Heavy Snow in Texas, December 6 to 7, 2017

Area Forecast Discussion
National Weather Service Midland/Odessa TX
533 PM CST Wed Dec 6 2017

.AVIATION...
00Z TAF issuance...

Currently have a mixed bag of flight conditions across the region
this evening, ranging from VFR at CNM/HOB/INK to MVFR at PEQ to IFR
at MAF/FST. Not expecting any terminals to improve given expected
increase in precip over the next 6 hours or so. Most precip remains
-RA however HOB has recently reported a change over to -SN. The
change over is expected to occur at all terminals at some point
however the timing is very uncertain. Will continue to monitor
radar/obs and amend if needed. Otherwise, precip and low cigs should
slowly shift southward through the day Thursday with improving
conditions expected.

&&

.PREV DISCUSSION... /issued 247 PM CST Wed Dec 6 2017/

DISCUSSION...

Precipitation continues to fall across most of the forecast area
early this afternoon under the entrance region of a 125kt h25 jet.
Temperatures have stayed mainly above freezing, with the exception
of the Guadalupe Mountains where temperatures have dropped below
freezing with light snow this afternoon.  Rainfall amounts of
0.10-0.5" were noted around the forecast area, with only a few
locations over Southeast New Mexico, the northern Permian Basin
and Upper Trans Pecos having reported sleet or snow.

Mid level support will increase late this afternoon/evening ahead
of a minor shortwave trough traversing the area within nearly
zonal flow aloft.  Precipitation will pick up, particularly over
southwest Texas, with forecast soundings around the area
indicating a transition to a mix of rain/sleet & snow, or all
snow, over Southeast New Mexico and the Permian Basin.  Soundings
indicate a transition to all snow in the mountains, and I-10/I-20
split, by late afternoon which will aid temperatures dropping
below freezing in these areas.  Precipitation amounts over
Southeast New Mexico and the Permian Basin will be lighter, so
even if rain changes completely to snow, surface temperatures will
stay above freezing, so little accumulation is expected.
Locations from the Presidio Valley, eastward across the Stockton
Plateau and Lower Trans Pecos will remain all rain until later
this evening when a transition to rain/snow, or all snow will
occur.

This round of wintry precipitation will likely last through
07/03Z before tapering off.  Since 3-5 inches of snow could still
fall in the Davis Mountains, will leave the Winter Storm Warning
in affect.  In the Winter Weather Advisory area, surface
temperatures outside the mountains will only be marginally cold to
support snow accumulation, but think there will be enough
snowfall to warrant the continuation of the Advisory in it's
current configuration, with 1-3 inch snowfall amounts the common
denominator.  Although much of the Permian Basin and Southeast
New Mexico Plains will see a rain/snow mix, or all snow,
overnight, surface temperatures mainly above freezing, along with
lighter precipitation amounts, will limit accumulations to an inch
or less.

By late tonight, the h25 jet will shift south and east, however
another, more potent mid level shortwave trough will translate
east/southeastward over New Mexico, and provide another round of
lift, especially for locations west of the Pecos River.  Will
lower precipitation chances east of the Pecos River through the
day Thursday.  But, precipitation will likely continue through
the day west of the Pecos River where forecast soundings indicate
all snow.  We could see snowfall amounts rise by another 2-4
inches in the Davis Mountains, so will change the Watch to a
Winter Storm Warning there until 600 pm CST.  Surface
temperatures outside the mountains will continue to be marginally
cold enough to support snowfall accumulation, but another 1-3
inches of snowfall appears likely, and will change the rest of the
Watch to a Winter Weather Advisory until 600 pm CST, and add
Reeves and Pecos counties to the Advisory.  Precipitation will
decrease from 07/21Z to 08/00Z, and expect skies to clear as the
shortwave trough passes east of the region.  Temperatures will
start a warming trend thereafter, but only after locations from
the Presidio Valley, eastward across the big Bend region and Lower
Trans Pecos possibly see their first hard freeze of the winter
Friday morning.

&&

.PRELIMINARY POINT TEMPS/POPS...
Big Spring                     30  42  26  55 /  30  10  10   0
Carlsbad                       28  36  22  52 /  40  30  10   0
Dryden                         34  38  27  52 /  90  80  20  10
Fort Stockton                  29  35  24  50 /  80  80  10   0
Guadalupe Pass                 22  29  21  43 /  70  60  10   0
Hobbs                          25  36  23  53 /  30  10  10   0
Marfa                          27  31  16  44 /  90  90  20  10
Midland Intl Airport           31  37  26  54 /  50  30  10   0
Odessa                         28  35  26  53 /  50  30  10   0
Wink                           30  37  23  54 /  70  40  10   0

&&

.MAF WATCHES/WARNINGS/ADVISORIES...
NM...Winter Weather Advisory until 5 PM MST Thursday for Guadalupe
     Mountains of Eddy County.

TX...Winter Weather Advisory until 6 PM CST /5 PM MST/ Thursday for
     Big Bend Area-Guadalupe Mountains-Marfa Plateau-Pecos-
     Reeves County and Upper Trans Pecos-Van Horn and Highway 54
     Corridor.

     Winter Storm Warning until 6 PM CST Thursday for Davis/Apache
     Mountains Area.

&&

27/72

Hazardous Weather Outlook
National Weather Service Midland/Odessa TX
147 PM CST Wed Dec 6 2017

NMZ027>029-033-034-TXZ045>048-050>053-057>063-067>070-074-075-
079>082-258-072000-
Guadalupe Mountains of Eddy County-Eddy County Plains-
Northern Lea County-Central Lea County-Southern Lea County-Gaines-
Dawson-Borden-Scurry-Andrews-Martin-Howard-Mitchell-
Van Horn and Highway 54 Corridor-Reeves County and Upper Trans Pecos-
Loving-Winkler-Ector-Midland-Glasscock-Ward-Crane-Upton-Reagan-
Davis/Apache Mountains Area-Pecos-Presidio Valley-Marfa Plateau-
Big Bend Area-Terrell-Guadalupe Mountains-
147 PM CST Wed Dec 6 2017 /1247 PM MST Wed Dec 6 2017/

This hazardous weather outlook is for portions of southeast New
Mexico, southwest Texas and western Texas.

.DAY ONE...THIS AFTERNOON AND TONIGHT

A Winter Storm Warning is in effect for the Davis Mountains above
6000 feet this afternoon through Thursday afternoon. A mix of rain
and snow will become all snow tonight. Although ice accumulations
will be less than one tenth of an inch, snowfall amounts of 3-5
inches are expected by late tonight.

A Winter Weather Advisory is in effect for the Guadalupe, Delaware,
and Glass Mountains, Marfa Plateau, Van Horn/Highway 54 corridor and
Pecos and Reeves Counties this afternoon through Thursday afternoon.
A mix of rain and snow will change to snow later tonight. Snowfall
amounts of one to two inches are expected in these areas through
tonight.

One inch or less of snow is expected across the Permian Basin
tonight.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

A Winter Storm Warning continues for the Davis Mountains above 6000
feet through Thursday afternoon. An additional 2 to 4 inches of snow
is expected in the Davis Mountains tomorrow.

A Winter Weather Advisory continues for the Guadalupe, Delaware,
and Glass Mountains, Marfa Plateau, Van Horn/Highway 54 corridor and
Pecos and Reeves Counties through Thursday afternoon. An additional 1
to 3 inches of snow is expected across these areas tomorrow.

A Hard Freeze is possible for along the Rio Grande, Big Bend area,
Terrell County, Lower Trans Pecos, and the southern Permian Basin
Friday morning.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not anticipated.

This product, along with other watches, warnings, advisories,
and statements issued by the National Weather Service Office in
Midland, can be found on the internet at...
http://weather.gov/midland