Special Weather Statement, NWS Amarillo, TX

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
620 PM CDT Fri May 14 2021

.AVIATION...
Thunderstorms are expected to affect all TAF sites this evening.
But storms should move east of the sites by midnight. Winds will
be strong and gusty near the storms and there may also be some
hail near the AMA TAF site. Southerly winds will prevail around 15
knots later this evening behind the storms. Southerly winds will
then start to get gusty by mid to late morning on Saturday.

&&

.PREV DISCUSSION... /Issued 229 PM CDT Fri May 14 2021/

SHORT TERM...through Tomorrow Night...

Looking at the current observations: With the exception of some
late morning convection now exiting the SE TX Panhandle, the
remainder of the Panhandles is under mostly clear skies, minus
some high cirrus moving into the Panhandles; from the NM high
terrain where showers and storms developing and cirrus is moving
SE in the mean H500 20-30 kt flow. Meanwhile, Td values well into
the 50s has moved in across all of the Panhandles under a
southerly and southeasterly surface flow. With the main surface
low/trough off to the west in northern New Mexico, this has
allowed southerly surface flow to be more established. 18Z KAMA
special sounding also shows very good mid level lapse rates over 9
deg C/km with large hail in play. However, we still have a large
cap in place where temperatures well into the 80s will be needed
to likely break the cap.

Latest hi-res guidance does erode the cap slowly, and with high
temperatures well into the 80s, convective temperatures should be
reached. However, although some shear is present, shear magnitude
is rather weak. Will monitor surface trough progression and any
H500 perturbations around the base of the main UL well to the west
closely. Especially a mid level perturbation, should be enough to
generate convection across the Panhandles and continues its
track into the central and perhaps the eastern Panhandles. Latest
hodographs from hi-res model data also show rather weak sub anvil
steering flow under 20 kts, which as a result would mean any
transient supercell and or multi cluster that develops over the
western Panhandles in particular may have a brief meso with large
hail and initial damaging downburst winds before cells cluster
along a line and move east throughout the evening hours. Effective
shear is also limited to around 20-30 kts this afternoon.
Although directional shear is present, the low scalar quantity
should limit the longevity of lone supercell characteristics to a
brief window this afternoon. MLCAPE of 1500-2500 J/KG should
support large hail in supercell development up to golf ball size
(1.75"). As we approach the evening hours, storm mode will become
more linear as storms moves east across the central and portions
of the eastern Panhandles with straight line damaging winds will
be the main threat, with some hail size perhaps up to quarter size
(1.00") still possible. Thunderstorm coverage will wane going
into tonight, but any residual surface boundary in a tamed shear
environment, similar to this morning may generate some additional
sub-severe morning convection, especially with continued surface
southerly flow into the Panhandles.

Starting mid morning tomorrow morning, with the exception of some
sub severe convection, similar set up will be in place in terms
of moisture return, limited shear, and pseudo dryline helping to
develop convection to the west across eastern New Mexico. The
other factor will be watching is a quasi-stationary front
positioned very close to the OK/KS border tomorrow afternoon. This
could be a focal point to watch along with the convection
development to the west where another broad area of lift is
expected. Although like today, shear is limited tomorrow, more
initial transient supercell development will be possible once
again across eastern New Mexico and across the northeastern
Panhandles closest to the front and perhaps aided by a cold pool
progression from the southwest into the NE Panhandles for other
decaying storms. Similar to today, storm mode overall once again
for tomorrow will be transient supercell to multi-cluster line
with large hail up to golf ball size and 60-70 MPH wind gusts. A
non-zero tornado chance may also exist, especially along and just
south of the stalled front where the most defined directional
shear is located, although limited scalar quantity, initial
updrafts in a more lone environment cannot completely rule out
this chance.

Temperatures today and tomorrow will still top out in the low to
mid 80s across the Panhandles.

Meccariello

LONG TERM...Sunday through Thursday Night...
Upper level trough will continue to dive south over the Las Vegas
area on Sunday and slowly track east towards the Panhandles over the
next 48 to 72 hours.  Several perturbations embedded in the westerly
flow will help aid in the lift for continued thunderstorms each day.
Given the continued return flow and higher dewpoints, ML CAPE values
each day look to range from 1000-2000 J/kg on Sunday and Monday.  So
strong to severe storms look favorable on both Sunday and Monday.
Weak surface cold front expected Sunday night and could help aid in
some of the lift for strong to severe storms.  Front may stall over
the Panhandles and hold an area of surface convergence right over
the southern Panhandles during the day Monday.  High CAPE values
around 2000 J/kg will be possible right along this area of
convergence.  So severe storms certainly look possible.

By Tuesday the upper level trough will take a bit of a negative tilt
and really enhance the low level flow over the Panhandles.  There is
some model divergence as to the placement of this upper level
trough. That being said, another round of showers and storms, likely
strong to severe, are expected again on Tuesday.  Wednesday is when
the upper level low finally tracks over and lifts to the northeast.
Showers and thunderstorms will again be possible, however it looks
like a much lower threat for strong to severe storms as highs could
be on the cool side.  Models are not in total agreement as to how
Wednesday will pan out, with some suggesting an open wave exiting to
the northeast, likely a drier solution, and others suggesting the
closed low lingers over the Panhandles.  The closed low solution
would suggest highs only in the 60s and a lot more moisture.

After this system exits, flow will return out of the southwest and
there could be rich low level moisture advection over the Panhandles
with much warmer temperatures returning.  Embedded shortwave will
possibly move over the Panhandle on Thursday aiding in additional
lift needed to get some thunderstorms.  Right now vertical profiles
do not look to exciting, however ML CAPE values could approach 2000
J/kg, so can't rule out severe storms, they just may not be very
organized.

Weber

&&

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

&&

15/15

Hazardous Weather Outlook
National Weather Service Amarillo TX
226 PM CDT Fri May 14 2021

OKZ001>003-TXZ001>020-317-151100-
Cimarron-Texas-Beaver-Dallam-Sherman-Hansford-Ochiltree-Lipscomb-
Hartley-Moore-Hutchinson-Roberts-Hemphill-Oldham-Potter-Carson-
Gray-Wheeler-Deaf Smith-Randall-Armstrong-Donley-Collingsworth-
Palo Duro Canyon-
226 PM CDT Fri May 14 2021

This Hazardous Weather Outlook is for the Texas and Oklahoma
Panhandles.

.DAY ONE...This Afternoon and Tonight.

Thunderstorms are possible across the combined Texas and Oklahoma
Panhandles this afternoon through this evening. Some storms could
be strong to severe, with large hail and damaging winds being the
main threat.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Thunderstorms may develop across portions of the Texas and
Oklahoma Panhandles Saturday through Thursday. Thunderstorms may
reach severe levels, especially on Saturday and Sunday. Large hail
and damaging winds are the mains threats.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may become necessary this afternoon through at
least Monday.

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