Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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187
FXUS64 KOUN 172038
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
338 PM CDT Thu Aug 17 2017

.DISCUSSION...
Subsidence behind eastward moving shortwave trough over the Great
Lakes and in the wake of MCS has resulted in mostly clear skies
across the area this afternoon. Some diurnal cumulus development
has been noted where low level moisture remains highest, mainly
across south-central and southeast Oklahoma. More extensive
vertical growth of cumulus and convective development should be
confined to just south of our forecast area.

Strengthening moist southerly flow over the High Plains should
support some diurnal surface based convective development later
today where 0-2 km stream lines are slightly convergent and near
the Raton Mesa. This would then move eastward with mean flow and
possibly grow up scale slightly potentially reaching our northwest
counties late this evening and progressing eastward in a weakened
state overnight. Models show a thin layer of enhanced mid-level
moisture on the 315k surface. Models can sometimes struggle with
depicting the details of moisture in these scenarios and this is
the main source of uncertainty in the overnight forecast. If mid-
level moisture is as extensive or more extensive than short term
guidance suggests, this would contribute to at least weak MUCAPE
and support elevated convection through tomorrow morning,
primarily over the northern half of the forecast area.

Current thinking is that overnight and early morning convection
shouldn`t be as deleterious to later afternoon potential as some
of the recent more intense MCSs. Later in the afternoon, moderate
to strong instability should develop near a weak cold front across
northwest Oklahoma. Mid-level height rises may work against
convective development, but given the degree of diabatic
heating/destabilization, isolated to scattered thunderstorm should
form within this zone of convergence. Deep layer shear should be
marginally supportive of storm organization and some wind/hail
potential. Some consolidation and increase in coverage may occur
through late evening as storms move eastward potentially lasting
into the night.

A drier pattern should develop this weekend into next week as mean
ridging builds slightly. We`ll need to watch boundary layer
moisture characteristics. If models are under forecasting low
level moisture slightly, isolated diurnal convective development
may become more likely. Otherwise, there may be a period of weak
synoptic scale forcing to aid in convective development late
Tuesday and Tuesday night.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  70  90  73  94 /  10  30  40  10
Hobart OK         72  94  74  96 /  20  20  30  10
Wichita Falls TX  73  94  74  96 /  10  10  20  10
Gage OK           68  92  69  94 /  30  40  40  10
Ponca City OK     69  90  70  92 /  20  30  40  10
Durant OK         72  92  74  95 /  10  20  30  20

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...None.
TX...None.
&&

$$

25/12



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