Area Forecast Discussion
Issued by NWS Oklahoma City, OK
FXUS64 KOUN 251454
Area Forecast Discussion
National Weather Service Norman OK
954 AM CDT THU AUG 25 2016
Flood Watch issued for portions of western and northern Oklahoma
for this evening and overnight.
For this morning and early afternoon, 14Z surface analysis
reveals the frontal boundary continues to loiter over
west/northwest Oklahoma, with scattered showers and isolated
thunder persisting along the boundary. Looking at model soundings
across western Oklahoma, and from radar/sat trends, it`s rather
stable across the area. Expect some decrease in shower activity
as, what little there was, of the low level jet decreases as well.
Several CAMs have picked up on this signal hand have pulled back
on convection through the late morning and the early to mid
afternoon. Agreeing with this scenario, trimmed back precipitation
chances, confining them to western and northern Oklahoma and
western north Texas through the afternoon.
Into the late afternoon, the short wave trough lifting off the
western high plains of New Mexico and the Panhandles will result
in increasing deep layer shear across the Panhandles into
northwestern Oklahoma. Additionally, Water Vapor imagery continues
to reveal an decent swath of gulf moisture feeding across Texas
into Oklahoma. This coupled with afternoon heating will help
develop MLCAPE values between 1500 and 2000 J/kg. Similar to
yesterday evening, storms will be capable of damaging wind gusts,
the primary severe concern, quarter to half dollar sized hail.
Of greater interest, tonight, will be flooding concerns, pwat
values are between the 75 and 90th percentiles for the time of
year, with 1.5 to 1.75 inches. With a slow, nearly stalled frontal
boundary providing focusing, locally heavy rainfall is more than
likely. Given the past two days of moderate to heavy rainfall,
there is a corridor across western and northern Oklahoma that
could easily see flash flooding concerns increase overnight. Given
these conditions, a Flood Watch has been issued for portions of
western and northern Oklahoma for Flash Flooding.
.PREV DISCUSSION... /issued 635 AM CDT THU AUG 25 2016/
The August 25, 2016 12 UTC TAF discussion is below.
Generally expect VFR conditions at most terminals through the TAF
period; however, moderate to heavy showers and thunderstorms that
would reduce visibility to MVFR to IFR conditons are likely in
northwest Oklahoma tonight.
Showers and isolated thunderstorms should dissipate this morning
and are not expected to restrict flight conditions. Showers and
thunderstorms are expected to develop in northwest Oklahoma this
afternoon and tonight, which will likely impact KGAG and KWWR--
especially after 00Z. Showers and thunderstorms may also impact
KCSM/KHBR/KPNC, but only included PROB30s at these sites for now.
Even lower confidence of impact for KOKC and KOUN, so opted not to
include in TAFS for now.
Winds will be light and variable across northwest Oklahoma in the
vicinity of a weak wind shift. Elsewhere, surface winds will be
predominantly from the south to southwest, but will be relatively
light (<12 knots).
PREV DISCUSSION... /issued 419 AM CDT THU AUG 25 2016/
Anomalous southwest flow aloft will continue another day of
unsettled weather, primarily across western and northern Oklahoma.
In addition, a cold front in northwest Oklahoma is expected to
slowly shift southward today; the cold front should enhance the
convective potential in its vicinity.
Effective bulk shear (>35 knots) and instability (MLCAPE >2000
J/kg) will be more than sufficient for strong to severe
thunderstorms once again this afternoon/evening. Progged DCAPE
near 1500 J/kg suggests damaging straight-line winds will be
possible. Storms may also exhibit occasional supercellular
characteristics with the progged combination of shear/instability.
Heavy rainfall/localized flooding will also be a hazard as
thunderstorms may train over the same locations as mid-level flow
is expected to be quasi-parallel to the cold front.
Opted to raise high temperatures today above initial guidance based
on high temperatures yesterday and similar low-level thermal
fields progged today. Temperatures will likely get hot (upper 90s)
in north central Oklahoma, ahead of the boundary.
Beyond today, the mid-level/500 mb ridge is progged to stay to our
east through the forecast period. Mid-level flow will weaken,
which should reduce the potential for any severe weather. Embedded
vorticity maxima/shortwave troughs are expected to rotate around
the periphery of the ridge, which will enhance chance of
showers/storms, primarily across eastern Oklahoma. In addition,
embedded shortwaves within the westerlies across the Plains will
enhance the chance of showers/storms across northern Oklahoma.
Therefore, there will be a persistent chance of showers/storms
through the forecast period with the greatest chances generally
across northern/eastern Oklahoma.
.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 92 70 90 70 / 10 30 20 10
Hobart OK 92 68 91 70 / 30 30 10 10
Wichita Falls TX 93 71 93 71 / 10 20 20 10
Gage OK 86 64 89 66 / 50 70 20 20
Ponca City OK 90 69 88 71 / 20 50 30 20
Durant OK 93 72 89 71 / 0 10 50 20