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000
FXUS64 KAMA 241911
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
211 PM CDT Wed Apr 24 2024

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

.SHORT TERM ...
(This evening through Thursday night)
Issued at 210 PM CDT Wed Apr 24 2024

Morning clouds are lingering this afternoon and should, for the most
part, linger throughout the night as well... though some breaks in
the clouds are possible this afternoon. Temperatures will remain in
the 60s for much of the area except for the southwest, where 70s are
possible. A surge of mid-level theta-e advection is expected this
evening in the southeastern half of the Panhandles which may be
enough to kick off some showers generally off the caprock. Previous
model suites suggested that portions of this area may be uncapped
which would support a threat for elevated strong to severe
thunderstorms, but latest models now suggest that the cap may be too
strong for updrafts to overcome. Can`t entirely rule out a strong to
severe thunderstorm in the SE TX Panhandle as that area has the
weakest cap, but it is generally not looking as favorable for strong
to severe thunderstorms tonight.

Clouds will linger into Thursday morning for much of the area,
perhaps with some showers and isolated thunderstorms in the east.
Meanwhile, the upper-level trough begins to take a negative tilt
with the upper-level jet streak approaching the CWA. By 12z
Thursday, the dryline is favored to be in the vicinity of the
Texas/New Mexico border, with low-60 dew points in the southeast and
low-50 dew points as far west as Dalhart and Boise City. Most model
guidance begins to clear the clouds from west to east from the mid
to late morning hours through the afternoon, allowing for
temperatures to warm and the dryline to move eastward and gradually
sharpen as it encounters the deeper moisture present in the east. It
is worth noting that the 12km and 3km NAM keep low clouds lingering
all day in the east, keeping temperatures in the 60s and 70s. This
would most likely negate any severe thunderstorm concerns as the cap
would be too strong to support convective initiation. However, it is
a known bias in those products to keep cool temperatures wedged in
and weaken mixing during the day. Given their known bias and that
those products are currently the outliers, will not be giving much
credence to the idea that clouds linger in the east all day at this
time.

The more favored solution is that the clouds clear out in the
afternoon and destabilization occurs in the central and east
Panhandles. Models suggest a robust cap will be in place prior to
destabilization occurring, with the warmest temperature in the
inversion around 11C to 13C, but this cap should weaken with daytime
mixing. By the mid to late afternoon hours, the dryline is most
favored to set up in the central combined Panhandles, aligned in a
north-south fashion from the vicinity of Guymon to Amarillo, perhaps
slightly further east. Significant uncertainties exist about the
environment at that time such as:

1) How much will the cap be weakened? Most guidance that isn`t the
3km or 12km NAM has MLCIN ranging from near-0 J/kg to -75 J/kg,
suggesting no cap to a moderate cap. This will depend on the actual
strength of the inversion and when the morning clouds clear out.

2) A lead wave with some mid to upper-level forcing is expected to
swing through the Panhandles in the afternoon, but the timing will
be important. If it arrives too early, the cap may still be too
strong for thunderstorms to develop. If it arrives too late in the
afternoon or early evening when temperatures are beginning to cool,
the cap may once again be too strong for thunderstorms to develop.

3) Some CAMs suggest that there may be a dryline bulge which may be
a cause for enhanced surface wind and moisture convergence. This may
aid in convective initiation.

Current thinking is if there was a more favorable corridor for
thunderstorms to develop, it would be in the northern TX Panhandles
or eastern half of the OK Panhandle as that area is currently
favored to clear out first, and is in a more favorable position for
upper-level divergence should the timing be favorable as well.
Regardless, if a thunderstorm is indeed able to develop anywhere
along the dryline, models suggest 1500-2500 J/kg of MLCAPE,
potentially as much as 3000 J/kg along with 45-55 kts of effective
shear. Storm relative helicity (SRH) values are favored to be
between 50-150 m2/s2 between 0-1km, and 100-200 m2/s2 between 0-3km.
If there is a sustained updraft, all of these factors suggest that a
supercell would quickly develop with all severe hazards possible,
and a splitting supercell would be possible given a long and fairly
straight hodograph in the afternoon. Baseball hail (2.75") would be
possible, if not larger if the higher end of the range of
instability verifies. Damaging winds and tornadoes would be possible
as well. A strong tornado (EF2+) would be possible given the low-
level shear, low-level instability, and LCLs between 1000m to 1250m
(not great but not necessarily unfavorable), with a peak timing
window in the late afternoon/early evening when the LLJ strengthens.
 Any thunderstorm would continue through the evening but presumably
weaken as convective inhibition increases. A Pacific front will
overtake the dryline Thursday night and push all moisture out of the
Panhandles.

Vanden Bosch

&&

.FIRE WEATHER...

Elevated to critical fire weather conditions are expected for the
western Panhandles, behind the dryline, due to windy conditions and
low RH values. Fuels and fuel loading is most receptive generally
along and north of the Canadian River with more uncertainty south of
the Canadian River. The Fire Weather Watch has been converted to a
Red Flag Warning along and north of the Canadian River, leaving a
Fire Weather Watch in the southwestern TX Panhandle given
uncertainty regarding fuel receptiveness.

Vanden Bosch

&&

.LONG TERM ...
(Friday through next Tuesday)
Issued at 210 PM CDT Wed Apr 24 2024

A concern for some potential fire weather conditions will continue
through the weekend with a dryline mixing well east of the
combined Panhandles early Friday. Depending on how far east this
dryline retreats into the Panhandles Sat, some severe
thunderstorms may be possible for the far eastern counties in the
combined Panhandles Sat afternoon.

Friday morning a dryline is expected to mix east into western
Oklahoma leaving Tds in the 20s to the west and bringing Tds in
the 30s to the east. Friday afternoon temperatures are progged to
be in the 80s with RH values falling to the low teens in the
middle of the afternoon. Looking aloft, a subsequent H5 low
pressure system will start to dig south along western CONUS inside
of the main parent trough left behind by the Thu system. By Fri
evening this low will be around the southern tip of NV and the
exit region of the jet maxima reaching into the combined
Panhandles. The increasing winds aloft will help develop a leeside
surface low and southwest surface winds in the 20 to 30 mph range
across portions of the combined Panhandles.

Going into Sat, this system is expected to traverse the Four
Corners Region with winds aloft increasing over the Panhandles to
around 70 to 80 kts at H5. Depending on the ability of low level
moisture to advect back into the eastern Panhandles with the
potentially retreating dryline some thunderstorms will be
possible for the far eastern counties. Have stuck with the NBM
PoPs which are around 15 to 20 percent across the far eastern FA.
If thunderstorms do occur there could be a chance for a severe
thunderstorms. However, most of the deterministic models have the
dryline mix back east taking the overall storm potential with it.
This could be an instance where storms pop in the eastern
Panhandles and quickly move east before they are able to become
severe.

Due to the increase in the winds aloft Sat, a second and much
strong leeside low is expected to develop over NW NM/SE CO/W OK
Panhandle. The pressure gradient and mixing of winds aloft are
expected to lead to windier conditions Sat with sustained winds
around 30 to 35 mph, and a 40 to 50 percent probability of gust
reaching 50 mph across central to western portions of the
combined Panhandles. With much of the area expected to be on the
dry side of the dryline, min RH values are progged to approach 10
percent as the afternoon highs reach into the 80s. Once again
elevated to critical fire weather conditions are possible
especially for areas not seeing greenup.

As the H5 low moves off Sat night, and the surface low with it, a
weak cold front is expected to dip into the area bringing
northerly winds for Sun. Highs on Sun are expected to be in the
upper 60s across the northwestern FA and 70s to the southeast
compared to the 80s on Sat. After Sun an H5 ridge is expected to
build in over the Great Plains temperatures will rebound into the
80s for Mon and even approach the low 90s for Tue.

36

&&

.Fire Weather...
Elevated to critical fire weather conditions are expected once
again on Friday and Saturday. This is especially for western and
northwestern parts of the combined Panhandles where moisture has
been really limited the past month and fuels remain dormant. RFTIs
will be limited to 3 to 6 in the southwest Texas Panhandle on Fri,
which may be more elevated for areas seeing greener vegetation.
However, on Sat winds are expected to be stronger with gust
potentially as high as 50 mph for much of the central to western
Panhandles, to include the northwest where vegetation is much
drier and dead still. RFTIs are expected to be around 5 to 7
especially around the Canadian River Valley west of Lake
Meredith. Min RH values will be approaching 10 percent both Fri
and Sat.

36

.AVIATION...
(18Z TAFS)
Issued at 1221 PM CDT Wed Apr 24 2024

IFR to MVFR ceilings are being observed currently at all TAF
sites. Ceilings will improve some at KAMA this afternoon but
return to MVFR tonight. KDHT will improve this afternoon to VFR
and remain VFR through this forecast period. KGUY may briefly
return to VFR this evening but drop into MVFR soon afterward. IFR
ceilings are possible at KGUY tonight, but confidence is too low
to include at this time.

Vanden Bosch

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                59  87  53  82 /  10  20  10   0
Beaver OK                  54  86  51  86 /  40  40  30   0
Boise City OK              52  85  47  81 /  10  10   0   0
Borger TX                  60  90  56  87 /  10  30  10   0
Boys Ranch TX              58  90  52  83 /  10  20   0   0
Canyon TX                  59  88  51  81 /  10  20  10   0
Clarendon TX               60  83  53  84 /  20  30  20   0
Dalhart TX                 52  85  46  81 /  10  10   0   0
Guymon OK                  53  88  49  84 /  10  30  10   0
Hereford TX                59  88  51  82 /  10  10   0   0
Lipscomb TX                57  83  54  86 /  40  40  30   0
Pampa TX                   59  83  54  84 /  20  40  20   0
Shamrock TX                60  79  53  84 /  30  40  40   0
Wellington TX              62  80  54  85 /  30  30  40   0

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Red Flag Warning from noon to 9 PM CDT Thursday for TXZ001-002-
     006-007-011-012.

     Fire Weather Watch from Thursday afternoon through Thursday
     evening for TXZ016-017.

OK...Red Flag Warning from noon to 9 PM CDT Thursday for OKZ001-002.

&&

$$

SHORT TERM...52
LONG TERM....36
AVIATION...52