Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 202037

Area Forecast Discussion
National Weather Service Norman OK
337 PM CDT Sat May 20 2017

The main concern is determining rain/storm chances Sunday night
through Tuesday.

Tonight, mostly clear and cool weather can be expected. Light
surface winds and clear skies with a surface high moving into the
Southern Plains should allow for strong radiational cooling
across the area. Model guidance lows in the 40s to lower 50s,
about 10 degrees F below average for this time of year, appeared
to be reasonable. Some patchy fog may form in parts of south
central and southeastern Oklahoma where low level moisture remains
abundant from last night`s heavy rain event and where daytime
evaporation rates have been reduced as clouds have been slow to
clear this afternoon, mainly southeast of a Madill to Ada to
Holdenville line. Thus, added patchy fog mention. Doubt this fog
will get widespread or too dense due to the weak advection of low
level drier air into these areas.

Sunday appears to be a mostly sunny day with low humidity and
fairly light surface winds. Highs are forecast to be slightly
below average for this time of year.

Sunday night, isolated to scattered weak showers and thunderstorms
may occur in far northwestern Oklahoma anytime after 7 pm, and
perhaps even western north Texas after midnight. No severe storms
or heavy rainfall are expected due to limited moisture (surface
dewpoints in the 50s at most and precipitable water values only
0.7-1.2") and limited instability (MUCAPE below 500 J/kg). Most
rainfall may stay west and over west Texas and Texas/Oklahoma

Monday, rain chances will spread eastward across much of the
western two thirds of Oklahoma and western north Texas ahead of an
approaching mid/upper level disturbance. Doubt all areas will
receive rainfall. There will be chance for a few strong to severe
thunderstorms mainly in the latest Day 3 SPC Marginal Risk area
in western Oklahoma and western north Texas during the afternoon
and evening hours due to sufficient shear (0-6 km bulk shear
30-50 kt) and instability (MUCAPE 1000-2000 J/kg). If severe
storms occur, a few reports of damaging winds and large hail would
be possible. Widespread and/or high end severe storms seem
unlikely due to the lack of significant moisture/instability.
Heavy rainfall appears unlikely as well.

Late Monday night into Tuesday, a cold front will move through the
area and allow for drier air to move in north to south. Lingering
showers and storms, mainly before noon Tuesday, may occur. Highs
on Tuesday should remain on the cool side for this time of year.

Tuesday night through next Saturday, dry weather and a warming
trend are forecast due to mid/upper level ridging. Latest models
indicated that moisture and potential instability will increase by
the end of the week, but capping may be rather strong (700 mb
temperatures +10 to +13C) and limit storm development through at
least Saturday.



Oklahoma City OK  49  77  54  75 /   0   0  10  30
Hobart OK         48  79  54  75 /   0   0  10  50
Wichita Falls TX  52  80  55  77 /   0   0  10  30
Gage OK           46  77  54  72 /   0  10  20  50
Ponca City OK     47  75  53  74 /   0   0  10  40
Durant OK         54  80  56  77 /   0   0  10  30




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