Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 200442
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
1142 PM CDT Wed Jul 19 2017

.AVIATION...
TAFS 2006/2106...

VFR conditions will prevail through the period.

&&

.PREV DISCUSSION... /issued 645 PM CDT Wed Jul 19 2017/

AVIATION...
TAFS 2000/2024...

VFR conditions will continue with a light to moderate south wind.

PREV DISCUSSION... /issued 202 PM CDT Wed Jul 19 2017/

DISCUSSION...

The primary focus will be the heat and related impacts. We ask
our partners to continue to stress the danger of heat related
illness over the next few days as hot/humid conditions persist.

On the synoptic scale, 12z 500 mb hand analysis reveals a band of
stronger flow confined to the northern Rockies and northern Plains
with weak flow prevalent across the central and southern Plains.
Broad high heights center was near Tulsa with a weak convectively
enhanced shortwave across western Iowa. Weak slow moving convection
has occurred this morning as far south as central Kansas. More
substantial MCS activity was seen on the periphery of upper high
within the band of stronger mid-level flow originating in Montana
and now moving east-southeast through the Dakotas.

A 500 mb height of 594 decameters was measured by this morning`s
sounding at Norman. This is the time of year where we see the least
spread between record min/max height values, but this is still about
6 decameters above the mean moving average and above the 90th
percentile approaching the daily maximum for the SPC sounding
climatology period of record. This will support hot conditions once
again through the rest of the afternoon. The moisture distribution
in the low levels of the sounding was slightly more favorable for
mixing down of drier air today and this should result in lower dew
points than was seen yesterday. Despite slightly higher temperatures
this should help offset heat indices some. Similar conditions are
expected tomorrow with a few locations possibly reaching Heat
Advisory criteria, particularly from north-central Oklahoma through
the far eastern portion of our forecast area.

The mid-upper high heights center should reorient itself to our east
over Arkansas Friday into Saturday while slowly deampifying. By late
Friday a compact shortwave trough should emerge onto the Canadian
prairies and trek east-southeastward toward the Great Lakes by
Saturday night. Attendant weakly baroclinic surface front should
drift southward into Kansas by Saturday. Orientation of the weak but
enhanced upper level flow will not be favorable for this boundary to
reach our area, with the exception being if it is augmented on the
western end by convection (possible MCS) that develops the previous
night from Palmer Divide and and Cheyenne Ridge into the central
High Plains.

Additional convection that occurs Saturday near a stationary surface
front across Kansas could move into far northwest Oklahoma by late
in the day. Forecast uncertainty grows by Sunday as remnant surface
front and/or convective outflow boundaries will likely be present
over the area. We favored higher precipitation probabilities across
the north, further away from flattening mid-upper ridge to our south
and where aforementioned boundaries are most likely. Another round
of diurnally driven convection may occur Monday and we were more
broad brushed with probabilities owing to uncertainty of remnant
boundary/outflow placement. GFS/GEFS are more pronounced with
aforementioned east-west oriented boundary while ECMWF becomes
laminar with southeasterly low level flow more quickly and thus has
comparatively less QPF. Flow aloft will be weak so organized
convection and severe potential is minimal during this period.

In the wake of Great Lakes/eastern trough, mid-level ridging should
gradually amplify across the western 2/3rds of the country with
neutral to weakly positive height anomalies prevailing through much
of next week across our area. This should generally mean a drier
pattern with temperatures near or slightly above normal but cooler
than this week. Once we get a little closer to this period we`ll
take a closer look at thermodynamics and introduce isolated
diurnally driven thunder if necessary, but it appears now that
coverage would be sub-20 percent.

BRB

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  74 100  76 100 /   0   0   0   0
Hobart OK         75 101  76 102 /   0   0   0   0
Wichita Falls TX  75 100  76 101 /   0   0   0   0
Gage OK           75 101  76 102 /   0   0   0   0
Ponca City OK     77 100  77 101 /   0   0   0   0
Durant OK         75  96  75  97 /   0   0   0   0

&&

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

$$


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