871 
FXUS64 KFWD 071746
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1246 PM CDT Thu Jun 7 2018

.UPDATE...
Another quick update to the forecast for the remainder of the
afternoon into the early evening hours. The complex of
thunderstorms to the north appears to be reinvigorated along a
southward moving outflow boundary as surface based instability
continues to climb. Surface objective analysis indicates that this
area of convection is moving into an axis of much stronger
instability and this trend has been reflected in the latest radar
imagery. A well established cold pool now appears to be in place
and it is appearing more likely that the convection will be able
to sustain itself for several more hours as it moves south. We're
going to update the PoPs across the region mainly along and north
of I-20 and increase them to 20-40%. Uncertainty does remain
higher than normal at this time based on a couple of things.
Visible satellite imagery shows a noticeable lack of cumulus ahead
of the complex, so it's unclear whether or not stronger subsidence
may be present and will eventually have an impact on ongoing
convection. Also, the KFDR radar shows an outflow boundary now
ahead of the main cluster of convection. Again, if this continues
to surge southward, the convection could weaken over time.

All that being said, the atmosphere across North Texas does remain
unstable and would support continued convection into the evening
hours. 

Dunn

&&

.AVIATION...
/18Z TAFS/

No significant changes are needed to the current forecast at this
time although it is appearing more likely that the complex of
thunderstorms to the north may have more of an impact than
previously thought. We'll maintain the VCTS from 22Z through 02Z
although timing may need to be adjusted forward if the complex
begins to accelerate southward. We may also have to add a period 
of TEMPO TSRA later this afternoon.

Otherwise, outside of convective chances, southerly flow will
prevail with VFR conditions. 

Dunn

&&

.UPDATE... /Issued 1027 AM CDT Thu Jun 7 2018/
We're continuing to monitor the complex of thunderstorms across
Oklahoma this morning. This area of storms has made steady
southeastward progress and this is likely to continue into the
early afternoon hours. There is an axis of low level moisture and
strong instability that extends from Central Texas northward 
along and east of I-35 into south-central Oklahoma. This area
features surface dewpoints in the low 70s and increasing low level
convergence northward into the complex of thunderstorms. The
current thinking is that the complex of storms will continue to
build south into the Paris/Bonham areas over the next few hours.
Additional isolated thunderstorms may develop farther south and
west within the strong instability axis through early evening.
While we are lacking some of the more favorable deep layer
directional shear that we had the other night when storms produced
very large hail, the thermodynamic parameters this afternoon may 
compensate for the lack of stronger shear. Mid level lapse rates 
are forecast to steepen through the day and although coverage of 
thunderstorms is expected to remain isolated (20% or less), any 
storms that develop could pose a large hail and damaging wind 
risk. Chance for storms will be a little higher in the 
Paris/Bonham areas given the proximity to the cluster of storms to
the north.

This update will raise PoPs some across the far northeast and will
drag the 20% PoPs back a little farther south and west into the
Metroplex for this afternoon/evening. No other changes needed at
this time.

Dunn

&&

.AVIATION... /Issued 706 AM CDT Thu Jun 7 2018/

Convection across Oklahoma has been slowly progressing southeastward
this morning, and will become the primary concern as we proceed 
into the afternoon. Given the poor handling by guidance with both
the development and propagation of thunderstorms, confidence 
remains low on when (if any) thunderstorms will make it to the TAF
sites. Latest radar trends do show additional storm development 
north of KSPS. Storm motion will initially be to the southeast, 
then veering to the south. 

The ongoing southward development can be attributed to an influx 
of moisture riding along the 35+ kt LLJ. The LLJ is expected to
weaken slightly after 15Z, albeit not completely dissipate. 
Depending on the orientation of incoming convection, or any 
remnant boundaries, thunderstorms will be possible this afternoon.
The highest confidence in aviation impacts will be to the north 
and east of the DFW TRACON, with likely impacts to the Bonham
arrival cornerpost. Thunderstorm potential will decrease with the
loss of daytime heating across the DFW Metroplex, with VFR 
remaining through the night. 

For Waco, VFR will persist through this TAF cycle, with
southeasterly winds around 11 kts. All convection will remain well
north and northeast of the airfield. 

Another MCS will develop across the Texas Panhandle overnight. The
expected motion will take this convection well west of all TAF
sites. At this point, a wind shift will not be mentioned, but it 
is possible that as the convection dissipates, an outflow boundary
may push through the DFW Metroplex leading to a brief period of
northwesterly winds very early Friday morning. 

Hernandez

&&

.SHORT TERM... /Issued 428 AM CDT Thu Jun 7 2018/
/Today and Tonight/

The main concern will be the potential for showers and storms 
affecting the region as northwest flow aloft continues to drive 
nocturnal convection into the area. 

There will be a low chance for a few showers and thunderstorms to
develop this morning across the far northeast where an old 
frontal boundary remains. It has become difficult to discern the 
exact location, but latest satellite imagery does depict an area 
of developing clouds northeast of a Paris to Sulphur Springs line.
Coverage of any precipitation that manages to develop would be 
limited to around 20%. 

Rain chances do expand in areal coverage as a MCS currently along
the Kansas/Oklahoma border approaches North Texas. With a
southerly 35+ kt LLJ (sampled by KTLX) advecting moisture into 
the thunderstorm complex, it is expected that propagation of new 
cells will begin to take a more southeasterly, and eventually a 
southerly track across Oklahoma. *If* the line of thunderstorms 
holds together through the rest of the morning, locations north of
I-20 and east of I-35 would have the best chance of showers and 
thunderstorms this afternoon and evening. The complex should be 
weakening as it crosses the Red River by mid afternoon, but a few 
strong to marginally severe thunderstorms can't be ruled out. 

Just as the complex of thunderstorms in the northeast weakens,
another complex is expected to develop across the Texas 
Panhandle. These storms will move southeast through the evening
with most of the activity concentrated across the Big Country. It
is possible that our western-most counties will see some showers 
and thunderstorms after midnight Friday, but overall strength and 
coverage should be on a downward trend. 

High temperatures today will remain in the 90s across North and 
Central Texas, with a few 100s possible in the west. Sufficient 
afternoon mixing will lead to breezy conditions west of I-35. Lows
will be in the 70s regionwide tonight, with wind speeds between 
5-10 mph. 

Hernandez

&&

.LONG TERM... /Issued 428 AM CDT Thu Jun 7 2018/
/Friday Through Next Week/

By daybreak Friday morning, little should remain of a nocturnal
complex that will make a charge at North Texas. Its residual
outflow boundary will struggle to survive as breezy southerly
winds homogenize the surface wind field. In addition, as mid-level
ridging strengthens aloft, intensifying subsidence in the mid-
levels will reinforce a summery capping inversion. This will keep
a lid on the rich Gulf moisture that will remain trapped within 
the boundary layer into the upcoming weekend. The humidity, 
combined with a steady south wind at the surface, will likely 
prevent the temperature from reaching the century mark. However, 
above normal temperatures will prevail, and all proper heat 
precautions should be undertaken if engaged in outdoor activities 
this weekend. Across much of the region, dew points will remain in
the 60s at peak heating, but this will be insufficient for heat 
index values much above 100.

Extended guidance still favors a weakening of the ridge early next
week as it gradually retrogrades, but areas along and west of the
I-35 corridor should remain under its grip. Daytime temperatures 
will change little, but as tropical moisture increases,
particularly across our eastern zones, heat index values will
climb early in the week. With diminished inhibition across East
Texas, daytime heating alone may be sufficient to realize this 
convective potential, albeit with rather disorganized short-lived 
convective elements. This pattern may also promote sea breeze 
convection, more indicative of July and August, that could 
penetrate far enough inland to bring late afternoon showers or 
storms into our southeastern zones. These potential rainmakers 
aside, much of the region may be rain-free through next week.

25

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    96  76  94  76  95 /  20   5   5   5   5 
Waco                95  74  95  74  95 /   5   5   5   5   5 
Paris               91  72  92  72  92 /  40   5  10   5   5 
Denton              95  75  94  74  95 /  20   5  10   5   5 
McKinney            93  72  93  72  93 /  30   5  10   5   5 
Dallas              96  78  96  77  95 /  20   5   5   5   5 
Terrell             93  74  94  73  94 /  20   5   5   5   5 
Corsicana           94  73  93  73  94 /  20   5   5   0   5 
Temple              94  73  94  72  94 /   5   5   5   0   5 
Mineral Wells       97  74  95  73  96 /  10  10  10   5   5 

&&

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

$$