195
FXUS64 KAMA 012139
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
439 PM CDT Wed May 1 2024

...New SHORT TERM, LONG TERM...

.MESOSCALE UPDATE FOR THE SEVERE THUNDERSTORM POTENTIAL THIS
AFTERNOON AND EVENING...Issued at 126 PM CDT Wed May 1 2024

We are watching the potential for severe storms to fire up in the
far eastern Panhandles later this afternoon and evening. An
elongated upper level trough at 500 mb is moving east off of the
Rocky Mountain range today and will promote storms to form along a
surface dryline as the height gradient tightens and upper level
vorticity increases. Near term mesoscale features will be
paramount to determine if storms will be able form in the CWA
today, where they will be, and what hazards could be present.

11 AM and onward, mesoscale parameters...

A weak surface boundary has moved through the northwest Panhandles
and will diminish it`s flow by the afternoon. A NE/SW dryline is
setting up with the sharpest gradient expected to develop by 4 PM
east of Amarillo, perhaps between the eastern half of the CWA and
the eastern two stacks of counties, (Beaver to Donley and
eastward). Current CAM guidance suggest that the cap will be
broken today and storms will generate along the dryline around the
4 PM hour. Some contingencies are still active, as low level
cloud coverage is still present in the eastern two stacks. A large
scale outflow boundary has also been detected moving west across
western Oklahoma from overnight convection in that area on the
previous day. These conditions may allow stable air to settle into
the setup area which may prevent storms from becoming severe or
even stop any storm from forming. Short term model guidance still
shows clouds clearing between 1 and 2 PM, (according to the latest
15Z and 16Z guidance). Satellite imagery also shows some areas of
clearing, but the process seems slow, and overcast conditions
remain in effect for most portions of the far east. CAM guidance
also has a history of not handling these outflow boundaries very
well, since it`s a smaller mesoscale feature that can be difficult
to forecast. Nevertheless, Satellite imagery and surface
observations hint at the boundary progression weakening and
slowing down. If this outcome of clearing skies and a dispersing
outflow boundary come to fruition, then storms have a better
chance to meet convective temperatures and break the cap this
afternoon. Otherwise, if any of the two preventatives pan out,
(cloud coverage lingers or stable air moves in), then expect
minimal chances for any storm to reach severe limits. Currently,
the CAMs and other near term models have no issues convecting
today. However, there are still small discrepancies concerning
coverage and potential severity.

Environment and hazards...

Concerning the threat area today in the eastern Panhandles, SBCAPE
and MUCAPE should reach values around 3,000 J/kg, with an area of
even higher values >3,500 J/kg in the southeast Texas Panhandle.
Strong lapse rates should be approaching 8 C/km, and effective bulk
shear could range between 30 - 40 kts. Continuing from the
surface and viewing upward with height, backed surface winds from
the southeast will veer well with height creating curved but not
very long or robust hodographs. LCLs will be lower in the
southeast Texas Panhandle compared to places further north.
Perhaps looking at values to range between 1,000 - 2,000 m
overall. FZL levels will reach around 11,000 ft for the area and
-20C levels should only be about 10,000 ft higher. Despite
 relatively modest bulk shear vectors, based off of the other
 parameters mentioned very large hail is possible with any storm
 that can become severe. Hail up to the size of teacups (3.00 in)
 is possible. Impressive DCAPE values may also be present between
 1,000 - 1,500 J/kg. Given this, strong outflow winds will be
 possible even up to 70 mph. Low level wind shear and 0- 1 km SRH
 are not overly impressive, but the low level jet should kick in
 by the evening hours as shown by model forecast 850 mb winds. By
 then, LLWS parameters will increase providing a short window for
 a tornado threat. Any discrete storm that can sustain itself
 through the evening hours will have that capability, though the
 threat is not high considering the parameters will marginally
 hit the criteria. Thunderstorms will initiate in an isolated
 manner, and a discrete storm mode is expected until the late
 evening. Afterwards, storms in the southeast Texas Panhandle
 should congeal into a multicellular cluster by the nightfall.
 Areas under these storm cells can anticipate heavy rainfall, as
 overall storm motion should be slower today given the steady and
 leisurely progression of the dryline as it moves east during the
 day and then retreats west during the nighttime hours.

Rangel

&&

.SHORT TERM...
(This evening through Thursday night)
Issued at 410 PM CDT Wed May 1 2024

For the rest of this afternoon and tonight, refer to the above mesoscale
update discussion for detailed information. Pops in the grids for tonight
reflect the reasoning outlined in the mesoscale discussion.

Semi-zonal to west southwest upper level flow is expected for Thursday
and Thursday night. A very minor shortwave trof embedded in this flow
is progged to zip eastward across the region during this time period,
and could bring a few showers and thunderstorms to parts of the eastern
OK and eastern TX Panhandles Thursday afternoon and night. NBM slight
chance pops look reasonable and were accepted.

02

&&

.LONG TERM...
(Friday through next Tuesday)
Issued at 410 PM CDT Wed May 1 2024

For Friday through Sunday afternoon, a few minor upper level shortwave
trofs embedded in the overall mean flow are forecast to move across
the region and will bring a threat for showers and thunderstorms
during this time frame. Based on the predicted track of these
minor features, the southern Texas Panhandle may have the best
chance of receiving precipitation, while the far northwestern
zones may have the lowest chance. NBM pops reflect the above
scenario and were utilized in the appropriate grids for Friday
through Sunday.

A much stronger upper level low pressure system is then slated to move
across the central and northern Rockies and adjacent plains Monday
into Tuesday. This suggested path offered by medium range models
would prove to be more of a dry, windy, and warm scenario for our
forecast area. Medium range models and associated ensemble members
are in reasonable agreement with that idea and were accepted. That
said, warmer temperatures along with breezy to windy conditions and
dry weather are in the offing for Monday and Tuesday.

02

&&

.AVIATION...
(18Z TAFS)
Issued at 1243 PM CDT Wed May 1 2024

For the 18Z TAFs, any thunderstorms that develop later this
afternoon and evening should remain east of the terminal sites at
this time based on the latest numerical model guidance. A cold
front will move through the region late tonight and Thursday
morning with gusty north winds in its wake. Some concern exists
for MVFR cloud development in the post frontal airmass, with KGUY
the most likely location to see this occur, and have added a low
end MVFR cig early Thursday morning. Did include a sct MVFR deck
of clouds at KDHT and KAMA where confidence is lower at this time.

02

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                53  76  51  73 /  20   0  10  30
Beaver OK                  51  75  46  77 /  30  10  10  30
Boise City OK              46  72  44  73 /  10  10  10  30
Borger TX                  55  80  51  77 /  20  10  20  30
Boys Ranch TX              52  78  50  77 /  10   0  10  30
Canyon TX                  52  77  51  74 /  20   0  10  20
Clarendon TX               56  77  53  72 /  50  10  20  30
Dalhart TX                 46  74  44  73 /  10  10  10  30
Guymon OK                  48  74  45  75 /  10  10  10  30
Hereford TX                51  78  51  75 /  10   0  10  20
Lipscomb TX                55  76  50  76 /  30  20  20  30
Pampa TX                   53  76  51  72 /  20  10  20  30
Shamrock TX                57  76  53  73 /  60  20  20  30
Wellington TX              58  79  54  73 /  70  10  20  30

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Red Flag Warning until 9 PM CDT this evening for TXZ001-002-006-
     007-011-012-016.

OK...Red Flag Warning until 9 PM CDT this evening for OKZ001.

&&

$$

SHORT TERM...02
LONG TERM....02
AVIATION...02