Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 300000

Area Forecast Discussion
National Weather Service Norman OK
700 PM CDT Mon May 29 2017

Isolated to widely scattered showers and isolated thunderstorms
in central and northwest Oklahoma, will continue to decrease
through the early evening. More numerous showers and storms over
the High Plains will continue to move east through the evening. A
few showers/storms may enter western Oklahoma mainly after
midnight. Overall surface winds will be on the light side tonight
with slightly stronger winds Tuesday afternoon.


.PREV DISCUSSION... /issued 404 PM CDT Mon May 29 2017/

Forecast focus is on the return of rain chances the next few days
and the potential for heavy rainfall Thursday into Friday across
southern Oklahoma into north Texas.

This afternoon, a few light returns on KTLX have started to show up,
moving off the Panhandles into far northwestern Oklahoma. From
Surface obs, none of this is likely reaching the ground, presently.
However, into the evening, a weak surface boundary, supported by a
modest mid-level, 850-700mb, impulse, may result in some widely
scattered shower and thunder activity through early Tuesday morning.

Tuesday, guidance is persistent in keeping a stout 500mb trough
anchored over the eastern half of the U.S., keeping the southern
plains on the western prefer of the prominent northwesterly flow
aloft. A weak short wave, in tandem, with the lingering surface
boundary, will allow for low chances for showers and isolated
thunder across northern Oklahoma through portions of the day.

Into Wednesday, low precipitation chances persist across portions of
the area, primarily due to the weak, negatively tilted, 500mb ridge
axis from east Texas into the Panhandles. 29/12z suite of mid-range
guidance has come into better agreement, increasing confidence,
Wednesday night into Thursday. Ahead of the approaching 500mb short
trough lifting off the Trans Pecos, eastern Texas into Oklahoma will
be open to decent low level return flow from the Gulf. Surface dew
points will steadily increase Wednesday into Thursday, with mid-60s
dew points pooling across southern into central Oklahoma by Thursday
morning. Precipitation chances will begin to increase, early
Thursday across western north Texas into southwestern Oklahoma.

Thursday into Friday, a broad area of isentropic ascent will
continue to spread across north Texas into southern Oklahoma in
response to the broad northeast lift of the 500mb low. Precipitable
water values from the GFS/ECMWF/SREF/Canadian are all similar, 1.50-
1.60 in over a wide area of Oklahoma. From the SPC sounding
climatology for KOUN, the max is 1.79, and if the models verify,
we`re looking at pwats in the 90th percentile, which is... fun.
Although not a classic Maddox or Moore Et Al. scenario, aspects of
each are present and suggest a decent swath of heavy rainfall
beginning Thursday and continuing into early Friday. With a nearly
diffuse stationary front draped across Oklahoma, and increasing
850mb moisture transport and theta E advection nudging into southern
Oklahoma, confidence is there for a decent swath of appreciable
rainfall across southern into eastern Oklahoma. Following with WPC,
increased amounts and stayed relatively true to their analysis, with
3 to 4 inches likely across much of southern Oklahoma between
Thursday and Friday.

Given the amount of rainfall that has occured over portions of the
region, flood potential will be watched closely. The good news is,
if this event, as it looks now, is spread over several hours, the
flood potential could be much less.



Oklahoma City OK  61  86  63  86 /   0  10   0  20
Hobart OK         60  88  63  87 /   0  10   0  20
Wichita Falls TX  61  88  65  88 /   0  10   0  20
Gage OK           58  86  61  87 /  20  20  10  20
Ponca City OK     61  84  62  86 /  20  20  20  20
Durant OK         63  87  66  86 /   0   0   0  20



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