Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 190547 AAC
AFDOUN

Area Forecast Discussion...UPDATED
National Weather Service Norman OK
1247 AM CDT Fri May 19 2017

.AVIATION...
19/06Z TAFs. MVFR cigs expected to expand once again late tonight
and last through at least 18Z many locations. IFR conditions
possible across far northwest Oklahoma terminals near and in post
frontal regime. Storms first 4 to 6 hours of forecast expected to
stay isolated enough to not mention in forecast and may stay
between KOKC and KPNC and will be monitored. Prevailing
thunderstorms expected latter part of forecast period as cold
front makes its move south and convection increases in coverage.

&&

.PREV DISCUSSION... /issued 655 PM CDT Thu May 18 2017/

UPDATE...
Mesoscale update is below.

DISCUSSION...
Severe thunderstorms will continue this evening mainly southeast
of I-44 and north of I-40.

Tornadoes remain possible this evening mainly with the ongoing
storms near and southeast of a Seymour Texas to Wichita Falls to
Walters to Purcell to Shawnee line where the air is most unstable
with MLCAPE 2000-4000 J/kg. Northwest of this line, the tornado
threat is lower due to cooler and more stable air from earlier
storms. Believe the tornado threat will slowly decrease after 8 pm
and be very low after midnight across the entire area.

Think storms will continue to move east over the next several
hours and affect locations mentioned in the top sentence. Large
hail and damaging winds will be possible with any storm. Severe
potential should decrease in most locations after 10 pm this
evening with the loss of daytime heating.

Heavy rainfall is another concern tonight. The complex of storms
from Wichita Falls to Walters will slowly move east over the next
few hours and produce very heavy rainfall as well as possible
localized flooding. There is some potential that new elevated storms,
mainly below severe limits, form later tonight somewhere across
the western two thirds of Oklahoma and western north Texas.
Pinpointing where and when this development occurs remain very
challenging.

Aviation discussion for the 00 UTC TAFs is below.

MBS

AVIATION...
Have low confidence in the TAFs.

Pinpointing when and where TSRA occurs remains very challenging.
Only kept mention before 03 UTC at some sites, mainly near KSPS,
KLAW, KOKC, KOUN, and KPNC. After 03 UTC, ISO-NUM TSRA may occur
across the area, but did not mention in the TAFs due to much
uncertainty on when and where TSRA occurs.

Generally, VFR conditions are forecast to become MVFR at most
sites 06-12 UTC. IFR conditions are possible as well, but only
mentioned these conditions near KWWR and KGAG where confidence of
occurrence is moderate 11-15 UTC. A slow improvement in conditions
can be expected after 15 UTC.

MBS

OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch through Saturday morning for OKZ005>048-050>052.

TX...Flood Watch through Saturday morning for TXZ083>090.

$$


&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK  55  71  50  75 /  90  20  10   0
Hobart OK         53  73  49  77 /  70  10  10   0
Wichita Falls TX  58  76  53  80 /  80  20  10   0
Gage OK           47  69  46  77 /  30   0   0   0
Ponca City OK     54  69  48  74 /  80  10  10   0
Durant OK         66  76  55  79 /  80  60  20  10

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Flood Watch through Saturday morning for OKZ005>048-050>052.

TX...Flood Watch through Saturday morning for TXZ083>090.

&&

$$

26/11



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