Area Forecast Discussion
Issued by NWS Amarillo, TX

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371
FXUS64 KAMA 201141
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
641 AM CDT Thu Apr 20 2017

.AVIATION...12Z TAFS...

For the most part VFR conditions can be expected at all three TAF
sites through 06Z Friday with mainly clear skies. With the cold
front passage, winds have shifted out of the north in the 25 knots
range with gusts to near 35 knots until around 17Z to 22Z. Then
speeds will diminish to around 10 to 15 knots as winds become
northeast to east. Northeast to east winds can be expected at the
Amarillo TAF site 20Z to 23Z at 10 to 15 kts. MVFR to IFR with a
slight chance of LIFR conditions at KAMA and KGUY after 09Z.

Weber

&&

.PREV DISCUSSION... /Issued 414 AM CDT Thu Apr 20 2017/

DISCUSSION...
Our overnight cold front will keep our high temperatures today
near 20 degrees cooler compared to yesterday. We also expect winds
to be in the breezy category out of the north around 20 to 25 mph
in the morning before decreasing throughout the day. Overall, it
will be a fairly nice day across the Panhandles with highs in the
upper 60s to mid 70s.

This evening, a shortwave is expected to move across the southern
Rockies to give us chances for precipitation across the
Panhandles. Forecast models show convection initiating along the
stalled cold front south of the Panhandles as early as 21Z before
increasing in coverage across the Panhandles. Our highest chances
for convection are anticipated to be between 9Z to 21Z Friday, and
across the eastern zones. There is a possibility for strong to
marginally severe storms overnight as far west as a Vega to Boise
City line with the highest chances for marginally severe storms
mainly over the off-Caprock counties. For any storm that does
become strong to marginally severe, the primary hazard would be
hail up to the size of quarters. Convection will start to clear
the area from west to east midday to Friday afternoon.

Now there are some factors which could limit the strong/severe
potential in areal coverage (containing it primarily to off-
Caprock counties). The first is the the location of the cold
front. Hi-res forecast models place the front much further south
than medium range models. This could reduce the isentropic forcing
needed for storms to overcome the cap further west/on the
Caprock. The next will be the synoptic vs. thermodynamic
environment towards sunrise. Forecast soundings show MUCAPE on the
Caprock maximizing between 9Z to 12z however, the synoptic
pattern during that time frame is not very conducive to storm
development; much less strengthening. During this timeframe, the
shortwave trough axis would be over the eastern portions of the
Panhandles, if not into Oklahoma, and we would be under the right
exit region of the upper jet. If these factors come to fruition,
then our strong/marginally severe potential would be very limited
across the Panhandles.

One other item of note is the recent trend in the CAMs showing
less development along the stalled frontal boundary and greater
convective development over the northeast New Mexico Plains. This
trend will need to be monitored as it could flip the area of
concern for strong storms overnight.

Once storms exit the area, we will see another cold front drop
across the Panhandles Friday evening. There does appear to be
some concern for increased wind speeds directly behind the cold
front. We could see the influence of a barrier jet to increase the
progression of the western portion of the cold front. This would
also bring the potential for greater winds gusts directly behind
the cold front. This would likely be a very temporary increase in
wind speeds as the pressure gradient slackens quickly behind the
front. The question of wind headlines will likely be determined by
the expected duration of the increased winds.

A fairly cool Saturday is expected with high temperatures
struggling to reach the mid 60s. With winds becoming light and
clear skies overnight, we could be looking at a late season frost
across the Oklahoma and northern Texas Panhandles. This frost
potential would only be for Saturday night/Sunday morning as we
start to modify the post frontal airmass.

Naturally, after talking about frost potential you talk about fire
weather potential. Warm air advection and the return of strong
southwest winds Monday, could easily cause our high temperatures
to reach into the 80s with the 90 degree mark not being out of
the question for some spots. Similar conditions are expected on
Tuesday however, another cold front is expected to push into the
Panhandles Tuesday night to help cool things down a little bit.

FIRE WEATHER...
A brief window for elevated fire weather conditions exist for the
southwestern Texas Panhandle Friday afternoon. Now the impact of
these elevated fire weather conditions could be greatly mitigated
if that area gets any rain Tonight/Friday morning. Better chances
for and areal coverage of elevated fire weather conditions are
expected early next week. The 850mb thermal ridge is expected to
be positioned over the Panhandles both Monday and Tuesday which
could push our afternoon high temperatures 10 to 15 degrees above
normal. with strong southwest to west winds both days we could see
elevated fire weather conditions both days.

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                72  52  72  41  61 /   5  50  20   5   0
Beaver OK                  73  50  53  40  61 /   5  60  60  30   5
Boise City OK              68  47  60  38  59 /   5  40  40  10   5
Borger TX                  74  53  70  42  63 /   5  60  30  10   0
Boys Ranch TX              74  52  73  41  63 /   5  40  20   5   0
Canyon TX                  72  53  75  41  62 /  10  40  10   5   0
Clarendon TX               72  54  75  43  63 /  10  50  20   5   0
Dalhart TX                 71  48  67  39  60 /   5  40  20  10   0
Guymon OK                  72  49  58  40  61 /   5  50  50  20   5
Hereford TX                73  52  76  40  63 /  10  30  10   5   0
Lipscomb TX                73  52  60  42  61 /   5  70  50  20   5
Pampa TX                   72  51  69  40  60 /   5  60  30  10   0
Shamrock TX                73  55  73  44  63 /  10  70  40  10   5
Wellington TX              73  57  77  45  65 /  10  60  30  10   0

&&

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

&&

$$

89/14



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