monday afternoon into early Monday evening.

By early Tuesday...an upper level trough digging into upper midwest
and great lakes region...will force the western portion of the
Gulf of Mexico upr high to separate. Both the GFS and ECMWF prog
this western portion of the the high to center over the borderland
as a weak feature by mid week. As such the fcst of chance/slight
chance storms looks good for Tuesday.

By later Wednesday the long range solutions bring a back door
cool front into the picture...with the ECMWF carrying it through
as a stronger feature further west towards the continental divide.
GFS on the other hand is the wetter solution...as its frontal
depiction leaves this sfc feature further east and weaker. This
is more effective with its focus to lift moisture into storms and
potentially another heavy rain scenario for Wed night...should
this solution pan out esp since the high aloft is weak.

By that time long range solns weaken the so cal low...with GFS
attempting to lift this feature northeast as an open wave over wrn
AZ on Thursday. In this scenario...another day with more of a potential
wind/hail threat from storms is possible. For Friday and early
next weekend...both the GFS and ECMWF solutions strengthen our
weak high aloft over the western four corners. This should
maintain our typical scattered mtn - isolated lowland storm
development scenario with winds/hail as main impacts.

Abundance of cloud cover-rain cooled air in place for the next
few days will ensure highs remain down to a few degrees below
normal through Monday. Highs thereafter rebound near or just
above normal for the rest of the week.

Still looks mostly cloudy in general for eclipse viewing in the El
Paso area...but less cloud cover is expected the further west you
go. We are expecting 60-70 percent cloud cover Monday at noon...however
I wouldn`t rule out `holes` that develop if we have a low cloud
deck going into Monday morning that starts to dissipate.

&&

.AVIATION...Valid 20/00Z-21/00Z...
Increasing moisture over period will lead to numerous 1-3SM TSRA
BKN015-025 over entire area.  Some periods of just SHRA BKN030-040
also expected between 06Z-18Z. Generally expect P6SM SCT-BKN050-070
BKN100-120 with winds out of the E to SE AOB 12KTS but stronger
gusts possible near thunderstorms.


&&

.FIRE WEATHER...
Moisture has made it into the region with an increase in showers and
thunderstorms expected tonight through Sunday.  Locally heavy rain
and flooding is expected through this period.  Now models showing a
little bit of a downturn, especially west going into early next week
with upper ridge building across region.  As this ridge gets broken
down toward midweek, expect moisture to spread back to the west with
more widespread showers and thunderstorms expected by Wednesday and
Thursday. More drying possible going toward next weekend as ridge
tries to rebuild over the Four Corners region.

&&

.PRELIMINARY POINT TEMPS/POPS...
El Paso                 66  83  67  88 /  80  60  50  30
Sierra Blanca           64  84  65  87 /  80  60  40  40
Las Cruces              63  80  63  87 /  80  60  50  30
Alamogordo              65  80  63  85 /  70  70  50  40
Cloudcroft              48  62  49  66 /  80  70  80  50
Truth or Consequences   64  81  63  88 /  60  60  50  40
Silver City             57  76  57  82 /  80  60  60  40
Deming                  61  81  62  88 /  80  60  40  30
Lordsburg               63  82  62  87 /  80  60  60  30
West El Paso Metro      65  82  66  88 /  80  70  50  30
Dell City               68  86  67  89 /  50  60  50  30
Fort Hancock            67  86  69  90 /  70  60  40  30
Loma Linda              61  78  62  83 /  80  60  50  40
Fabens                  65  84  67  89 /  80  60  50  30
Santa Teresa            64  82  65  88 /  80  70  50  30
White Sands HQ          65  80  64  86 /  80  70  60  30
Jornada Range           64  80  62  87 /  80  60  60  30
Hatch                   64  82  63  89 /  80  60  60  30
Columbus                62  82  63  87 /  90  60  40  30
Orogrande               65  81  65  87 /  80  60  50  40
Mayhill                 55  70  54  75 /  70  70  80  70
Mescalero               55  69  53  75 /  80  70  80  50
Timberon                54  69  53  74 /  70  70  80  50
Winston                 55  75  54  80 /  60  70  60  50
Hillsboro               59  78  58  85 /  70  60  60  40
Spaceport               63  81  62  87 /  70  60  60  40
Lake Roberts            53  74  52  81 /  60  70  60  40
Hurley                  57  76  57  83 /  80  60  60  40
Cliff                   58  82  57  88 /  60  60  60  30
Mule Creek              60  81  58  85 /  60  60  70  50
Faywood                 58  77  57  84 /  80  70  60  30
Animas                  62  81  61  86 /  80  60  40  30
Hachita                 60  81  61  87 /  80  60  50  30
Antelope Wells          60  80  61  87 /  80  60  50  50
Cloverdale              59  76  60  82 /  70  50  50  40

&&

.EPZ WATCHES/WARNINGS/ADVISORIES...
NM...Flash Flood Watch from 6 PM MDT this evening through late Sunday
     night for NMZ401>417.

TX...Flash Flood Watch from 6 PM MDT this evening through late Sunday
     night for TXZ418>424.

&&

$$

22/26



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