786
FXUS64 KAMA 180423
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
1023 PM CST Sun Nov 17 2024

...New AVIATION...

.KEY MESSAGES...
Issued at 342 AM CST Sun Nov 17 2024

Heavy rainfall that could lead to flooding will start this
evening and continue well into Monday.

Colder temperatures will occur behind a cold front Tuesday into
Wednesday and a widespread freeze will occur Wednesday morning.

&&

.SHORT TERM ...
(This evening through Monday night)
Issued at 245 PM CST Sun Nov 17 2024

Impressive mid-upr level storm system has bottomed out in NRN
Mexico and is poised to make its turn NE before making a beeline
to the Panhandles. Model Q-Vector convergence shows better lift
arriving around 00 UTC Monday across the west, but the greatest
lift associated with the storm will occur between 6 UTC and 18
UTC and this is when most of the precipitation will occur with
this event. Models have come into agreement wrt track and strength
of the upper low (which means the GFS had to trend back N/W to
the mean solution).

With model settling on a favorable track across the area that
maximizes lift and moisture transport, QPF has increased
slightly. The NBM has significantly increased probability of 3 or
more inches and now shows a 10 to 50 percent chance of occurrence
east of a line from Friona to Canyon to Spearman to Beaver with
highest probabilities along an axis from Pampa to Canadian and
Higgins. That said, there are still some significant model
differences wrt where the highest rainfall will occur. This seems
to be related to the position of the area of H85 convergence
associated with strong frontogenesis that develops as the low
approaches as this feature seems aligned with higher QPF in all
models. So, the models most agressive with producing higher QPF
further west, do so because they really pull this feature well
west of where the current frontal boundary is located across the
far SE Texas Panhandle as the low approaches. The strongest lift
associated with the low based on the track actually is across the
west which better aligns those features. Models in the further
east camp wrt highest QPF only slightly pull this feature back to
the NW as the low approaches. The ICON provides a 3rd solution
which creates 2 separate zones of higher QPF, one in the SE
(frontogenesis area?) and one across the west (stronger lift?).
The current QPF forecast is a compromise that is in good agreement
with the axis of highest 3" probability.

As we have seen with the past few systems, the rain rates will
not reach levels of spring/summer storms and HREF probabilities
of seeing rates of 1 inch per hour or great are only 10-30
percent. This will help mitigate the flash flood threat some. That
said, the shear volume of water here can become a problem and we
expect streams and rivers to see rises and there certainly could
be some flooding of low lying areas, county and farm roads, etc.
Streams, creeks and rivers will also see rises as all this water
drains off and several river forecasts points should at least
reach action stage. Based on the QPF trends, we have added Randall
(mainly for the far eastern/southern areas), Hutchinson,
Ochiltree and Beaver Counties to the FLood Watch.

Gittinger

&&

.LONG TERM ...
(Tuesday through next Saturday)
Issued at 245 PM CST Sun Nov 17 2024

Fewer and fewer models and ensemble members shown a strong enough
secondary disturbance Tue/Wed to produce any significant
precipitation early in the period (Tue/Wed) and NBM probabilities
have dropped to around 5%. If anything, operational models have
backed off slightly on the cold air behind the Tuesday front. H85
temps are now forecast by all the 12Z operational models to be
1-3 Deg C rather than below freezing. That said, with light winds
Wed morning given SFC high pressure near the region should still
allow for enough radiational cooling for a widespread freeze for
most if not the entire region with a hard freeze for a significant
portion of the area, although it has been noted the NBM
probabilities for below 28 deg lows Wed morning have decreased
slightly. These probabilities are now down around 20-40 percent
surrounding Amarillo and the highest probabilities greater than 70%
are now confined to the NW 3rd of the Panhandles.

Not much to write home about wrt weather the remainder of the
period as the next systems will be much more progressive and
further north. Winds will be all over the map given reinforcing
front indicated by models Thursday and the next wave crossing the
plains may bring the next front by Sunday. After Wednesday,
temperatures are forecast to warm slightly and be very close to
average (lows 30s / highs low 60s) with a trend toward slightly
above average toward the end of the period.

Gittinger

&&

.AVIATION...
(06Z TAFS)
Issued at 1015 PM CST Sun Nov 17 2024

MVFR ceilings have arrived in Amarillo, and ceilings will
gradually continue to lower at all terminals through the night to
the point where all terminals will be IFR or LIFR by around 09z.
Ceilings will rise from southwest to northeast in the afternoon
hours. Otherwise, showers will continue through the night and at
least the morning hours at all terminals. Have continued a PROB30
for thunderstorms at Amarillo later tonight.

Vanden Bosch

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                63  44  57  36 /  40 100  70   0
Beaver OK                  59  43  53  32 /  20 100  90   0
Boise City OK              51  36  51  27 /  20  90  80   0
Borger TX                  63  45  57  35 /  20 100  80   0
Boys Ranch TX              63  43  60  33 /  20 100  90   0
Canyon TX                  64  44  60  35 /  50 100  70   0
Clarendon TX               65  48  60  39 /  60 100  40   0
Dalhart TX                 57  38  57  29 /  20 100  90   0
Guymon OK                  56  39  51  29 /  10 100  90   0
Hereford TX                65  44  61  36 /  50 100  80   0
Lipscomb TX                61  48  59  35 /  30 100  80   0
Pampa TX                   62  45  56  35 /  30 100  70   0
Shamrock TX                65  50  62  39 /  60 100  50   0
Wellington TX              65  51  64  40 /  70 100  40   0

&&

.AMA WATCHES/WARNINGS/ADVISORIES...
TX...Flood Watch through Monday morning for TXZ004-005-008>010-
     013>015-017>020-317.

OK...Flood Watch through Monday morning for OKZ003.

&&

$$

SHORT TERM...88
LONG TERM....88
AVIATION...52