Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 281849
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
149 PM CDT THU JUL 28 2016

.MESOSCALE UPDATE...
Northwesterly flow around the east-northeast side of an upper level
598 decameter high pressure system centered near northwest Arizona
will be the main steering synoptic setup of convection over portions
of our region today. Current synoptic set up and surface observations
shows a complex of showers and thunderstorms moving
southeast across the central high plains upstream of our region in
the northwesterly flow across western KS and western NE. This
thunderstorm complex and its outflow boundaries could be the set up
for our convection over the OK Panhandle and far northeastern TX
Panhandle later this evening into the overnight period.

Synoptic: In-conjunction with the previous mentioned current set up
across the central plains, other brief synoptic mentions include
H500 temperatures upstream that are in the -8C to -11C range across
western KS and eastern CO to further enhance mid level ascent. As we
go between 21Z and 00Z, latest Hi-Res RAP and operational HRRR model
indicate a lee low development across SE CO to further enhance wind
shear and that may produce a supercell or two out ahead of the main
convection across SW KS that may move into the OK Panhandle. Although
directional shear is present with H850 S-SE flow and H700 S-SW flow,
magnitude is weak, as our region is south of the main 500-250 hPa
WNW-ESE steering flow. The mean upper level flow will also dictate
whether the far eastern Panhandles get little or no convection from
this event. The current 0-6 KM shear also shows below 30 kts across
most of the CWA. However, ahead of the main MCS that will move across
KS later this evening, mid level shear could pick up after 00Z
across the OK Panhandle.

Thermodynamics: SBCAPE currently between 500-1000 J/Kg with small
region of CIN is expected to erode as we go well into the mid afternoon
and evening hours. Surface Td are into the lower 60s currently across
portions of the OK Panhandle and all across the eastern TX Panhandle
with mid to upper 50s elsewhere. This will elevate SBCAPE and MUCAPE
to around 1500 J/Kg with perhaps even as high as 2000 J/Kg across the
far eastern Panhandles by late this afternoon as our region is under
mostly clear skies with latest visible satellite already showing some
popping Cu in the far eastern Panhandles.

Evolution/Impacts: This event can be categorized as a moderate to
high CAPE/low shear set up across the Panhandles. The better shear
for this event should stay confined further to the north across
western Kansas and easter Colorado as they are near the main upper
level features. Latest RAP/NAM/GFS forecast soundings across
northeast TX Panhandle and OK Panhandle illustrate weak 700-500 hPa
flow. However, inverted V-soundings do show strong to severe wind
gusts possible as we go past 00Z initialized by the main outflow
boundary and developing MCS well after 00Z across KS moving SE into
our far northeastern Panhandles. The expected timing of this event
includes a supercell or two possibly first developing across the
southward moving outflow boundary from the main weak convection
just before 00Z along the localized wind shift boundary. Large hail
and damaging winds will be the main threat with these supercells.
Once we lose daytime heating and the main MCS complex across NW KS
then develops near the 500 hPa shortwave trough, this will be the
main focus of convection as it moves SE. Where the upper level high
sets up is key for direction of movement. At this time, the highest
probability of damaging winds along the MCS complex will be across
the far eastern OK Panhandle and far NE TX Panhandle well after 00z
Friday.

Overall...Earlier on in the mid afternoon, possible supercell
development that moves into the central Ok Panhandle may produce
damaging winds and large hail along the southward moving outflow
boundary. The main wx threat still is damaging winds late Thursday
early Friday time frame across the far eastern OK Panhandle and far
NE TX Panhandle with the main MCS complex. There is still a chance
that the MCS complex may miss our area altogether but confidence of
a complete miss to our area is low at this time.

Meccariello

&&

.AVIATION...
VFR conditions are expected at all TAF sites throughout most of the
18Z TAF period. The only exception would be at KGUY where MVFR
conditions at times can occur if convection moves over the TAF site.
The highest chance of showers and thunderstorms near KGUY will be
between 03Z and 07Z Friday where MVFR conditions may occur.
Otherwise, as we go past 12Z, with the exception of some leftover
cloud cover from the convection, especially across KGUY/KDHT, VFR
conditions will return to all TAF sites for the remainder of the
forecast period.

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                70  93  68  96  70 /  20  20  20  20  20
Beaver OK                  67  87  67  94  70 /  60  20  30  20  20
Boise City OK              63  86  62  95  66 /  20  20  30  20  20
Borger TX                  72  93  70  98  73 /  30  20  30  20  20
Boys Ranch TX              71  93  67  99  70 /  10  20  30  20  20
Canyon TX                  69  94  66  96  68 /  10  20  30  20  20
Clarendon TX               69  94  69  97  71 /  20  20  20  20  10
Dalhart TX                 67  91  65  98  66 /  20  20  30  20  20
Guymon OK                  67  90  66  98  69 /  30  20  30  20  10
Hereford TX                69  94  67  97  68 /   5  20  30  20  20
Lipscomb TX                69  89  68  95  71 /  60  20  30  20  20
Pampa TX                   68  91  68  96  70 /  30  20  30  20  10
Shamrock TX                69  94  69  96  71 /  40  30  30  20  20
Wellington TX              71  94  71  98  72 /  30  30  30  20  10

&&

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

&&

$$

29/2



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