352 
FXUS64 KFWD 121233
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
733 AM CDT Tue Jun 12 2018


.UPDATE...
Quick update this morning to address upstream convective complex.

The storm complex across parts of Central and Eastern Oklahoma 
continues to plow southward. With the complex maintaining its 
linear structure a bit longer than suggested by CAMs through 
sunrise, there's an increased potential that it'll survive 
southward as surface based convective inhibition erodes with the 
onset of diabatic heating. While I'm a little hesitant to blindly 
follow suite with the 10 UTC HRRR, building instability and 
convergence along a probable outflow boundary should equate to a 
realistic chance for this thunderstorm complex to continue 
southward. Strict extrapolation yield a time of arrival of around 
15 to 18 UTC around the Red River. For this time frame, I've 
raised PoPs considerably. 

Farther south, there is still a large degree of uncertainty as to
what happens this afternoon. Again, the 10 UTC HRRR offers a 
plausible scenario in which the convective cells develop along the
leading edge gust front/outflow. Forecast soundings also suggest 
that the boundary layer will become hot and well mixed with 
inverted-v profiles. This will support large DCAPE values and the 
potential for thunderstorm clusters along southward propagating 
outflows. I've nudged PoPs upward across parts of North and East 
Texas where this seems more likely. 

In terms of severe weather, the potential is certainly non-zero. 
While deep layer shear will be lacking, thunderstorms that do re- 
develop will do so in an environment characterized by steep 0-3 
km lapse rates and DCAPE values near 1500 J/kg. This will 
necessitate a downburst risk with severe-caliber wind speeds. 

24

&&


.AVIATION... /Issued 657 AM CDT Tue Jun 12 2018/
12 UTC TAF Cycle

Concerns---MVFR stratus cessation & afternoon convective chances.

Patchy MVFR stratus continues its trek northward this morning 
aided by a 20 to 30 knot low level jet. This stratus will 
gradually lift and erode through the 15-16 UTC time frame with 
VFR likely through the rest of the morning. The attention will 
then turn upstream across Oklahoma where a line of TS continues to
plunge southward. At this time, it appears more likely that a 
bulk of this activity will make it to the Red River such that 
disruptions to the Bowie cornerpost and northbound departures 
appear more probable. The convection may become less linear and more
cellular as it nears the I-20 corridor from the north and thru 
midday. Additional SHRA and TS clusters are expected to develop 
along an outflow boundary and as a result, I've elected to add in 
a mention of VCTS between 19-22 UTC for this afternoon at the 
Metroplex. While not reflected in the current set of TAFs, an 
outflow boundary may result in a brief wind shift to the north. 
This and the potential for TEMPO TS will be monitored through the 
morning hours. For Waco, I've kept the TAF precipitation-free, but
if the TS complex across Oklahoma is able to maintain more of a 
linear structure, an inclusion of VCSH or VCTS may be needed. 

MVFR stratus may attempt to make another run at the Waco TAF site
on Wednesday morning and for now, will have cigs around FL030. 
The potential at the Metroplex TAFs is non-zero, but too low to 
include in the TAF at this time.

24

&&

.SHORT TERM... /Issued 321 AM CDT Tue Jun 12 2018/
/Today and Tonight/

The main challenge during the short term will be the potential 
for showers and a few thunderstorms this morning, this afternoon 
and early Wednesday morning. Otherwise, it'll be hot with daytime 
temperatures in the upper 90s to near 100 degrees with overnight 
lows in the mid to upper 70s. 

Regional radar imagery this hour indicated a stout cluster of 
storms was diving southward out of the Flint Hills of SE Kansas. 
WSR-88D VWPs in advance of this complex sampled an unseasonably 
strong LLJ of around 25 to 35 knots this morning and this will 
likely fuel the storms over the next 2-4 hours. A strong consensus
of NWP, indicates that the magnitude of the low level wind field 
will gradually veer and diminish towards daybreak with 850mb winds
falling to or below 20 knots. This would result in the swift 
demise of this complex and at this time, this appears like the 
most probable solution. As such, I'll maintain just a low chance 
for showers and storms along the Red River from mid- morning into 
the early afternoon hours. While the veering and weakening LLJ 
this would certainly limit the influx of higher theta-e air into 
the MCS and thus support the conservative PoP forecast, there is a
big caveat that could result in its sustenance farther south than
advertise. If convection is able to continue through sunrise, 
it's possible that surface based inhibition could diminish enough 
such that new updrafts develop and continue to trudge southward 
along the advancing cold pool and beneath the northerly steering 
flow along the eastern periphery of the H5 ridge. If this scenario
is to unfold, some noteworthy changes to forecast PoP, Wind, QPF 
and T grids will be required. Again, it's probable that this
activity will diminish with just some remnant outflow slipping
south of the Red River. This potential seems high enough and I'll
keep a 20 PoP between HWY 380 and the Red River even in the
afternoon hours.  

Additional afternoon convection is anticipated as the sea breeze 
front across the upper Texas Coast develops. Similar to the past 
several days, showers/storms will likely reinforce this boundary 
northward via stochastic outflow collisions. The most probable 
locations for this afternoon convection will be across the Brazos 
Valley and East Texas. We will have to monitor the potential for 
storms capable of strong winds this morning and especially this 
afternoon when the potential for downburst winds will be greatest.

Otherwise, it'll be hot today with widespread mid to upper 90s for
temperatures. A few temperature readings near or just above 100 
degrees will be possible west of the HWY 281 corridor where the 
influence of the H5 ridge will be the greatest. Heat index values 
will climb into the 103-105 degree range today. With heat index 
values expected to be a tad lower on Wednesday (upper 90s), we'll 
forgo the issuance of a Heat Advisory. Overnight into Wednesday 
morning will remain mild and sultry as low level winds remain 
elevated and minimize boundary layer decoupling.

24

&&

.LONG TERM... /Issued 321 AM CDT Tue Jun 12 2018/
/Wednesday through Monday/

Upper level high pressure will remain centered near the Texas/New
Mexico border on Wednesday while a weak cold front stalls out 
across the Central Plains. Thunderstorms will likely accompany the
cold front but these should weaken as they move into more stable 
air near the Red River. Morning clouds associated with the dying 
storm complex as well as some northward moving stratus will all 
scatter or clear by Wednesday afternoon allowing temperatures to 
warm into the mid 90s.

The ridge of high pressure will build eastward Wednesday night
through Thursday which will keep hot and subsident air in place. 
However, a few afternoon showers and thunderstorms may still 
develop across the extreme southeast zones as the sea breeze 
front moves northward from the upper Texas coast. 

The ridge axis is progged to move east of the region on Friday
while an upper trough moves northward across the Gulf of Mexico. 
As this upper trough approaches the Texas Coast it will bring a 
significant increase in deep layer moisture through the weekend 
with increasing precipitation chances from south to north. 
Precipitable water values are forecast to reach or exceed 2 inches
across the forecast area Sunday and Monday. The combination of 
moisture, surface heating and weak perturbations on the western 
periphery of the upper ridge will result in scattered to numerous 
showers and thunderstorms, especially as we move into early next 
week. These storms will be efficient rain produces and should 
bring some much needed moisture to the parched ground currently 
in place across much of North and Central Texas.

High temperatures this weekend through early next week will 
gradually cool due to the increase in moisture/cloud cover with 
near normal values in the upper 80s and lower 90s expected by 
Monday. Lows will remain in the 70s through early next week. 

79

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    96  78  96  77  96 /  30  10  10   5   5 
Waco                98  74  96  74  96 /  10  10  10   5  10 
Paris               93  75  93  73  93 /  40  20  10   5  10 
Denton              96  76  95  75  96 /  30  10  10   5   5 
McKinney            95  76  95  72  94 /  30  10  10   5   5 
Dallas              97  78  97  78  97 /  30  10  10   5   5 
Terrell             95  75  95  74  95 /  30  20  10   5   5 
Corsicana           96  75  95  74  95 /  20  20  10   5  10 
Temple              97  73  95  73  94 /  10  10  10   5  10 
Mineral Wells       98  75  96  73  96 /  10  10   5   0   5 

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

24/79