Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 201151
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
651 AM CDT TUE SEP 20 2016

.UPDATE...
Updated forecast to include patchy fog and issued 12z TAFs.

&&

.DISCUSSION...
Fog has spread farther into the forecast area with KWDG down to
3/4sm (although KEND nearby is still 7sm) and KADM is down to
1/2sm (although K1F0 nearby is also still 7sm). It may be patchy,
but the visibility is still low enough at places to include the
mention of fog. And with high dewpoints continuing to advect into
the area, the fog may become a little more widespread briefly this
morning.

&&

.AVIATION...
Despite the patchy fog, the visibility reduction is not affecting
the TAF sites and at the moment the probability is not high enough
to include a tempo group in the TAFs. Will continue to watch
trends and amend if necessary.

&&

.PREV DISCUSSION... /issued 355 AM CDT TUE SEP 20 2016/

DISCUSSION...

The main issues in the short term are unseasonable warmth and poorly
modeled dewpoints. Dewpoints came in much higher than forecast by
the models yesterday and we ended up with widespread heat index
values between 105 and 110. Most of the explicit model dewpoint
forecasts are already quite low this morning, so we appear to be
already set up for dewpoints higher than models are forecasting.
Increased dewpoints in the grids a few degrees for today and
tonight, but this still may be low especially given the 00z ECMWF
finally coming on board with 75-76 dewpoints southeast at
00Z/Wednesday. The calculated heat index values with the grids do
support another heat advisory today for counties along and east
of US-81. Low-level winds do become more easterly late tonight and
early Wednesday above the surface which will advect lower low-
level dewpoints into the eastern sections of the area and shift
the moisture axis farther west. Although have raised dewpoints
tomorrow up from initialized model values, they are still forecast
to be somewhat lower tomorrow keeping heat index values in check.

Later this week, the forecast high-amplitude mid-level trough
approaches the Plains with associated precipitation chances.
Energy associated with the northern part of this trough keeps
moving east into the Great Lakes region this weekend which helps
nudge a cold front down the Plains and into the area late Saturday
or early Sunday. But the south end of the trough looks like it may
get cut off over the four-corners states which keep the area
under a southwest flow aloft into early next week.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  95  72  93  69 /   0   0   0   0
Hobart OK         96  71  94  69 /   0   0   0   0
Wichita Falls TX  98  72  95  70 /   0   0   0   0
Gage OK           96  71  93  70 /   0   0   0  10
Ponca City OK     96  71  93  68 /   0   0   0   0
Durant OK         96  71  94  69 /   0   0   0   0

&&

.OUN Watches/Warnings/Advisories...
OK...Heat Advisory from 1 PM this afternoon to 7 PM CDT this evening
     for OKZ007-008-012-013-018>020-024>032-039>043-045>048-
     050>052.

TX...None.
&&

$$



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