Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 220550 AAB
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
1250 AM CDT Wed Mar 22 2017

.AVIATION...
For the 06Z TAFs, upslope low level winds and a corresponding
increase in moisture will result in the development of low clouds
at the terminal sites between 08Z and 10Z this morning. IFR cigs
will likely develop at KDHT and KAMA with MVFR cigs at KGUY
anticipated. Fog and drizzle are not expected to develop at this
time, but will monitor trends closely this morning. The IFR to
MVFR cigs should slowly dissipate during the early to mid
afternoon hours.

Andrade

&&

.PREV DISCUSSION... /Issued 556 PM CDT Tue Mar 21 2017/

AVIATION...
Low clouds are expected to increase on upslope surface winds
overnight. DHT and AMA should see cigs fall into the IFR range
with MVFR cigs at GUY. Low clouds should slowly dissipate during
the afternoon on Wednesday. Southerly winds will increase toward
the end of this forecast.

PREV DISCUSSION... /Issued 541 PM CDT Tue Mar 21 2017/

DISCUSSION...

Although high pressure will continue to dominate the area for the
next couple of days cooler air associated with an upper level
trough over the Great Lakes will briefly squeak into the area
from the northeast on Wednesday. With a strong inversion above
this cooler air low level saturation will be possible. This will
provide the potential for some light rain/drizzle. Due to the
strength of the inversion and the low level winds expected to
shift more southerly late in the day, it`s possible that the
stratus deck/drizzle could linger for most of the day, with a few
breaks in the late afternoon to early evening. Highs look to only
be in the 70s on Wednesday, with some areas in the 60s. If this
stratus deck holds all day, we can probably knock off another 5 to
10 degrees from the forecasted highs.

Now for the active portion of the forecast period. Low level
moisture advection ahead of an approaching deep upper level low
pressure system will aid in the potential for a CWA wide
thunderstorm day on Thursday. This will be mainly in the evening
and possibly continue overnight. We have a lot of good parameters
for severe weather, surface dewpoints into the mid 50s, 0-6km
bulk shear 40-50kts, and increasing through the night, with a good
veering vertical wind profile, 100-300m2/s2 0-1km helicity
values, and large scale forcing ahead of the upper low. Prior to
this forcing it looks as if most surface based convection will be
capped. There may be some exceptions to the western counties that
high based convection could occur to start of the day, but some
models soundings keep as stable layer above the saturation point.
All other areas should see elevated convection as the forcing
should take care of the cap in the boundary layer. The
500-1000J/kg CAPE values that we have when the forcing arrives
combined with the aforementioned upper level dynamics supports
the possibility of supercells or at least organized multi-cells.
Hail will be the main threat but, wind is a possibility as well.
Expect that thunderstorms could continue through the night as a
50-60kt low level jet becomes established across the Panhandles.

As we move into Friday, cooler drier air will be in place behind
the upper low, however wrap around precipitation is still a
possibility, mainly across the northern and eastern portions of
the Panhandles. If enough surface based heating occurs with the
cold core aloft, we might be able to pull off an isolated
thunderstorm or two amongst these showers on Friday.

As the upper low exits the area on Saturday southwest flow will
return as brief ridging once again is expected. Another upper
level system similar to Thursdays is expected to move over the
four corners Saturday night. It appears that this system will not
be as deep and will be further north, likely dry slotting the area
on Sunday (See Fire Weather), keeping any convection to the north
and east of our area.

Yet again another weak ridge should be in place on Monday for dry
conditions, with another weather system moving towards the four
corner`s Tuesday morning, to set up another thunderstorm day on
Tuesday.

Weber

AVIATION...
18Z Issuance...VFR conditions expected until after 05Z when sites
will drop to at least MVFR and perhaps lower. Low clouds are
expected to start moving into the area and should stick around
through most of the end of the period. Confidence is low on how
low ceilings will get, so for now have stopped at MVFR. Winds look
to stay northeasterly.

Beat

FIRE WEATHER...

The potential for elevated to critical Fire Weather along the
western TX/OK counties still exists on Thursday, but there are a
lot of uncertainties in the models as to what Thursday will bring.
Some models suggest the RH`s will only drop to 35 percent while
the driest model has a min RH of about 7 percent at KDHT. The
setup of the dryline and where the low level moisture transport
occurs before the dryline progresses east will be a big factor. If
we stay dry along the northwestern counties, we could see strong
inverted V soundings that could produce 40-50 mph wind gusts.

Sunday the humidities are very dry but with the surface low
overhead it seems that best possibility would be elevated for Fire
Weather.

Weber

&&

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

&&

$$


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