Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 200521
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1221 AM CDT SAT AUG 20 2016

.AVIATION...
06Z TAF Cycle

A cold front will push southeast into the Panhandles shifting the
winds to the north and will increase to around 15 to 20 knots with
some higher gusts to near 25 knots. The cold front will move through
the Guymon and Dalhart TAF sites around 06Z to 08Z Saturday...and
then across the Amarillo TAF site around 08Z to 10Z Saturday.
Convection will affect the three TAF sites through around 11Z to 12Z
Saturday with mostly VFR to MVFR ceilings and erratic and gusty
winds in and near any thunderstorms. IFR to LIFR ceilings will be
possible at all three TAF sites behind the cold front between about
11Z and 17Z Saturday. VFR conditions will return after 16Z to 18Z
Saturday. Winds will become east and southeast after 19Z to 21Z
Saturday and will diminish to around 5 to 10 knots or less.

Schneider

&&

.PREV DISCUSSION... /Issued 628 PM CDT FRI AUG 19 2016/

AVIATION...
An area of thunderstorms may track southeast and affect the DHT TAF
site at the start of this forecast. Winds could gust to 45 knots with
these storms. Other isolated storms near the AMA TAF site should fall
apart with sunset. Another round of showers and thunderstorms may
affect the DHT and GUY TAF sites overnight in association with a cold
front. Northeast winds will gust to 25 to 30 knots with this front
as it moves southward across the panhandles. The winds will gradually
decrease toward Saturday afternoon. IFR cigs are also expected to
fill in behind the front and they should decrease by around mid day
on Saturday.

PREV DISCUSSION... /Issued 321 PM CDT FRI AUG 19 2016/

SHORT TERM (Tonight Through Saturday)...

Latest surface observations continue to show some surface boundary
setting up across the bottom two row of counties in the Texas
Panhandle. With dewpoint temperatures in the lower to mid 60s across
the southern TX Panhandle, in-conjunction with SBCAPE around 2000
J/kg, some convection well out ahead of the main cold front may
develop along a secondary surface boundary. Latest run of the
NAM/HRRR shows convection firing along and south of the boundary,
especially across the SE TX Panhandle in-conjunction with DCAPE
around 1200 J/Kg will provide an elevated chance of strong to near
severe wind gusts possible with these thunderstorms. Other
convection may develop in the NW panhandles as convection
development in the high terrain of New Mexico moves east in the 700
hPa mean flow. These storms across the far western OK Panhandle and
NW TX Panhandle show low severe potential at this time. However,
severe weather cannot be completely ruled out with H500 temps
between -7C to -9C along with better bulk shear values between 25-30
kts as we go further into the afternoon which can support some
further vertical ascent and some organized convection.

More widespread thunderstorms are possible as the main cold front
across the central plains makes its way south toward our region.
Latest model guidance shows the timing of the cold front starting
across the northern parts of the region around 02-03Z Saturday and
reaching the southern TX Panhandle by 05-07Z Saturday. As the front
moves south across the region, in its wake, winds will shift to the
north with gusts over 20 kts possible. Convection along the cold
front itself may produce some thunderstorms near severe criteria
with gusty winds being the main threat. As we go past 12Z Saturday,
conditions will improve across the Panhandles as the main cold front
will be moving south of our region. High temperatures as we go into
Saturday will range from upper 70s to lower 80s.

LONG TERM (Saturday Night Through Friday)...

Looks like the cold front will stall somewhere from NE Texas south
into Cen TX and back NW into NM as the main upr trough moves east across
the great lakes Sat-Sun. That said, sometimes convection along the
boundary will push stalling fronts further south into TX than models
think this time of year. Low level should winds will turn SE by
Sunday across the Panhandles allowing the onset of moisture recovery.
A decent southern stream trough will move into CA by Monday with srly
flow increasing and aiding in moisture transport on Monday. Models
show enough increase in moisture and instability for storms on
Monday, but not sure how much I am buying that. Kept 20 pops across
the SE third per model blends for now. Influence of the upr trough
approaching from the west will increase Tue-Wed. Current forecast
show better POPS on WED assoc w/ this system, however timing remains
in question and latest model trends seem to have sped things up
somewhat. Either way, it appears the trough will provide a good
chance for storms somewhere in the Tue-Wed timeframe across the area.
Similar to today, it appears we may see an initial weak front in the
area followed by a stronger secondary frontal boundary assoc more
with a NRN stream trough dropping into the NRN plains on Tue. There
is very little confidence in the forecast beyond Wednesday as models
are not in good agreement wrt timing of the second stronger front and
arrival of drier air from the north. This has led to a broadbrush of
slt chc to low end chc POPs in model blend forecasts Thu-Fri as
additional vort maxes moves into the region from the WNW, however
POPs strongly depend on how much drying occurs in the wake of the
Tue-Wed upr trough and fronts. If drying is too significant, the
disturbances will pass with little fan-fair. After seeing above
normal temps all summer, the recent below normal trend in high temps
is expected to continue except perhaps Tue ahead of the next front
and upper systems.

&&

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

&&

$$

11/16



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