Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 181732

Area Forecast Discussion
National Weather Service Amarillo TX
1232 PM CDT Wed Apr 18 2018

18Z Issuance...All sites expected to remain VFR. Northerly winds
should ease early this afternoon and drop below 10kts by around
00Z when they start turning easterly. Winds should be southerly by
16Z and will be around 15kts or so through late morning.



.PREV DISCUSSION... /Issued 536 AM CDT Wed Apr 18 2018/

12Z TAF Cycle

VFR conditions will prevail through 12Z Thursday at all three TAF
sites. North winds 15 to 25 knots with gusts to 30 knots at the
Amarillo TAF site and 10 to 20 knots at the Dalhart and Guymon TAF
sites will increase to around 20 to 30 knots with gusts to 35 and
40 knots between 14Z today and around 19Z to 22Z today. The winds
will become northeast to east and will decrease to around 5 to 10
knots after 22Z today and 00Z Thursday.


PREV DISCUSSION... /Issued 520 AM CDT Wed Apr 18 2018/

Progressive upper shortwave is now advancing through the
central/northern High Plains and towards to Midwest states. The
attendant cold front has quickly moved through the Panhandles
tonight and is now almost to the Permian Basin area. Winds have
subsided behind the front with 15-25 knot winds common as of
0900z. A fairly strong low level jet still resides over the
northeastern zones on the backside of the departing low. It won`t
take much time after sunrise to mix into the stronger winds at
around 850mb before the jet leaves the area. Moreover, expect
north winds to increase into the 20-30 knot range not too long
after sunrise but only lasting into the mid-afternoon as the low
level jet streak exits the area and the pressure gradient relaxes.
Temperatures will be in the 60s for most of the area with very
dry air continuing to filter in behind the front.

A transient upper ridge axis is progged to cross the area late
Wednesday into Thursday. Temperatures aren`t expected to be much
warmer Thursday as a surface high moves south keeping the cooler
airmass in place. A Frost Advisory might need to be considered
for mainly the northern zones Thursday morning given low temps in
the low to mid 30s and light winds. Return flow sets up later in
the day as the next system moves down out of the Pacific becoming
a closed 500mb low over southern Nevada by late Thursday. Surface
winds are expected to shift out of the south to southeast Thursday
afternoon and may become breezy at 15-25 knots especially in the
western zones near a developing surface trough. Guidance has
continued to shift precip chances west into central New Mexico on
Thursday evening as the movement of the upper low continues to
trend slower.

More pronounced warm air advection profiles start showing up late
Thursday and into Friday as a narrow axis of higher low level
theta-E finally start shifting east out of NM and into West
Texas. It is during this time that low clouds begin to show up as
the 800-700mb layer saturates per GFS model time-lagged Bufkit
profiles. The low clouds will keep high temperatures below
average Friday and Saturday (50s). The mid/upper Pacific moisture
doesn`t arrive until later in the day Friday (and this is still
trending later and later based on slower upper low). The delayed
cooling of the mid/upper levels will not be good for steep lapse
rates with a strong warm nose persisting until the better upper
dynamics arrive late Friday. Even then, instability looks marginal
with only 200-500 J/kg SBCAPE showing up briefly Friday evening.
Otherwise, there are some periods where some shallow layers of
elevated instability show up, and thus kept isolated mention of
thunder Friday through Saturday. Rain showers look to be common
across the area as a long duration of 500-300mb Q-vector
divergence overspread the low level warm advection during the day
Friday. Precip chances increase from west to east with all of the
Panhandles under likely or greater chances from Friday evening
through Saturday afternoon when chances begin shifting east and a
cold front shifts into the Panhandles. Most areas should receive
some measurable precip, with a quarter inch to one half inch being
common. Isolated amounts of an inch are certainly possible once
it`s all said and done Saturday night.

Dry conditions return Sunday with northwest flow aloft.
Temperatures gradually warm with near average temperatures
expected Sunday and Monday. Guidance has not been very consistent
beyond Monday with GFS bringing a fast moving shortwave and cold
front across the area Tuesday while the ECMWF shows a much weaker
wave and keeps the Panhandles mostly in northwest flow stalling a
front in the area with developing precip.


North winds will pick up into the 15-25 knot range during the
morning with 20 to 30 knots possible in the eastern zones. These
winds will gradually decrease through the day, becoming 10 to 15
in the afternoon. Min RH values will decrease into the 10-12
percent range this afternoon as very dry air moves in behind the
front. Even though the timing of lowest RH values may not sync
with the highest winds today, went ahead with a Red Flag Warning
for the eastern half of the outlook area based on the volatile
fuel conditions. ERC percentiles were measured above the 90s
percentile for almost all of the Panhandles yesterday. Elevated
conditions are expected in the western half of the area where
winds magnitudes should be lower.

Elevated conditions are possible during the afternoon Thursday
mainly in the western Panhandles where min RH values approach 20
percent with south winds of around 20 knots.



.AMA Watches/Warnings/Advisories...
TX...Red Flag Warning until 6 PM CDT this evening for the following
     zones: Armstrong...Carson...Collingsworth...Donley...Gray...

OK...Red Flag Warning until 6 PM CDT this evening for the following
     zones: Beaver...Texas.



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