Special Weather Statement, NWS El Paso, TX

Area Forecast Discussion
National Weather Service El Paso Tx/Santa Teresa NM
529 AM MDT Wed Jul 19 2017

.SYNOPSIS...
An upper level disturbance will bring an increase in thunderstorms
over Far West Texas and much of Otero County late this afternoon,
with isolated thunderstorms elsewhere. Thunderstorm activity will
likely increase across southern New Mexico during the night as
this upper level disturbance moves to the northwest. High
temperatures will remain in the lower-90s across the lowlands
today, but will be stuck in the 80s for most areas on Thursday.
Overall increasing moisture will bring better chances for
afternoon and evening thunderstorms area-wide through the weekend
and into early next week.

&&

.DISCUSSION...
Water vapor imagery shows our next mid-level inverted trough
(developing upper tropospheric low) has moved to near the Big
Bend and matured significantly in the past 12 hours. However,
drier continental air aloft is wrapping into the CWA from the
east. Last night's 00z soundings and current model soundings
indicate that most of the drying is above 600mb, but the 00z MAF
sounding also showed a significant cap associated with the dry air
right around 560 mb. The 500mb temp of -3.9C at MAF also reflects
this overall warmer air aloft. However, models show cooler temps
aloft moving in from the SE out ahead of the upper low this
afternoon, with the tongue of warmer/dry air mainly affecting
northern and western parts of the CWA, which may help hold back
thunderstorm activity until the evening hours.

GOES-16 PW product also shows most of the drier air (PW <1 inch)
over the northern CWA and stretching into the western TX
Panhandle, with PW ramping up to around 1.5 inches north of the
Big Bend. This supports the idea of increasing moisture ahead of
the upper level low. GOES-16 data is still 'experimental and non-
operational', but you already knew that.

The NAM and GFS both show the upper disturbance as a weak inverted
trough at 500mb, and a closed circulation at 200 mb, moving into
the eastern CWA around 21z. Differences remain with respect to the
amount of instability (GFS on the low side, NAM on the high side)
that develops across Far West Texas and most of Otero County, but
both have continued to ramp-up QPF amounts and coverage with each
run. The NAM-initialized University of Arizona WRF model run from
00z seems to offer a reasonable solution, showing widespread
thunderstorms developing across Hudspeth and El Paso Counties as
the upper low rolls closer after 20z. It may be a little stingy on
thunderstorms over the Sacramento Mountains (especially
considering steady low level SE upslope flow). Bottom line is, I
raised PoPs for this afternoon to Scattered/Numerous over most of
the eastern CWA, especially Hudspeth County, with mostly isolated
elsewhere (except really close to the AZ border). PoP Minimum is
over Sierra County associated with the more stable airmass under
the warm/dry band aloft.

As the upper low moves to the NW this evening, precip chances will
spread along with it. AZ-WRF run isn't too excited about overnight
precip chances, but upper level support, continued low level
moisture increase with fairly deep SE flow, and modification of
that dry/warm band aloft suggests otherwise. NAM and especially
the GFS appear to more or less concur.

Going into Thursday, the trick will be how much convective debris
we're left with from the previous day/night's activity. The upper
level disturbance will weaken but stall out over western NM, while
at the mid-levels another inverted trough takes shape over the
Sierra Madre. At first glance you might think that's the same
system moving over us today, but a closer look suggests it is
actually a convectively-induced wave left in the wake of a
weakening MCS near the Sonora/Sinaloa border this morning. With
the subtropical ridge re-centering itself over the Central Plains
states, this little disturbance (and abundant Sierra Madrean
moisture) will be pulled up northwards. Overall precip chances
should favor the western CWA given that's there the deeper
moisture will be, but still expect scattered storms elsewhere, as
eastern areas will have the better chance at recovering from
overnight rainfall.

Took temperatures down a few degrees for Thursday, with upper-80s
for much of the lowlands...this is reflected in guidance...and may
even be a bit conservative depending on leftover cloud cover.

Heading into Friday and the weekend, the subtropical ridge will
continue to drift east towards the mid-Mississippi valley with a
very weak ridge axis extending towards the Four Corners. South to
SE flow aloft will weaken heading into the weekend, with a weak
trough developing over Colorado Saturday as the ridge axis breaks
down. This actually induces lee low formation at the surface over
the Colorado Front Range, and our low level flow will shift more
to the South and South-Southwest Fri-Sun, especially west of the
Rio Grande. However, we will have plenty of recycled mid-level
moisture hanging around in the light/variable flow aloft, and the
S to SSW low level flow will actually help feed low level
moisture into our area from the Sierra Madres (which were
drenched last night and will continue to be drenched the next few
nights).

Overall, Friday through at least Tuesday looks active with PW
values ranging from 1.25 to 1.50 inches across the area, and more
widely spread-out precip chances. The collapse of any mid-level
flow will promote nearly stationary thunderstorms which will
enhance the risk of localized flash flooding.

&&

.AVIATION...
An upper level disturbance will increase the risk for
thunderstorms at KELP late this afternoon and evening, while more
stable air will keep isolated thunderstorms in the higher terrain
until the evening and overnight hours. Upper disturbance should
promote nocturnal thunderstorms, especially west of the Rio
Grande. Heavy rainfall (brief IFR visbys) will be the main risk,
with some gusts to 35 knots possible.

&&

.FIRE WEATHER...
An approaching upper level disturbance will bring an increase in
thunderstorms over the far eastern part of the area today,
including The Sacramento Mountains southward into Far West Texas.
Elsewhere, activity will remain isolated and mostly preferring
the higher terrain due to a more stable airmass. However, the
upper level disturbance will bring an increase thunderstorms
during the evening and overnight hours. The overall trend is
looking much better for increased thunderstorm activity and
rainfall heading into the weekend and early next week, with RH
values increasing.

&&

.PRELIMINARY POINT TEMPS/POPS...
El Paso                 92  73  88  72 /  30  40  30  20
Sierra Blanca           86  69  88  69 /  60  30  30  20
Las Cruces              92  69  88  68 /  20  50  30  20
Alamogordo              91  69  89  69 /  30  10  20  20
Cloudcroft              67  51  67  53 /  50  10  40  30
Truth or Consequences   94  69  90  69 /  10  20  30  20
Silver City             88  61  84  62 /  20  50  60  50
Deming                  92  70  87  67 /  10  50  40  20
Lordsburg               91  68  87  66 /  20  50  60  40
West El Paso Metro      90  72  88  71 /  30  50  30  20
Dell City               90  70  92  70 /  40  20  30  20
Fort Hancock            91  75  89  74 /  60  30  30  20
Loma Linda              82  65  81  65 /  50  30  30  20
Fabens                  92  74  88  71 /  40  40  30  20
Santa Teresa            92  72  87  69 /  30  50  30  20
White Sands HQ          91  70  86  70 /  30  20  20  20
Jornada Range           93  67  89  68 /  30  30  20  20
Hatch                   93  68  88  67 /  10  50  30  20
Columbus                92  70  86  68 /  20  50  40  30
Orogrande               93  72  89  71 /  30  20  20  20
Mayhill                 78  55  80  57 /  40  10  40  30
Mescalero               80  57  78  58 /  40  10  40  20
Timberon                76  56  76  56 /  50  10  40  30
Winston                 86  59  82  58 /  10  20  50  30
Hillsboro               93  64  89  64 /  10  50  40  30
Spaceport               93  67  89  67 /  10  20  30  20
Lake Roberts            85  55  81  54 /  30  40  60  50
Hurley                  88  62  84  61 /  20  50  60  40
Cliff                   93  61  90  61 /  20  40  60  50
Mule Creek              90  64  86  63 /  30  40  60  50
Faywood                 89  63  84  62 /  10  50  50  30
Animas                  91  69  88  66 /  30  50  60  40
Hachita                 92  67  88  65 /  20  50  50  40
Antelope Wells          90  66  83  64 /  30  50  50  40
Cloverdale              85  65  82  62 /  50  50  70  50

&&

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

25-Hardiman

Hazardous Weather Outlook
National Weather Service El Paso Tx/Santa Teresa NM
1205 PM MDT Wed Jul 19 2017

NMZ401>417-TXZ418>424-201815-
Upper Gila River Valley-Southern Gila Highlands/Black Range-
Southern Gila Foothills/Mimbres Valley-
Southwest Desert/Lower Gila River Valley-Lowlands of the Bootheel-
Uplands of the Bootheel-Southwest Desert/Mimbres Basin-
Eastern Black Range Foothills-Sierra County Lakes-
Northern Dona Ana County-Southern Dona Ana County/Mesilla Valley-
Central Tularosa Basin-Southern Tularosa Basin-
West Slopes Sacramento Mountains Below 7500 Feet-
Sacramento Mountains Above 7500 Feet-
East Slopes Sacramento Mountains Below 7500 Feet-Otero Mesa-
Western El Paso County-Eastern/Central El Paso County-
Northern Hudspeth Highlands/Hueco Mountains-Salt Basin-
Southern Hudspeth Highlands-
Rio Grande Valley of Eastern El Paso/Western Hudspeth Counties-
Rio Grande Valley of Eastern Hudspeth County-
1205 PM MDT Wed Jul 19 2017

This Hazardous Weather Outlook is for portions of south central
New Mexico, southwest New Mexico, and southwest Texas.

.DAY ONE...This Afternoon and Tonight.

Scattered thunderstorms this afternoon and into much of the night.
A few of these storms could produce heavy rain and local flooding.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday.

Isolated to scattered thunderstorms through Friday, then becoming
scattered to numerous over the weekend into the beginning of next
week. Heavy rain and flash flooding will be the main threat in
this period.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

Hefner

Special Weather Statement
National Weather Service El Paso TX
120 PM MDT WED JUL 19 2017

TXZ421-192000-
Salt Basin TX-
120 PM MDT WED JUL 19 2017

...SPECIAL WEATHER STATEMENT...

At 119 PM MDT, Doppler radar was tracking a strong thunderstorm 9
miles east of Salt Flat, or 11 miles southwest of Pine Springs,
moving northwest at 10 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Salt Flat and Guadalupe Mountains National Park.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm, and may lead
to localized flooding. Do not drive your vehicle through flooded
roadways.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 3172 10520 3196 10505 3188 10492 3164 10491
TIME...MOT...LOC 1919Z 117DEG 9KT 3175 10491

CRESPO