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

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FXUS64 KFWD 142356

Area Forecast Discussion
National Weather Service Fort Worth TX
556 PM CST Tue Nov 14 2017

A shortwave trough extending from Southern Manitoba to Kansas can
be seen on satellite moving east across the Plains this evening.
This system will force a weak cold front southward into North
Texas on Wednesday. For tonight, veering low level flow should
advect a lower stratus deck northeastward from the Hill Country.
Cloud bases will likely be in the MVFR category, arriving at all
areas in the 09-12Z timeframe. There may be some brief
improvement to VFR in advance of the cold front, followed by a
second post-frontal MVFR deck in the Metroplex Wednesday
afternoon. The current forecast indicates FROPA around 22Z in the
DFW area and after 16/00Z at KACT. A few showers will be possible
with the front, but thunder is not likely due to the shallow
frontal layer and lack of any upper level support.

The front will retreat north late Wednesday night and Thursday as
the next storm system approaches the West Coast. This will bring
a return to southeast winds Thursday morning at KACT and around
midday Thursday in the Metroplex.



.SHORT TERM... /Issued 325 PM CST Tue Nov 14 2017/
/Through Tonight/

Temperatures have responded quickly this afternoon to the first
real glimpse of sunshine after a rather gloomy stretch of weather,
with highs topping out in the upper 70s to near 80 degrees across
the I-35 corridor. The sunshine will be short-lived, however, as
widespread low cloud cover, light rain, and drizzle will be making
a return in earnest later Wednesday and into Thursday. More on
that below.

For tonight, cloud cover will begin to thicken up as an influx of
additional Gulf moisture encounters a cooling boundary layer. This
moisture surge will be strongest across our Central Texas
counties, where some patchy fog may materialize after midnight.
Fairly strong mechanical mixing owing to stout 35-40 kt
southwesterly winds around 925 mb, and this should help keep
visibility reductions from becoming widespread, but it does appear
that some localized reductions down to 1 mile are possible. Patchy
fog has been added to the forecast for locations south of a
Lampasas to Hillsboro to Corsicana to Palestine line.



.LONG TERM... /Issued 325 PM CST Tue Nov 14 2017/
/Wednesday through next Tuesday/

Low cloud cover, which will be pervasive on Wednesday morning,
will attempt to gradually scatter out during the afternoon hours.
Our Central Texas and southwestern counties look to benefit the
most from better insolation as skies attempt to go partly cloudy,
and temperatures will respond by rising into the mid and upper 70s
here. To the north, our attention will be turning to yet another
cold front, which will be approaching our northwestern counties
during the morning hours. Once again, this front is expected to be
rather shallow, with a frontal inversion depth of around 1000-1500
feet or so. The NAM, with its much finer vertical resolution in
the very lowest levels, has a great track record with these
shallow boundaries so far this fall, and we see no reason to
deviate from this line of thinking at this time. This faster
solution offered by the NAM also has support from some recent hi-
res guidance like the TTWRF and NSSL-WRF.

As a result, we`ve muted the diurnal temperature range for
locations along and north of the I-20 corridor as north winds and
additional low cloud cover tamp down on daytime heating. Only very
modest ascent will be associated with this front, and a layer of
warm air just under 700 mb will greatly limit available
instability as the front slides through. Some showers will be
possible both ahead of and on the cool side of the front Wednesday
and into Thursday morning, but with such limited forcing for
ascent and instability, any precipitation amounts will be quite
light. Drizzle may become more prevalent Wednesday night and into
Thursday as the four or five thousand foot layer on top of the
frontal inversion begins to really saturate.

Some showers will likely linger across the eastern 2/3rds of our
forecast area Thursday afternoon where the southern extent of
lee-cyclogenesis-associated warm advection will be impinging upon
relatively deep low-level moisture. Once again, thunderstorms
appear unlikely at this time given the lingering warm base of an
EML plume between 850 and 700 mb.

The aformentioned lee cyclogenesis--which will begin in earnest
Thursday afternoon across Nebraska under the diffluent right exit
region of a very stout 130+ kt jet streak--will result in a decent
mass response across our region on Friday. As morning stratus
erodes, vertical mixing will transport 30 kt winds around 925 mb
to the ground in the form of southwesterly wind gusts to around
30 mph. With 850 mb temperatures of around +16 to +18 C, clearing
skies, and southwesterly surface winds, it seems likely that we`ll
manage high temperatures in the mid and even upper 80s across our
western counties.

These very warm conditions will be short-lived, however, as the
next very strong cold front looks to blast through the region on
Saturday. Medium range guidance continues to slow the front`s
passage, and this is supported by today`s ECMWF ensemble runs as
well. Strong and gusty north winds will prevail for much of the
day on Saturday, and associated stout cold advection will hold
highs in the 60s north and 70s south. Winds will slacken quickly
Saturday night, and decent radiational cooling should allow
temperatures to fall into the 30s across our northwestern counties
and outlying sheltered areas.

Temperatures will then begin to moderate on Monday as
southwesterly winds return and cold high pressure shifts off to
our east.



Dallas-Ft. Worth    64  73  57  68  64 /  10  30  30  20  10
Waco                63  77  59  73  65 /   5  20  20  20   5
Paris               59  68  53  63  58 /  10  30  30  30  10
Denton              63  70  53  67  62 /  10  30  30  20  10
McKinney            63  70  55  67  62 /  10  30  30  20  10
Dallas              64  73  58  68  63 /  10  30  20  20  10
Terrell             63  74  58  70  62 /  10  20  30  30  10
Corsicana           62  76  60  72  64 /   5  20  20  30  10
Temple              62  79  59  75  64 /   5  10  20  20   5
Mineral Wells       61  71  54  67  59 /  10  30  20  20   5



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