National Weather Service Raw Text Product

Displaying AFOS PIL: AFDFWD Received: 2018-08-10 15:57 UTC

FXUS64 KFWD 101557 AAA

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1057 AM CDT Fri Aug 10 2018

An expansive area of showers and embedded thunderstorms--roughly
along and south of the I-20/30 corridors--was forced by early-
morning isentropic upglide. Area VWPs indicate that the earlier
25-35 kt, largely convergent flow, in the 925-850 mb layer
continues to veer and weaken late this morning. As a result, the
main forcing from upglide/warm advection is diminishing, and this
explains recent trends seen in radar imagery. Overall, anticipate
a gradual downtrend in both convective vigor and coverage into 
the early-afternoon hours, with most of the precipitation in the 
form of a highly beneficial rainfall, which is certainly welcome 
relief to D3 and D4 drought-stricken North and Central Texas. I've
pared PoPs back across our immediate Red River and far southern 
counties (which unfortunately will miss out on the wetting rains).
I've also significantly cut back on PoPs later this afternoon as 
this large area of precipitation has exhausted numerous 
stabilizing outflows both to the north and south. With extremely 
weak low-level flow and a dearth of large-scale forcing 
mechanisms, convective re-development this afternoon seems pretty 
doubtful, especially given lingering meso-alpha-scale-induced 
subsidence in the wake of this morning's convection. 

Temperatures will also be tricky today, and I've trimmed several
degrees of our highs where cloud cover is expected to remain thick
into the afternoon. Locales near the Red River and Central Texas
will still likely see their temperatures rise into the low and mid
90s, but mid and upper 80s seem more likely from I-20 and down to
a Gatesville to Athens line. 



.AVIATION... /Issued 643 AM CDT Fri Aug 10 2018/
Abundant moisture and weak flow aloft is leading to another day of
disorganized convection across North and Central Texas. The
current thinking based on recent RADAR trends and high resolution
guidance is that we will likely see the two areas south of DFW 
TRACON fill in and stream slowly east this morning. The only 
TEMPO thunder group at this time is for the KACT TAF where storm 
clusters may fill in overhead during the next few hours. VCTS 
should suffice at least in the immediate future for the rest of 
the TAF sites.

After a lull in activity this afternoon and evening, additional
showers ans storms will likely redevelop overnight, but will
likely occur even farther south than the ongoing activity.



.SHORT TERM... /Issued 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.



.LONG TERM... /Issued 338 AM CDT Fri Aug 10 2018/
/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. 



Dallas-Ft. Worth    87  75  89  74  86 /  60  30  50  60  60 
Waco                87  73  89  76  89 / 100  50  50  60  50 
Paris               94  72  88  70  85 /  30  30  50  40  60 
Denton              90  73  88  71  86 /  40  30  50  50  60 
McKinney            88  73  89  72  86 /  40  30  50  50  60 
Dallas              87  75  90  76  87 /  60  30  50  60  60 
Terrell             85  73  89  73  87 / 100  40  50  50  60 
Corsicana           84  73  88  74  89 / 100  50  50  60  50 
Temple              91  72  89  73  90 /  80  50  50  60  50 
Mineral Wells       85  71  88  70  84 /  50  30  50  60  60