National Weather Service Raw Text Product

Displaying AFOS PIL: AFDFWD Received: 2018-08-10 08:38 UTC

FXUS64 KFWD 100838

Area Forecast Discussion
National Weather Service Fort Worth TX
338 AM CDT Fri Aug 10 2018

/Today and Tonight/

An unsettled weather pattern will continue as we approach the
weekend due to the presence of a nearly stationary upper level 
trough and a diffuse surface front. Showers and embedded
thunderstorms will remain possible this morning, particularly in
the moisture-rich airmass south of I-20 where PWATs are generally
at or slightly above 2 inches. Diurnally driven convection will
become more widespread as we press on into the afternoon and
instability increases area-wide. Slow storm motion and abundant 
moisture points at localized flooding being the primary threat in 
the stronger convection, though a few storms may also produce 
gusty downburst winds during peak heating hours. 

Rain-cooled air should keep temperatures well below normal along 
a swath just south of the I-20 corridor where the highest coverage
of precipitation is expected based on the presence of the weak 
surface front, and have gone with upper 80s for highs in this 
region. Cloud cover and scattered convection should keep highs in 
the lower 90s elsewhere. 

Convection allowing models are hinting and a resurgence of
convection overnight, which is possible given the moisture laden 
environment and the presence of weak ascent. Will keep chance POPs
going overnight, and keep open the idea of increasing to likely
in some areas if guidance and future trends support it.



/Saturday through Friday/

By Saturday morning,  a slightly more amplified shortwave 
embedded within the longwave pattern will approach the region from
the north. Over the course of the day, this shortwave will likely
become detached from the main flow, and move southwestward as a 
closed upper level low. This feature will act as the primary upper
level support for convection through the weekend and into early 
next week. 

Given the expected positioning and evolution of this feature on
Saturday, the best rain chances will likely be for areas south of
I-20. It is in this area that PWs will remain above 2 inches and 
the possibility for heavy rain does increase. A weak jet streak 
will develop on the eastern side of the upper level low, helping 
to kick up some additional showers and storms for areas across 
North Texas.

Sunday's story will be much like Saturday with the upper level
closed low parked in the Texas Panhandle. The one difference will
be that upper level heights will be slightly higher across 
Louisiana and into East Texas, implying the presence of weak 
ridging trying to develop east of the region. Low and mid level 
winds will respond to the weak ridging and help transport abundant
moisture into the region, especially west of I-35. The overall 
consensus is that the best associated lift will also be west of 
I-35. Given widespread PWs of 2+ inches across the region, 
mesoscale features will likely play a role in additional 
development east of I-35. 

Model guidance continues to show much drier air mass making its
way from the Gulf of Mexico across the region Monday into Monday
night. Rain chances will still be relatively high west of I-35 
given the presence of moisture rich air. The closed low that had 
been stalled across the Texas Panhandle will jump back into the 
steering flow on Tuesday, leading to decreasing rain chances 
through the day. 

Another ripple in the atmosphere will flow southeastward across
the region Wednesday into Thursday. The ECMWF has this shortwave 
much more removed from North Texas, while the GFS continues to 
drive it into Oklahoma and Arkansas. For now, will maintain a low 
chance for showers and storms mainly along the Red River. 

Region wide temperatures are likely to remain below normal through
Monday given the extensive cloud cover and rain potential.  With 
the arrival of the dry air and less clouds on Tuesday, 
temperatures will begin an upward trend, but still remain around 
normal for this time of the year. 



.AVIATION... /Issued 1157 PM CDT Thu Aug 9 2018/
/06Z TAFs/

Undaunted by nightfall, a cluster of thunderstorms was able to
feed off an inordinate amount of instability on the northern
fringes of the Metroplex, surviving deep into the evening. 
Although the activity was primarily to the north and northeast of 
the big airports in the Metroplex, it caused considerable 
disruptions to commercial operations. A few sprinkles of light
rain will still be possible from the remaining mid clouds, but the
updrafts will no longer be supportive of lightning.

A low-level trough will remain draped across the Metroplex
overnight. This will promote some continued upglide, but the main
corridor of warm/moist advection will be oriented through Central
Texas into East Texas. Despite being worked over late this 
afternoon, this buoyant inflow beneath steep lapse rates aloft 
will promote the redevelopment of thunderstorms across Central 
Texas. Late in the evening, some precip-bearing updrafts had
already returned to areas west of I-35 and south of I-20. This 
activity should steadily increase in intensity and areal coverage 
during the early morning hours, eventually producing some embedded
thunderstorms with steep lapse rates aloft. Morning showers will 
be possible as far north as the Metroplex, but the environment 
across North Central Texas will be less favorable for thunder.

The wind field has been governed by outflow, but with the
proximity of surface troughing, light easterly winds should take
hold across the Metroplex, veering to the southeast by daybreak.
Outside of renewed outflow, south flow will prevail through

With a moisture-rich boundary layer still in place on Friday
beneath weak troughing aloft, some redevelopment of thunderstorms
should occur at peak heating. The weak surface wind field will
allow residual boundaries to linger. With much of the forcing on 
the mesoscale, initiation will be largely dictated by the location
of these boundaries, which may be determined by the nocturnal 
activity that has yet to occur. Despite the uncertainties in
placement, the timing of this convection would be focused yet
again during the typical peak heating period. As a result, will 
introduce some late afternoon/early evening thunder in the TAFs.



Dallas-Ft. Worth    90  75  89  74  86 /  50  30  50  60  60 
Waco                91  73  89  76  89 /  70  50  50  60  50 
Paris               92  72  88  70  85 /  40  30  50  40  60 
Denton              92  73  88  71  86 /  40  30  50  50  60 
McKinney            92  73  89  72  86 /  40  30  50  50  60 
Dallas              92  75  90  76  87 /  50  30  50  60  60 
Terrell             91  73  89  73  87 /  50  40  50  50  60 
Corsicana           89  73  88  74  89 /  70  50  50  60  50 
Temple              92  72  89  73  90 /  70  50  50  60  50 
Mineral Wells       89  71  88  70  84 /  60  30  50  60  60