Area Forecast Discussion
Issued by NWS Dallas/Fort Worth, TX

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FXUS64 KFWD 281533
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1033 AM CDT Tue Mar 28 2017

.UPDATE...
An upper low over New Mexico will continue to advance east into
the Southern Plains over the next 48 hours. Convection associated
with the system is already ongoing over the Texas Panhandle, and
additional storms will develop farther east auring the afternoons
we move into the afternoon and evening. We will be monitoring the
position of a warm front this afternoon as it lifts north of the
I-20 corridor. The position of the boundary may be crucial in the
location of isolated thunderstorm development during peak heating
hours. At this time, it looks like the front may still be located
near the Red River, which may be one area to monitor this
afternoon.

Better thunderstorm potential will exist across our western-most
counties (and west-northwest of the forecast area) during the
late afternoon and evening hours as strong lift associated with
the upper low develops. Shear and instability should be sufficient
for rotating cells capable of producing large hail. The latest
SPC Moderate and Enhanced risk areas highlight these locations
well. Damaging winds and a few tornadoes will also be possible in
any discrete storms. During the evening, storms should develop
upscale into a linear MCS and push east across the entire forecast
area. Damaging winds should be the main threat, though hopefully
the time of day will help mitigate the overall severe threat. All
in all the forecast remains on track with only minor grid updates
needed. More significant updates may be possible this afternoon
during the evolution of the system as more specific information
about location and intensity are realized.


30

&&

.AVIATION...
/ISSUED 702 AM CDT Tue Mar 28 2017/
Stratus has invaded the region early this morning, encouraged
northward on 30-35 kt low-level flow. Most cigs at this hour
remain MVFR, with sporadic IFR cigs appearing south of the
Metroplex TAF sites. A warm front, which currently stretches from
near a KF44-KCRS-KMNZ line will continue moving northward this
morning, which will help spread richer moisture across the
Metroplex sites. This, in theory, should help cigs build down
towards IFR, but it`s looking like these may be more ephemeral and
have moved them into a TEMPO group with some drizzle/mist as a
bit more warm advection/isentropic ascent gets going. There are
some conflicting signs regarding cig trends this afternoon, but it
does appear that mixing will help steadily lift the cloud deck
towards VFR by this evening--potentially even by mid-afternoon.

At the Metroplex sites, narrowed the window of VCTS a bit for this
evening as most guidance suggests a brief lull will occur behind
the first batch of (likely severe) storms, which will move
northeast towards the Red River. There is a chance these storms
may directly impact terminals, but confidence in this was too low
to warrant introducing an explicit TSRA mention. The western
Metroplex sites (AFW, FTW) would be most susceptible to these
storms. Opted to keep Waco dry through this period as better
ascent looks to remain to the north. Late tonight, a squall line
is forecast to blast across all terminals. There are signs that
this line may begin to weaken somewhat as it approaches the I-35
corridor, but will nonetheless bring a risk for severe-caliber
wind gusts and hail to all of our TAF sites.

Carlaw


&&




.LONG TERM.../Friday through Tuesday/
Quiet weather is expected on Friday as upper level ridging moves
across the Southern Plains in advance of the next upper level
system. Thursday`s front will have pushed deep into the Gulf of
Mexico but some moisture return will occur Friday night and
Saturday in response to the next approaching system. Another
dryline will sharpen to our west and most models place this
dryline not too far west of our CWA Saturday afternoon. By this
time, the upper level trough will be in New Mexico with height
falls spreading across the state. Even with the limited amount of
moisture return (dewpoints in the mid to lower 50s), the models
are attempting to convect storms that may affect our western
counties Saturday afternoon and evening. Have trimmed back PoPs on
Saturday with 20-30 percent ranging across the area. The amount of
instability near the dryline is in question due to the limited
amount of moisture return but at least a low severe weather risk
may exist for now. So far, most the model soundings indicate
MUCAPE 1000-2000 J/kg with profiles of tall, skinny CAPE. Shear
values over 40 kts would be sufficient for rotating updrafts.

The dryline retreats west Saturday evening and then more rain
develops across the State on Sunday. There are significant
discrepancies between the models on the timing of the upper level
trough, but most track the system through North and Central Texas.
In response to this, the surface low develops along the Texas
coast and tracks east. This track would keep the best rains across
Central Texas and to the south. Based on the set-up, it`s
possible another squall line may track across this region on
Sunday as storms develop on the dryline in the Hill Country.
Again, severe weather would be a threat, and we will further
refine the severe weather threats as the weekend approaches. Areas
to the north won`t necessarily completely miss out on all the
rain, but the coverage could be significantly less, and have the
highest PoPs across our southern/Central Texas counties on Sunday.

Unfortunately this doesn`t look to be the end of the upper level
train as another upper level trough will move into the Plains
around the middle of next week.

JLDunn

&&

.SHORT TERM.../Tuesday through Thursday/
Our next round of rain, storms, and severe weather starts today
and increases tonight. An upper level low currently encroaching on
the Four Corners region will continue steady progress east, moving
into West Texas and the Texas Panhandle tonight. Currently, the
remnants of yesterday`s front are stalled across our Central
Texas counties with upper 60s dewpoints south of the boundary.
This boundary is expected to return north as a warm front today in
response to surface cyclogenesis over West Texas and eastern New
Mexico. As the warm front moves north, 60s dewpoints will spread
across Central and North Texas, and a dryline will sharpen to our
west. It doesn`t appear anything will impede the northward
advancement of the warm front, but if the front is slower to move
north and remains across our northern counties late this afternoon
and evening, it could be an area of increased tornadic potential
IF storms develop near the warm front later today. Currently, we think
the warm front will be north of the Red River by late afternoon,
but its position will be one to watch. Here`s how we anticipate
rain and storm chances will evolve today and tonight...

With the increasing moisture spreading north today, isolated to
scattered areas of light rain and/or showers will be possible. By
afternoon, it appears the cap may be weak enough to allow a few
thunderstorms, but the best lift will still be located to our
west. Thunderstorms, likely severe, are expected to fire on the
dryline to our west this afternoon and move into our western
counties late this afternoon or early this evening. In addition,
we may have a few thunderstorms develop in our western counties
late this afternoon and evening, ahead of the dryline, as some
large scale lift begins to spread into the region. These storms
could be severe with a threat for large hail, damaging winds, and
possibly a tornado or two. These initial storms will be moving
north-northeast and any training of cells may result in a flash
flood threat.

While this first round of storms is likely to be moving north of
the region late this evening, another round of storms will develop
along the dryline to our west. This next round of storms is
expected to move across the region tonight as a squall line.
Initially this line may be severe, but may weaken as it progresses
east. Damaging winds will be the main hazard and hail will also
be a threat. QLCS tornadoes are also not out of the picture, and
flash flooding may be a concern, especially in areas that receive
heavy rainfall with the first round of storms in the late
afternoon and evening.

As we move into Wednesday morning, the line of rain/storms is
expected to move east of the region, but unfortunately we don`t
look to be done for the day. The dryline looks to stall somewhere
east of Interstate 35 Wednesday morning. As the upper level low
continues to move east across the Southern Plains providing plenty
of lift, additional storms are forecast to develop near the
dryline, possibly as early as the late morning hours. The models
are in good agreement that the area over our eastern counties will
recover from the earlier rains, and an unstable environment would
support another round of severe storms with a threat for large
hail, damaging winds, and possibly a tornado or two. The location
of the dryline is a bit uncertain and will need to be monitored,
so left PoPs on Wednesday a little farther west into the I-35
corridor. All activity is expected to move east of the CWA
Wednesday evening.

One last uncertainty surrounds the potential for more storms
across our northern counties Wednesday night and Thursday. Some
models suggest a few storms may develop near the core of the upper
level low as it moves near the Red River. If this happens, these
storms could possibly be elevated storms with a threat for hail.
For now, will keep low PoPs mainly north of Interstate 20
Wednesday night and Thursday for this potential, and reassess
this threat as more hi-res guidance comes into this time window.

A front will move through the region on Thursday making for a
chilly day with highs likely only in the mid 60s to mid 70s.

&&

.LONG TERM.../Friday through Tuesday/
Quiet weather is expected on Friday as upper level ridging moves
across the Southern Plains in advance of the next upper level
system. Thursday`s front will have pushed deep into the Gulf of
Mexico but some moisture return will occur Friday night and
Saturday in response to the next approaching system. Another
dryline will sharpen to our west and most models place this
dryline not too far west of our CWA Saturday afternoon. By this
time, the upper level trough will be in New Mexico with height
falls spreading across the state. Even with the limited amount of
moisture return (dewpoints in the mid to lower 50s), the models
are attempting to convect storms that may affect our western
counties Saturday afternoon and evening. Have trimmed back PoPs on
Saturday with 20-30 percent ranging across the area. The amount of
instability near the dryline is in question due to the limited
amount of moisture return but at least a low severe weather risk
may exist for now. So far, most the model soundings indicate
MUCAPE 1000-2000 J/kg with profiles of tall, skinny CAPE. Shear
values over 40 kts would be sufficient for rotating updrafts.

The dryline retreats west Saturday evening and then more rain
develops across the State on Sunday. There are significant
discrepancies between the models on the timing of the upper level
trough, but most track the system through North and Central Texas.
In response to this, the surface low develops along the Texas
coast and tracks east. This track would keep the best rains across
Central Texas and to the south. Based on the set-up, it`s
possible another squall line may track across this region on
Sunday as storms develop on the dryline in the Hill Country.
Again, severe weather would be a threat, and we will further
refine the severe weather threats as the weekend approaches. Areas
to the north won`t necessarily completely miss out on all the
rain, but the coverage could be significantly less, and have the
highest PoPs across our southern/Central Texas counties on Sunday.

Unfortunately this doesn`t look to be the end of the upper level
train as another upper level trough will move into the Plains
around the middle of next week.

JLDunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    79  65  80  55  68 /  20 100  50  20  20
Waco                82  65  80  56  72 /  20 100  50  10   5
Paris               77  64  74  56  65 /  20  80  70  30  20
Denton              76  63  80  52  66 /  30 100  50  20  20
McKinney            77  65  77  54  66 /  20 100  50  20  20
Dallas              80  66  80  56  68 /  20 100  50  20  20
Terrell             81  66  78  56  68 /  20 100  60  30  20
Corsicana           83  66  77  57  70 /  20  90  60  20  10
Temple              82  64  81  57  73 /  20  90  50  10   5
Mineral Wells       78  57  80  50  69 /  50 100  20  20  10

&&

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

$$

/30



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