Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 130444
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1044 PM CST Thu Jan 12 2017

.AVIATION...
For the 06z TAFs...Only a few changes have been made to the forecast
of six hours ago.  Still expecting MVFR ceilings to arrive in AMA
around 07z, but have delayed onset at northern terminals to around
11z to 12z, owing to the drier near-term low-level trajectories.  Have
also kept AMA ceilings above 1000 feet with visibilities held to no
lower than six miles.  Mention of light freezing rain retained at
AMA from 14z to 21z Friday, and at DHT after 00z Saturday.  MVFR
conditions will prevail at all terminals during the day Friday and
through 06z Saturday.

Cockrell

&&

.PREV DISCUSSION... /Issued 808 PM CST Thu Jan 12 2017/

UPDATE...
Have issued update to graphical forecasts, lowering 1st period
temperatures by about 4 to 7 degrees Fahrenheit across the board.
Drier low-level air being drawn into forecast area via northeast and
east winds will have the potential to cool more rapidly than
previously anticipated, particularly across northern sections where
thinner cloud cover will radiate more effectively.  Dewpoints have
been lowered also.  No changes to later periods at this time.
Updated text products will be issued shortly.

Cockrell

PREV DISCUSSION... /Issued 553 PM CST Thu Jan 12 2017/

AVIATION...
For the 00z TAFs..Expect VFR flight conditions to prevail for at
least the next six hours, with easterly surface winds around 10 kt.
MVFR ceilings expected to develop around 07z Friday at AMA, and by
11z at northern terminals.  IFR ceilings in light freezing rain
expected to develop around 14z at AMA, with northern terminals
remaining MVFR through the day with precipitation being less likely.
Surface winds expected to remain at or below 10 kt during the day at
all terminals.

Cockrell

PREV DISCUSSION... /Issued 434 PM CST Thu Jan 12 2017/

DISCUSSION...
Tonight... Thanks to our early morning cold front we have a wide
range of temperatures across the Panhandles. The southwestern Texas
Panhandles has been able to warm into the lower 60s while the
eastern Oklahoma Panhandle hasn`t broken into the 40s yet. We will
see temperatures fall well below freezing across the area Tonight
while isentropic lift brings ample low level moisture into the
southeastern Panhandles. This lift could be enough to spark off some
patchy freezing drizzle/rain for the southeast just prior to 6 am.
Very little frozen accumulation is possible prior to 6 AM Friday.
There does remain a bit of uncertainty on the temperature profile
this early in the event so stay tuned for updates.

14

Friday through Monday Night...Isentropic lift in conjunction with
lift from the nearby upper level jet will allow for freezing drizzle
to start in the southeastern Texas Panhandle on Friday morning and
spread northwestward with a transition to freezing rain on Friday
afternoon through Friday night. As the mid level low gets closer to
the area, more large scale dynamics take over as vorticity advection
increases along with being placed in a more favorable jet entrance
region. This will allow precip rates to increase on Saturday. This
will also help the warm air aloft erode the cold air at the surface
and allow for areas to see more rain than freezing rain. By Sunday,
the low is just to the west of the Panhandles and isentropic lift
will be screaming on the 300K surface with 35 to 50 kts of winds.
With forecast atmospheric profiles showing the cold surface air
eroded away and slight instability in the area, there will be a
complete shift to rain, which will be moderate to heavy at times with
the possibility of thunder even. As the surface low swings over the
area Sunday night, northerly winds come into the Panhandles and a
transition to snow will take place as colder air settles in. This
will slowly drive away the moisture that was being brought in from
the south and cut off precip from south to north. By Monday
afternoon, precip will be entirely cut off and the Panhandles will
begin to recover as mid level heights rise and surface temps respond
accordingly. Models during this period were a bit more consistent.
The GFS has been overly warm with this system, so have discounted it
and have stuck with more of a blend of the Canadian, SREF, NAM, and
ECMWF which were more in line with each other.

Beat

Tuesday Through Next Thursday... Forecast models differ as to how
the upper pattern evolves on after the low moves off to the north
and east. Generally an upper trough will still be positioned over
the area Tuesday. This trough will be replaced with rising heights
Wednesday through thursday. This will help up gradually warm into
the mid to upper 50s. No additional precip is expected after Monday.

14

&&

.AMA Watches/Warnings/Advisories...
TX...Ice Storm Warning from 6 AM Friday to noon CST Sunday for the
     following zones: Hemphill...Lipscomb...Ochiltree...
     Roberts...Wheeler.

     Freezing Rain Advisory from 6 AM Friday to noon CST Sunday for
     the following zones: Armstrong...Carson...Collingsworth...
     Dallam...Donley...Gray...Hansford...Hartley...Hutchinson...
     Moore...Oldham...Potter...Randall...Sherman.

OK...Ice Storm Warning from 6 AM Friday to noon CST Sunday for the
     following zones: Beaver...Texas.

     Freezing Rain Advisory from 6 AM Friday to noon CST Sunday for
     the following zones: Cimarron.

&&

$$

03/15



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