Area Forecast Discussion
Issued by NWS Amarillo, TX

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098
FXUS64 KAMA 262149
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
449 PM CDT Wed Apr 26 2017

.DISCUSSION...
Broad cyclonic flow continues to expand over the CONUS today as
the southern Plains shortwave can be seen moving into the Ark-La-Tex
region. The cold front has nearly pushed through the Permian Basin
towards south Texas and should be to the coast within the next few
hours.

Northwest flow today will slowly become more zonal as the broad
cyclonic flow expands across the CONUS. A strong ~70 knot 500mb
jet is still being progged to develop and lift into the southern
Panhandle region Thursday ahead of a developing upper low over
the Great Basin. A weak surface low will develop near an area of
differential heating over the Raton Mesa and move over the
Panhandles during the day Thursday. This will result in a tricky
wind/temp/pop forecast. It still looks like near advisory
criteria winds could develop on the southwest side of the sfc low
over the far southwest Texas Panhandle where mixing potential will
be greatest. However, due to the borderline windspeeds and
uncertainty with extend of coverage/time, will punt to next shift
for headline decision. Showers and an isolated thunderstorm are
possible on the north/east side of the sfc low where just enough
moisture may be pulled up on the S/SE low level winds combined
with some ascent beneath a left-exit region of the jet. Model
profiles are showing mostly high based CAPE around 500-1000 J/kg
as mid- level lapse rates increase in the afternoon. With the
mid/high level jet streak in the area, effective shear values in
the cloud bearing layer will be on the order of around 40 knots
(mostly due to speed shear). With the limited moisture/instability
and low level forcing, severe weather will be unlikely. However,
any storm that can realize higher CAPE values in the northeastern
zones may have some potential for marginally severe wind gusts
(~60 mph) and hail (~1.0 inch).

The real interesting weather is expected for the weekend as the
developing low over the Great Basin is expected strengthen
considerably as it moves over the Four-Corners region Friday. By
mid-day Saturday deterministic models show a closed ~555 DAM 500mb
low over northern New Mexico and a strong sw/ne oriented jet over
the Panhandles. Meanwhile, a developing 700mb low is expected to
move across the the Panhandles. There is still some small
variations in the models on the track and strength of this low as
it moves across the area. The overall pattern still supports and
extended period of rain showers across a large portion of the
Panhandles (especially north of I-40) late Friday through early
Sunday. Elevated thunderstorms, some strong to severe, will also
be possible early Saturday morning between midnight and 9AM for
portions of the southeastern Texas Panhandle ahead of the low as
increasing LSA, height falls and low level moisture leads to
strong elevated instability (~1500-2500 J/kg) combined with 40-60
knots of cloud bearing shear.

Models are coming into better agreement with rain changing over
to snow on Saturday for the western Panhandles as strong CAA and
dynamic/evaporative cooling occurs in an area of deformation and
maximum isentropic moisture transport on north/northwest side of
700mb low. This will be combined with an area of increasing DCVA
as TROWAL tries to develop in area of divergent Q-vectors aloft.
Models show well developed ~550 DAM closed 500mb low over eastern
Panhandle by Sunday morning. Snow accumulations could be well
within advisory criteria for portions of the western Oklahoma
Panhandle and northwestern Texas Panhandle from early Saturday
through early Sunday. How far west and south the snow is able to
accumulate will largely depend on the exact track and strength of
the low, which will be refined over the next couple days.

Models are struggling some with exactly how long this system will
hang around depending on the amount of negative tilt the low
takes on as it strengthens. At this time it looks like
precipitation will be ending by Sunday afternoon from west to
east as northwest flow takes over aloft. Northwesterly flow will
become more zonal early next week before our next system of
interest approaches on Tuesday into Wednesday with a warming
trend.

Ward

&&

.FIRE WEATHER...
While west/southwest winds will be approaching 20-30 mph Thursday
afternoon for the southwestern Texas Panhandle with RH values
dropping to around 15 percent, elevated fire weather is not
expected given the fuel conditions and rainfall on Wednesday
morning.

Ward

&&

.PRELIMINARY POINT TEMPS/POPS...
Amarillo TX                44  79  45  74  44 /   0  10   5  20  50
Beaver OK                  40  74  43  68  39 /   0  30  20  30  70
Boise City OK              40  71  39  63  32 /  10  20   5  30  80
Borger TX                  47  78  46  73  41 /   0  10  10  20  60
Boys Ranch TX              43  79  44  73  40 /   0  10   5  20  70
Canyon TX                  43  79  45  75  44 /   0  10   5  20  50
Clarendon TX               43  82  50  76  48 /   0  10   5   5  50
Dalhart TX                 42  75  42  68  36 /   5  10   5  30  80
Guymon OK                  42  76  42  68  36 /   0  20  10  30  80
Hereford TX                45  79  45  75  44 /   0   5   5  20  50
Lipscomb TX                43  77  45  71  44 /   0  30  20  20  60
Pampa TX                   45  79  45  72  43 /   0  20  10  20  60
Shamrock TX                44  81  50  76  48 /   0  20  10   5  60
Wellington TX              44  83  52  79  51 /   0  10   5   5  50

&&

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

&&

$$

11/7



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