587
FXUS64 KLUB 230805
AFDLUB

Area Forecast Discussion
National Weather Service Lubbock TX
305 AM CDT Thu May 23 2024

...New SHORT TERM, LONG TERM, FIRE WEATHER...

.SHORT TERM...
(Today and tonight)
Issued at 305 AM CDT Thu May 23 2024

Low clouds are rapidly expanding northwestward early this morning as
southeasterly winds continue to transport better moisture into the
forecast area. Unfortunately, this moisture won`t last long as a
dryline is positioned across eastern New Mexico and far West Texas
and will begin to spread eastward by mid-morning. This will lead to
the quick dissipation of low-clouds across the forecast area from
west to east with mostly sunny skies expected by early afternoon as
drier downsloping winds move across the Caprock. These downsloping
winds will help to boost temperatures back above normal into the low
to mid 90s across the forecast area. This hot and dry airmass,
combined with breezy southwest winds will lead to near-critical to
critical fire weather conditions on the Caprock (see fire weather
discussion below for additional details).

The dryline is expected to stall across the eastern Rolling Plains
this afternoon and serve as a surface forcing mechanism for
thunderstorm development. While forcing for ascent aloft won`t be
overly strong, a weak ripple in the southwest flow combined with the
exit region of a 250 mb jet moving overhead should be more than
sufficient for isolated thunderstorm development along the dryline.
While most guidance has the dryline mixing to the edge of our
forecast area, previous experience suggests that the dryline will
end up farther west so have kept a slight chance mention for severe
thunderstorms across our eastern most column of counties (Childress
to Stonewall). East of the dryline MLCAPE around 3000 J/kg will be
present thanks to a combination of steep mid-level lapse rates and
surface dewpoints in the upper 60s to lower 70s. With the exit
region of the jet moving overhead, effective bulk shear values of
around 45 kts will also be present with nearly straight hodographs
present. This would favor splitting supercells with the potential
for large hail and damaging winds. Thunderstorm activity will
quickly shift east and out of our forecast area this evening with
dry weather persisting through the remainder of the night. A surface
cold front will begin to move into the forecast area around sunrise
Friday morning with breezy northerly winds developing in its wake.
/WI

&&

.LONG TERM...
(Friday through Wednesday)
Issued at 305 AM CDT Thu May 23 2024

The split-flow regime in the upper-levels will begin to phase on
Friday as a negatively-tilted shortwave trough pivots over the far
northern Great Plains and the apex of an anomalous ridge wobbles
westward over the northeastern Pacific Ocean. Quasi-zonal flow will
develop in response to this phasing of the 250 mb jet stream pattern
as the large-scale gyre centered across the northern Rocky Mountains
and west-central Canada finally begins to dissipate, and as the 594
dam ridge remains anchored over central Mexico. At the surface, a
fast-moving cold front will arrive in the extreme southern TX PH
prior to sunrise and weaken as it crosses into the northern Permian
Basin. A brief period of strong gusts (30-40 mph) are forecast to
accompany the front immediately following its passage given the
moderate spike in pressure tendencies, and winds were raised from
the NBM to account for this scenario. However, winds should quickly
slacken by late morning as the front stalls and the southern
periphery of a weak anticyclone located in the central Great Plains
eclipses the region. High temperatures will also be 5-8 degrees
cooler, though it will still be very warm area-wide. Return flow
will become established once again on Friday night as a shortwave
trough digs into the Great Basin, with the dryline forming east of
the edge of the Mescalero Escarpment and quickly mixing into the
Rolling Plains by Saturday afternoon. Deep, vertical mixing of the
boundary-layer is expected as the dryline crosses east of the 100th
meridian; however, the presence of a cirrus deck should temper the
overall magnitude of mixing that has been observed in prior days
(i.e., 500 mb) with forecast soundings indicating a theta-e bulge
around 600 mb as a west-southwesterly, mid-level jet streak near 50
kt translates overhead. Strong, southwesterly winds between 20-30
mph will develop on the Caprock and into the Rolling Plains as
cyclogenesis of a <=994 mb surface low continues in the central
Great Plains. The magnitude of southwesterly winds, in addition to
the hot surface temperatures, will facilitate the potential for
elevated-to-critical fire weather conditions on Saturday afternoon.

The dryline will remain east of the Rolling Plains on Sunday as a
another shortwave trough emerges over the central Rocky Mountains,
though winds may attain a west-northwesterly component due to the
possibility of an outflow-reinforced, pre-frontal surface trough.
High temperatures will be a few degrees lower than Saturday due to
the weakness in adiabatic compression compared to a southwesterly
fetch, and temperatures will range from the lower-to-upper 90s from
west-to-east across the CWA, respectively. Winds were raised from
the NBM for Sunday (50 percent weighting applied with the NBM 90th
percentile) as renewed cyclogenesis of a 994-996 mb surface low
occurs near the OK PH and the boundary-layer mixes above 700 mb in
the afternoon. Elevated-to-critical fire weather conditions are,
therefore, forecast to develop once again across portions of the
Caprock on Sunday afternoon. A tertiary shortwave trough is forecast
to eject into the north-central Great Plains on Sunday evening,
which will generate another cold front (perhaps also reinforced by
convective outflow from thunderstorms in the central Great Plains),
with the cold front moving through the CWA early Monday morning.
High temperatures on Monday may stay below 90 degrees for most of
the CWA, with the trend continuing into the middle of the week. All
suites of the global NWP guidance continue to indicate that the
anomalous ridge originally positioned over the northeastern waters
of the Pacific Ocean will shift inland and across the Intermountain
West. However, there remains discrepancies in its amplitude and the
geometry of the synoptic-scale flow. Regardless, presence of return
flow at the surface and low-levels beneath a west or northwesterly
component to the steering flow points towards favorable chances for
thunderstorms across portions of the CWA from late Tuesday through
Thursday, some of which could be severe.

Sincavage

&&

.AVIATION...
(06Z TAFS)
Issued at 1237 AM CDT Thu May 23 2024

Low ceilings are expanding northwest across the forecast area
early this morning. MVFR to IFR ceilings are expected at all TAF
sites by 10z this morning. These low ceilings will stick around
through the middle of the morning before quickly eroding from west
to east as breezy southwest winds expand across the area. This
will allow all TAF sites to return to VFR conditions by late this
morning. There is a 15% chance for thunderstorm development near
CDS late this afternoon and evening however confidence in a direct
impact at the TAF site remains too low at this time to include a
prevailing mention. Winds will diminish around sunset with light
southwest winds persisting through the night.

&&

.FIRE WEATHER...
Issued at 305 AM CDT Thu May 23 2024

Clouds will quickly dissipate this morning as a dryline surges
eastward. Behind this dryline, downsloping southwesterly winds will
boost temperatures into the low to mid 90s and bring a much drier
airmass into the South Plains and far southwestern Texas Panhandle.
This drier air combined with the hot temperatures will drop
afternoon relative humidity values into the lower to middle single
digits across the far southwestern Texas Panhandle and South Plains.
Southwest winds will also become breezy (sustained winds of 15-20
mph and gusts to 30 mph) across this same area with the strongest
winds expected across the far southwestern Texas Panhandle and the
southwestern South Plains where sustained winds of 20-25 mph and
gusts up to 35 mph will be possible. The combination of breezy and
dry conditions will lead to RFTI values of 4-6 across the Caprock.
Therefore, a Red Flag Warning has been issued from 1 pm until 9 pm
today for the far southwestern Texas Panhandle into the western
South Plains. While a Fire Danger Statement is in effect for the
remainder of the Caprock. Very poor relative humidity recoveries
will be observed overnight on the Caprock only increasing into the
mid to upper teens until a cold front arrives around sunrise on
Friday bringing relative humidity values up to around 30 percent.
Unfortunately, this front will also switch winds around to the north
with sustained winds around 20 mph and gusts up to 35 mph behind it.

&&

.LUB WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 1 PM this afternoon to 9 PM CDT this
evening for TXZ021-022-027-028-033-039.

&&

$$

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