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

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FXUS64 KFWD 191134

Area Forecast Discussion
National Weather Service Fort Worth TX
634 AM CDT Thu Apr 19 2018

/12z TAFs/

Light north winds prevail at all TAF sites this morning with
surface high pressure in control of the Central Plains. As the
surface ridge shifts east today, winds will come around to the
northeast at 10-15 kts. An increase in mid/high clouds can be
expected late today and overnight, but VFR conditions will
prevail. By midnight, winds should become light easterly before
shifting to the southeast later Friday morning.



.SHORT TERM... /Issued 314 AM CDT Thu Apr 19 2018/
/Today and Tonight/

A mild and pleasant day is in store with slightly below normal
temperatures. Cold advection continues behind yesterday`s front
with northeast winds of 10-20 mph expected through this afternoon.
With this in mind, have decreased forecast high temperatures
slightly, especially across our northeastern zones where cold
advection will be strongest. These areas will top out in the 60s
while areas farther southwest will reach the low to mid 70s.

There will be a gradual increase in mid/high cloud cover late
this afternoon and into the overnight hours as some Pacific
moisture arrives in advance of a deepening upper trough along the
West Coast. Have nudged overnight lows up a couple degrees due to
both increased cloud cover and an anticipated wind shift to the
east. Meanwhile, a lead wave of ascent will be responsible for
initiating numerous showers and storms across the Big Bend region
late this evening and overnight. As this disturbance moves east,
it could prompt the generation of a few showers or isolated
storms farther east into the Texas Hill Country or Central Texas
as mid-level moistening occurs. However, it appears this activity
should stay just west of the forecast area through around
daybreak Friday morning.



.LONG TERM... /Issued 314 AM CDT Thu Apr 19 2018/
/Friday through next week/

Our upper level pattern will transition to southwest flow aloft on
Friday as the long-talked about upper level trough moves across
the Desert Southwest. During the morning hours, a weak embedded
disturbance will cross Central Texas, and several hi-res model
members are generating radar reflectivity as it moves across the
region. Some hi-res guidance is rather bullish with
precipitation, but an analysis of forecast soundings reveals very
dry mid levels are forecast to remain in place. Very small
glimpses of elevated convection are present which could support
elevated showers or even an isolated thunderstorm quickly moving
west to east across Central Texas. Top-down processes may allow
for more rain to reach the ground than is currently expected, but
am not expecting much at this time given the amount of dry air
below about 550 mb. Will have a 20 PoP generally south of I-20 and
west of I-45 on Friday, and further assess if the rain chances
need to be increased.

At the surface, a cool continental airmass will remain in place on
Friday, even with 10-15 mph southeast winds at the surface. Mostly
cloudy skies are expected due to a mix of mid and high clouds, and
high temperatures will be below normal in the upper 60s to mid
70s. Rain chances increase across the region starting Friday
evening and night.

As the upper level trough continues moving east into the Southern
Plains Friday evening, widespread showers and thunderstorms are
expected to develop to our west and northwest where the strongest
height falls are occurring. This area of convection will travel
east during the night, spreading into our western counties early
Saturday morning. Ahead of this area of rain, an increasing
southerly low level jet and warm air advection above the surface
will likely aid in the development of scattered showers and maybe
isolated thunderstorms across North and Central Texas overnight.

Widespread showers and storms will spread across the region during
the day on Saturday. A warm front will quickly lift north, and
the highest concentration of rain is expected to be north of this
warm front, across roughly the northern half of the CWA. Any
convection north of the warm front will be elevated, but meager
instability aloft precludes a severe weather concern in this area.
South of the warm front, a low threat for severe storms still
exists IF breaks in the clouds can occur. Breaks in the clouds may
allow for meager measures of SBCAPE to combine with strong wind
shear due to strong winds aloft to support a few strong or severe
storms. Hail near quarter sized and downburst winds would be the
main hazards.

A cold front will sweep across the region Saturday evening and
night, ending the rain from west to east. The NAM is significantly
faster than the other operational models, with the front pushing
through most of the region on Saturday afternoon, and this
solution may become reality as the ongoing rain cools the
continental air already in place, allowing for the cooler air to
seep south during the day. If this happens, any severe weather
concerns across Central Texas would be limited even further.

An upper level ridge will build to our west as the upper level
trough exits the region. The GFS and ECMWF output additional light
rain in our eastern counties on Monday where mid level moisture is
forecast to remain trapped. However, downglide on the back side of
the departing upper trough should suppress any rain chances and
have kept silent 10 PoPs for now. After a cool day with
temperatures in the 60s and lower 70s on Sunday, temperatures will
slowly warm during the early part of the work week. Within
northwest flow aloft, the ECMWF drops another front across the
region on Wednesday, with additional light rain chances, but the
GFS stalls the front to our north. The GFS is quick to move
another upper level trough through the Plains on Thursday with
widespread rain possible again. However, the ECMWF holds this
upper level trough off the West Coast until the weekend. Until
better agreement can be reached, will keep low PoPs spread across
the area Wednesday and Thursday.



Dallas-Ft. Worth    71  51  71  52  63 /   0   0  10  40  90
Waco                73  49  72  53  68 /   0   5  20  40  80
Paris               65  44  69  49  64 /   0   0   5  30  90
Denton              68  46  70  50  62 /   0   0  10  50  90
McKinney            67  43  69  50  62 /   0   0  10  30  90
Dallas              70  51  72  53  64 /   0   0  10  30  90
Terrell             68  46  70  51  66 /   0   0  10  30  90
Corsicana           72  46  70  52  65 /   0   0  10  20  90
Temple              74  49  72  54  70 /   0  10  20  40  80
Mineral Wells       72  46  71  50  64 /   0   5  10  70  90




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