Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 251716
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1216 PM CDT SAT JUN 25 2016

.Aviation...
18Z TAF Cycle

An upper trough over the central and southern Rockies today will
allow for scattered convection to develop this afternoon into tonight
across the northwestern portions of the Texas and Oklahoma
Panhandles. A frontal boundary across southeastern Colorado and
western Kansas is expected to push south and east into the Panhandles
tonight. The convection should affect the Dalhart TAF site after 00Z
to 02Z Sunday...and could possibly affect the Guymon TAF site after
01Z to 03Z Sunday as the convection lifts northeastward. South to
southwest winds 10 to 20 knots with some higher gusts possible to
around 25 to 30 knots through 00Z to 04Z Sunday...then winds shifting
to the north 5 to 10 knots or less behind the frontal boundary at the
Dalhart and Guymon TAF sites and backing around to the southeast 5 to
10 knots or less at the Amarillo TAF site. VFR conditions are
expected except in and near the convection at the Dalhart and Guymon
TAF sites where MVFR ceilings will be possible.

Schneider

&&

.Prev Discussion... /Issued 611 AM CDT SAT JUN 25 2016/

Aviation...
Southerly winds will increase and will get gusty this morning.
Showers and thunderstorms will again form over northeast New Mexico
and then they should move into the northwest CWA. At this point, it
appears showers and thunderstorms may affect the DHT and GUY TAF
sites with MVFR conditions between about 02z and 07z. Will leave the
AMA TAF site dry for now. A surface trough will turn the winds around
to the north at DHT and GUY about the time the showers and
thunderstorms move in.

Prev Discussion... /Issued 401 AM CDT SAT JUN 25 2016/

Discussion...
Previous forecast remains largely unchanged with only minor
adjustments needed based on latest model guidance. Daily chances of
showers and thunderstorms are expected and we tried to better define
where/when highest probabilities are. We will continue to add more
detail with subsequent forecasts. Hazards for this forecast period
should be limited isolated marginally severe thunderstorms and the
potential for heavy rainfall amounts.

Two main synoptic scale features are of note for the short term. A
shortwave trough passing across the northern Rockies and a weak
upper low drifting slowly north from the Big Bend of Texas.
Convergence along a surface trough/weak front associated with the
northern stream wave will focus convective development this
afternoon across the northwest Texas Panhandle and the Oklahoma
Panhandle. This justifies fairly high probabilities in close
proximity to the front, probably in a narrower zone than currently
indicated. We have increased portions of the area to likely
category. Up to around 1,500 J/kg MLCAPE by late afternoon will be
present but deep layer shear sufficient for storm organization/persistence
will be just north of the area. Isolated brief episodes of damaging
winds may be possible from short lived storms given fairly deep dry
sub-cloud layer, but widespread severe weather is not expected. Heavy
rainfall amounts are possible given moist environment (model
projected PWAT values 1.25-1.5 inches) and slow storm motions.
Coverage should decrease overnight slowly as instability decreases,
although we kept low probabilities late in the night through Sunday
morning given presence of convergent surface boundary, convective
outflow and increasing large scale ascent from approaching upper low
from the south.

As diurnal destabilization occurs on Sunday coincident with the
northern edge of upper low, thunderstorm coverage will be higher
across most of the area, not just the northwest as has been the case
in prior days. Next week the flow aloft increases gradually and
shifts to northwesterly. A series of small scale difficult to time
shortwaves necessitate maintaining precipitation chances through the
week. Medium range guidance agreement decreases as the week goes on
with handling of these smaller waves and resultant surface front
positions.

BRB

&&

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

&&

$$

11/18



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