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145
FXUS64 KAMA 210817
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
317 AM CDT Sat Sep 21 2024

...New KEY MESSAGES, SHORT TERM, LONG TERM...

.KEY MESSAGES...
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Issued at 311 AM CDT Sat Sep 21 2024

- Thunderstorms are very likely today across the Texas and
  Oklahoma Panhandles. Some of the thunderstorms could be severe,
  with the primary hazards being large hail and damaging winds. A
  tornado or two are also possible this afternoon through early
  this evening.

- The thunderstorms today through Sunday morning could also
  produce very heavy rainfall which could lead to flash flooding,
  especially from this evening through tonight across the central
  and southern Texas Panhandle.

- A cold front will bring in much cooler temperatures on Sunday
  with highs in the 50s to 60s across the combined Panhandles.
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&&

.SHORT TERM ...
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(Today through Sunday night)
Issued at 311 AM CDT Sat Sep 21 2024

An active weather day is in store for the Texas and Oklahoma
Panhandles. Widespread showers and thunderstorms are very likely
today through Sunday morning. Some of these thunderstorms have the
potential to be severe, with the primary hazard being large hail
and damaging winds, but a tornado or two cannot be ruled out. The
more widespread threat will be heavy rainfall which could lead to
flash flooding. Cooler temperatures are expected both today and
tomorrow with a cold front passing over the region on Sunday.

The well advertised H500 low pressure system currently is located
across the far southern tip of Nevada and is slowly moving off to
the east. Out ahead of the system, plentiful low to mid level
moisture continues to stream in across the Southern High Plains
and a shortwave trough is providing ample lift to generate showers
for some areas this morning. With the amount of moisture in the
low to mid levels, the light showers may continue the rest of the
morning provided subtle lift remains over the region.

Looking towards later this morning into the afternoon hours, PVA
associated with the strong upper level low will make its way
across the Southern Plains. This wave will be associated with
strong H700 theta-e advection across eastern New Mexico into west
Texas. Numerous thunderstorms and showers should develop across
this area starting later this morning and should continue into
Sunday morning. Initially discrete storms, potentially
supercells, look to form across eastern New Mexico and quickly
track northeast with the strong southwest to northeast oriented
flow across the region. Skinny CAPE profiles are depicted by
forecast soundings along with a lot of sfc-6km shear on the order
of 50 to 60 kts. Given the above parameters, a few severe storms
look possible even though temperatures are forecast to only be in
the 70s to low 80s. The primary hazard looks to be large hail with
the mid levels cooling combined with the high shear. However, a
tornado or two is certainly possible, especially if discrete
supercells can remain along a stalled front across the western TX
Panhandle. The severe potential will need to be closely monitored
throughout the day today as there are certainly quite a bit of
caveats, but the overall set-up will support some severe storms
early this afternoon through this evening.

The more widespread hazard looks to be heavy rainfall associated
with these storms. Forecast PWAT values around 1.5 inches across
the entire area are above the climatological max for this time of
year. The 21/00z HREF probabilities for 1 inch of rain per hour
are on the order of 30 to 70 percent for some locations across the
Panhandles. Rain rates upwards of 2 to potentially 3 inches per
hour are not out of the question given the aforementioned skinny
CAPE profiles and the anomalously high PWATs. Storms look to be
fast movers, which may limit the overall flash flood threat, but
multiple rounds of heavy rain could move over some locations which
would lead to a flash flood threat. This is especially the case
going into tonight into Sunday morning. Thunderstorms with high
rain rates could train along the stalled boundary during the late
evening into the night time hours. Current model guidance has the
front located across the southern Texas Panhandle during this time
frame with a LLJ setting up with wind speeds of 30 to 40 kts. With
all that being said, a Flood Watch has been issued for most of the
Texas Panhandle from this afternoon through Sunday morning. Cannot
rule out additional areas in the southeast being added to the
watch should the front move a bit further southeast than currently
forecast.

The H500 low pressure system will weaken and move northeast
towards the Central Plains on Sunday. As this occurs, a cold front
should propel southward across the Panhandles and should be
through the entire area by the afternoon hours. The front should
push any rain showers or thunderstorms to the south and the rain
chances should end by late afternoon for the CWA. The front will
push in the coolest air of the season thus far with H850
temperatures progged to drop down to the upper single digits
Celsius. Highs on Sunday look to be in the 50s to the north with
60s to maybe low 70s south. With the widespread cloud cover and
the cold air mass moving in, NBM temperatures perform very poorly
in these scenarios. Have continued the trend of lowering highs on
Sunday using other blended guidance while noting there is room to
go cooler if some of the hi-res models turn out to be correct.

Muscha
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&&

.LONG TERM ...
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(Monday through Friday)
Issued at 311 AM CDT Sat Sep 21 2024

Cooler temperatures will continue into early next week but will
gradually warm back up late in the work week back up into the low
to mid 80s. After a brief break in the rain chances on Monday,
rain chances return Tuesday and Wednesday across the Texas and
Oklahoma Panhandles.

Upper level troughing looks to remain in place across the
Panhandles early next week. This will keep the cooler airmass in
place over the region which will suppress highs mainly below 80
on Monday and Tuesday. A low pressure system is forecast to dig
south across the Rockies towards the Southern High Plains on
Tuesday into Wednesday. Model guidance deviates tremendously on
the evolution of this low pressure system. In any case, this
system will bring a return of precipitation chances to the
forecast area starting early Tuesday morning and continuing
through Wednesday. At this time, the latest ensemble guidance
suggests the better rain chances may remain to the west and south
of the Panhandles, but models have been all over the place with
whether or not the low will close off and slow down or be
progressive. This leads to high uncertainty in the forecast from
Tuesday onward, but the overall trend looks to be increasing
temperatures into the 80s and drier conditions towards the later
half of next week.

Muscha
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&&

.AVIATION...
(06Z TAFS)
Issued at 1226 AM CDT Sat Sep 21 2024

VFR conditions are forecast to start this TAF cycle. MVFR to IFR
ceilings and visibility will be possible at all sites due to
showers and thunderstorms starting around or after 18z through the
end of this TAF issuance. Winds will initially be out of the
southwest but will become northerly behind a front. Sporadic winds
with higher gusts will be possible at the sites when thunderstorms
move over the terminals. MVFR to IFR ceilings are very likely at
the sites after 00z along with continued showers and potentially
thunderstorms.

Muscha

&&

.PRELIMINARY POINT TEMPS/POPS...
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Amarillo TX                86  58  65  46 /  90  90  40  10
Beaver OK                  86  53  60  43 /  80  90  50  10
Boise City OK              71  48  56  40 /  90  90  20   0
Borger TX                  87  59  66  45 /  90  90  40  10
Boys Ranch TX              83  56  65  44 /  90  90  20  10
Canyon TX                  86  58  67  44 /  80  90  40  10
Clarendon TX               91  62  70  48 /  70  80  60  20
Dalhart TX                 74  51  59  40 /  90  90  10   0
Guymon OK                  79  50  58  39 /  90  90  40   0
Hereford TX                84  58  68  44 /  90  80  30  10
Lipscomb TX                91  58  64  45 /  80  90  50  10
Pampa TX                   88  58  65  44 /  90  90  50  10
Shamrock TX                94  63  72  48 /  40  70  70  20
Wellington TX              95  65  74  50 /  30  60  70  30
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&&

.AMA WATCHES/WARNINGS/ADVISORIES...
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TX...Flood Watch from 1 PM CDT this afternoon through Sunday morning
     for TXZ001>004-006>009-011>014-016>019-317.

OK...None.
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&&

$$

SHORT TERM...05
LONG TERM....05
AVIATION...05