Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 190518
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1218 AM CDT Sat May 19 2018

.AVIATION...
06Z TAF Cycle

VFR conditions are expected at the three TAF sites through 06Z
Sunday. Showers and thunderstorms will be possible at the three
TAF sites mainly after 00Z Sunday. Some MVFR ceilings and
visibilities cannot be ruled out in the stronger storms as
confidence just too low and just too soon to mention for the end
of the TAF forecast period. Winds at the Dalhart and Guymon TAF
sites will be mainly northeast and north 5 to 15 knots but then
increasing to 20 to 30 knots with gusts near 35 to 40 knots after
00Z Sunday. Winds at the Amarillo TAF site will be mainly southeast
to southwest and west 15 to 25 knots with gusts near 30 knots but
then diminishing to 5 to 15 knots after 10Z today and then
becoming north and northeast after 00Z Sunday and increasing to 20
to 30 knots with gusts near 35 to 40 knots.

Schneider

&&

.PREV DISCUSSION... /Issued 620 PM CDT Fri May 18 2018/

AVIATION...
00Z TAF Cycle

VFR conditions will prevail at all three TAF sites through 00Z
Sunday. Southeast to southwest winds 10 to 20 knots will become
northwest and north 10 to 20 knots at the Guymon and Dalhart TAF
sites. South to southwest winds 15 to 25 knots with gusts near 30
knots at the Amarillo TAF site can be expected through 00Z Sunday.

PREV DISCUSSION... /Issued 256 PM CDT Fri May 18 2018/

DISCUSSION...
Current surface analysis shows storms beginning to develop across
the Texas South Plains ahead of the dryline across far western TX
Panhandle. Also interesting to note that the latest visible
satellite imagery along with surface obs across northern areas are
indicating a surface low developing with cyclonic flow situated
across portions of SE Colorado and far northern OK Panhandle. This
has helped to establish a southwesterly surface flow across the
northeastern Panhandles. Across the eastern Panhandles, some
residual outflow boundaries from yesterdays convection are
drifting northwest to northeast across the region. These
boundaries will help initiate thunderstorms going further into
the afternoon hours. Looking at KAMA 18Z RAOB data, low level
moisture is present with SBCAPE and MUCAPE over 2500 J/Kg with
large CAPE pronounced in the hail growth zone. With that said, as
storms initiate, very large hail will be the main threat,
especially across the eastern Panhandles where low and mid level
moisture is more present as seen in the latest hi-res upper air
profiles compared to the 18Z soundings for KAMA is a bit more
limited in mid level moisture availability. Mild level lapse rates
however are quite steep across all of the central and eastern
Panhandles. Compared to our 18Z sounding where wind shear is a
bit more limited with weak backing and veering in the bottom 8-10
kft, a LLJ is expected to move across the eastern Panhandles later
this evening along with a mid level perturbation in the mean
flow. This will increase wind shear later on in the evening and
aid in convection lasting into the evening hours.

The initial storm development this afternoon will bring very large
hail as the main threat. If the low level winds across the east
have enough low level veering, hail growth size in the strong
updraft of supercells may be as big as baseballs during the onset
of convection initiation. Eventually as the LLJ develops, a
multicell linear convection should develop and as sufficient
mixing and outflow will allow damaging winds to be the main threat
with convection ending around midnight as the remainder of the
precipitation moves east-northeast out of the Panhandles region.

Going into the day tomorrow, a cold front will slowly makes its
way south through the region, this should generate more
widespread chances of showers and thunderstorms across the entire
Panhandles region going into the afternoon hours. Timing of the
cold front is not in full agreement between the latest 18/12Z
model and numerical data. Eventually though the cold front will
makes its way south of the Panhandles by Sunday morning bringing
temperatures below average by Sunday.

Going through the remainder of the forecast period, it shall be
the battle of the airmasses. Of course with different global model
solutions out with time, the dryline setup will be the main
focal point of diurnal convection throughout most of the forecast
period. A gradual warming trend through the coming week will be
expected as a warm front will move north up into Kansas by early
next week. Precipitation chances will shift east throughout the
week as southerly and southeasterly surface winds will eventually
become more southeasterly as an upper level ridge builds into the
region toward the end of the forecast period. High temperatures
will rise to well above average by the end of the forecast period.

FIRE WEATHER...
Elevated to critical fire weather conditions are expected across
the far western areas this afternoon as 20 ft. winds around 20 kts
along with low min RH vales around 9-12% will establish fire
weather conditions.

Elevated fire weather conditions are possible across the far
western areas again for tomorrow.

&&

.AMA Watches/Warnings/Advisories...
TX...None.
OK...None.

&&

$$

11/98



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