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

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000
FXUS64 KFWD 281004
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
404 AM CST Tue Feb 28 2017

.DISCUSSION...

It feels very much like a mid-spring morning across North Texas
with temps/dewpoints both in the mid/upper 60s. A rather large
warm sector remains in place across much of Texas and will expand
northeast into the mid-Mississippi River Valley by late this
afternoon ahead of a strong, fast-moving shortwave trough.

At the surface, southerly winds continue to pump in Gulf moisture
across the region. Near 70 degree dewpoints reside across the
southern half of the CWA although there is a sharper moisture
gradient just north of I-20 where dewpoints drop into the lower
60s and upper 50s. This moisture boundary is expected to spread
northward through the morning hours. Farther west, a dryline is
currently positioned across the western half of Oklahoma and
drapes back to the southwest of Abilene. Later today as the
shortwave progresses through the Plains, a surface cyclone will
deepen across southwest Kansas and race into the Midwest by this
evening. As stronger forcing for ascent spreads into the Plains
this afternoon, severe convection is expected to develop
especially off to the northeast of our area.

The main concern for today across North Texas will be the
potential for convective activity in an unstable environment. Deep
layer steep lapse rates in excess of 8.5 degC/km will remain in
place across the region resulting in SBCAPE in excess of 2500 j/kg
by this afternoon. The main difference today as opposed to
yesterday will be a strengthening capping inversion thanks to
increasing southwesterly winds aloft. FWS/GRK VAD wind profiles
already show 20-30kt of southwesterly flow at 5000ft and this is
expected to strengthen to around 40kt later this morning. This
increasing warm advection should result in a rather stout cap by
later this morning that will be difficult to break this afternoon.

With the upper trough axis still over the four-corners region by
mid afternoon and the best low level warm advection shifting to
the east with the low level jet, it appears that North Texas will
have insufficient forcing to contend with the robust capping. This
is reflected in most of the guidance including the all of the hi-
res output with the exception of one lone NCAR ensemble member
which does develop some convection by this evening. That being
said, I don`t want to entirely remove PoPs for this afternoon.
There will be a dryline in place across the western half of the
CWA by 21Z and this is expected to sharpen into the early evening
hours with temperatures climbing into the upper 80s to the west of
the dryline. While convergence along the dryline is unlikely to
be sufficient in itself to break the cap, some of the coarser
resolution guidance attempts to convect east of the dryline in an
area of increasing height falls by 00Z. This area is also beneath
a strengthening upper jet max that will continue to spread into
the region overnight. So, we`ll retain 20% PoPs generally from the
Metroplex east and north with some 30% PoPs near Paris for the
late afternoon hours. Any isolated convection that can manage to
break through the cap would likely become severe with primarily a
very large hail threat, although all modes of severe weather could
be possible.

By tonight, a rapidly moving cold front will slide through the
Plains and will overtake the dryline, surging into North Texas
after midnight. There is likely to be convection ongoing along the
front to the northeast of the region, much of which could be
severe. We`ll still be contending with capping across North Texas,
but it should break from northeast to southwest through the
overnight hours. Our east and northeast counties will have the
best chance for thunderstorms overnight along the front. These
storms too will pose a threat for severe weather, primarily in the
form of damaging winds. Any convection should clear the area by
early Wednesday morning.

High pressure will build into the region Wednesday through Friday
with considerably cooler temperatures than today. Highs will be in
the 60s each of these days with the potential for a light freeze
in outlying areas to the northwest on Thursday morning.

Another system will move into the western U.S. over the weekend
allowing moisture to spread back to the north. A strong shortwave
will swing well south of Texas on Saturday and shouldn`t result in
any precipitation in our area. Low rain chances may spread back
into the area Sunday through Tuesday of next week.

Dunn

&&

.AVIATION...
/ISSUED 1134 PM CST Mon Feb 27 2017/
Low clouds currently over South Texas and parts of the Hill
Country will continue streaming northward through the night. The
low clouds will reach Waco between 06z and 07z and the Metroplex
TAF sites by 09Z. Ceilings initially will be between 1000 and 2000
ft but will fall below 1000 ft in the predawn hours Tuesday.
Visibilities will also fall between 2 and 5 miles, especially
around sunrise. Ceilings and visibilities will slowly improve
through the morning Tuesday with VFR conditions expected at all
TAF sites by mid afternoon.

There will be a chance of thunderstorms Tuesday afternoon as a
shortwave moves east across the state. The best thunderstorm
chances will be east of the Interstate 35 corridor.

A south wind will prevail through Tuesday evening at speeds
between 10 and 16 knots. A cold front will move through North
Texas overnight Tuesday and will result in a wind shift to the
west/northwest before sunrise Wednesday, so will include a
windshift in the extended portion of the DFW forecast.

79


&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    80  51  66  39  64 /  20  30   5   0   0
Waco                81  51  66  37  64 /  20  20   5   0   0
Paris               77  51  63  36  63 /  30  50   5   0   0
Denton              82  46  63  33  64 /  20  20   5   0   0
McKinney            76  49  64  36  64 /  20  40   5   0   0
Dallas              79  50  65  40  65 /  20  30   5   0   0
Terrell             77  51  65  38  64 /  20  40   5   0   0
Corsicana           80  54  66  40  64 /  20  30   5   0   0
Temple              83  53  67  38  64 /  10  20   5   0   0
Mineral Wells       87  46  64  32  65 /  10  10   0   0   0

&&

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

$$



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