Area Forecast Discussion
Issued by NWS Midland/Odessa, TX

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FXUS64 KMAF 171134

Area Forecast Discussion
National Weather Service Midland/Odessa TX
634 AM CDT Thu May 17 2018

.DISCUSSION...Please see 12Z Aviation Discussion below.


.AVIATION...Fog imagery is not showing low clouds near any TAF
sites. The dryline has moved a little east off the Mtns since GDP
now has a SW wind. Our tower cam is showing what looks like
ACCAS. The latest HRRR does indc convection possibly affecting
KFST and KMAF around 21-23Z. The 06Z NAM NEST CAM model indc
convection developing along the TX/NM border around 21Z...possibly
as far west as KHOB. The convection moves east rapidly. However
the 06Z NAM12 and GFS keeps most of the convection to the north.
Due to model inconsistencies and boundaries that are left over
from previous convection it is too difficult to have much
confidence when and where convection will occur. Therefore...have
left it out of the TAFs for now and will amend as needed. Any
convection that forms could have large hail and damaging winds.



.PREV DISCUSSION... /issued 345 AM CDT Thu May 17 2018/


Despite multiple boundaries knocking about due to last night`s
convection, area radars are a lot less busy than 24 hours ago.  WV
imagery shows the upper-lvl ridge remaining anchored over West Texas
and Southeast New Mexico, w/a trough over the west coast.  This
feature will begin nudging the ridge east today.  However, despite
thicknesses beginning to decline w/this eastward progression,
afternoon temps the next couple of days should remain very similar
to yesterday`s, as the low-lvl thermal ridge stubbornly remains in
place.  KMAF VWP this morning shows a more easterly component to the
LLJ, which will push the dryline west of the CWA by 12Z.  Models are
then in pretty good agreement later today in mixing the dryline east
only to the Texas/NM border or so, resulting in critical fire wx
conditions in the Guadalupes/SE NM.  See Fire Wx Discussion below
for more details.  The net benefit of this scenario will be better
chances for convective initiation further west.  Forecast soundings
continue to show very steep mid-lvl LRs of ~ 9C/km, w/dry subcloud
layers and DCAPEs well in excess of 1000 J/kg., so we`ll mention
severe threat w/large hail/damaging winds in the grids.

Friday, w/continued warm temps, models mix the dryline further east,
expanding critical fire wx coverage out west and keeping rain
chances to the east.  Temps begin dropping off Sat, but not my much,
w/POPs similar to Friday`s.  By this time, the west coast low is
forecast to be ejecting into the Central Plains, sending an
unseasonably strong cold front into the area by 12Z Sun.  Again,
models form a triple pt in SE NM, w/the dryline backed up against
the higher terrain, and most of the CWA in the warm sector.  This
will result in increasing chances of convection thru Sun night over
most of the CWA as the trough passes.  If the lwr lvls moisten up
like the models want them to, heavy rainfall will be possible,
especially Sun night.

All indications persist that, w/the cold front, cloud cover, and
moisture, highs Sun/Mon will come in below-normal.  During this
time, a secondary trough will be working its way down the west
coast, keeping SW flow aloft over West Texas and Southeast New
Mexico and a chance of convection in play each day.  Temps will warm
to just a few degrees above-normal by the end of next week.  As has
been the case the past few weeks, extended POPs are unrealistically
high, given the drought, and we`ll keep toning them down.


Even though the dryline is banked along the mtns early this morning
winds will turn southwest by mid morning as the dryline mixes east.
Therefore...will not make any changes to the current Red Flag
Warning for today. The area under the Warning today will have
southwest winds of 15 to 30 mph and minimum RHs in the single
digits. In addition the atmosphere will be in a dry and unstable
state. RFTI values will range from 2 to 4 on the NM Plains Thursday
to 5 in the GDP Mountains. On Friday RFTI values increase...was
tempted to upgrade Friday`s Watch to a Warning. avoid
confusion with having multiple Warnings and to let the later shifts
to evaluate later model data will let the Watch stand. Most areas
are well into the 90th percentile fuels for ERC-G, except 75-80th
percentile Marfa Plateau/Davis Mtns. Recent fire activity in the
Davis Mtns certainly suggest fuels are receptive to fire. Another
concern is the possibility of a few dry lightning strikes in the
Davis Mtns on Thursday that could potentially be associated with
strong gusty outflow winds. RHs will not improve until Sunday across
these western areas.


Big Spring                    100  69 100  69 /  10  10  10  10
Carlsbad                      101  59  97  57 /  10   0   0   0
Dryden                        100  68  99  67 /  10   0  10  10
Fort Stockton                  99  68  99  65 /  20  10  10  10
Guadalupe Pass                 95  63  88  61 /   0   0   0   0
Hobbs                          97  61  95  56 /  10  10   0   0
Marfa                          93  56  92  52 /  20  10   0   0
Midland Intl Airport          100  70 100  67 /  20  10  10  10
Odessa                         98  70  99  67 /  20  10  10  10
Wink                          101  64 100  61 /  10  10   0  10


NM...Red Flag Warning from 9 AM this morning to 9 PM MDT this evening
     for Guadalupe Mountains-Southeast Plains.

     Fire Weather Watch from Friday morning through Friday evening
     for Guadalupe Mountains-Southeast Plains.

TX...Red Flag Warning from 9 AM this morning to 9 PM MDT this evening
     for Guadalupe Mountains.

     Fire Weather Watch from Friday morning through Friday evening
     for Davis/Apache Mountains Area-Guadalupe Mountains-Loving-
     Marfa Plateau-Reeves County and Upper Trans Pecos-Van Horn
     and Highway 54 Corridor-Ward-Winkler.



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