571 
FXUS64 KFWD 100541
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1141 PM CST Sat Feb 9 2019


.AVIATION...
/06Z TAFs/

Challenge continues to be timing/trends of lowering CIGs/VSBYs at
all TAF sites through Sunday night. Regardless, expect most
locations to remain at IFR/LIFR CIGs through most, if not all, of
their respective TAF periods.

Surface winds have begun to veer more notably to the southeast, in
response to one shortwave impulse lifting away from North Texas.
VSBYs have risen slightly / held above IFR levels at all sites
recently, perhaps due to a slight weakening of low-level ascent in
the wake of this impulse. Therefore, prevailed 6SM at all sites
for a few more hours, with TEMPO 3SM. As a broader trough to the 
west (and another embedded impulse in leading southwesterly flow) 
approach towards 10-12Z, rain/drizzle should be reinvigorated over
the region. Expect this to slowly reduce VSBYs from this time 
period onward, although small fluctuations between MVFR and IFR 
are possible through mid-day. CIGs will likely remain IFR or lower
overnight into the day tomorrow. KACT may have a greater 
likelihood of LIFR CIGs by 08-09Z this morning, but confidence 
was too low to include in the TAF at this time.

With that said, expect another round of low-level moistening
through the afternoon and evening tomorrow, given gradual height
falls to the west and a strengthening, poleward mass response 
over our region. Therefore, continue to show all sites with CIGs
lowering below 005 Sunday afternoon. Additionally, VSBYs should
gradually lower into the evening and overnight. Prevail 1SM by  
21Z at KACT and 01Z at Metroplex sites, and some potential exists
for LIFR/VLIFR during the overnight hours. However, confidence
remains too low to introduce at this time range.

Picca

&&


.UPDATE... /Issued 927 PM CST Sat Feb 9 2019/
/Tonight/

Only notable change with this update is increasing PoPs in the
near-term from the I-35 corridor northeastward towards Paris.
Light echoes have blossomed from Central Texas to DFW and then
northeast to the ArkLaTex this evening, and KFWS data illustrated
some enhancement of winds veering with height over the last
several hours (correlating with increasing warm-air advection).
This round of precipitation should gradually lift north/northeast
through the early morning hours, followed by another round (or
simply another expansion of ongoing echoes) of light rain 
developing towards daybreak.

Surface temperatures are above freezing across the vast majority
of North and Central Texas this evening. The only exception is
near the Red River, where some modest wet-bulb cooling and neutral
surface temp advection has kept a few sites near 32 F. Still, 
further veering of winds to a slightly more southeasterly 
direction should gradually push temps to around 33-34 through the 
night. Additionally, temps are not expected to fall any lower than
32, such that impacts on road surfaces are not anticipated.

Picca

&&

.SHORT TERM... /Issued 231 PM CST Sat Feb 9 2019/
/Tonight/

Cold and very dreary conditions are anticipated through the
overnight hours across North and Central Texas. Temperatures at
this time appear that they will be high enough to mitigate the
potential for any freezing rain/drizzle. 

Light rain continues this afternoon across North and East Texas in
response to isentropic ascent along the 295-310K theta surfaces.
While the depth of the lower tropospheric moisture isn't overly
impressive, it appears sufficient for measurable rainfall across
the area and this is likely to continue periodically through the
overnight hours. Some model guidance indicates some gradual drying
aloft and so we may see some periods of drizzle as well waves of 
very light rain. I'll keep PoPs in the 40-70 percent range across
the area, but the threat for thunder looks low with generally 
poor lapse rates. 

Initially, it was thought that surface temperatures would be low 
enough to support a round or two of light freezing rain/drizzle 
across the Big Country and along the Red river. Northeast surface
winds could certainly support this potential as wet-bulb cooling 
would help temperatures fall below 32. However, latest guidance 
and observations indicate more of an easterly wind field across 
the area which hampers the magnitude of dry air advection. While 
temperatures may cool initially due to evaporative effects, the 
lack of a continual feed of dry air should mitigate the potential 
for sustained sub-freezing temperatures and thus a threat for 
icing. Moreover, the latent heat release associated with freezing 
coupled with veering low level flow (thus WAA) should allow 
temperatures to remain just above freezing. As such, I've removed 
any frozen/freezing precipitation from the worded forecast, but an
occasional report of a very thin glaze of ice is not entirely out
of the realm of possibility on elevated surfaces such as 
powerlines, road signs and tree branches. Road surfaces should 
remain just fine. 

Bain

&&

.LONG TERM... /Issued 231 PM CST Sat Feb 9 2019/
/Sunday through Saturday/

Sunday morning should start off cloudy and cool with areas of
drizzle and fog and perhaps some areas of light rain as persistent
warm advection continues atop a slowly modifying cold airmass. The
warm advection will be maximized along the I-35 corridor into our
northeast counties through the day which is where we'll have the
highest PoPs. As we get into the late evening and nighttime hours,
large scale forcing for ascent will increase as a fast-moving lead
disturbance swings across northern Mexico into North Texas. The
main upper shortwave will spread through the four-corners region
by early Monday morning.

With the cold airmass currently in place being eroded by Sunday
night, temperatures are likely to remain steady or increase
through the overnight hours into Monday morning. On Monday, with
the main shortwave ejecting from the southwest U.S. and into the
Plains, a surface low will develop and race northeast into Kansas.
Low level southerly flow will increase and we may have some
instability by afternoon for a few thunderstorms mainly east of
I-35. Rain chances will continue into Monday evening when a cold
front swings through the region.

Tuesday and Wednesday should be precipitation free with
temperatures warming back above normal by Wednesday afternoon. On
Thursday, another disturbance will swing through the Central
Plains with winds becoming more westerly across North Texas. This
should allow temperatures to climb into the mid 70s especially
west of I-35. Some low chances for rain will occur across our far
eastern counties with this system on Thursday, but the bulk of any
precipitation should be well to our east. Another front will slide
through the region Thursday night.

Dunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    36  47  47  67  41 /  70  80  90  60  20 
Waco                35  48  48  69  42 /  50  60  50  50  20 
Paris               33  43  43  62  40 /  70  90 100  80  30 
Denton              35  45  45  67  38 /  70  80  90  50  10 
McKinney            34  46  46  65  40 /  70  80  90  70  20 
Dallas              37  47  47  67  42 /  70  80  90  60  20 
Terrell             36  47  46  67  41 /  70  70  80  70  20 
Corsicana           36  49  48  66  42 /  60  60  70  70  30 
Temple              35  49  49  69  43 /  40  50  40  40  20 
Mineral Wells       33  46  46  68  37 /  40  50  60  40  10 

&&

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

$$

11/30