515
FXUS64 KLUB 050757
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
257 AM CDT Fri Jul 5 2024

...New SHORT TERM, LONG TERM...

.SHORT TERM...
(Today and tonight)
Issued at 257 AM CDT Fri Jul 5 2024

06Z upper air analysis reveals a shortwave trough pivoting over the
Corn Belt with its mid-level closed low rotating east of the
Minnesota River Valley beneath an amplified, cyclonically-curved,
250 mb jet streak approaching 100 kt as per the 05/00Z objectively
analyzed map data. Farther west, amplification of a subtropical
ridge across the Pacific coast continues via interaction with a
baroclinic cyclone rotating over the northern Pacific Ocean and as
the broadly cyclonic flow is maintained across the eastern half of
the Lower 48. The CWA is positioned to the south of the base of this
mid/upper-level trough, with the right entrance-region to the 250 mb
jet streak translating over the TX PH as per recent water-vapor
imagery amidst a broad area of difluent flow in the mid-levels that
stretches across the southern Great Plains. This corridor of
deformed flow at the inflection point of the mean troughing and
barotropic airmass has resulted in the maintenance of a Mesoscale
Convective Vortex (MCV) evident on KMAF WSR-88D imagery, where a
narrow shield of showers and thunderstorms continues across the
southern Rolling Plains.

At the surface, a slow-moving cold front was drawn along a line from
TCC-HOB and into the I-20 corridor as per recent METAR and West
Texas Mesonet (WTM) data. Pressure tendencies over the last hour
have been as high as -3 mb nearest the remnant MCV in the southern
South Plains, and the resultant mesoscale high temporarily muddled
the more-brisk, northeasterly winds in wake of the cold front across
the rest of the South Plains as the 1020 mb anticyclone builds in
from the north. The movement and position of the stalling front was
also governed by the more-widespread convection from last evening,
and the cold front will remain stalled to the west and south of the
CWA through the remainder of the period (06/12Z or 7 AM CDT
Saturday). Convective contamination of the surface wind pattern
should erode entirely by sunrise, with northeasterly winds gradually
veering eastward throughout the day as the aforementioned surface
high rotates into central Kansas. Genesis of a low stratus deck
should occur across the portions of the South Plains and persist
throughout the mid-morning and afternoon hours as the low-level
isentropic surfaces remain moistened via the component of upslope
flow along the southern periphery of the surface high and to the
north of the stalled front. High temperatures for today were lowered
from the NBM to align with the 00Z raw statistical guidance as dense
overcast and adiabatic expansion from the easterly fetch restricts
diabatic heating.

To the north of the CWA, a convergence zone situated beneath the
belt of deformed, mid-level flow exists along the I-40 corridor.
This, combined with northeasterly, upslope flow, has generated
scattered, elevated thunderstorms across northeastern NM eastward
across the TX PH and into western OK; and it is possible that these
cells drift into the extreme southern TX PH by sunrise. The best
potential appears to be across the extreme southeastern TX PH and
Rolling Plains; however, flow throughout the steering layer is
oriented from the west near 15 kt while 850-300 mb flow is less than
10 kt and slightly more-backed to the southwest. Thus, as evident on
KAMA WSR-88D data, the mean storm motion with these multi-cellular
clusters is east-southeast at 10 mph or less across northeastern NM
to a more-southeastward direction in western OK. The 05/00Z RAOBs
from WFOs AMA and MAF also observed precipitable water (PWAT)
content of 108 and 139 percent above normal, respectively; with PWAT
values of 1.11" and 1.57", respectively. RAP-derived PWATs exceeded
1.50" across the Rolling Plains, and localized flooding may occur
through the morning hours as the multi-cellular clusters across
western OK merge into a MCC and potentially clip portions of the
Rolling Plains.

The forecast for this afternoon is even more complex, and a broad
area of chance PoPs has been delineated across all locations west of
the edge of the Caprock Escarpment while lesser potential for storms
exists across the Rolling Plains. The 05/00Z RAOB from WFO ABQ
observed superadiabatic lapse rates throughout the low-levels and a
plume of mid-level lapse rates in excess of 8.0 deg C/km, which was
advecting eastward at the time the data was observed. Convective
overturning, perhaps further enhanced by the morning MCC forming in
western OK, in addition to the restriction of diabatic heating from
overcast, should temper storm potential across the eastern zones
this afternoon and evening even in the presence of residual outflow
boundaries owing to the poor lapse rates. However, across the
Caprock Escarpment, and particularly near the TX/NM state line,
evolution of a more-mixed boundary-layer will be possible,
facilitating the potential for heavy thunderstorms once again this
afternoon into tonight compared to areas farther east into the
Rolling Plains.

The potential for severe-caliber gusts will be contingent on the
erosion of the stratus deck and how much vertical mixing can occur
to facilitate downburst potential via the formation of Inverted-V
profiles beneath cloud base. However, this scenario appears to be
more-probable towards the evening hours as any breaks in clouds
would enhance localized areas of differential heating and mixing
occur beneath MLCAPE values in excess of 1,000 J/kg. Similar to
yesterday, a wet-microburst potential will exist particularly with
cells that remain isolated across portions of the South Plains this
late-afternoon and evening. Localized enhancements of isentropic
ascent may occur via merging cold pools with storms propagating
southeastward heading into tonight which would serve as the foci for
localized flooding, and the highest PoPs are delineated across the
southern South Plains by this time before storm chances wane heading
into Saturday morning.

Sincavage

&&

.LONG TERM...
(Saturday through Thursday)
Issued at 257 AM CDT Fri Jul 5 2024

The overall pattern for the extended has an upper ridge to our west
across California building slowly eastward into the Great Basin
region towards the end of next week. Meanwhile, troughing will
persist across the Plains and into the Mid-Atlantic as a subtropical
ridge builds into the GoM behind Hurricane Beryl. Given this, the
flow aloft will be mostly northwesterly through the extended
forecast period. A few elevated weak showers and storms may linger
Saturday morning from Friday night`s activity across portions of the
South Plains and Rolling Plains; however, the bulk of the activity
will be to the south. Lingering morning clouds, along with an
increase of cumulus clouds and chances for thunderstorms during the
afternoon hours may help to limit daytime heating. Temperatures are
expected to remain slightly below normal in the upper 80s to lower
90s. South southeast surface winds will help to pump in low level
moisture with dewpoints in the lower to mid 60s. Afternoon diurnal
convection along the higher terrain of New Mexico is likely.
Additionally, a shortwave aloft may help to kick off and drive some
showers and storms across the forecast area Saturday afternoon and
evening. Temperatures should warm enough to the break any morning
capping inversion with MLCAPE values around 500-1000 J/kg and
effective shear of 30 to 35 knots, which is capable of supporting a
few strong to potentially severe storms. Main threats with the
storms would be damaging wind gusts with steep low level lapse
rates, but large hail up cannot be ruled out either. With the mean
flow aloft being west northwesterly and increasing slightly with the
shortwave, storm motion will be east southeast and concerns of
flooding due to slow moving storms remains low at this time.
However, heavy rainfall with localized flooding cannot be ruled out.

Sunday, clearing skies with a more south southwesterly downsloping
surface wind will give way to a return of hot temperatures in the
mid to upper 90s, with a few areas approaching triple digits.
Another shortwave aloft Sunday evening may introduce a few showers
and storms to the far southeast Texas Panhandle and Rolling Plains.
In addition, a surface low across northeast New Mexico will slide
southward late Sunday night with a passing cold front early Monday
morning. Showers and storms may develop along the frontal passage
with ample moist surface convergence. Modest elevated instability
will be present and supportive of a strong storm or two. Post
frontal precipitation chances and low clouds will support cooler
below normal temperatures for Monday ranging from the upper 70s to
upper 80s.

Heading into the middle and end of next week, temperatures will
remain mild in the upper 80s to lower 90s, which is slightly cooler
than normal. Afternoon diurnal convection across the higher terrain
in New Mexico may occur each afternoon and with embedded shortwaves
in the northwest flow aloft, the chances for late afternoon and
evening thunderstorms across portions of the area remains possible
each day.

&&

.AVIATION...
(06Z TAFS)
Issued at 1223 AM CDT Fri Jul 5 2024

A cold front will continue to move southward across the region
throughout the overnight hours, with northeasterly winds expected
for the TAF period. CIGs will lower into at least MVFR towards
sunrise at KCDS, KLBB, and KPVW; and chances for TSRA will follow
at KCDS later this morning, too. Overcast CIGs will return to VFR
by this afternoon. The potential for convection affecting KLBB
and KPVW this afternoon remains unclear, and will be assessed
further for the 12Z issuance. The complex of thunderstorms
currently to the southeast of KLBB will gradually dissipate over
the next couple of hours.

Sincavage

&&

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

$$

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