Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 241917
AFDAMA

Area Forecast Discussion...Updated Locations
National Weather Service Amarillo TX
217 PM CDT WED AUG 24 2016

.MESOSCALE UPDATE...
...Marginally severe weather possible today...

* Summary: Thunderstorms are anticipated to redevelop across the
  Panhandles this afternoon. Some of the storms could become severe
  mainly across the southeastern and eastern Texas Panhandle and be
  capabale of producing wind gusts of 65 MPH and hail up to the size
  of quarters. Thunderstorms capable of producing minor flooding or
  flash flooding are possible across the western Oklahoma and
  northwestern Texas Panhandles this evening and tonight.

* Synoptic Overview: Plume of monsoonal moisture is situated across
  the far western Panhandles and eastern NM this afternoon. The
  primary upper trough is currently positioned over western NM and is
  slowly moving to the east at roughly 20kt. Water vapor imagery
  shows the axis of the trough rotating through AZ towards western
  NM. This is helping the trough to transition from positive tilt to
  more of a neutral tilt. This transition to a more neutral tilt as
  well as the strength of the upper high pressure centered over the
  SE US have not been handled well by near-term models. A cold front
  is draped from Liberal, KS to Eva, OK southwestward to Boise City,
  OK then westward to Clayton, NM. Cloud cover continues to erode
  across portions of the Panhandles early this afternoon. Where
  clouds have thinned temperatures have risen into the upper 70s to
  mid 80s. Dewpoints range from 50s on the Caprock to 60s off the
  Caprock. Regional radar shows residual light showers moving
  northeastward across the far eastern Panhandles with one storm
  hanging onto a northeastward moving outflow boundary near Guymon,
  OK.

* Mesoscale: The better instability values across the Panhandles are
  expected across the southeastern Texas Panhandle where dewpoints
  remain in the mid to upper 60s with temperatures in the lower 80s.
  Both NAM and RAP BUFR soundings show CAPE increasing into the 1500
  J/kg range with 0-6km Bulk Shear of 30 to 40kts by 7PM this
  evening. This should be sufficient for a few storms to become
  strong to marginally severe. RAP DCAPE values are forecast to
  increase into the 1200 J/kg range showing that damaging wind gusts
  will be possible with any storm that becomes severe. Relatively
  skinny CAPE through the hail growth zone should help to keep the
  maximum hail size limited to quarter. Torrential downpours, which
  could lead to localized minor flooding or flash flooding, will also
  be a concern with the stronger storms due to access to ample low
  level moisture.

  The cold front which has struggled to make much inroads into the
  northwest Panhandles today should help to develop convection
  despite relatively little instability. These storms could present
  a minor flooding or flash flooding threat given the combination of
  monsoonal flow and parallel storm motions along the stalled front.
  Training storms along this front will have PWATs in the
  climatological 75th percentile for this time of year.

* Threats: A few marginally  severe thunderstorms will be possible
  across the southeastern and eastern Texas Panhandle this evening.
  Any storms that become severe will be capable of producing damaging
  wind gusts up to 65 MPH and hail up to the size of quarters.
  Torrential downpours within severe storms could also lead to
  localized minor flooding or flash flooding. Minor flooding or flash
  flooding will also be possible with storms across the western
  Oklahoma and northwestern Texas Panhandles.

* Timing & Location: Thunderstorms are expected to develop over the
  southeastern and eastern Texas Panhandle roughly between 3 and 4 pm
  CDT with the best chance for severe storms between 3PM CDT and 8PM
  CDT. Storms capable of producing minor flooding or flash flooding
  are expected to move into the western Oklahoma and northwestern
  Texas Panhandles around 5PM CDT and persist until 1 AM CDT.


&&

.PREV DISCUSSION... /Issued 1233 PM CDT WED AUG 24 2016/

AVIATION...
VFR conditions are expected for the start of the 18Z TAF cycle but
confidence declines as we move into the evening hours due to
convective chances. The general thought on the next round of
convection will come in two primary areas; S. and SE. Texas
Panhandle and the NW. Texas and W. Oklahoma Panhandles. Both areas of
convection are anticipated to being relatively around the same time,
21Z to 23Z, and expected to persist into the late evening hours. Have
carried PROB30 groups for KAMA and KDHT due to them being near the
periphery of the two storm areas while going prevailing SHRA for GUY
at 22Z. Any storm that develops this afternoon will have the
potential for heavy downpours which can easily drop visibilities into
the LIFR range for a short duration.

Left mention of precip out of the terminals after 9Z as there looks
to be a break in activity during the morning hours. Another round of
convection will be possible late tomorrow morning/tomorrow afternoon
but confidence on timing is too low to mention at this time.

PREV DISCUSSION... /Issued 439 AM CDT WED AUG 24 2016/

DISCUSSION...
Upper trough over the central Rockies and Four Corners region will
track slowly east today and tonight towards the Panhandles. A cold
front over southwest Kansas and southeastern Colorado will push
slowly south and east today into the Oklahoma Panhandle and then into
the Texas Panhandle by late tonight or early Thursday. The front
should become stationary across the Texas Panhandle by late Thursday
before starting to push slowly south again Thursday night and early
Friday. Convection chances will increase through the end of the week
with the possibility for some storms to become strong to marginally
severe this afternoon and this evening...and again Thursday afternoon
and evening. Main threats will be damaging thunderstorm wind gusts to
around 60 mph and hail up to quarter size.

Abundant low level Gulf moisture remains in place over the Panhandles
today ahead of a pre-frontal surface trough now moving southeast
across the northwestern portions of the forecast area. Ahead of the
pre-frontal surface trough...surface dew points remain in the 60s
while behind the surface trough...dew points are in the 50s. Model
soundings forecasting PWATs in the 75th percentile for August today
through Thursday...therefore locally very heavy rainfall resulting in
flooding or flash flooding issues can be expected. Continued
southwesterly flow aloft across the Panhandles into the weekend and
early next week will allow for an active weather pattern as abundant
low level Gulf moisture will remain in place. Convection chances will
continue through early next week.

Schneider

&&

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

&&

$$

14/1



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