National Weather Service Raw Text Product

Displaying AFOS PIL: AFDOUN Received: 2018-08-10 09:18 UTC

FXUS64 KOUN 100918

Area Forecast Discussion
National Weather Service Norman OK
418 AM CDT Fri Aug 10 2018



VFR conditions and light winds are expected to persist until
111200. Isolated showers and thunderstorms are expected most
anywhere across Oklahoma this afternoon, but coverage is too low
to include in most TAF sites.


.PREV DISCUSSION... /issued 345 AM CDT Fri Aug 10 2018/ 

There were only a few minor changes to the previous forecast. We 
will transition into a cooler/wetter pattern this weekend through 
the first half of next week. Weather hazards should be minimal.
Heavy rain could lead to flooding in some areas by early next
week, although this appears to be a localized/low end threat at
this time. 

A moist and unstable airmass later this afternoon coupled with 
forcing from approaching minor shortwave trough should result in 
development of isolated to scattered thunderstorms today across most 
of the area. Storm organization/persistence is unlikely given weak 
deep layer shear, but in a moderately unstable environment, short-
lived updrafts in single cells and multi cells could result in 
brief strong wind gusts this afternoon through early evening.

A broad weak upper low will evolve from the aforementioned
shortwave over the area by Saturday. Negative 500-hPa height
anomalies associated with this system as moisture through a
significant depth persisting, will lead to the potential for
widespread precipitation in the form of generally weak convection.
Mid-level lapse rates in these scenarios are typically weak given
large amounts of latent heat release from persistent recurring
convection, and absence of differential advection/EML due to more
southerly/meridional trajectories through a deep layer. Thus,
severe thunderstorms are unlikely. 

However, these profiles can support efficient warm rain processes
through collision-coalescence and bring high rainfall amounts.
While this may not materialize as a more robust deep/intense
convective event with backbuilding/training, cumulative rainfall
amounts could result in flooding for some areas. We'll watch
trends for this potential closely. 

Increased clouds and rain showers should result in temperatures
well below mid-August climo Sun-Tue, and probably cooler than the
blended approach we stuck with in this forecast package. 

Medium range guidance is in reasonably good agreement with opening
the low up and moving it northeast by mid-week. ECMWF/EPS is not
quite as progressive as GFS, although most of the guidance
generally supports decreasing rain chances for the latter half of
the week. Still, some periodic convection could occur as weak
shortwave troughs traverse the area in northwesterly flow aloft,
albeit not as widespread as the early week pattern. Models fail to
show noteworthy building of heights/increased ridging until
perhaps the following weekend (beyond the current forecast



Oklahoma City OK  91  71  89  69 /  20  20  30  30 
Hobart OK         93  71  91  68 /  30  20  30  30 
Wichita Falls TX  93  72  90  70 /  30  20  30  40 
Gage OK           91  64  90  65 /  20  10  10  20 
Ponca City OK     94  68  91  69 /  30  20  20  10 
Durant OK         92  72  88  70 /  20  20  30  40