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fxus64 koun 270432 aac 
afdoun

Area forecast discussion...updated
National Weather Service Norman OK
1032 PM CST sun Feb 26 2017

Aviation...
27/06z tafs. Visibility/ceiling trends still expected to diminish
late tonight and Monday morning as low level moisture gets drawn
northward. Mainly IFR-MVFR primarily from ksps and klaw up toward
kokc and eventually kpnc. Impacts over far western Oklahoma
expected to be brief as lower level winds veer quickly to
southwest after daybreak. Will keep MVFR kokc to kpnc tomorrow
afternoon.

Previous discussion... /issued 723 PM CST sun Feb 26 2017/

Update...

Discussion...
minor changes were made based on trends in observations and short
term guidance. Our evening sounding shows a pronounced capping eml
with low levels still quite dry. A saturated layer further up is
associated with mid-level clouds that should continue to slowly
move east. We may have a period early in the night where minimal
cloud cover and light winds allow temperatures to drop fairly
quickly and we have accounted for this in the update to the hourly
temperatures. The significance of this may be that temperatures
fall low enough such that when low level moisture moves in with
strengthening southeasterly winds later tonight, some fog could
form. We will monitor trends and adjust the forecast as needed,
but this does not appear to be a particularly robust fog scenario
and it's still quite conditional.

Ascent/mid-level height falls with approaching low amplitude
shortwave trough should be minimal and likely not sufficient to
erode aforementioned warm layer. The best chance of this happening
would be near the Red River and across our far southeast
counties, but confidence in convection occuring is not
particularly high. Short term guidance may be too aggressive with
moisture depth but some models do suggest sufficient depth for
drizzle even as far northwest as Oklahoma City and as far west as
Wichita Falls late tonight through at least early morning. We have
added this to the forecast.

Other very minor adjustments were made. Hourly temperatures were
adjusted to show a stronger non-climatological pattern as warm
advection strengthens late in the night causing lows for many
locations to occur well before sunrise. Sky cover was increased
late tonight through tomorrow morning given high confidence in low
stratus overspreading much of the area.

Additional updates may be needed as we continue to assess fog
potential.

Brb

Previous discussion... /issued 539 PM CST sun Feb 26 2017/

Aviation...
27/00z tafs. Visibility/ceilings expected to fall into IFR from
ksps northward through most of Oklahoma terminals late tonight and
tomorrow morning as warm front develops near Red River and lifts
north as 50+ dewpoints spread northward into large area of 40
degree T/TD low level environment. Conditions will improve over
western Oklahoma into ksps toward and after 18z as low level flow
veers and mixing increases. Will likely stay at least MVFR
tomorrow afternoon near and east of kokc-kpnc. Drizzle and perhaps
showers possible late tonight and Monday morning but main
restriction will be fog and stratus.

Previous discussion... /issued 353 PM CST sun Feb 26 2017/

Discussion...
for tonight, scattered showers/storms will be possible across
southeast Oklahoma as isentropic ascent increases and a warm front
lifts northward. As this front lifts northward, abundant cloud
cover is expected for most locations on Monday. Showers and
isolated storms will remain possible as well--especially east of
Interstate-35.

By Tuesday, a mid/upper-level trough will eject into the Southern
Plains. In response, a surface low is expected to develop across
the Oklahoma Panhandle and shift eastward through the day. This
will veer the surface to 700 mb winds toward the southwest/west,
which will propagate a dryline eastward into western
Oklahoma/North Texas. Mixing behind the dryline will allow 45+
knot 850-700 mb winds to at least partially reach the surface--
especially across the west. Therefore, locations near the 100th
Meridian could see wind gusts over 45 mph. The combination of
warm temperatures, low relative humidity, and gusty winds will
result in a critical to extreme fire weather conditions.
Therefore, opted to issue a Fire Weather Watch for Tuesday.

Across eastern Oklahoma, progged moisture advection is forecast
to advect 60f+ dewpoints into the region. These dewpoints will be
sufficient for MLCAPE of 800-1200 j/kg. In addition, effective
bulk shear is progged to be 50-55 knots. This combination of
instability/shear will provide a parameter space that could result
in some strong to severe thunderstorms Tuesday.

A cold front is expected to pass by Tuesday night, bringing a
return to more seasonable temperatures for Wednesday. At least
elevated fire weather conditions will continue on Wednesday with
breezy northerly winds.

Many locations are expected to see a freeze by Thursday morning
with a surface ridge overhead. As the ridge shifts eastward,
southerly winds will return by Thursday with a warming trend into
next weekend (with a continued elevated fire weather conditions).

Mahale

&&

Preliminary point temps/pops...
Oklahoma City OK 43 65 51 78 / 10 10 10 0
Hobart OK 39 66 46 79 / 10 0 0 0
Wichita Falls Texas 46 74 52 82 / 10 10 10 10
gage OK 32 70 45 75 / 0 0 0 10
Ponca City OK 35 65 49 74 / 10 20 0 10
Durant OK 50 70 58 78 / 40 20 10 30

&&

Oun watches/warnings/advisories...
OK...Fire Weather Watch from Tuesday afternoon through Tuesday
evening for okz004-005-009>011-014>017-021>023-033>038-044.

Texas...Fire Weather Watch from Tuesday afternoon through Tuesday
evening for txz083>089.

&&

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