Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 242341

Area Forecast Discussion
National Weather Service Norman OK
641 PM CDT Thu May 24 2018

00Z TAFs.


The current showers and storms across northern and central
Oklahoma should stay between the TAF stations, primarily between
KPNC and KOKC. One thing we will have to watch closely is the
storms in Colorado moving into Kansas. The HRRR model brings those
into Oklahoma late tonight, a bit earlier than when we have the
storm chances in the current TAFs based on the synoptic models
(mainly the NAM). Have not gone with this timing yet as the RAP
dissipates the current convection before reaching Oklahoma, so the
signal is still rather mixed. But if it does look like the storms
will roll in earlier or be more widespread based on radar and
satellite trends or updated runs of the high-res models, we will
update the TAFs with this scenario.


.PREV DISCUSSION... /issued 400 PM CDT Thu May 24 2018/

Primary forecast issues are the chance of thunderstorms on Friday
and hot temperatures toward the end of the forecast period.

For this afternoon/evening, a remnant MCV is resulting in
scattered to numerous thunderstorms across north central Oklahoma.
These thunderstorms are expected to continue through at least the
mid-evening hours with hail and gusty winds possible.

For Friday, there continues to be a risk of strong to severe
thunderstorms, but the location of the greatest risk will be
modulated by any remnant outflow boundary/MCV from tonight.

Various convective-allowing models (e.g., NAM NEST/HRW NSSL)
indicate an MCS and its attendant outflow boundary and/or MCV will
develop and move southward somewhere across northern Oklahoma.
The uncertainty is how far south will any remnant feature reach
before the potential for redevelopment in the afternoon.
Currently, the highest chance of redevelopment is somewhere from
northern central into west-central Oklahoma.

Environmental conditions tomorrow afternoon will be more than
sufficient for strong to severe thunderstorms. Forecast soundings
indicate large downdraft CAPE (~1500 J/kg) and steep low-level
lapse rates in the subcloud layer, so damaging wind gusts from
downbursts will be possible. In addition, effective bulk layer
shear and large/wide CAPE in the hail-growth zone suggest large
hail will be possible as well (especially with initial, single-
cellular development that could have embedded supercellular
characteristics). Organization/cold pool generation may result
convection to eventually grow upscale into an MCS. If an MCS
develops, it would likely propagate southward through the evening
hours with a continued damaging wind gust threat.

For Sunday through Tuesday, northwest Oklahoma will maintain a
low to moderate chance of showers and thunderstorms to account for
any remnant High Plains convection and/or influence from
shortwave troughs embedded in the stronger mid-level flow. This
area will on the western periphery of the mid-level ridge and
closer to a western U.S. trough. Otherwise, the forecast looks hot
and dry for most locations.

Beyond Tuesday, both the 24/12Z GFS and ECMWF indicate that a
very hot pattern may develop toward and just beyond the forecast
period with a strengthening mid-level ridge across the Southern
Plains. Forecast mid-level heights ~596 dam (more typical for July
or August) and 850 mb temperatures in the upper 20Cs to low-30Cs
would result in widespread temperatures in the upper 90Fs and low
100F. These temperatures would be near record high temperatures.



Oklahoma City OK  70  89  67  93 /  30  30  20  10
Hobart OK         70  97  67  98 /  20  30  20   0
Wichita Falls TX  71  96  70  98 /  10  20  30   0
Gage OK           69  97  65  98 /  10  20  10   0
Ponca City OK     69  87  66  94 /  50  30  20  10
Durant OK         70  91  69  92 /  10  20  30  10



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