367
FXUS64 KLUB 141106
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
606 AM CDT Sat Sep 14 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 242 AM CDT Sat Sep 14 2024

06Z upper air analysis depicts a regime of broadly cyclonic flow
across the central and western portions of the U.S. as a result of
the deamplification of the negatively-tilted trough at 250 mb over
Saskatchewan. To the east, a well-defined Rex Block is evident on
water-vapor imagery, and is a result of the post-tropical remnants
of Francine and a small, mid/upper-level anticyclone meandering over
the Rust Belt. The presence of this blocking pattern has augmented
the forward-progression of the mean troughing over the western U.S.,
while also modulating the amplitude of the subtropical ridge that
remains anchored over the Gulf of Mexico and into north-central
Mexico. A 250 mb, anticyclonically-curved jet streak continues to
arc over West Texas this early-morning, which continues to advect
cirrus bands originating from the upper-level outflow channel
associated with Tropical Storm Ileana as it moves northward into the
Sea of Cortez. Embedded within the branch of broadly cyclonic flow
to the west of the CWA is a small vorticity lobe that was detected
on the water-vapor bands over the Sandia Manzano Mountains, and this
smaller-scale feature was convectively augmented beneath the left
entrance-region to the anticyclonically-curved, 250 mb jet streak.
Large-scale subsidence persists within the mid-levels, with a sharp
warm nose observed on the 14/00Z RAOB from WFO AMA while increasing
in depth farther south as observed from the RAOB at WFO MAF. Cirrus
bands will continue to advect northeastward towards and over the CWA
throughout the short-term period.

At the surface, a lee cyclone with a central minimum pressure near
1006 mb was rotating near the Raton Mesa with a trough branching
southward along the TX/NM state line. The diffuse dryline extends
southeastward from the surface low into the central TX PH before
bending southward along the I-27 corridor before sloshing to the
southwest along the HWY-62 corridor as per recent West Texas Mesonet
(WTM) data. A quasi-stationary front also extended southeastward
across the TX PH and into the Upper Red River Valley where a plume
of middle 60 degree dewpoints exists across the eastern Rolling
Plains. Winds remained breezy area-wide this early-morning given the
proximity of the weak surface low and maintenance of the leeward
pressure falls beneath the broadly cyclonic flow aloft, with the
greatest confluence occurring along the stalled front. Temperatures
were several degrees warmer than the current forecast indicates, as
the southerly fetch beneath the cirrus shield aloft suppress the
escape of longwave radiation. Surface winds will continue to veer
southwestward over the next couple of hours as the lee cyclone in
the OK/TX PH continues to weaken, causing the dryline to translate
near or west of the NM state line through the mid-morning hours.

High-level flow will become nearly zonal by this afternoon as the
blocking pattern to the east continues to modulate the amplitude of
the subtropical ridge, while the convectively-augmented vorticity
lobe over the Sandia Manzano Mountains slowly progresses eastward
throughout the day and rotates through the low-amplitude apex of the
mid-level ridge. Dissipation of the lee cyclone across the TX PH is
expected to occur this afternoon while secondary cyclogenesis occurs
near the Raton Mesa once again. This will cause winds to back
southward across the Caprock and Rolling Plains even as the diffuse
dryline mixes eastward while the surface trough lags behind near the
TX/NM state line. Confluent flow will remain weak; however, similar
to yesterday, intense dry-bulbing will occur in the wake of the
dryline as boundary-layer heights soar into the mid-levels with LCLs
near 600 mb. As the small-scale vorticity maximum rotates overhead
and beneath the 250 mb jet streak, weak, large-scale forcing for
ascent in conjuction the westerly mid- and high-level flow
maintaining the elevated mixed layer atop the LCLs will facilitate
the potential for isolated to perhaps widely-scattered thunderstorms
this afternoon.

Thunderstorm initiation should occur behind the dryline, which is
counterintuitive, but the LCLs will be rooted far above the
mesoscale circulation. Shallow-topped single-cells and perhaps a
multi-cell cluster or two will be the primary storm mode with an
easterly movement near 15-20 kt. Low PoPs were manually added in
compared to the dry NBM given the thinking discussed across most of
the South Plains, all of the extreme southern TX PH, and the
northern Rolling Plains. The window for storms will be similar to
yesterday (i.e., a few hours) with most storms dissipating prior
to or at sunset. A small tranche of PoPs were drawn between 00-03Z
this evening across the extreme southeastern TX PH this evening
in the event a high-based cell is able to advect into or over the
dryline, before boundary-layer decoupling eliminates convective
potential entirely. Else, temperatures for today were raised a
smidgen from the blended initialization based on current trends
discussed above with near-record highs possible. Another warm
night will follow with winds diminishing below 10 mph while the
southerly component is maintained from the cyclogenesis to the
north-northwest of the CWA.

Temperature climatology for September 14th:

           Lubbock Airport          Childress Airport
          Forecast   Record         Forecast   Record
Today        98    100 (1965)         101    103 (1965)
--
Sincavage

&&

.LONG TERM...
(Sunday through Friday)
Issued at 242 AM CDT Sat Sep 14 2024

Tomorrow, the upper trough will be entering the Pacific Northwest,
while a remnant low from Hurricane Francine will be present over the
southeast Gulf states. This setup will keep weak ridging aloft
through the day tomorrow with surface troughing and warm downsloping
winds giving way to above normal highs in the 90s. Afternoon
thunderstorms will develop across the higher terrain of New Mexico
where southwesterly flow aloft brings in mid-level moisture. There
remains a very low chance for these storms to clip the northwest
portions of the forecast area tomorrow evening. A few models are
hinting at showers and storms developing east of the I-27 corridor
tomorrow, thus PoPs were hedged towards 10 percent across the
aforementioned area. Dewpoints will be in the upper 50s to lower 60s
along and east of the sharpening dryline, along with a stationary
boundary draped across the far southeast Texas Panhandle and
northern Rolling Plains. Instability parameters support thunderstorm
development, but this potential remains highly conditional and
justifies the reasoning behind adding the 10 PoP slight chance
mention of thunderstorms.

The upper trough axis will push eastward Monday into the Great Basin
region with the weak ridging being pushed just east of the forecast
area. This will introduce west-southwesterly flow aloft, but the
flow will remain weak with the main jet axis remaining well to the
west of the forecast area. Thus, the better mid-level moisture and
dynamics will keep much of the precipitation chances to our west
with only a slight chance for some moisture to creep into the far
southwest Texas Panhandle and northwest South Plains. Tuesday
through Thursday will feature a few troughs phasing across the
western CONUS, leaving the forecast area under southwesterly flow
aloft and the presence of increased mid-level moisture. Each day,
500mb winds of 30 knots will clip the western portions of the
forecast area, while the main jet once again remains to the west.
Daily lee troughing will give way to strong southerly low level
winds with breezy surface winds and increased low-level moisture
with dewpoints in the lower to mid 60s. Temperatures will remain
near or slightly above normal in the upper 80s along the Caprock and
lower to mid 90s off the Caprock. Thunderstorms are possible Tuesday
through Thursday afternoon/evening across portions of the area.
Friday, precipitation chances will be more widespread with the best
moisture and dynamics as the trough pushes eastward into the Plains.
With the passing trough will come a cold front, but there remains
uncertainty on the strength of the front and how much cold air will
dive south into the area.

&&

.AVIATION...
(12Z TAFS)
Issued at 606 AM CDT Sat Sep 14 2024

VFR prevails for the TAF period. Cirrus overcast will continue to
thicken throughout the day with CIGs above 25 kft AGL. Isolated
storms are forecast to develop across the South Plains and far
southern TX PH this afternoon, but given the expectation of
limited coverage, mention of -TSRA has been omitted from this TAF
cycle. -TSRA potential wanes by sunset at all terminals. Check
density altitude today.

Sincavage

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

SHORT TERM...09
LONG TERM....11
AVIATION...09