Area Forecast Discussion
Issued by NWS Amarillo, TX

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000
FXUS64 KAMA 311148
AFDAMA

Area Forecast Discussion
National Weather Service Amarillo TX
648 AM CDT WED AUG 31 2016

.AVIATION...
For 12z TAFs...Some low level stratus and scattered showers will
lead to occasional MVFR/IFR cigs/vsbys this morning. Patchy fog is
also likely especially near KAMA and KDHT where there is good soil
moisture and very light winds mainly prior to 15z. After this
morning ceilings should lift to prevalent VFR cigs but MVFR
showers are expected to increase in coverage towards mid to late
morning...especially across the southern zones so kept prevalent
showers at KAMA with vicinity showers for KDHT and KGUY where
there is more uncertainty in timing and coverage. Kept in PROB30
for all sites this afternoon as airmass does become more
supportive of thunder during that time.

Ward

&&

.PREV DISCUSSION... /Issued 420 AM CDT WED AUG 31 2016/

SHORT TERM...Today
08z upper level analysis shows upper level high squeezing against
what`s left of sheared cyclonic spin over lee of Rockies as high
retrogrades westward. This is helping to keep weak return flow and
good deep level moisture in place across the Panhandles. Model
soundings show dewpoint depressions of only 1-3 degrees celsius from
H800-H400 through the day. Precipitable water values will continue
to be around or above the 90th percentile. Steepening low level
lapse rates during the afternoon will lend to 1000-1500 J/kg
uninhibited SBCAPE. Albeit skinny CAPE...this will once again lead
to scattered to numerous showers with embedded thunderstorms capable
of producing heavy rain. Flooding will continue to be a concern
especially during the afternoon hours. Brought max temperatures down
a few degrees below guidance based on poor model performance as of
late. Also added patchy fog with light surface flow and moist ground
conditions.

LONG TERM...Wednesday Night through Tuesday
Overnight Wednesday, the upper level flow will continue to
transition from southwesterly to zonal. Even through the flow is
transitioning, the conveyor belt of subtropical moisture will
persist. This ample moisture will keep heavy rain producing
thunderstorms a strong possibility. Models continue to show an
elongated vort. max rounding the periphery of the upper ridge as a
cold front attempts to slide into the far eastern CWA Thursday. Both
lifting mechanisms will help to sustain thunderstorms Thursday
morning through the early afternoon hours.

Thursday night into Friday morning will see storms clearing the
northeastern Panhandles as the vort max weakens. The cold front will
continue to lose definition throughout the late morning hours and
surface winds will shift back out of the south by the early
afternoon. Some storms remain possible Friday afternoon and evening
but will be far more scattered in nature than storms have been so far
this week.

Saturday will see the return of southwesterly winds aloft in response
to a longwave trough moving into the northwest US. This will mark
the start of another round of general troughing across the western US
and southwesterly flow for the Panhandles. This pattern is
anticipated to last through the first half of the coming week, and
we should see scattered diurnally driven convection each day. Even
though SW flow has return, we won`t see the same ample subtropical
moisture as earlier in the week.

HYDROLOGY...
Heavy rain will continue to be a concern through Today with much
of the eastern and southern Texas Panhandle having received
spotty amounts of several inches over the past few days. We have
also seen responses on area rivers such as the Prairie Dog Town Fork
of the Red River at Wayside which briefly went into flood stage
yesterday. Have kept the Flood Watch intact with the expiration set
for this evening.

There is some concern the Flood Watch may need to be extended to
encompass Thursday`s storms. Forecast PWATs remain in the +2SD for
this time of year and the introduction of a surface front to provide
focusing near the surface could help heavy rain producing
thunderstorms across the eastern and southern Texas Panhandle. Have
held off on extending the watch for now as models continue to narrow
in on timing and area affected by Thursday`s convection.

&&

.AMA Watches/Warnings/Advisories...
TX...Flood Watch through this evening for the following zones:
     Armstrong...Carson...Collingsworth...Donley...Gray...
     Hansford...Hemphill...Hutchinson...Lipscomb...Ochiltree...
     Roberts...Wheeler.

OK...Flood Watch through this evening for the following zones:
     Beaver...Texas.


&&

$$

7/14



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