-- Discussion containing changed information from previous version are highlighted. --
945
FXUS64 KMAF 091128
AFDMAF

Area Forecast Discussion
National Weather Service Midland/Odessa TX
628 AM CDT Thu May 9 2024

...New AVIATION...

.SHORT TERM...
(Today through Friday afternoon)
Issued at 308 AM CDT Thu May 9 2024

A broad upper low over northern CONUS will transition to a
positively tilted trough, while a lobe of vorticity cuts off
from the western part of this trough over the Great Basin and
becomes a separate upper low over Utah, helping to push a cold
front into West Texas and SE NM today into tomorrow. High-res
guidance is faster with southward progression of the cold front
than runs from yesterday. NAM MOS is indicating highs behind the
front may not exceed the 70 degree mark over northeastern Permian
Basin, but this is an outlier when comparing to highs from GFS and
European models, and NBM has consistently lowered highs over the
northeastern Permian Basin over the last few runs. Therefore, went
with NBM for highs today. Westerly downsloping winds are expected
south of the cold front again today. Increased wind speeds and
gusts to a 1:1 blend of NBM and NBM 90th percentile from 17Z
Thursday through 01Z Friday to account for higher wind speeds
indicated in NAM and GFS MOS for GDP during time of expected peak
winds. However, like yesterday, no mountain wave signature was
present on 500mb and 700mb geopotential and vorticity charts, nor
cross-sections, so winds meeting high wind criteria are not
expected neither today nor tomorrow. The aforementioned cold front
will make steady progress south today before stalling near the
Pecos River. With nightfall, the cold front will resume its
southward trek, clearing the area by Friday. South of the front,
highs look to be similar to yesterday, a few degrees above average
and in the 90s, 80s in higher elevations and 100s near the Rio
Grande. Lows tonight under southwesterly flow aloft and increasing
clouds will average near or slightly above average for this time
of year, with lows falling into the upper 50s farther south into
the Permian Basin in the wake of the cold front, with lows in the
50s also being reached over most of the SE NM plains, higher
elevations of West Texas, most of the Trans Pecos, and Marfa
Plateau, and 60s elsewhere.

Rain chances increase across Terrell County into the Stockton
Plateau and Big Bend tomorrow morning along and behind the cold
front, decreasing fire risk. More on this in the Fire Weather
Discussion. Highest PoPs Friday are south of I-20, across
southeastern Pecos County into Terrell County, and will spread
west through the day into the lower Trans Pecos and Marfa
Plateau as northeasterly flow advects higher moisture to regions
farther west. Thunder is indicated, and convective rather than
stratiform rain is forecast, so not expecting widespread
accumulations above more than just a few hundredths of an inch.
Increased moisture and dewpoints above 40 will move in behind the
cold front from the northeast, covering all of the forecast area
by Friday morning, with dewpoints above 50 extending along the
Pecos River and points south into the Big Bend, and dewpoints
increasing above 60 over most of Terrell County. Winds will be
gusty both northeast and southwest of the Pecos River on Friday,
with a relative minimum in winds along the Pecos River. With
increased clouds, northeasterly flow and CAA, highs belwo normal
for early to mid May are forecast, in the 70s for most of the area
aside from 80s close to the Rio Grande and maybe some 80s
extending as far northwest as Ward and Crane Counties. 90s will be
confined to right along the Rio Grande. Rain chances will
continue to increase after Friday. Read the Long Term Discussion
for more details.

&&

.LONG TERM...
(Friday night through Wednesday)
Issued at 308 AM CDT Thu May 9 2024

Friday night, the relatively stationary low over the Great Basin
will finally begin its eastward trek, translating across the Four
Corners Region Saturday and transitioning to an open wave Sunday
before swinging into the Central Plains Monday. Ensemble clusters
and deterministic guidance remain in fairly good agreement
regarding this evolution, with this trough acting as the primary
driving force behind the weather through the upcoming weekend.
Ahead of the approaching trough, upslope surface flow as well as
southwesterly flow aloft and increasing mid-level moisture will
allow for increasing rain chances, especially late Friday night
into Saturday as ascent increases and heights begin falling as the
low moves eastward. The dryline is progged to remain well to the
west owing to persistent easterly surface flow, thus allowing for
the potential for fairly widespread showers and thunderstorms,
especially on Saturday. Ensembles have trended upward on the
probability for measurable rainfall, with a medium to high
(40-100%) probability for greater than a tenth of an inch for the
24-hr period from Friday night through Saturday night for most of
the area, though the best chance for rain will be along and east
of the Pecos, where ensembles continue to indicate a low (10-40%)
probability for greater than a half inch over the same time frame.
Currently, severe potential looks to be low given the isentropic
upglide regime and a lack of steep mid-level lapse rates, and
showers with embedded thunderstorms look to be more likely than
organized severe weather. Of note, however, is the potential for
localized heavier rainfall where thunderstorms develop, or where
storms train over the same location. Given the expected
precipitation, continued cold advection, and cloud cover, Saturday
looks to be the coolest day of the forecast with highs in the
middle 60s to middle 70s for most, and 80s and 90s focused across
far southern zones closer to the Rio Grande.

Convective activity gradually shifts eastward Sunday and Sunday
night as the trough moves into the plains, with dry conditions
returning for much of the region early next week as developing
quasi-zonal flow aloft and westerly surface flow shunt moisture
to the east. By early next week, thunderstorm chances will be
confined to far eastern areas, with temperatures progged to
quickly rebound toward normal Sunday and Monday, and above normal
Tuesday and Wednesday. By Wednesday, widespread highs in the lower
to middle 90s will be common, with upper 80s in the mountains,
and highs around 105F-110F along the Rio Grande in the Big Bend.
As far as rain chances for midweek, guidance indicates potential
for a southern stream shortwave to take shape to the west of the
region Wednesday, with a bit of a westward trend in thunderstorm
chances Wednesday afternoon as the dryline returns across the
Permian Basin. However, the details are almost certain to change
between now and then, so stay tuned.

JP

&&

.AVIATION...
-- Changed Discussion --
(12Z TAFS)
Issued at 625 AM CDT Thu May 9 2024

VFR VIS all terminals throughout TAF period. MVFR CIGs likely to
develop at all terminals after 09Z-10Z Friday and IFR could
develop at FST as early as 07Z. MVFR CIGs could also develop at
terminals as early as 03Z-05Z Friday depending on speed of cold
front. Winds shift northeasterly 00Z-06Z Friday with cold front
passage. Gusts near or above 20kts likely at all terminals
16Z-02Z, and from 03Z- 10Z Friday at terminals northeast of Pecos
River.
-- End Changed Discussion --

&&

.FIRE WEATHER...
Issued at 308 AM CDT Thu May 9 2024

A cold front will move into the area today, resulting in slightly
cooler, but still above normal temperatures. The front looks to
stall out across Southeast New Mexico and the northern Permian
Basin, with northeasterly winds behind the front, and westerly
winds continuing to the south. In a change from previous days,
winds will be lighter, with 20ft winds around 15 to 20 mph
expected only across the higher terrain of Southeast New Mexico
and Southwest Texas, slightly stronger in the Guadalupes. Thus,
despite the continued dry conditions today along and west of the
Pecos River where RHs drop to around 5-8%, the reduced wind speeds
will preclude more significant fire weather concerns. Given ERCs
above the 80th percentile and dry to critically dry fuels across
the west, IA will certainly remain a concern, even if lighter
winds will limit fire growth and spread potential. Given this,
have issued a Rangeland Fire Danger statement for this afternoon
and early evening for the Guadalupe Mountains south to the
Presidio Valley and Big Bend, where temperatures today will be
warmer ahead of the front, and where locations across the higher
terrain of these areas will see near critical and potentially
brief localized critical conditions today.

Improvement is expected tonight as the front surges southwestward,
accompanied by cooler temperatures and an increase in moisture.
Recovery tonight will be poor to fair across the Presidio Valley
and portions of the Big Bend, but good to excellent elsewhere in
the wake of the front. RHs Friday and Saturday will largely remain
above critical levels, with below normal temperatures and
potential for widespread wetting rains and thunderstorms,
especially late Friday night and Saturday. Westerly winds return
Sunday and temperatures start to rebound, with dry conditions
returning across the west, yielding a potential resurgence in fire
weather conditions late in the weekend or early next week,
depending on where rainfall is received over the next couple of
days.

JP

&&

.PRELIMINARY POINT TEMPS/POPS...
Big Spring               88  58  78  59 /   0   0  10  20
Carlsbad                 89  56  76  57 /   0   0  10  30
Dryden                  100  66  82  65 /   0  10  30  30
Fort Stockton            94  60  77  62 /   0  10  30  30
Guadalupe Pass           79  53  68  54 /   0   0  10  30
Hobbs                    86  53  74  54 /   0   0  10  30
Marfa                    87  50  80  54 /   0   0  20  30
Midland Intl Airport     90  59  76  59 /   0   0  10  20
Odessa                   90  60  77  60 /   0   0  10  20
Wink                     92  59  81  60 /   0   0  10  30

&&

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

$$

SHORT TERM...94
LONG TERM....84
AVIATION...94