681
FXUS64 KLUB 182310
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
610 PM CDT Wed Sep 18 2024

...New AVIATION...

.SHORT TERM...
(This evening through Thursday)
Issued at 224 PM CDT Wed Sep 18 2024

The upper level pattern remains relatively benign across West Texas
early this afternoon, with water vapor channel imagery depicting a
belt of modest southwest flow aloft locally as a pair of upper lows
remains over the northwestern CONUS. At the surface, a diffuse
trough axis / pseudo-dryline is oriented roughly NE-SW across the TX
Panhandle and South Plains with dewpoints in the mid/upper 60s off
the Caprock at 19z with a drier, more well-mixed airmass further
west. Regarding today`s rain chances, a stubborn zone of midlevel
lift and associated elevated showers has lifted out of the Permian
Basin into southern portions of the Rolling Plains, and have
expanded low PoPs eastward off the Caprock through the rest of this
afternoon with this activity expected to persist. Further west,
uncertainty is much higher on whether any additional convection will
fire this afternoon. Large-scale forcing for ascent is essentially
non-existent, but model soundings do continue to indicate an erosion
of capping along the I-27 corridor by late afternoon which may
result in a few isolated storms firing in this area. However, the
absence of any cumulus field at 19z and only very weak low level
confluence adds some skepticism on the degree of convective
development we will see today, and recent hi-res model runs have
begun to back off on storm coverage. Will keep PoPs as-is from the
previous forecast for now, especially given a conditional threat for
a strong storm or two if cells are indeed able to develop; an
isolated damaging wind gust of instance of hail to quarter size will
still be possible within any storms that do develop, but overall
this threat currently looks to be limited.

Broad upper ridging to our south will expand slightly northward on
Thursday, with a slight increase in layer thicknesses resulting in
highs a couple of degrees warmer area-wide compared to today. Most
guidance suggests a weak surface boundary will linger over our
region with a few hi-res solutions suggesting isolated weak
convection will develop on Thursday afternoon. Still not
particularly impressed by this setup given a continued lack of
broader forcing and only very weak low-level confluence. This
combined with even warmer midlevel temperatures compared to today
suggest that any convection that attempts to develop tomorrow will
struggle, and will therefore keep PoPs sub-mentionable area-wide on
Thursday at this time.

&&

.LONG TERM...
(Thursday night through next Tuesday)
Issued at 224 PM CDT Wed Sep 18 2024

A brief period of active weather is expected this weekend with the
weather pattern representing more of a spring like characterization.
This active period will stem from a strong closed low moving across
the southwestern US. This will begin on Friday as the closed low
moves eastward across southern California into western Arizona.
Upper ridging will remain over Texas but slight height falls aloft
will begin to occur from eastern New Mexico into the South Plains.
Large scale ascent on Friday afternoon will not be terribly strong
this far from the center of the upper low but broad upper level wind
divergence overhead will bring some weak ascent. However, lower
levels of the atmosphere will see broad, moist upslope flow in the
afternoon. Convective activity in New Mexico is likely but there is
high uncertainty in this convection reaching the South Plains.

Greater attention will then turn to Saturday as the upper low moves
northeastward from Arizona over the four-corners and into eastern
Colorado by the evening. An upper level jet streak around 100kt or
so will be positioned from central New Mexico into southeastern
Colorado and western Kansas on Saturday afternoon. The strongest
ascent with this system will again be to the north of the area,
mostly in Colorado closer to the upper level jet but will extend
southward into West Texas. At the same time, a weak short wave
around 700mb with a separate wind max will be moving more overhead
than the upper level features on Saturday. Timing on the trough will
be optimal for peak heating convection as the base of the trough
will not move over the area until Saturday evening. At lower levels
of the atmosphere, surface cyclogenesis will be stronger compared to
Friday as the upper trough approaches. A dryline is expected to
considerably tighten up and not mix very far eastward during the
day. Very strong low level theta-e advection will persist through
the day preceding convective initiation. This will result in strong
instability values in an uncapped atmosphere which is likely to
bring at least isolated to scattered convection with some
possibility of severe.

As the system pulls away from the area on Sunday a cold front will
be sent down into the area but there are differences in model timing
on the front. This may ultimately bring some additional convective
chances on Sunday afternoon primarily off the caprock if the slower
solutions were to verify. The front will bring down temperatures
back to or below seasonal averages from Sunday and beyond. Another
short wave trough will be diving southward around Tuesday of next
week potentially bringing additional rain and thunder chances.

&&

.AVIATION...
(00Z TAFS)
Issued at 608 PM CDT Wed Sep 18 2024

VFR conditions will prevail. A slight chance for showers and
thunderstorms exists at all terminals before 03Z. The main
threats from any storm affecting a terminals are wind gusts up to
45 knots and brief heavy downpours that could reduce CIG and VIS
temporarily to IFR.

&&

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

$$

SHORT TERM...30
LONG TERM....01
AVIATION...51