Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 291616
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1116 AM CDT WED JUN 29 2016

.Update...The MCS that was moving across the combined Panhandles this
morning has dissipated, though redevelopment of isolated convection
may occur on the western periphery of the remnant cold pool aided by
an upper level shortwave trough. Elevated instability of 1000-1500
J/kg noted in the 12Z sounding this morning (noted between H7 & H2)
should become available this afternoon as daytime heating helps
destabilize the environment. There is some question as to how much
recovery will occur in eastern zones due to cold pool from last
night`s activity, but another shortwave trough approaching from the
northwest will aid in the development of a lee side low over
southeastern Colorado to southwestern Kansas. Southwesterly winds
should develop in response to this low, bringing drier air into the
southwestern combined Panhandles and increased isentropic lift along
a developing boundary in the northern portion of our CWA. Have
updated grids to account for the cold pool present over our eastern
CWA, and to account for potential convective environment this
afternoon and evening. Otherwise, the rest of the forecast remains on
track.

Bieda

&&

.Aviation...Previous Discussion...12z TAFs...Expect that morning
convection will continue moving south this morning, with likelihood
for a direct impact at the terminals being greatest during the
morning. Variable gusts up to 40 kt will be possible near the
stronger storms. Outflow boundary seen as a fine line on KAMA 88D
currently moving south at 30 kt toward KAMA, with northeast surface
winds expected for a couple of hours following it. Southwest surface
winds will then prevail this afternoon and overnight. Isolated
thunderstorms possible this afternoon and this evening.

Cockrell

&&

.Preliminary Point Temps/Pops...
Amarillo TX                88  67  94  67  92 /  50  10  30  30  20
Beaver OK                  91  69  93  66  86 /  60  30  50  60  40
Boise City OK              91  64  87  62  83 /  40  20  50  60  50
Borger TX                  93  70  95  68  92 /  70  20  40  40  20
Boys Ranch TX              92  68  95  67  93 /  30  10  30  30  20
Canyon TX                  90  66  96  67  94 /  40  10  20  20  20
Clarendon TX               87  67  94  69  93 /  50  20  20  20  20
Dalhart TX                 93  66  92  64  90 /  40  20  50  40  30
Guymon OK                  94  68  91  66  87 /  70  20  50  60  40
Hereford TX                92  66  97  66  94 /  20  10  20  20  20
Lipscomb TX                90  68  96  67  89 /  80  20  50  60  40
Pampa TX                   86  68  94  67  91 /  70  20  40  40  20
Shamrock TX                90  68  96  69  94 /  70  20  30  30  20
Wellington TX              92  69  96  71  97 /  50  20  20  20  20

&&

.Prev Discussion... /Issued 354 AM CDT WED JUN 29 2016/

Discussion...
Diurnal/terrain driven MCS activity will continue to periodically
move southeast within northwesterly flow aloft through Thursday. Some
notable synoptic scale changes occur at the end of the week through
the weekend that have implications for our weather and this will be
discussed further down.

The immediate concern is the mesoscale convective system moving into
the Oklahoma Panhandle from southwest Kansas. Driven by a well
developed cold pool in a sufficiently unstable environment (RAP
MUCAPE around 1,500 J/kg) storms should sustain through much of the
morning, probably moving along a weak low-level theta-e gradient
across the eastern Panhandles. Nocturnally stabilized low levels
should limit the wind threat although a few severe gusts have been
noted over southwest Kansas within the last couple of hours.

Today, the synoptic pattern is generally the same as yesterday with
the mid-upper high positioned slightly further east and weakening
some. These changes yield neutral tendencies in 500 mb heights
through the day over our area with some decrease by evening.
Convective development in our region will depend on how the ongoing
convective system over southwest Kansas and southeast Colorado
evolves with significant overturning possibly precluding afternoon
redevelopment. Residual outflow boundaries will largely determine
specifically where isolated convection may be most likely to develop
this afternoon, if any develop at all. Afternoon development may be
most likely along the western flank of residual MCS possibly further
west than our current forecast indicates. We will make adjustments as
needed but overall the most widespread rain today is anticipated this
morning in the Oklahoma and northeast Texas panhandles.

A strengthening lee low is indicated in all model guidance later
tonight just to our north in response to a weak shortwave trough in
phase with a stronger northern stream wave. This surface low
will elongate and become increasingly baroclinic by Thursday
morning. Increase surface convergence along this quasi-stationary
front, low level theta-e ridging, and subtle forcing for ascent from
passing minor shortwave is expected to result in a fairly high
probabilities for precipitation, particularly across the northern
portion of our area Thursday afternoon and evening. Preceding that
activity, initiation of convection this afternoon over the central
Rockies will probably lead to another MCS overnight that will move
across eastern Colorado and western/central Kansas possibly reaching
northern portions of our area late in the night or Thursday morning.
We have this covered with low chance probabilities for now, but may
need to make adjustments upward. This may augment synoptic boundary
and complicate the convective potential later in the afternoon, so
some changes to timing and probabilities may be needed between now
and then.

We have attempted to highlight when the best chance for precipitation
will be late this week into the weekend during what is expected to be
the more active period. Thursday night through Saturday we will be
on the northern edge of the ridge with mid level flow being more
westerly. The aforementioned front will probably be over the area
through that period although it becomes more diffuse with time.
Periodic convective systems that originate in the mountainous terrain
to the west may impact the area each evening/overnight, although
timing is complicated on Saturday by a shortwave trough that develops
and moves toward the area. This may cause greatest convective
coverage to be earlier in the day mostly moving east by evening. For
now, have stayed consistent with the forecast and kept probabilities
highest during the evening (terrain/diurnally driven convective
system moving east over the area again) given uncertainty in timing
of this shortwave in the model guidance.

Medium range guidance shows that the strongest westerlies will be
north of the area Sunday through Monday with generally weak flow
aloft over our area. Small perturbations in the flow necessitate at
least low probabilities though.

BRB

&&

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

&&

$$

11/98


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