Area Forecast Discussion
Issued by NWS Oklahoma City, OK

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46

000
FXUS64 KOUN 281140
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
640 AM CDT Fri Apr 28 2017

.DISCUSSION...

&&

.AVIATION... /For the 12z TAFs/
VFR conditions should prevail through the day with the only
exception possibly being OKC and OUN where MVFR stratus is
possible for a period this morning. Confidence is not
particularly high and have only included as a TEMPO group for a 3
hour period where MVFR conditions would be most likely, if they
occur at all. NAM and RAP differ on degree of saturation, and a
preliminary look at the 1-second raw sounding data from KOUN
sides with the drier RAP, which leads to even lower confidence
that MVFR ceilings will occur.

The main concern for aviation will be thunderstorms this evening
and overnight. It is not clear exactly how this will play out, but
thunderstorms are expected to develop sometime this evening and
become widespread overnight. It is rare that we prevail thunder
for 6+ hours but there is a reasonably good chance that at least
the northern sites see thunderstorms for an extended period of
time. There is potential for visibility to briefly be considerably
lower than the TAF indicates. The timing indicated is the best
guess given available model guidance, with lower probabilities
earlier in the evening and much higher chances around and after
midnight.

BRB

&&

.PREV DISCUSSION... /issued 342 AM CDT Fri Apr 28 2017/

DISCUSSION...
Main concerns revolve around potential for severe weather and
flooding rainfall Friday evening through Saturday.

Initial lead shortwave making its way through the area this
morning will continue to lift to the north and northeast with
showers and isolated thunderstorms exiting the area before
sunrise. A combination of subsidence behind wave, capping
inversion above somewhat limited boundary layer moisture and
height rises are expected to limit convective activity through
much of the day today.

By this evening, several low-level/surface boundaries will be
lying across the area. Main boundaries to watch will be retreating
warm front which is expected to be just north of the I-44
corridor along with a developing dryline. This dryline looks to be
retreating west during the afternoon into the early evening as
the warm front lifts to the north and surface pressure falls occur
across west Texas in response to developing western trough. GFS
still tries to develop storms near the dryline across southern
Oklahoma into north Texas by 00Z and would expect if this does
occur to remain rather isolated as soundings would suggest low
level capping remains in place.

As upper wave approaches by late evening more widespread
thunderstorm activity is expected to occur. Very unstable airmass
will exist above the low level cap and expect main impacts with
the severe storms, as most are expected to be elevated in nature,
to be large hail. However, if a storm can maintain a more robust
updraft in the warm sector of southern Oklahoma into north Texas a
low tornado risk will exist as low level shear will increase
during the evening hours. Large hail and perhaps a few damaging
wind gusts could linger through much of the overnight period into
the morning hours on Saturday.

As we go through the day Saturday, large closed upper low will
continue to shift east and southeast with mid level flow becoming
increasing parallel to low level boundary, increasing the heavy
rain potential across much of the eastern half of Oklahoma. This
should gradually shift east of the area Saturday night into Sunday
morning, but not before many areas receive between 2 and 5 inches
of rain.

As the upper low ejects out across the area Saturday night into
Sunday morning, column may cool enough for some snow to mix with
the rain across far western and northwestern Oklahoma. Do not
anticipate any accumulations at this time as surface temperatures
remain too warm. Much cooler/colder air will once again, as has
been the case a few times this last couple of weeks, overspread
the area beginning late Saturday and Sunday. Some lingering
showers will remain possible across northern Oklahoma through the
day Sunday.

Quieter weather expected for Monday, but models amplify next wave
dropping southeast through the plains by late Tuesday into
Wednesday with another chance of rain and thunderstorms.

Dry and mild weather anticipated for Thursday into next weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  78  56  61  43 /   0  90 100  60
Hobart OK         79  50  57  40 /   0  70  80  50
Wichita Falls TX  86  62  68  44 /  10  70  60  50
Gage OK           74  42  47  34 /  10  80  80  70
Ponca City OK     75  51  58  43 /   0  90 100  70
Durant OK         82  72  75  50 /  20  50  90  70

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch from this evening through Sunday morning for OKZ025-
     026-028>032-040>043-046>048-050>052.

TX...None.
&&

$$

12/30



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.