Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 151654 AAB
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
1154 AM CDT Tue Aug 15 2017

.AVIATION...
Southerly winds will prevail at around 15 knots or less through
much of the night. A surface trough will move south across the
Panhandles late tonight into Wednesday morning which will switch
the winds around more to the northwest. Thunderstorm chances look
best at AMA this evening so have kept a PROB 30 group there.
Chances do not look as good at DHT and GUY, so have kept them dry
for now. Skies are expected to remain VFR outside of
thunderstorms. However, some low clouds may try to move into AMA
Wednesday morning in association with the trough.

&&

.PREV DISCUSSION... /Issued 644 AM CDT Tue Aug 15 2017/

AVIATION...12Z TAFS...

Multiple categories expected through the TAF period. For now it
looks like low clouds and fog will be less likely this morning as
showers and cloud cover had lingered overnight. As daybreak
approaches any clearing should lead to mostly VFR conditions. But
another round of showers and storms expected tonight at all TAF
sites, with various categories due to lowered CIG`s and/or
visibilities. Right now it looks like TAF sites should be impacted
by storms after 00Z, and could even be as late as 03Z before they
start impacting TAF sites.

Weber

PREV DISCUSSION... /Issued 345 AM CDT Tue Aug 15 2017/

DISCUSSION...
Southwest flow aloft is anticipated to persist over the Panhandles
through the next 24 hours. This pattern will continue to allow
embedded shortwaves in the upper flow to move across the area to
spark showers and thunderstorms. The early morning convection will
likely persist past sunrise but we do expect to see a lull in
convective activity around midday. This lull will be short-lived
as the influence of the next shortwave emanating out of central
New Mexico by the early evening. Models show the west recovering
enough for CAPE to build into the 2000 J/kg - 3000 J/kg range.
Deep layer shear of 20-25kt will continue to be a limiting factor
for the overall organization of convection. The presence of DCAPE
on the order of 1000-1800 J/kg keeps the potential for downbursts
as a potential hazard. Since there has been very little chance in
the expected PWATs, it`s no surprise that heavy rain which could
result in localized flooding and flash flooding will remain a
hazard. Storms that develop will be ushered eastward with the
initial shortwave through the overnight hours Tuesday, but a
longwave trough sweeping across the High Plains will help to bring
an end to convective activity shortly after the Wednesday morning
commute.

The upper trough which will help to end convection Wednesday
morning will also send a boundary across the Panhandles. This
will help to keep our rain chances low through the better part of
the daylight hours Wednesday. The return of precip comes Wednesday
evening initially along the stalled boundary across the south
before mountain convection sneaks into the west early Thursday
morning. It is possible that we may not see the initial storms
impact the southern Texas Panhandle should the boundary move
sufficiently southward. For this forecast, have kept low end PoPs
across the southeast. Zonal flow aloft returns Thursday and
persists through the approaching weekend. This will open the
Panhandles once again to passing embedded shortwaves which will
keep rain chances in the forecast throughout this time period.
Should the timing of the shortwaves sync with peak heating then
strong to marginally severe storms can not be ruled out.

&&

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

&&

$$

15/24



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