NWS Area Forecast Discussion

FXUS64 KFWD 180844

Area Forecast Discussion
National Weather Service Fort Worth TX
344 AM CDT Thu Oct 18 2018

/Today and Tonight/

An upper low located over Utah will begin to transition into an
open shortwave over the next 24 hours as it moves east into
Colorado. Meanwhile, a stationary front currently parallels the
Gulf Coast, keeping a shallow cool airmass in place across all of
Texas. Southwest flow aloft ahead of the shortwave keeps the
overrunning conditions going, and will leave us damp and chilly
for yet another day.

A rare lull in precipitation occurred late last night, but this
was short lived as isentropic lift above the 850MB cool layer
already appears to be ramping up again. Light rain showers will
become more widespread later today with the best rain chances
being along and west of I-35 where the stronger lift will occur.
The coolest conditions will also be across the western counties
where mid-50s high temperatures are likely. Highs should approach
60 along the I-35 corridor with lower and mid 60s attainable
across the eastern counties this afternoon.

Steady rainfall overnight will be mostly run-off and will simply
add to the ongoing river flooding across much of the region. Low
temperatures in the lower and mid 50s look reasonable for most
locations except for the western-most counties where upper 40s
are likely.



/Friday through Wednesday/

Friday should be the last day of widespread rainfall before the
much anticipated break occurs over the weekend. A fairly extensive
area of moderate rain should be ongoing early Friday morning
especially across the northwest half of the region as this area
will be beneath the most favorable upper synoptic forcing. The
very slow moving upper low over the southwest U.S. will be in the
process of ejecting into the Plains early Friday and this process
will help spread forcing for ascent across the northern half of
North Texas. Combined with persistent low level warm advection, we
should see a fairly steady rainfall through at least the first
half of the day. Despite the lack of any appreciable instability,
deep moisture content with PWs still near 2" should support a
little heavier rainfall rates than currently expected for today.
The next shift will have to consider a small duration flood watch
for portions of the area given saturated grounds, but in all,
another 1 to 3 inches of rain will be possible across the
northwest parts of the CWA.

Later in the day Friday, a strong shortwave trough will dig
through the Great Lakes region helping to send a weak cold front
southward through the Plains. While it won`t be significantly
colder, there will be significantly drier air above the surface
ushered in behind this front. This will begin to spread into the
region early Saturday morning and we will see a north to south end
to the precipitation during the morning hours on Saturday. The sun
will try to make an appearance on Saturday if we can get the high
cloud cover out of the way, but will be plentiful on Sunday with
temperatures in the 60s areawide. Monday and most of Tuesday
should be dry across the region, but high cloud cover will again
increase during the day Monday.

Unfortunately, the aforementioned front won`t be strong enough to
scour out moisture entirely and a pool of 2"+ PWs will still be
pooled across Deep South Texas by Tuesday morning just waiting to
spread back northward. It looks like it will get its chance on
Tuesday as a strong shortwave spreads across northern Baja
California and southerly winds increase in response. We`ll also be
watching a potential tropical cyclone in the eastern Pacific
during this time. Most of the global ensemble guidance has a
mature tropical cyclone making landfall across central Mexico late
Tuesday night and spreading northeast. Combined with the
approaching shortwave trough, surging PWs into North Texas, and
enhanced upper jet dynamics, this type of setup has the potential
to produce very heavy rainfall across North Texas by Wednesday.
While not trying sound the alarm too loudly, it bears close
watching over the next several days as soils across the region
will remain saturated through the week and additional heavy
rainfall would be very problematic. We`ll continue to bump PoPs up
late Tuesday night into Wednesday.

Temperatures will be warmest on Saturday with an end to the rain
and a return to some sun. Next week should feature temperatures
5-10 degrees below normal given the increased cloud cover and rain
chances through mid week.



.AVIATION... /Issued 1151 PM CDT Wed Oct 17 2018/
/06Z TAFs/

Low VFR cigs will continue to prevail overnight and into the
morning hours across DFW area airports, while MVFR cigs will prevail
at Waco. Waco could see some sporadic low VFR cigs as dry low
level air tries to entrain from the north-northeast through mid
morning Thursday. This will be due to a south to north sloping
frontal inversion which is deeper across DFW and closer to 850mb,
whereas Waco`s inversion is more shallow. During this time period,
the area will be in between mid level shortwave disturbances.

The next mid level shortwave disturbance currently over the Texas
Coast will slowly migrate northward through the day Thursday. By
afternoon, cigs everywhere will be in the MVFR category as showers
increase from the south. Waco will likely see these showers by
late morning/midday, while DFW may be delayed more during the
mid-late afternoon hours. Rain coverage should increase across the
entire area by 00z Friday and beyond with both vsbys and cigs
falling. Low MVFR cigs with occasional heavier showers causing
vsbys to fall to IFR are expected across the DFW Metro airports
Thursday evening, while RUC soundings show Waco going down into
IFR even on cigs.

Otherwise, light northerly winds around 5 knots overnight will
veer northeast or even east-northeast 6-9 knots by Friday
afternoon as a secondary shallow surge of cool air arrives from
the north. By Thursday evening, northeast winds 4-6 knots will



Dallas-Ft. Worth    61  54  59  55  69 /  30  80 100  60  20
Waco                60  56  60  57  67 /  60  70  90  70  40
Paris               63  52  57  54  69 /  20  40  90  60  10
Denton              61  53  57  55  68 /  30  80 100  50  20
McKinney            62  53  58  55  69 /  30  70 100  60  20
Dallas              62  55  59  56  69 /  30  70 100  60  20
Terrell             64  55  59  56  69 /  30  50  90  70  20
Corsicana           63  54  60  55  65 /  50  50  90  70  30
Temple              58  56  61  57  65 /  70  70  80  70  50
Mineral Wells       58  53  59  54  68 /  50  90 100  60  20




NWS FWD Office Area Forecast Discussion