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

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000
FXUS64 KFWD 231253 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
753 AM CDT Thu Mar 23 2017

.AVIATION...
/12Z TAFs/

A low-level jet in excess of 40 knots helped MVFR stratus surge
into North Texas before daybreak. This flow has been so vigorous
that the thin layer has struggled to avoid significant gaps. This
may continue, and although additional moist advection may suggest
it will eventually fill in completely, the thin layer will begin
mixing out by mid-morning. Only a quickly diminishing scattered
deck should remain at midday, with deeper vertical mixing limiting
additional cumulus this afternoon.

This mixing will also allow the momentum from within the low-level
jet to reach the surface, and gusts will occasionally exceed 30
knots today. An approaching system will prevent the surface layer
from decoupling and the breezy conditions will prevail much of the
night.

As a dryline surges down the High Plains of West Texas late in the
day, showers and thunderstorms are expected to develop in vicinity
of the boundary. This activity may travel eastward overnight,
reaching the I-35 corridor around daybreak Friday morning. Strong
warm/dry advection 850-750mb will assure a stout inversion
persists in advance of the convection, which will likely diminish
its intensity if not dissipate it altogether. Short-range
guidance is still inclined to have some precipitation near our TAF
sites during the morning push, but it appears unlikely to be a
significant disruption to commercial operations.

Another breezy day will follow with veering winds Friday
afternoon. With gusts in excess of 30 knots, this may introduce
some crosswind issues on DFW diagonals and at Love Field. Any
downstream redevelopment of thunderstorms Friday afternoon should
be east of our TAF sites.

25

&&

.PREV DISCUSSION... /ISSUED 402 AM CDT Thu Mar 23 2017/
We continue to monitor a large and dynamic upper level system
over the Great Basin and Rockies this morning. Meanwhile height
falls over the Central and Southern High Plains are helping to
lower pressures along the Rockies Front Range. 35-45 knot flow in
the boundary layer will combine with a tightening gradient over
the Southern Plains to promote windy conditions over much of the
area. By late morning and through midnight tonight, the strongest
winds will be west of I-35/35E: 20 to 30 mph with gusts of 35 to
40 mph. It is possible that even stronger winds will occur along
and west of Highway 281 where the strongest southerly low level
wind fields will exist. We have issued a Wind Advisory starting
later this morning and lasting through this evening generally
along and west of a line from Bonham and Rockwall to Marlin and
Cameron. A deep southerly flow in advance of our western U.S
system will make momentum transfer easier to achieve and it`s
possible wind speeds may need to be updated for a few hours this
afternoon. Otherwise, it will be warm and in the 80s most
locations with increasing humidity as the Gulf of Mexico fetch
will be in full swing. For tonight, changes were made to relegate
best rain chances across the far western counties as the system
will continue to deepen and slow down, which will hold the surface
dryline back until we get near sunrise Friday. Severe weather is
not expected late tonight as the elevated mixed layer remains
strong most of the night.

The upper low will begin to march out over the High Plains early
Friday morning and shunt the surface dryline eastward. It appears
the elevated mixed layer will slowly moisten and weaken around
sunrise, near or just west of the I-35/35W corridor. At this
time, we expect an increase in convection that will shunt to areas
mainly east of I-35 by midday. It is very conditional how much our
eastern counties will destabilize with current convective
evolution. Nevertheless, increasing 0-6km bulk shear occurring
right at primary afternoon heating should allow for a few storms
to reach severe limits over the east and southeast counties Friday
afternoon into mid evening. Large hail and damaging winds will be
the main threats. In addition, partial clearing over the west with
gusty southwest winds and temperatures warming into the lower 80s.
As such, and with less coverage and rainfall amounts west of I-35,
we have coordinated with our neighboring offices to the west for
a Fire Weather Watch Friday afternoon.

All strong/severe convection will exit stage right later Friday
evening as the upper low lifts east across the Ozarks and into the
Mid Mississippi and Tennessee Valleys. A Pacific cold front will
bring in a drier and cooler airmass for a nice day on Saturday
with highs mostly in the 70s. The cool down will be short-lived
however as the surface pattern transitions back to south wind
Saturday night, becoming gusty with highs warming back into the
80s areawide. With low afternoon humidity values across the west
Sunday afternoon, it is likely that fire concerns will increase
once again. The next dynamic shortwave trough will move east into
the Central Plains, with a more northerly track than seen in
recent forecasts. Nevertheless, there will be enough lift and
moisture east of another dryline and north of I-20 for a few
discrete supercell storms. The more progressive and northern track
of this system will only result in a brief surge of Gulf moisture
northward late Sunday afternoon and Sunday night. A squall line
across KS/OK will likely zipper down the dryline Sunday evening,
especially into areas east of I-35 and north of I-20. All modes
of severe weather are possible early on, but do expect overnight
that a more linear system will mean damaging winds and some
severe hail will be the primary hazards. This system will lift
out east of the area Monday morning, with a few mostly dry days
the first half of next week as shortwave ridging settles overhead
Monday and Tuesday. It will continue to remain breezy and warm
with temperatures remaining well above seasonal normals for late
March.

Medium range models are now slowing down and deepening the 3rd
system later next week, which was pretty much expected. Both the
Canadian and ECMWF are deeper and slower, but still slightly more
progressive than the GFS. Our main threat for convection and --
I stress -- the `possibility` of severe storms would appear to be
later Wednesday into Thursday. We should know more on the timing,
track, and strength of this system as we move through the weekend
and the upper air network better samples this energy. It will
remain unseasonably warm all of next week.

05/

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    85  65  82  55  77 /   5  20  60   5   0
Waco                83  65  81  53  79 /   5  10  60   5   0
Paris               82  60  72  53  72 /  10  10  80  20   5
Denton              84  63  81  52  76 /   5  20  50   5   0
McKinney            83  62  75  53  73 /   5  20  70   5   0
Dallas              85  65  79  55  76 /   5  20  70   5   0
Terrell             84  63  74  55  75 /   5  10  70  10   0
Corsicana           85  63  75  56  75 /   5  10  80  10   0
Temple              84  63  81  54  80 /   5  10  60   5   0
Mineral Wells       85  60  83  51  75 /   5  30  30   5   0

&&

.FWD WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Friday morning through Friday afternoon
for TXZ091-100-101-115-116-129.

Wind Advisory from 11 AM this morning to 1 AM CDT Friday for
TXZ091>094-100>104-115>120-129>134-141>145-156>160-174.

&&

$$

25/05


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