485
FXUS64 KLUB 151707
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
1207 PM CDT Sun Sep 15 2024

...New AVIATION...

.SHORT TERM...
(Today and tonight)
Issued at 254 AM CDT Sun Sep 15 2024

The mid/upper-level pattern remains similar to yesterday as a Rex
Block continues to meander over the eastern U.S., while an
amplifying, positively-tilted trough digs into the Pacific Northwest
which has maintained the belt of broadly cyclonic flow over the
Intermountain West. A shortwave ridge was evident on water-vapor
imagery this early-morning over West Texas as the synoptic pattern
is slow to progresses and the Rex Block keeps the amplified,
subtropical ridge centered over central Mexico. Farther west, a
vorticity lobe was also evident on the water-vapor bands over the
southern Great Basin, with its center now rotating over LAS; and
this feature will continue to rotate eastward and emerge over the
Four Corners later this afternoon. Large-scale subsidence was not as
pronounced as in prior days, as observed by the 15/00Z RAOBs from
WFOs AMA and MAF last evening, and geopotential height tendencies
were neutral to slightly-positive based on the objectively analyzed
upper air map data and current water-vapory imagery. The cirrus
shield generated by the upper-level outflow channel from the
weakening tropical storm offshore Sinaloa have since advected east
of the CWA given the superposition anticyclonically-curved, 250 mb
jet streak over the State of Texas.

At the surface, a weak, lee cyclone was analyzed across the Raton
Mesa, with a quasi-stationary front branching eastward into the OK
PH and bending southeastward across western Oklahoma as per recent
mesonet and METAR data. The dryline is very diffuse and the
circulation continues to disperse owing to the loss of large-scale,
geostrophic deformation aloft, and has since translated west of the
TX/NM state line. A surface trough also extends southward from the
aforementioned lee cyclone, and is anchored to the west of the
Mescalero Escarpment. Moist, southerly flow remains intact with the
highest dewpoints analyzed in the Rolling Plains (i.e., upper 60s)
while lowering into the 50s across the Caprock Escarpment and
temperatures were much cooler than this time yesterday. The influx
of moisture/higher dewpoints should result in slightly cooler
temperatures, with highs ranging in the lower-middle 90s area-wide.

Emergence of the vorticity lobe over the Four Corners this afternoon
will generate diurnally-driven convection along the southern Rocky
Mountains, and the inflection point of the shortwave ridge moving
over the region and the broadly cyclonic flow to the west will
govern a more-southwesterly component to the steering flow today.
Isolated convection may propagate into the extreme southwestern TX
PH this afternoon with an expectation for the dryline circulation to
disperse entirely, leaving only the surface trough west of the edge
of the Mescalero Escarpment to serve as one of two foci for
convergence in the low-levels. The northwest-to-southeast-oriented,
quasi-stationary front, which will be located near or to the
northeast of the extreme southeastern TX PH, will serve as another
focus for low-level convergence for the initiation of storms this
afternoon.

Therefore, very low PoPs (i.e., 10-percent) were reintroduced across
the far southern TX PH for the late-afternoon and early-evening
hours. At least isolated convection should clip and/or form in
portions of the northern zones late this afternoon especially as
surface flow backs to the southeast as cyclogenesis persists near
the Raton Mesa and southeastern Colorado. The severe weather threat
is low; however, given LCLs above 700 mb, a rogue, strong wind gust
or two cannot be ruled out. The potential for storms will once again
wane near and after sunset, followed by cool temperatures and a
light, southeasterly wind heading into Monday morning.

Sincavage

&&

.LONG TERM...
(Monday through Saturday)
Issued at 254 AM CDT Sun Sep 15 2024

The extended forecast will feature slightly above normal
temperatures in the upper 80s to mid 90s through the week with
increased precipitation chances. Monday, the upper low will come
barreling over southern California and into Nevada. Weak upper
ridging will still persist over the forecast area with the bulk of
precipitation chances kept to our west. With the approaching upper
trough axis comes height falls and the development of strong lee
troughing leading to breezy southerly surface winds. By Tuesday, the
upper low will eject northeastward towards Montana as the 500mb jet
axis is shoved eastward. The right entrance region of the 40-50 knot
jet will clip the northwestern zones Tuesday evening and provide
dynamical lift for convection. With the forward progression of the
ridging, southwesterly winds aloft will open the door for mid-level
moisture advection. Storms are likely to fire along the higher
terrain in New Mexico Tuesday afternoon and push east-northeast. The
aforementioned jet placement and modest shear will help to keep
convection alive past sunset as it approaches and enters West Texas
late Tuesday evening. The increasing low level jet will also help to
maintain showers and storms through the overnight hours as they push
eastward. Buoyancy parameters are relatively weak with less than
1000 J/kg of MUCAPE. A storm or two may become strong to marginally
severe, especially earlier on in the evening as storms enter the
western zones.

Another upper low will come barreling south along the coast of
California Wednesday, with continued southwesterly flow aloft and
increased mid-level moisture. Additionally, the dryline will sharpen
Wednesday and be draped across the far southwest Texas Panhandle and
into the South Plains. Dewpoints will be in the 60s east of the
dryline with a slight chance for evening showers and thunderstorms
near and east of the I-27 corridor. The trough axis out west will
continue to meander east with the jet skirting West Texas on
Thursday. The dryline will retreat Wednesday night to eastern New
Mexico and become the focal area for storm development Thursday
afternoon. Southerly surface winds and increased low level moisture
across much of the area will give way to better instability
parameters for convection. Additionally, the low level jet ramping
up will help in storm maintenance through the late evening hours. By
Friday, the upper trough will continue to swing east before ejecting
northeast by Saturday night into Sunday. Model output has
inconsistencies in the timing and strength of the trough axis,
which could be the difference in the cold front timing and depth
of the cooler air mass. However, precipitation chances look
possible through the end of the week and into the weekend.

&&

.AVIATION...
(18Z TAFS)
Issued at 1205 PM CDT Sun Sep 15 2024

VFR conditions will prevail. There is a slight chance for showers
and thunderstorms at PVW and CDS after 00Z and before midnight.
Any storm that develops is expected to be weak with the main
hazards being wind gusts up to 35 knots and brief MVFR conditions.

&&

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

$$

SHORT TERM...09
LONG TERM....11
AVIATION...51