Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 192332 AAA
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
632 PM CDT Sat Aug 19 2017

.AVIATION...
For the 00Z TAFs, isold to sct showers and tstms over northeast
New Mexico may make some headway into the northwest parts of our
fcst area early this evening before dissipating. Have decided to
leave tstms out of the KGUY and KDHT TAFs due to uncertainty in
how much eastward progress these showers and tstms will make into
our area before falling apart. Will monitor radar trends closely
this evening. Isold showers and tstms may develop again late
Sunday afternoon across parts of the fcst area. However,
confidence is low with respect to where or if this will occur,
which precludes mentioning in the TAFs at this time.

Andrade

&&

.PREV DISCUSSION... /Issued 418 PM CDT Sat Aug 19 2017/

DISCUSSION...
Current upper level analysis reveals high pressure centered over
south Texas helping to shift some monsoonal moisture into the far
western Panhandles. A subtle shortwave rounding the high pressure
has helped initiate a few showers and thunderstorms over the
higher elevations of NM/CO. These may push into the northwestern
zones later this afternoon and evening but should loose steam near
the north-central zones as they encounter some dry air around
600mb-300mb noted on the 12z AMA sounding. This dry air is being
modified some around Guymon and Dalhart due to the monsoonal flow,
so keeping pops through the evening for those areas. Otherwise, a
CU field is noted in the east-central Texas Panhandle due to
diurnal heating. The HRRR has tried to initiated a storm in this
region but it will be difficult given the previously mentioned dry
mid- level air. There is plenty of instability and some low level
theta-E advection, so some very isolated convective initiation is
not out of the question through early evening as temperatures
peak around 90-95 degrees. Some storms could be on the strong
side mainly as a wind threat given steep low level lapse rates
with very marginal 10-20 knots of deep layer shear.

Going Sunday into Monday, the upper level high pressure shifts
eastwards and elongates over the southeastern CONUS while an upper
level cutoff closed low forms and beings spinning off the coast of
southern California. This will lead to more southwesterly flow
over the Panhandles. In addition, a shortwave is progged to move
through the southwest flow late Sunday into Monday. Prior to this,
conditions on Sunday should be mostly dry with mid and upper level
clouds with highs again around average. However, as the upper
shortwave approaches late Sunday, clouds will increase as will
precipitation chances. At this time, models are keeping most of
the influence of this wave across the northwestern half of the
combined Panhandles as an area of showers and thunderstorms
move out of New Mexico and into the western Panhandles late Sunday
into early Monday, and then move east-northeast across the rest of
the area through the day Monday into Monday night. This will lead
to some major challenges for those hoping to see the partial
eclipse across the Panhandles Monday afternoon as most of the area
will see at least mostly cloudy conditions. For now, it looks
like folks in the southeastern Texas Panhandle stand the best
chance of getting to see the eclipse, but if the shortwave tracks
further south that could easily change.

On Tuesday, a "cold" front is expected to move in behind the main
shortwave. This will bring additional chances for showers and
thunderstorms depending on the timing of the front and how much
the atmosphere can recover behind the shortwave. For now the
southern and eastern zones seem to be the most likely to see
precip along the front where mid level moisture is increased.
Temperatures should drop below average behind the front, with most
of the Panhandles in the 80s for highs on Wednesday.

Models suggest the return of northwest flow towards the end of
next week as high pressure builds over the southern Rockies with
a warming trend back to around average. Showers and thunderstorms
should become more nocturnal as they move off the higher terrain
in response to shortwaves moving through the northwest flow. This
will also lead to a better chance for some strong to severe storms
as deep layer directional shear increases in combination with
steep lapse rates and plenty of moisture and buoyancy.

Ward

AVIATION...18Z TAFS...
VFR conditions are expected to prevail over the next 24 hours.
Thunderstorm chances look very dim at this point. If storms should
develop they will likely be west of KGUY and northwest of KDHT
and should stay out of the 10 mile range for VCTS. Thusly, if
things should change will defer to TAF amendments should
conditions become more favorable. Winds will generally be out of
the south 5 to 15 kts.

Weber

&&

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

&&

$$



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