Area Forecast Discussion
Issued by NWS Oklahoma City, OK

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FXUS64 KOUN 201102
AFDOUN

Area Forecast Discussion
National Weather Service Norman OK
602 AM CDT Tue Aug 20 2019

.DISCUSSION...
12Z TAF discussion.

&&

.AVIATION...
VFR conditions to continue. Mainly mid and high clouds expected
with south winds around 10kts. Could see some isolated
thunderstorms in northwest Oklahoma this evening, but chances
remain too low to mention in WWR TAF at this time.

&&

.PREV DISCUSSION... /issued 355 AM CDT Tue Aug 20 2019/

DISCUSSION...
..Dangerous Heat Indicies Continue Today and Wednesday...

Another hot and humid day is expected across the area with a mid-
level ridge centered across the Southern Plains. The OUN RAOB had a
596 dam height at 500 mb and 25 C temperature at 850 mb last
evening. The expectation is similar synoptic conditions today,
which should result in high temperatures in the upper 90s to mid
100s F. Afternoon dewpoints are expected to be in the 60s and 70s F
once again, which will result in dangerous heat indicies from 105
to 115 F across much of the area.

Isolated to widely scattered showers and thunderstorms may develop
across far northwest Oklahoma late afternoon into the evening hours.
Any thunderstorms could produce gusty winds as they collapse due to
relatively high temperature-dewpoint spreads and downdraft CAPE.

By Wednesday, a mid-level trough is forecast to dig across the
Midwest. As this occurs, the mid-level ridge will become less
amplified. This should result in slightly lower temperatures
Wednesday afternoon--especially across the north. However, mid 90s
to low 100s F are still expected for most locations. Opted to issue
a Heat Advisory for central and south central Oklahoma where
dewpoints will likely remain high enough for 105+ F heat indicies.
Confidence is lower near the Oklahoma/Kansas border where convection
and/or cloud cover could temper temperatures.

The attendant cold front associated with the trough is expected to
move into at least northern/northeastern Oklahoma late Wednesday
into Thursday with a chance for showers and thunderstorms. The
primary hazard with any thunderstorms will be damaging wind gusts.

For Thursday afternoon through Saturday, convection chances will
be modulated by the day-to-day location of any effective
boundaries and any subtle shortwave troughs (as the synoptic front
should dissipate).

Precipitable water values will be quite high (~1.5 to 2.0")
during this period, so it would not take much forcing for some
convection. Confidence on exact locations are low given the day-
to-day dependency; however, it currently appears the highest
probabilities for rain will be across north central into eastern
Oklahoma (where the coolest temperatures are also forecast). The
lowest chances will be across western north Texas.

The mid-level ridge may expand back to the east by early next week,
which would result in warming trend for Sunday and Monday.

Mahale

&&

.PRELIMINARY POINT TEMPS/POPS...
Oklahoma City OK 100  77  97  75 /   0  10  10  20
Hobart OK        102  76 101  75 /   0  10  10  20
Wichita Falls TX 102  77 100  77 /   0   0   0  10
Gage OK           99  72  96  69 /  10  20  20  30
Ponca City OK     99  76  93  72 /   0  10  20  40
Durant OK         99  77  97  76 /   0   0   0  10

&&

.OUN WATCHES/WARNINGS/ADVISORIES...
OK...Excessive Heat Warning from noon today to 9 PM CDT this evening
     for OKZ007-008-012-013-019-020-026-030>032.

     Heat Advisory from noon to 9 PM CDT Wednesday for OKZ018>020-
     024>032-040>043-046>048-050>052.

     Heat Advisory from noon today to 9 PM CDT this evening for
     OKZ006-011-017-018-023>025-027>029-037>048-050>052.

TX...Heat Advisory from noon today to 9 PM CDT this evening for
     TXZ083>090.

&&

$$

30/10/30


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