286
FXUS64 KLUB 081746
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1246 PM CDT Mon Jul 8 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 256 AM CDT Mon Jul 8 2024

06Z upper air analysis depicts a positively-tilted shortwave trough
ejecting over the north-central Great Plains and into the Corn Belt,
with several other vorticity maxima evident on water-vapor imagery
that were rotating southeastward along the western tranche of the
broadly cyclonic waveguide. Farther west, a subtropical ridge was
located over the Sierra Nevada Mountains and was beginning to
deamplify via the influence of a vertically-stacking, baroclinic low
over the northern Pacific Ocean. Convectively-augmented vorticity
lobes were located across southeastern Colorado and the Upper Red
River Valley, the latter of which was responsible for generating the
widespread convection yesterday afternoon and evening. A 250 mb jet
streak analyzed at 55 kt by the 08/00Z upper air map data continues
to nose into the Four Corners while the right entrance-region to the
upstream jet streak remains over the CWA. The superposition of these
synoptic-scale features results in broadly difluent, mid-level flow;
and divergent, high-level flow over the region which has aided in
regenerative, elevated thunderstorms to the north of the CWA and
south of the I-40 corridor within the upslope flow regime. Anvil
debris from the prior episode of convection continues to gradually
advect eastward and the sky is crystal clear in its wake owing to
subsidence on the backside of the weakening MCS. However, patchy,
low-level stratus is beginning to increase in areal coverage based
on recent trends from the GOES-East Nighttime Microphysics band as
moistening of the boundary-layer is accelerated in the wake of the
anvil debris. Low stratus are expected to continue to develop
throughout the rest of the morning across the CWA.

At the surface, the cold front was located along the southern South
and Rolling Plains as per recent West Texas Mesonet (WTM) data, with
a quasi-stationary front located entirely south of the CWA. Brisk,
northeasterly winds have followed the cold front and are expected to
remain intact throughout the short-term period as the position of
the mid/upper-level trough over the southern Great Plains moves very
little over the next 24 hours (excluding the translation of the
associated jet streaks rounding the base of the trough). Pressure
tendencies near 1-2 mb/hr observed by the WTM will gradually
neutralize as the cold front continues to move southward and the
1016 mb surface high settles into the region. Multi-cellular
clusters currently located across the Raton Mesa and OK PH will
continue to advect southeastward towards the CWA, and arrive near or
shortly after sunrise. The 08/00Z RAOB from WFO AMA sampled an
elevated mixed layer (EML) yielding ~1,500 J/kg for most-unstable
parcel trajectories with a sharp warm nose between 700-650 mb.
Warming of the mid-levels was underway, evident by the subtle
increases in theta-e atop the boundary-layer. This RAOB data, albeit
launched over six hours ago, is supportive of the maintenance of
elevated convection. PoPs were tweaked at the start of the period
(12Z) with 60+ percent covering most of the CWA through late-morning
as the convective complex should remain intact as it moves into the
extreme southern Texas Panhandle.

The mid-levels will continue to gradually warm throughout the day
today as the temporary dampening of the subtropical ridge over the
western U.S. causes it to slosh eastward. Such warming aloft will
erode the magnitude and depth of the EML, with updrafts potentially
struggling to reach heights high enough to generate lightning by the
afternoon. So, while PoPs are above 60 percent (i.e., likely and
definite for showers), thunderstorms have been kept within the
chance category owing to the latter thinking. The severe weather
threat is low today, and a moist sub-cloud layer will temper the
potential for strong-to-severe-caliber gusts. Brief, heavy rainfall
will be the primary hazard, particularly with the convective
episodes in the morning before the overturned airmass results in the
demise of organized convection. Low-level stratus will also remain
intact throughout most of the day, too; and this will restrict the
full effects of insolation with temperatures struggling to reach 80
degrees across the Caprock and most of the Rolling Plains. Shower
and thunderstorm chances will wane entirely after dark tonight as
the base of the mid/upper-level trough shifts east of the CWA and
NVA begins advecting overhead, with winds becoming light and
variable as the surface high becomes centered across the TX PH. The
combination of a clearing sky and light winds will enhance radiative
cooling effects tonight, with low temperatures forecast to cool into
the upper 50s to lower 60s across the Caprock and into the middle
60s in the Rolling Plains.

Sincavage

&&

.LONG TERM...
(Tuesday through Sunday)
Issued at 256 AM CDT Mon Jul 8 2024

The mid/upper-level trough will begin to pivot east of the CWA by
Tuesday morning, with the longitudinal expansion of the subtropical
ridge over the eastern Atlantic Basin, in conjuction with the
northern-stream shortwave trough pivoting across the Mississippi
River Valley, causing the 250 mb jet streak to translate towards the
Great Lakes region. The deamplification of the high-level flow
combined with the further increase in subsidence aloft from the
dampened belt of northwesterly flow will lead to drier and warmer
conditions area-wide on Tuesday, with high temperatures rising into
the middle 80s to lower 90s from west-to-east across the CWA. The
surface high will also rotate eastward on Tuesday, with winds
remaining light and east-northeasterly throughout the day amidst
full insolation. A compact, 250 mb jet streak is forecast to
translate southeastward over the central Rocky Mountains on Tuesday
which should generate diurnally-driven convection across eastern New
Mexico, but the weakened and more-northerly component to the
steering flow should keep the convection west of the TX/NM state
line. Therefore, the blended PoPs outlined across the western zones
have been removed with this forecast cycle.

Northwesterly flow aloft will persist heading into Wednesday as the
shortwave trough slowly progresses eastward and as the subtropical
ridge to the west begins to amplify once again. The 250 mb jet
streak translating southeastward over the Rocky Mountains should be
significantly attenuated by this point, at or around 40 kt, as it
noses into the northern TX PH/OK PH region on Wednesday afternoon.
At the surface, return flow will have become established as the
anticyclone rotates into central North Texas with a well-mixed
boundary-layer evolving as temperatures rise to near 90 degrees
across the Caprock Escarpment. Isolated-to-widely-scattered
thunderstorms are forecast to develop across eastern New Mexico
during the afternoon hours with convection moving southeastward into
the western South Plains prior to dusk, and the blended PoPs were
maintained along and west of the I-27/HWY-87 corridors for Wednesday
afternoon and evening. Global NWP guidance is in agreement with the
amplification of both subtropical ridges over the western U.S. and
the North Atlantic, attenuating the shortwave trough entirely with
doldrum-like conditions returning to by the end of the work week and
into next week. Temperatures will rise and hold steady in the middle
90s through the end of the period as subtropical ridge to the west
remains centered over the Four Corners region.

Sincavage

&&

.AVIATION...
(18Z TAFS)
Issued at 1236 PM CDT Mon Jul 8 2024

VFR conditions are expected to prevail at all terminals through
the TAF period. Clouds should scatter out this afternoon and
evening, becoming mostly clear overnight. There is a potential
for patchy fog around sunrise, particularly at PVW and LBB,
due to this morning`s rainfall and low temperatures nearing the
dewpoint early tomorrow morning. However, confidence is too low to
include in the TAF at this time.

&&

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

$$

SHORT TERM...09
LONG TERM....09
AVIATION...58