NWS Amarillo, TX wrote its last area forecast discussion before the first event at Oct 26, 4:26 PM CST, 39 minutes earlier.
Area forecast discussion, Oct 26, 4:26 PM CST, 39 minutes before
Area Forecast Discussion
National Weather Service Amarillo TX
526 PM CDT Tue Oct 26 2021
.MESOSCALE UPDATE...
...Severe weather possible late this afternoon and this evening...
* Synoptic Overview: 22z WV satellite shows a highly amplified
pattern across the CONUS with strong troughs over the Delmarva and
just off to our west over CO. At the surface, strong lee cyclone
has developed in E CO. Latest surface observations and fine scale
radar signatures suggest an attendant dryline is currently located
along a Liberal-Perryton-Miami-Memphis axis and a Pacific front is
beginning to push eastward through E NM. Upper 50s and low to mid
60s dewpoint are present east of the dryline in the far eastern
Panhandles and southwestern Oklahoma, with moisture continuing to
be advected north-northwestward this afternoon.
* Mesoscale: Given the amplified pattern, strong winds aloft should
continue to mix down to the surface across the western two thirds
of the Panhandles, with the dryline continuing to mix eastward
accordingly. As the surface cyclone continues to deepen, south-
southeasterly winds east of the dryline should continue to pull
rich moisture north-northwestward, resulting in a sharpening
dryline as it approaches the far eastern Panhandles. Given their
proximity to the surface cyclone and the fact that these areas
have a bit more easterly component to their winds currently, the
northeastern Panhandles should remain in the moist sector for a
bit longer than areas farther south. While early convective
initiation may occur given the presence of a few cumulus, most
favorable time for thunderstorm generation will be around 00z,
when a pair of lead upper disturbances, whose presence is
currently suggested by subtle perturbations seen in WV satellite
and in clear air radar signatures, approach the dryline. All that
being said, a stout EML, as measured by our 12z RAOB and WV
satellite channels, may keep a lid on convection altogether.
* Threats: Deep layer shear is oriented somewhat off the dryline, so
while initial discrete development is possible, quick upscale
growth to a linear mode is likely. Additionally, progged
hodographs have trended toward a straighter orientation, so any
initial supercells may split, increasing confidence that quick
upscale growth will occur. All that being said, significant
veering in the low levels is seen, which should be locally
enhanced as surface winds back as the dryline sharpens. Thus,
hazard assessment is as follows: 1) Large hail up to golf ball
size. While this is limited by modest MLCAPE values, mid-level
lapse rates around 9 C/km and 0-6km bulk shear greater than 50
knots should allow for both rotating storms and robust hail
growth. 2) Damaging wind gusts up to 70 mph. Those steep mid-level
lapse rates suggest a strong EML with very dry air in the
midlevels. DCAPE values are accordingly 1500 J/kg or greater in
the eastern Panhandles. 3) An isolated tornado or two. While the
window with a tornado risk will be short following convective
initiation due to upscale growth, surface to 500m helicity values
look to increase to over 100 m2/s2 as sunset approaches, so any
rotating storms would be capable of generating a tornado.
* Timing & Location: Around 6pm through around 9pm in the far
eastern Panhandles, generally from Beaver County southward to
Collingsworth County.
* Summary: While the chance for thunderstorm development is
relatively low, a brief window for potential severe
thunderstorms will exist late Tuesday afternoon and early
evening. Should storms develop, all severe hazards are possible,
with large hail and damaging winds the more probable threats,
with a tornado or two possible as well.
Ferguson
&&
.PREV DISCUSSION... /Issued 312 PM CDT Tue Oct 26 2021/
SHORT TERM...Tonight through Wednesday Night...
Strong upper level system moving through the Panhandles today
continues to provide dry and windy conditions to the western and
central Panhandles. Dryline setting up east of Amarillo but a
decent cap should still be in place through about 6 to 7 PM. If
storms manage to form it will still likely be in the eastern
column of counties. CAPE, shear, and helicity values all support
organized severe storms, and once storms develop they will likely
go severe quickly. But again, unless storms develop earlier and
further west, they will be out of the area fairly quick. Still
keep in mind that once storms form there will be the potential for
all hazards, especially if they are isolated supercells.
Cold front expected to move through tonight with a wind shift out of
the northwest. A very strong well stacked jet is expected to mix
down in the northwest Panhandles. We may see gusts that could reach
60 to 70 mph. As a result High Wind Warnings will be issued for the
portions of the western TX Panhandle and the northwest TX and OK
Panhandle. This area may need to be expanded as there is concern for
these strong winds to progress further southeast. Confidence is
still very high that we will have 30-40 mph winds in the southeast
Panhandles and therefore the rest of the Panhandles will have a Wind
Advisory. Gusts in these areas are currently projected to be around
50 to 55 mph. The slow progression of this system will allow for
the winds to linger through the day. The northwest will likely
start to recover and slow down wind speeds around noon on Wednesday,
but the eastern Panhandles will likely still have strong winds
through sunset. With much cooler air in place highs are only
expected to be in the 60s on Wednesday, and doubt it will feel much
like a mid 60 degree day with winds blowing as strong as expected.
Wednesday night will be a bit cooler, with the west seeing upper 30s
and the east in the mid to upper 40s. Winds will still be a bit
breezy overnight in the east as the upper level trough will take a
negative tilt. That will stall out the stronger low level jet over
the eastern Panhandles and bring more windy conditions for the
eastern Panhandles on Thursday.
Weber
FIRE WEATHER...This evening and Wednesday...
Critical Fire Weather conditions expected to continue in the
western an central Panhandle today as winds have been in the 25-35
mph range for the most part and RH values have dropped as low as
8 percent. RFTI's of 7 are coming in for the Amarillo area. So
solid critical Fire Weather Days. So far highest wind gusts that
have come in are in the Oklahoma Panhandle around 50 to 55 mph.
Strong cold front tonight will lead to winds 30-40 mph and RH values
down to 15 percent again on Wednesday. RFTI's will be a solid 4
and maybe even get to 5 if RH values come down or sustained winds
exceed 40 mph. The western Panhandles have the drier ERC's and thus
will likely have critical Fire Weather again. The eastern
Panhandles will be tricky as the winds are not quite as strong, and
the ERC's are a little better, so it will likely be covered with an
RFD.
Weber
LONG TERM...Thursday through Monday...
As the main upper level low continues to move east into the
central Mississippi River Valley, rather steep H500 height
gradients remains upstream, especially into the eastern
Panhandles throughout the day on Thursday. This will result in one
more breezy day across the Panhandles with wind gusts may approach
35-40 mph, especially in the eastern Panhandles.
Otherwise going forward, dry conditions will remain in place
across the Panhandles throughout the long term forecast period.
Winds after Thursday will also greatly subside as a small
amplitude H500 ridge builds into the central Plains through the
weekend. High temperatures Thursday through Saturday will slowly
moderate from the mid 60s into the mid 70s by Saturday.
Watching a cold front moving south through the Panhandles on
Sunday which will drop high temperatures back into the upper 50s
to mid 60s which is below average for late October. Cooler
temperatures will hold steady into Monday. Looking ahead past the
long term forecast period into the middle of next week, quite the
cool down may be in store. We will watch closely as we go into
early November.
Meccariello
FIRE WEATHER...Thursday...
Elevated fire weather conditions will be possible for the central
and eastern Panhandles. This will be mainly wind driven with max
RFTI values of 3 to 4. However, min RH values will be around 18 to
20 percent. ERC percentiles should be sub 70th percentile,
especially in the east where strongest northwest winds are of
interest.
Meccariello
AVIATION...18z TAFS...
VFR conditions expected to prevail at all TAF sites over the next
24 hours. Winds will be the main story as west winds 20 to 30kts
gusts as high as 45kt will be possible through about 06z,
thereafter north to northwest winds will come into play behind a
strong cold front. Winds could gust over 50kts in some areas
behind the cold front. These winds are expected to be sustained
25-35kts and will likely continue through the end of the 18z TAF
into the next 00z cycle. Blowing dust will be possible with these
windy conditions, however timing and visibility is tricky to
pinpoint, so amendments may be needed to cover this.
Weber
&&
.AMA Watches/Warnings/Advisories...
TX...Wind Advisory from 4 AM to 7 PM CDT Wednesday for the following
zones: Armstrong...Carson...Collingsworth...Deaf Smith...
Donley...Gray...Hemphill...Hutchinson...Lipscomb...
Ochiltree...Palo Duro Canyon...Potter...Randall...Roberts...
Wheeler.
High Wind Warning from 1 AM to 1 PM CDT Wednesday for the
following zones: Dallam...Hansford...Hartley...Moore...
Oldham...Sherman.
Red Flag Warning until 7 PM CDT this evening for the following
zones: Dallam...Deaf Smith...Hansford...Hartley...
Hutchinson...Moore...Oldham...Palo Duro Canyon...Potter...
Randall...Sherman.
Wind Advisory until 1 AM CDT Wednesday for the following zones:
Dallam...Hartley.
Wind Advisory until 7 PM CDT this evening for the following
zones: Deaf Smith...Oldham.
OK...Wind Advisory from 4 AM to 7 PM CDT Wednesday for the following
zones: Beaver.
High Wind Warning from 1 AM to 1 PM CDT Wednesday for the
following zones: Cimarron...Texas.
Red Flag Warning until 7 PM CDT this evening for the following
zones: Cimarron...Texas.
Wind Advisory until 1 AM CDT Wednesday for the following zones:
Cimarron.
&&
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