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

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FXUS64 KFWD 230923
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
423 AM CDT Wed Aug 23 2017


.DISCUSSION...

Morning regional radar imagery shows a cluster of showers and a
few thunderstorms primarily along the Red River with some
additional development along I-20 west of the Metroplex. A well
defined outflow boundary is pushing southward and is along a line
from near Comanche to just north of Hillsboro to Sulphur Springs.
The actual cold front appears to be draped across west Texas then
northeast into central Oklahoma based on my rough subjective
analysis of wind/temp/pressure with some assistance from the
latest HRRR. The location of the actual cold front becomes
important in determining if additional convection will develop
later today or tonight.

For the remainder of today, the outflow boundary will continue to
push southward and should be a primary focus for new shower and
thunderstorm development later this afternoon mainly along and
south of the I-20 corridor. In the meantime, the ongoing
convection will slowly drift southward with time and should weaken
through the early morning hours. This means that a good portion of
the area may miss out on rainfall as the morning stuff weakens and
new convection develops to the south later today. The afternoon
convection should be primarily diurnally driven and diminish in
coverage this evening. We`ll have 50% coverage through the morning
hours focused on the northern areas then shift higher
probabilities south of I-20 this afternoon.

Later tonight, the actual cold front appears that it will enter
North Texas and should be near the I-20 corridor overnight. Most
of the high-resolution guidance does develop additional new
convection during the overnight hours along the frontal boundary
and in an area of generally weak warm advection. We`ll maintain
some 30-50% PoPs during the overnight hours to account for this
activity.

As we get into Thursday through the upcoming weekend, the forecast
becomes heavily impacted by what is expected to be a tropical
cyclone which makes landfall along the middle Texas coast sometime
late Friday. If the system becomes better organized, expect the
Hurricane Center to begin issuing advisories later today. For
Thursday, we`ll begin to see increasing synoptic flow around the
developing low over the western Gulf of Mexico. With the frontal
boundary still lingering in the area, there should be a fair
coverage of afternoon showers and thunderstorms during peak
heating of the day across a good portion of the area.

By Friday, PoPs will be driven by the track of the tropical
cyclone. This current forecast will continue to use a slightly
more progressive timeframe to PoPs through the weekend as opposed
to the slower ECMWF. It should be noted that a number of the GFS
and ECMWF ensemble members do slow the system down and make an
abrupt right turn on Saturday, which would mean a period of very
heavy rainfall across parts of southeast Texas. While the specific
details are still too far out, we will continue to monitor this
potential closely over the next 24-48 hours. Persons with
interests in southeast Texas should closely monitor the latest
forecast given the potential for significant rainfall and
extensive flooding. Our latest forecast will show increasing rain
chances late Friday night with best chances Saturday into early
Sunday primarily across our east and southeast counties. We`ll
hang on to some higher rain chances across our southeast counties
Sunday night into Monday to account for a potentially slower
system.

As of now, it appears that the greatest threat in our area will
be across our southeast counties. Areas west of I-35 and north of
I-20 appear to have limited impacts from this system at this time.

Dunn

&&

.AVIATION... /Issued 1227 AM CDT Wed Aug 23 2017/
/06Z TAFs/

An extensive area of showers and thunderstorms developed along an
early season cold front from West Texas into Oklahoma. This
activity has diminished in intensity, but some thunder remains as
it approaches the Dallas/Fort Worth Metroplex. The outflow is
indistinguishable from the postfrontal winds, and this effective
frontal boundary will arrive nearly coincident with the
precipitation. The weak shear and marginal lapse rates aloft
should limit the incidence of thunder, and the 06Z TAFs will
maintain only showers. The activity will taper off during the
morning push.

The boundary should reach Waco mid to late morning by which time
the nocturnal showers will have dissipated. The main focus for
redevelopment along the boundary during the afternoon hours will
likely be to the south of the Waco terminal, but it may be close
enough to warrant inclusion in subsequent TAF issuances. Deeper
into the postfrontal air, the Metroplex terminals should have a
lull in activity Wednesday afternoon/evening through Wednesday
night.

Winds near the top of the frontal inversion will veer Wednesday
night, sending an upglide of moisture above the shallow
postfrontal layer. This bout of stratus has been introduced into
the extended portion of the DFW TAF.

25

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    90  74  88  72  89 /  50  50  40  20  20
Waco                96  75  91  73  90 /  50  50  40  30  30
Paris               87  69  84  66  86 /  40  10  10  10  10
Denton              88  72  88  70  88 /  40  50  30  20  20
McKinney            89  71  87  67  88 /  40  40  30  20  20
Dallas              90  75  88  73  89 /  50  50  40  20  20
Terrell             92  73  89  71  89 /  50  50  30  20  20
Corsicana           94  74  88  73  90 /  50  50  40  30  20
Temple              96  74  92  73  90 /  40  40  40  30  40
Mineral Wells       86  71  87  69  88 /  50  50  40  30  20

&&

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

$$



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