Area Forecast Discussion
Issued by NWS Amarillo, TX

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057
FXUS64 KAMA 191124 AAA
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
624 AM CDT Wed Jul 19 2017

.AVIATION...
For the 12Z TAFs, VFR conditions will prevail at the terminal
sites through 12Z Thursday.

Andrade

&&

.PREV DISCUSSION... /Issued 405 AM CDT Wed Jul 19 2017/

DISCUSSION...
The rest of the work week looks hot and dry as high pressure aloft
settles over the southern Plains. This area of high pressure is
much better defined in the latest water vapor imagery with broad
anti-cyclonic flow noted. Subsidence will be on the stronger side
today, and should prevent any rogue storms from developing. Model
guidance also suggest high temperatures will be around 8-10
degrees above average with 850mb temperatures progged around 27-30
deg C. Weak downslope winds will also help boost temperatures a
bit, so went a few degrees above guidance as it has not handled
the high temperatures well as of late. Also nudged towards the
warmer guidance for overnight lows as a moderate low level jet
should help prevent maximum decoupling.

Not a lot more can be said for Thursday and Friday except that it
should be slightly warmer each day as a more robust lee trough
develops leading to slightly stronger downslope flow /
compressional heating. Will be approaching heat advisory criteria
in some places such as the PDC floor each of those days.

Going into Saturday, the upper level high pressure center starts
shifting eastward some as a shortwave trough develops in the zonal
flow across the northern Plains. This shortwave trough is expected
to stay well north of the area as it moves into the Great Lakes /
Ohio Valley region. However, as the high pressure shifts eastward,
streamlines are expected to become more favorable for some
increase in mid level moisture. Unfortunately, models have had
inconsistencies with the GFS now the drier model through the
extended period and the ECMWF/Canadian bringing multiple days of
precip mainly Sunday through Wednesday. These wet solutions are
characterized by much better sfc-500mb moisture and cooler
temperatures compared to the latest 19/00z GFS. The forcing
mechanism for any convection is not real clear at this time. The
models do show an approaching back door front associated with the
OH Valley shortwave with some upslope flow ahead of the front, but
will have to see if this materializes. Earlier guidance also
showed a subtle wave crossing the Rockies Sat- Sun, but this is
not as evident is the latest model runs (especially the GFS). For
now, kept broad brushed chance pops starting Sunday into early
next week along with at least slightly cooler temperatures.

Ward

&&

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

&&

$$



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