Area Forecast Discussion
Issued by NWS Amarillo, TX

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536
FXUS64 KAMA 240214
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
914 PM CDT TUE AUG 23 2016

.UPDATE...
Have issued update to graphical forecasts, increasing pops across
southeast and south sections for the remainder of tonight.  Southwest
flow aloft will contain a few perturbations which will track across
this area.  Also, this area will remain moist and unstable owing to
steady moist flow.  Updated text products will be issued shortly.

Cockrell

&&

.PREV DISCUSSION... /Issued 623 PM CDT TUE AUG 23 2016/

AVIATION...
Ongoing convection near the KAMA terminal and anticipated convection
this evening will keep confidence low for the 00Z TAF cycle. Thunder
will be a possibility for the KAMA terminal through the first few
hours of this TAF cycle with shower activity expected through the
better part of the overnight hours. Have carried prevailing SHRA
through 12z tomorrow morning but expect updates should storms clear
the terminal sooner than expected. The heavy downpours with storms
that move over the terminal could significantly lower flight
categories. A lull in convective activity is anticipated for the late
morning hours before the next round of convection develops late
tomorrow afternoon/evening. Have left mention of this round out of
the TAF due to low confidence on timing.

KDHT and KGUY should remain clear of convection this evening, but
will watch closely as storm outflows approach the terminals. Wind
should remain out of the south-southwest direction with gust
potential diminishing after sunset. Gusts will return once again
tomorrow morning during the late morning hours. As with KAMA, have
left mention out for now given timing uncertainty.

PREV DISCUSSION... /Issued 334 PM CDT TUE AUG 23 2016/

DISCUSSION...
Scattered convection has already begun to develop mainly south of
the Panhandles...with recent development over the SE Texas Panhandle.
We expect to see further development of convection as we go into the
late afternoon and evening hours along and south of a convergence
boundary stretching roughly from Amarillo to Beaver. Instability
values of 1000 - 2500 J/kg MLCAPE and weak deep layer shear will
likely lead to pulse style storms. This would indicate that brief
gusty winds and heavy downpours would be the primary hazards with
storms this afternoon.

Overnight, instability will be on the decline but embedded weak
disturbances will help to keep precip chances possible across the
southeastern Texas Panhandle through the overnight hours. A brief
lull in convective activity is expected during the late morning hours
on Wednesday. This precipitation reprieve won`t last long past noon as
convection is anticipated to develop along and ahead of a pacific
front that will sneak into the northwest zones. While instability
values will be similar compared to Today, our deep layer shear values
of 30 kts will present a better chance for organized convection. This
means a strong to severe storm can`t be ruled out and the primary
hazards will be damaging wind gusts and hail. While forecast PWAT
values remain below the +2SD for this time of year (1.5 inches),
storm motions show the potential for training storms which could lead
to locally higher rainfall amounts and potentially localized
flooding. Precip chances will persist through the overnight hours
with primary hazards switching from severe to hydro during the late
evening hours as the low-level jet ramps up.

There is some difference between model outputs on how far south the
front will push Friday night with the NAM being the most aggressive.
The NAM pushes the front south of the area by Thursday morning which
seems plausible given the additional push southward from convective
outflows. The ECMWF is slightly behind the NAM to bring the front
south of us by Thursday mid-day with the GFS stalling the front over
the Panhandles. The forecast reflects the more aggressive southerly
push of the front but recovers quickly which leans back towards the
ECMWF and GFS in the following days. The result shows precip chances
persisting well into Thursday before we start to see precip chances
lessen towards the weekend.

Persistent southeasterly flow aloft starting Friday night will allow
weak disturbances to move across the Panhandles to keep low-end pops
in the forecast into early next week. Expect these chances to change
as we move forward in time as slight changes in timing will have
significant changes in the chance and location of precip.

&&

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

&&

$$

3/10



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