Area Forecast Discussion
Issued by NWS Amarillo, TX

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FXUS64 KAMA 221713 AAB
AFDAMA

Area Forecast Discussion...UPDATED
National Weather Service Amarillo TX
1213 PM CDT SUN MAY 22 2016

.Mesoscale Update...
...Severe weather expected today...

* Synoptic Overview: This morning an upper-level low pressure system
  was spinning over southern Alberta and western Montana, with a
  pronounced ridge of high pressure aloft extending from Texas
  toward the Great Lakes. The Texas and Oklahoma Panhandles remain
  beneath southwesterly flow aloft between these features and just on
  the western periphery of the ridge. A northern stream jet maximum
  extends from Utah to the Dakotas, while the southern stream jet
  maximum is confined to northern Mexico and South Texas. The
  Panhandles remain under an area of diffluence between the jets, but
  300mb winds will be at a relative minimum across this region today.
  Water vapor imagery showed the remains of yesterday`s convection
  being swept eastward by that shortwave and hints of a few other
  shortwaves rounding the upper low and traversing the Rockies. The
  overall upper-level support will be somewhat limited today due to
  the lack of direct influence from an upper-level jet and the fact
  that passing shortwaves are not expected to be very deep or extend
  very far southeast into our area. At the surface a surface low will
  deepen over eastern Colorado, and a dryline will tighten up
  extending to its south through the length of West Texas.
  Thunderstorms (some of which will be severe) are expected to
  develop along much of the dryline this afternoon and evening.

* Mesoscale: With the deepening surface low over Colorado, we expect
  the dryline to hang back across far western portions of the Texas
  and Oklahoma Panhandles - likely extending from near Boise City to
  Hereford by the late afternoon. In response to the developing
  surface low and dryline, expect low-level winds to back more from
  the southeast as the afternoon progresses. This will aid in low-
  level convergence near the dryline and keep low to mid 60s
  dewpoints in place across most of the Panhandles. Low and mid-level
  clouds are breaking up across the area, with temperatures quickly
  climbing into the 80s. Model guidance suggests that a combination
  of mid-80s temps and low-to-mid 60s dewpoints will lead to a narrow
  corridor of MLCAPE values approaching 3000-4000 J/kg near and just
  east of the dryline. Steep mid-level lapse rates of 8 to 9 C/km
  also expected east of the dryline. Any thunderstorms developing
  near this area will have the chance to rapidly intensify. Deep
  layer shear will be on the marginal side (only around 30-35 kts of
  0-6km shear) during the afternoon and evening but will be
  perpendicular to the dryline, suggesting a weakly organized storm
  mode with a few supercells possible. Increasing low-level wind
  shear by late evening does indicate at least some threat for
  isolated tornadoes, though lack of upper-level support means these
  should be short lived. Storm motion should be to the northeast at
  around 25 kts, though right-moving supercells would have a slower
  ENE trajectory similar to yesterday`s storms.

* Threats: With such a high potential for instability, large hail to
  the size of baseballs and damaging wind gusts will be the primary
  hazards. Increasing low-level wind shear near sunset will also
  allow for a brief window when isolated tornadoes will be possible.
  Slow storm motions for the strongest storms and recent rainfall
  over portions of the threat area mean that localized flooding and
  flash flooding will be possible as well.

* Timing & Location: Though there is some slight uncertainty on just
  how far east the dryline will develop this afternoon, confidence is
  fairly high that it will set up between the TX/NM state line and an
  Amarillo-to-Guymon line. The greatest threat for severe weather
  will be for central portions of the Texas and Oklahoma Panhandles.
  Timing for storm initiation is expected to be around 2 to 4 pm this
  afternoon, with storm severity and coverage decreasing by midnight.

NF

&&

.Prev Discussion... /Issued 628 AM CDT SUN MAY 22 2016/

Aviation...
12Z TAF CYCLE

A dryline in eastern New Mexico will allow for low cloudiness to
spread across all three TAF sites this morning with IFR to MVFR
conditions through about 14Z to 16Z today. VFR conditions will
prevail after 14Z to 16Z today...with thunderstorms developing across
the western and central Panhandles after 18Z to 20Z today. The storms
will likely affect all three TAF sites after 18Z to 21Z today with
MVFR conditions and strong and erratic winds in and near the
convection. Southerly winds 15 to 25 knots with gusts near 30 to 35
knots through about 04Z to 08Z Monday...then diminishing to around 10
to 15 knots.

Schneider

Prev Discussion... /Issued 429 AM CDT SUN MAY 22 2016/

Discussion...
Dryline over the eastern plains of New Mexico today will move to near
the Texas and New Mexico state line by tonight. A surface low will
track east and south into the forecast area by Monday ushering in a
cold front across the northern portions of the Panhandles. The cold
front will become stationary Monday and then lift north as a warm
front late Monday or Monday evening. With the dryline remaining near
the Texas and New Mexico state line or across the far eastern plains
of New Mexico and a surface low and frontal boundary from
southeastern Colorado or the western Oklahoma Panhandle eastward
across the Oklahoma Panhandle or extreme southwest Kansas
Tuesday...abundant low level moisture will surge north and west into
the forecast area with chances for convection continuing today
through early this week...Monday and Tuesday...and mainly across the
eastern portions of the forecast area. Convection expected to become
severe mainly this afternoon and evening across most of the
Panhandles...and then again Monday and Tuesday afternoon and evening
and mainly across the eastern portions of the forecast area.

The surface low to track north and east across western Kansas by
Tuesday night and Wednesday lifting the warm front further north into
Kansas by the middle of this week. Dryline to remain south of the
surface low in western Kansas south into the Panhandles. Convection
expected to remain east of the Panhandles by Wednesday and Thursday
as closed upper low tracks into the southwestern states to the four
corners region late this week. Closed upper low weakens into open
wave late this week over the central and southern Rockies as the
upper level support tracks west and north of the forecast area. Drier
and warmer conditions Wednesday through Friday with the surface low
and frontal boundary finally pushing south across the Panhandles
Friday night into Saturday morning. Slightly cooler conditions
possible by next weekend.

Schneider

&&

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

&&

$$

17/6


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