FXUS64 KFWD 210002

Area Forecast Discussion
National Weather Service Fort Worth TX
702 PM CDT Mon May 20 2019

/00Z TAFs/

Challenges and Concerns: No issues through 06z, then timing
MVFR/VCSH stratus into the area, as well as trending a broken
line of convection through the I-35 corridor around 12z Tuesday.

Latest check on the ongoing 00z FWD U/A run shows warming has
occurred well aloft, or based around 7.5 kft/750mb. This, along
with copious dry air and subsequent dry-air entrainment has
really limited potential for development. As such, expected
multi-level CU and mainly scattered in nature to continue until
05z-07z with strong southerly winds around 20 knots with gusts
30-35 knots.

As the main upper low across the SW Deserts approaches the region
between 06z-12z Tuesday, mid level height falls will help to lift
and slowly weaken the elevated cap. In addition, a LLJ will be
screaming between 50-60 knots, which should begin with initially
developing SCT -SHRA across the region by 09z, before a broken
line of TSRA moves across the I-35 corridor and airports in the
11z-15z time frame. Meanwhile, MVFR cigs, mostly BLO FL020 will
prevail between 06z-15/16z Tuesday, before veering low level flow
and subsidence help draw drier -- more stable air into the region.
Expect SW winds around 15 knots and partially clearing/VFR
conditions by 18z Tuesday and beyond.



.SHORT TERM... /Issued 243 PM CDT Mon May 20 2019/
/This afternoon through Tuesday/

The primary concern in the short term forecast period will be the
risk for strong to severe thunderstorms across the area this
afternoon and through the day on Tuesday. This afternoon`s risk
for thunderstorms is HIGHLY conditional with a better risk for
storms during the overnight hours.

Summary: There are a couple of opportunities for strong to severe
storms across the area over the next 12 to 24 hours. 1) This
afternoon near and north of I-20...mainly for areas near and north
of I-20. The risk this afternoon is VERY conditional given decent
capping and modest ascent. All facets of severe weather will be
possible. 2) The BEST chance for strong to severe storms across
the area will be after midnight tonight through the early
afternoon hours on Tuesday. The main threats will be damaging
winds and perhaps a low tornado potential. There will be a risk
for additional main stem river and lake flooding as well as
isolated instances of flash flooding...but a widespread
significant flash flood risk is NOT anticipated. Details on both
of these bouts of strong to possible severe weather are
highlighted below.

Surface analysis early this afternoon has revealed that the
surface warm front that was along the I-20 corridor early has
lifted very quickly into Central Oklahoma. Visible imagery shows
that clouds are slowly breaking up under the mid-May sun. While
considerable moisture transport northward continues, our 18 UTC
FWD RAOB indicates considerable capping. This will mean that the
coverage of strong to severe storms...should they develop...will
be low south of the Red River as WAA continues. Given the
instability values in excess of 2500 J/kg and deep layer shear
greater than 35 knots...there will be a threat for supercellular
storm modes capable of large hail, damaging winds and perhaps a
tornado or two *IF* updrafts can penetrate the 15 C capping
inversion. At this time, it would appear that potential is
dwindling. Heavy rain will be a threat as well with isolated
instances of flooding possible. At this time, the storm motion
should preclude a widespread significant flash flood risk.

Most of North Texas should be free of any convective chances as we
near 00 UTC Tuesday...the exception may be near and north of the
US HWY 380 corridor where the magnitude of WAA may be greater.
Otherwise, 925mb flow will ramp up with forecast progs indicating
near 50 knots. More impressive is the 850mb flow with some
guidance suggesting near 70 knots along the US HWY 281 corridor. A
band of convection is expected to develop after midnight across
the Big Country and should move eastward towards North and Central
Texas. This complex of storms will bisect this very strong low
level flow. Within the strong southerly regime...rich theta-e air
will streak northward and should fuel convection. Morning and
early afternoon hi-res guidance has consistently hinted that
activity may weaken as it trucks eastward toward the I-35
corridor. The fly-in-the-ointment to these solutions that weaken
the line of storms abruptly is the magnitude of the low level
flow is (925mb ~50 knots, 850mb ~60 knots). This may promote a
longer cessation of severe weather than advertised by these hi-
res models as higher theta-e air may be available for convective
updrafts along the leading edge. With this in mind...we will
continue to advertise a damaging wind hazard as the line continues
eastward. A greater damaging wind and QLCS-type tornado potential
may evolve if convection can remain rooted along the its cold
pool. If the latter does NOT happen...then convective cells may
tend to be undercut by the cold pool and may hamper downward
momentum transfer efficiency and this is something that will be
monitored as storms develop. I expect that storms will be near
the US HWY 281 corridor around 4 to 5 AM Tuesday...I-35 corridor
(including the D/FW Metroplex...Waco and Killeen/Temple/Belton)
around the 6 to 7 AM timeframe and then across East Texas around
10 AM. There could be some re-invigoration of the
line...if the line slows down and can take advantage of some
heating. This scenario, however, looks quite low. The best severe
weather potential will likely be near and west of I-35..unless
the line strengthens after sunrise. Periodic flooding will be
possible, but given the expected storm motion, the threat for
widespread flash flooding is too low to warrant a Flash Flood
Watch at this juncture.



.LONG TERM... /Issued 243 PM CDT Mon May 20 2019/
/Tuesday Night through Monday/

The midweek pattern will continue to feature troughing over the
western U.S. with a strengthening ridge over the southeastern part
of the country keeping us near or slightly above normal on
temperatures. On Wednesday a strong shortwave will rotate around
the base of the overall broad trough and dig into Arizona.
Strengthening southerly flow will result in a northward surge of
moisture into the region although we`ll generally be capped during
this time with stronger forcing for ascent well removed to the

With the overall slow eastward progression of the troughing (due
to the strong ridging over the east), most of the convection will
be closely tied to the dryline through the latter part of the
week. This should be primarily to our west. We`ll continue to
mention some low PoPs mainly across our northwest counties late
Thursday night into early Friday morning when the dryline may get
a little farther eastward push thanks to an ejecting shortwave
into the Plains.

We`ll continue to be positioned between the troughing to the west
and the stronger ridge to the east into the weekend. We`ll
maintain generally low PoPs (10% or less) each afternoon with
highs in the upper 80s to near 90 degrees.



Dallas-Ft. Worth    70  83  69  89  74 /  50  80   0   0   0
Waco                69  83  70  89  73 /  30  70   0   0   0
Paris               71  78  67  87  71 /  30  70   5   5   0
Denton              68  82  66  89  73 /  70  80   0   5   0
McKinney            71  82  66  87  73 /  50  80   5   0   0
Dallas              71  85  71  89  74 /  50  80   0   0   0
Terrell             72  82  69  89  73 /  30  80   5   0   0
Corsicana           72  82  71  89  72 /  20  70   5   0   0
Temple              68  84  70  89  73 /  20  70   0   0   0
Mineral Wells       64  82  62  88  70 /  80  60   0   5   5


Wind Advisory until 1 AM CDT Tuesday for TXZ091>093-100>104-




NWS FWD Office Area Forecast Discussion