Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 261144 AAA
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
644 AM CDT Tue Sep 26 2017

.AVIATION...
For the 12Z TAFs, a low confidence forecast overall continues
with amendments possible. Expect IFR cigs at all terminal sites
along with some BR this morning. A trend towards MVFR cigs seems
plausible this afternoon before lowering to IFR conditions again
at KDHT and KAMA later this evening. Kept precipitation out of
this fcst cycle due to low confidence and expected less coverage
compared to previous day.

Andrade

&&

.PREV DISCUSSION... /Issued 337 AM CDT Tue Sep 26 2017/

DISCUSSION...
Current observations this morning indicates widespread low clouds
and even some patchy fog in a few locations across the Panhandles
this morning. Low clouds and patchy fog should remain for most of
the morning hours and perhaps even into the afternoon hours as
the airmass behind the passing cold front keeps low level
moisture in place under the north to northeasterly surface flow.
Current observations also show some showers and heavier downpours
across portions of the far southern TX Panhandle as the
precipitation moves east across a equatorward moving cold front
and its established theta-e gradient.

Another short wave in the steep sinusoidal flow with its axis
across the inter-mountain west will advect later today across
eastern New Mexico helping to focus some heavier rains and perhaps
some embedded convection as well progressing east across the
region throughout the day. However, the main
ingredients/thermodynamics of more robust convection should remain
well to the south of the Panhandles as the cold front continues
to move slowly south into central TX. This according to the latest
26/00Z model/numerical guidance will be the region where the best
instability and lift will be located for thunderstorm
development, although, it cannot be completely ruled out for our
region, especially across the TX Panhandle with the associated
shortwave trough moving out of New Mexico. Otherwise, the other
main weather headline for today will be the well below average
temperatures with high temperatures today only ranging from the
low to mid 60s.

The latest 26/12Z guidance does have some discrepancies between
the different model outputs. The steep meridional flow is hinting
at perhaps a cut off low pressure system west of the Four Corners
region by mid week keeping weather unsettled across all of the
Panhandles. With a ridge building across southern Alberta toward
the end of the week, a Rex Block signature appears to be present
over the inter-mountain west which will continue to bring
persistent SW mid level flow into the Panhandles with chances of
showers and storms through Thursday as this flow taps into a moist
eastern Pacific source. By Friday, the block begins to erode as a
90-110 kt. 250 hPa southern stream jet entering the western CONUS
begins to displace the main upper level low centered over western
Colorado into the main flow which at this time is increasingly
zonal. This will bring additional chances of showers and storms
across the western Panhandles through Saturday as the decaying
process of the meridional flow is ongoing. Sunday through early
next week will bring back tranquil weather conditions and
downsloping 850-700 hPa SW flow which should warm temperatures
back to average to perhaps even above average by next week.

Meccariello

&&

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

&&

$$



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