Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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000
FXUS64 KOUN 110255
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
855 PM CST Sun Dec 10 2017

.UPDATE...
Updated hourly dew points/temperatures/winds based on current
trends and short-term models.

&&

.DISCUSSION...
A very dry air mass continues to be in place across Oklahoma and
western north Texas this evening. Dew points near the
Oklahoma/Texas border are in the single digits, which has kept
relative humidities below 20% at some locations even at this hour.

Similar to last night, the dry air mass, light winds, and clear
skies has resulted in local terrain effects modulating the
boundary layer temperature profile. Consequently, large
temperature differences are occuring over short distances (e.g.,
55F at the Minco Mesonet vs. 37F at the Chickasha Mesonet at 8:40
PM). The surface inversions are quite steep at the coldest
locations. For example, there is a +13F change in temperature
between 1.5 m and 9 m at the Marshall Mesonet.

Wind speeds are expected to stay relatively light tonight--
especially across the southern half of Oklahoma/adjacent parts of
north Texas. Therefore, expect local terrain effects to be the
primary factor for tonight`s lows in this area (e.g., colder low-
lying areas). In northwest Oklahoma, temperatures might be a
little more homogeneous as wind speeds will be a higher (i.e.,
more turbulent mixing).

Mahale

&&

.PREV DISCUSSION... /issued 525 PM CST Sun Dec 10 2017/

DISCUSSION...
Aviation discussion for the 00 UTC TAFs is below.

AVIATION...
VFR conditions are expected to continue.

Surface winds will remain light (under 10 kt) and vary between
northwesterly and southwesterly before 15 UTC, then increase from
the north/northwest after 15 UTC. Some gusts in northern Oklahoma
will be near 25 kt after 17 UTC.

MBS

PREV DISCUSSION... /issued 331 PM CST Sun Dec 10 2017/

DISCUSSION...
Fire Weather remains out primary forecast concern.

Near critical fire weather conditions have developed this afternoon
across portions of western Oklahoma and western north Texas. Winds
have been the limiting factor, as modest winds, 10 to 15 mph with
gusts just near 20 mph have been reported.

Overnight, a weak surface trough will slide southeast, across the
region, with north and northwest winds developing through mid to
late morning, Monday. Conditions will be similar to today, but winds
will be stronger across northwestern Oklahoma, through the
afternoon, 15 to 20 mph, gusting near 25 mph. ERC-G values, an
estimate of the state of fuels, continue to approach the 90th
percentile for western Oklahoma into the Panhandles. These
conditions, along with highs in the 60s, in addition to the breezy
winds, a Red Flag warning will be in effect for northwestern
Oklahoma. This was coordinated with our neighboring offices,
including the issuance of a Fire Weather Watch for the counties
surrounding the Warning.

With an upper level northwest flow regime persisting, temperatures
will fluctuate day to day only slightly as weak surface troughs dip
southeast across the southern plains. Highs will vary in the 50s and
60s through the end of the work week, before we`ll see a gradual
pattern change over the weekend. Therefore, fire weather will remain
our primary concern through the week ahead, with elevated conditions
persisting from Tuesday into the weekend.

Kurtz

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  36  66  33  52 /   0   0   0   0
Hobart OK         33  68  31  56 /   0   0   0   0
Wichita Falls TX  36  72  33  56 /   0   0   0   0
Gage OK           32  65  27  57 /   0   0   0   0
Ponca City OK     31  63  29  50 /   0   0   0   0
Durant OK         39  73  37  53 /   0   0   0   0

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Fire Weather Watch from Monday morning through Monday afternoon
     for OKZ006>008-011>018.

     Red Flag Warning from 11 AM to 6 PM CST Monday for OKZ004-005-
     009-010.

TX...None.
&&

$$

10/17



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