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

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FXUS64 KFWD 230004
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
704 PM CDT SUN MAY 22 2016

.AVIATION...
VFR through the evening with only few to scattered cu and
increasing high clouds associated with storms approaching from the
low rolling plains. The 00Z FWD sounding shows two elevated
subsidence inversions which were the primary limiting factors to
storm development this afternoon. We expect the storms to continue
to weaken overnight as they approach North Texas with no impacts
anticipated at the local terminals.

MVFR ceilings will return to the region overnight as a 30 knot low
level jet develops. These ceilings will lift slowly through the
morning hours Monday and become VFR around midday.

A south to southeast will continue in the 8 to 14 knot range.

79

&&




.SYNOPSIS...
There will be chances for showers and thunderstorms through the
week across parts of North and Central TX. Rain chances this
afternoon through Thursday will remain low and the coverage of
showers and storms is generally expected to remain low due to the
presence of a strengthening cap. If storms breach the cap on any
of these days, instability coupled with sufficient vertical wind
shear will support a risk for strong to severe storms. The better
threat for more widespread precipitation appears to be on
Thursday and Friday.

&&

.SHORT TERM (Tonight through Tuesday)...
Radar imagery this afternoon continues to be rather unimpressive
compared to output offered by most hi-resolution NWP. Think that
this is a result of large scale subsidence implied from both the
radar presentation and manual sky observations this afternoon. As
a result, it appears that the threat for widespread storms will be
low.

For tonight---Our attention turns to the west and northwest as
convection is expected to develop along the dryline. Flow aloft
would allow this activity to gradually push towards the east and
southeast. Some of the latest hi-resolution guidance does suggest
that a majority of the convection will congeal and remain along
and north of the Red River. As a result, I have lowered PoPs down
to around 20-30 percent. With the moist regime, however, it is
possible that the complex of storms may backbuild and with
backward propagating Corfidi vectors oriented to the southeast, it
is conceivable that a few storms will slip to the south of the Red
River. Given the weak flow aloft and increasing subsidence with
eastward extent---it`s likely that these storms will weaken. We
will maintain a mention of a low- end severe wind threat in
graphics and the HWO. Outside of that, it should be a warm and
humid night. Wind speeds should generally mitigate the development
of widespread fog, but will let the evening shift monitor trends
to see if inclusion into the worded forecasts is necessary.

For Monday---The loosely organized complex of storms may continue
mainly along and north of I-20 in the morning. I have maintained
slight chance PoPs along and northeast of a Graham to Glen Rose to
Hearne line, but it`s likely that most areas will remain dry on
Monday morning. As we head into the afternoon hours, the airmass
across North and Central TX should destabilize as low level
warm/moist flow continues due to weak troughing across the OK/TX
panhandles. The shortwave ridge responsible for suppressing
today`s convection should gradually slide eastward. The dryline
will sharpen and mix eastward, but is expected to remain across
the OK/TX panhandles. Forecast soundings do indicate that the cap
may weaken sufficiently to allow for the development of convection
in the afternoon hours. CAPE values on the order of 2000-3000
J/kg are forecast which would certainty support robust updrafts.
Deep layer shear values on the order of 25 to 30 knots will
support mainly multicell mode with perhaps some transient
supercellular storm structures. These modes will favor more of a
damaging downburst and hail threat. Given the moist regime and
probable slow/chaotic storm motions, isolated flood problems may
also develop due to heavy rain. The biggest caveat, however, is
the lack of lift at least on the synoptic scale. If morning
convection is capable of producing any type of outflow boundaries,
this source of mesoscale lift may be enough for convective
initiation during the afternoon hours on Monday. Unfortunately,
these details likely will not be resolved until Monday morning.

Another complex of storms may develop Monday evening into Monday
morning. The latest ECMWF output does suggest that a weak
shortwave trough may lift out of the Big Country and into portions
of western North TX during this time. This may be sufficient to
produce showers and storms during the overnight hours. Given the
expected instability it is possible that a complex of storms may
develop and impact areas along and north of an Eastland to DFW to
Sulphur Springs line. The main hazards if storms develop during
this time will be strong winds, hail and heavy rain. Low
confidence at this time, however, only warrants slight chance PoPs.

For Tuesday---It appears that weak shortwave ridging should keep
much of the day quiet, outside of the potential for lingering
convection across far northeastern zones in the morning. The
dryline should mix a bit further to the east on Tuesday, but is
still expected to remain west of North and Central TX. Convection
may fire along the dryline and venture towards areas west of the
U.S. Highway 281 corridor late in the afternoon, however. If
storms develop, they will move into an environment characterized
by nearly 3000 J/kg of CAPE and deep layer shear of around 30 to
35 knots. This would certainly foster more of a supercell mode
with the potential for large hail and damaging winds. The low
level wind field does not appear to support an appreciable tornado
risk, but we will re-evaluate this potential as additional model
output becomes available. Again, the risk is highly conditional
and it is quite possible that little to no convection will develop
on Tuesday afternoon into Tuesday evening. Much of this convection
should weaken, however, as it encounters the stabilizing boundary
layer and increasing subsidence.

&&

.LONG TERM (Wednesday through Saturday)...
For Wednesday---Low rain chances will exist on Wednesday, but the
capping inversion is expected to be much stronger. With the lack
of large scale ascent, it`s likely that a majority of North and
Central TX will remain precipitation-free, humid and warm. High
temperatures will climb into the mid to upper 80s with a few heat
index values nearing 100 degrees across southern zones. If
isolated storms do develop, they will likely become severe with
the potential for large hail and damaging winds.

For Thursday---The threat for precipitation will actually be the
highest on Thursday and Friday as a very potent upper trough
lifts out of the four corners region and as 30 to 40 meter height
falls overspread the area early Thursday morning. Interestingly
enough, GFS forecast soundings show a gradual top-down moistening
of the troposphere which could be either due to an invading
cirrus canopy from the tropical Pacific or actual elevated
convection. This will have to be monitored over the next several
days as it could play a role in the potential severe weather
episode on Thursday.

That being stated, instability fields on Thursday still look
fairly impressive with CAPE values in excess of 2500 J/kg. Deep
layer shear will be on the increase and is expected to range in
the 30 to 40 knot range. This will certainly easily support
supercells capable of large hail, damaging winds and potentially
tornadoes.

For Friday and beyond---Rain chances will linger on Friday as the
main upper trough overspreads 40 to 50 meter height falls across
the area. A good chunk of the area will be in the entrance region
of a 90-100 knot jet which should help in dynamically forced
ascent across the region. Convection will certainly be possible,
but the intensity is somewhat unknown at this point in time. It
does appear that a brief break from the active pattern will come
on Saturday as subsidence in the wake of Friday`s trough moves
across North and Central TX.

Bain

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    71  85  71  86  73 /  20  20  10  10  10
Waco                72  86  71  86  73 /  20  20  10  10  10
Paris               65  84  69  83  70 /  20  30  20  30  20
Denton              69  83  70  84  72 /  20  20  20  10  20
McKinney            69  83  70  83  72 /  20  30  20  10  10
Dallas              72  85  71  86  74 /  20  20  10  10  10
Terrell             69  86  70  86  72 /  20  30  10  10  10
Corsicana           71  86  70  86  74 /  20  20  10  10  10
Temple              70  86  71  85  73 /  30  20  10  10  10
Mineral Wells       70  86  69  86  72 /  30  20  20  10  20

&&

.FWD Watches/Warnings/Advisories...
None.
&&

$$

79/15



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