Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 240505

Area Forecast Discussion
National Weather Service Amarillo TX
1205 AM CDT Sun Sep 24 2017


For the 06Z TAFs:

Terminals will be in and out of MVFR for the next several hours
with possibly brief IFR conditions within the stronger storms.
Thunderstorms will linger around through the morning hours with
storms eventually pushing east away from the terminals. One worry
is possible redevelopment behind the current line of storms which
could lead to longer periods of MVFR conditions. Will assess this
later as the atmosphere works itself over with current convection.
Otherwise, wind speeds will be breezy throughout this TAF period.
Thunderstorms are possible later in the afternoon Sunday, but
decided to leave this out for now until we get a grip of how the
atmosphere will respond to current convection. Thunderstorms may
be added to subsequent TAFs either as routine or amendments.





.PREV DISCUSSION... /Issued 645 PM CDT Sat Sep 23 2017/

Large area of showers and thunderstorms over western part of
forecast area expected to spread east this evening and overnight.
Ceilings and visibilities will be highly variable as convective
elements more north northeast within the rain shield.  Southeast
surface winds around 20 kt expected to prevail overnight, with
variable and stronger gusts near thunderstorms.  MVFR ceilings
expected to eventually become prevalent by late tonight as lower
levels moisten from continued precipitation.  Return to VFR
conditions expected mid to late Sunday afternoon.


PREV DISCUSSION... /Issued 458 PM CDT Sat Sep 23 2017/

The main line of showers and thunderstorms has pushed into the
western Panhandles. Popcorn showers and thunderstorms have also
been streaming northward ahead of the line across the central and
eastern Panhandles. This area of storms will bring heavy to very
heavy rainfall chances to the area over the next several days and
will be discussed more below. As for the severe threat from any of
the storms, some storms may become strong to marginally severe,
however, with very meager CAPE, miniscule DCAPE, and shear
vectors only supportive of multicells to marginal supercells, feel
that the threat for severe wind or hail will be very hard to get.

The southwest flow aloft responsible for bringing the abundant
moisture to the area will continue through all of next week as
well. Right now there is an upper level trough in the western
CONUS that is digging south. The trough looks to lift and cross
the Rockies Monday which will push a surface front through the
area and drop high temps 10 to 15 degrees in some places from
Sunday to Monday.

As the upper level trough ejects into the northern Great Plains on
Tuesday, mid and long range models continue to trend that energy
will be left behind and form a closed low in the southwestern US.
This will continue to maintain southwest flow for our area and
allow Pacific moisture to flow in along with shortwaves. This will
keep clouds in place and chances for precip across the Panhandles
through the week. By week`s end, an upper level high builds into
the northern Pacific states, creating a Rex block. This will allow
the flow to change to zonal for us and let us finally dry out at
the end of the week.


Of the CAMs, the HRRR seems to have the best handle on timing of
the main wave of precip. All CAMs and and hi-res models indicate
the line will continue to move very slowly eastward with precip
training northward. Scattered popcorn showers continue to develop
and stream northward as well. PWATs remain near to above the 90th
percentile. This in conjunction with training storms leads to
concerns of flooding or flash flooding issues, and thus the
issuance and extension in area of the Flash Flood Watch on
previous shifts. Think this area is still valid and will need to
be watched for shifting the watch area eastward as the main
convective line progresses. Areas could receive 1 to 3 inches of
precip over the next few days with isolated higher amounts of up
to 5 inches for spots that see the popcorn showers in addition to
heavier training areas.



.AMA Watches/Warnings/Advisories...
TX...Flash Flood Watch through this afternoon for the following
     zones: Dallam...Deaf Smith...Hansford...Hartley...Moore...

OK...Flash Flood Watch through this afternoon for the following
     zones: Cimarron...Texas.



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