National Weather Service Raw Text Product

Displaying AFOS PIL: AFDFWD Received: 2018-10-12 05:06 UTC


906 
FXUS64 KFWD 120506
AFDFWD

Area Forecast Discussion
National Weather Service Fort Worth TX
1206 AM CDT Fri Oct 12 2018


.AVIATION...
06 UTC TAF Cycle

Concerns---SHRA potential, timing FROPA and post-frontal stratus.

VFR mid-level clouds continue to lift northward mainly across
western portions of the ZFW airspace. These clouds, between
FL050-FL100, will spread eastward with time. Hi-res guidance 
yields high confidence in SHRA during the pre-dawn hours on Friday
with SHRA continuing through a majority of the day at Metroplex 
TAFs. Waco will see rain chances increase later in the day. With 
the dry air below FL070, there will be a potential for some 
turbulence as precipitation evaporates. If this dry layer 
saturates, cigs may fall into the MVFR category with perhaps some 
reduction in visibility earlier than reflected in the current 
TAFs. 

While south flow operations are ongoing now, winds should shift to
the east and eventually northeast after 00 UTC Saturday. The
continued moistening atop the cooler airmass should result in MVFR
stratus at Metroplex TAFs after 02 UTC. Towards 06 UTC, IFR cigs
are possible, but overall confidence is too low to include in the
TAF. For now, I'll advertise MVFR stratus around FL012 in the D/FW
extended with a SCT deck of clouds at FL007. Reduction in vsby
will also be possible due to BR/DZ. FROPA looks to occur just
beyond the current valid TAF for Waco and VFR is currently
advertised.

Bain

&&


.UPDATE... /Issued 920 PM CDT Thu Oct 11 2018/
Overall, the short term forecast is in good shape. However, 
updates were made to overnight and early Friday PoP/Wx grids based
on latest expectations and incoming 00 UTC hi-res NWP. 

Generally tranquil conditions were noted this evening across much
of North and Central Texas...but the increase in mid and upper
level clouds signal what will likely be the end of our fair
weather conditions that we've experienced over the past 48 hours.
The aformentioned mid/upper level clouds are indicative of 
ongoing isentropic ascent and comparison between the 12 UTC Thu/00
UTC Fri FWD RAOB show that this lift has likely yielded an increase
in moisture within the 700-850mb layer. RAP and NAM isentropic 
progs show continued lift through the overnight hours with 
several SPC HREF members indicating scattered to numerous 
convective elements between the 9-15 UTC Friday time frame. I've 
increased PoPs into the likely category across the Big Country and
towards the Red River Valley with these factors in mind. Thunder 
prospects generally look low at this time owing to low amounts of 
instability as seen in forecast soundings and while I cannot rule 
out a rumble of thunder or two...the overall chances look too low 
to include an explicit mention of thunderstorms in the forecast 
at this time and rain showers should suffice.

Otherwise, the rest of the short term forecast is in excellent 
shape and no other changes were needed. Updated products have 
already been transmitted. 

Bain

&&

.SHORT TERM... /Issued 352 PM CDT Thu Oct 11 2018/
/Tonight/

The surface high pressure across the Northern Plains leading to 
our northeasterly winds will be moving to the east, and allow for 
a gradual veering of the winds overnight. The southeasterly winds 
will allow for better moisture to stream northward, ahead of a 
mid-level disturbance. As the disturbance approaches late tonight,
isentropic ascent will begin to increase, leading to a gradual 
uptick in precipitation through the early morning hours. 

Given the increasing cloud cover due to the surge in moisture, 
low temperatures across Central Texas will not be as cool as last 
night. Lows are expected to be in the low 50s across the 
northeast, to around 60 degrees across the southwest. 

Hernandez

&&

.LONG TERM... /Issued 352 PM CDT Thu Oct 11 2018/
/Friday Through Wednesday/

Low level warm advection in correlation with increasing isentropic
ascent in the 305K-315K layer(or basically 700mb-850mb) will
continue to modify our environment from west-east Friday/Friday 
night. This will be in advance of a strong shortwave disturbance 
exiting out of our detached upper low over the East Pacific and 
strong shortwave energy moving across the Central/Northern Plains 
into the Midwest Friday afternoon. Column moisture(PWAT) will 
increase quickly to 1.5-1.75 inches across a good chunk of Texas 
in response the the aforementioned warm advection by the end of 
the day. In addition, the NAM12 (not the GFS) will have a 
reinforcement of shallow and cooler low level airmass moving into
our northern counties through the day, but this is not the main 
cold front we'll be experiencing later in the weekend. The 
combination of these elements will result in scattered showers 
with the ascent from the shortwave enhancing mid level lapse 
rates enough for some embedded rumbles of thunder later Friday 
morning and lasting until the afternoon. A brief reprieve in 
between our lead shortwave and a strong shortwave dropping 
southward across the plains can be expected Friday evening, but 
it's not a certainty that all outdoor events or high school 
football will be unaffected. Otherwise, the additional shallow 
frontal surge across the north and increased cloud cover and 
scattered precipitation will result in a wide range of 
temperatures for highs Friday. Highs may struggle into the 60s 
north of I-20/30, while warming to between 75 and 80 degrees 
across our far southern Central Texas counties. 

The weekend continues to look very wet, and even potentially
stormy across Central Texas Saturday into Saturday night. Deep and
intensifying warm advection/isentropic ascent occurring in advance
of what will be the remnants of Eastern Pacific Hurricane Sergio
will commence. The GFS looks to bomb surface cyclogenesis across
the Permian Basin and Southeast New Mexico during the day
Saturday, while the NAM12(and European to a slightly lesser 
extent) mainly forms a broad and weaker surface low off the lee 
of the Davis Mountains in Far West Texas. I believe with the GFS, 
it is likely underestimating the shallow cool surge across West 
Texas, along with carry low level characteristics from the 
Sergio's remnants that it believes this circulation would survive 
the mountain ranges it will be crossing. I will be leaning with 
the cooler and wetter NAM12/European blend across our area, with 
mid level shortwave energy tracking slightly further south as 
Sergio's remnants get absorbed with the northern stream energy 
quickly. If the GFS was to be believed, the entire area would be 
warm section with the bulk of showers and thunderstorms being 
confined north of I-20 and across the I-40 corridor from Amarillo 
to OKC. I just don't believe this will be the case with the 
aformentioned northern stream energy digging south allowing the 
shallow front to move well into northern and western Texas. 

So what does this mean for North and Central Texas? Well, I
believe a small warm sector will be confined south of I-20 where I
believe if low levels can warm and destabilize enough with
steepening lapse approaching from the west and increasing westerly 
effective bulk shear of 40-50 knots, a window for local strong to
severe storms could develop in a corridor south and west of a 
line from Comanche, to Hillsboro, to Cameron or Hearne, maybe even
further east depending on the how all these elements transition. 
The threat across these areas could linger well into the evening 
hours as southerly low level winds in the lowest 1-3km increase 
to, or in excess of 20 knots. IF this scenario were to evolve, 
that could result in a few shallow, rotating, discrete supercells 
across parts of Central Texas late Saturday. What needs to be 
stressed here is confidence on evolution, track, and timing of 
both surface and features aloft this weekend is not overly high 
and forecast changes could change if the initial surface front 
either stalls or drives further south than what is currently 
forecast. I'm sure more adjustments and changes are to come, but 
interests, especially those outdoor activities such as college and
high school football and other events need to be vigilant. 

Rain chances will continue on Saturday night, as a strong upper
level jet max near the Red River Valley and embedded mid level
shortwave energy continues interacting with the rich moisture in
place. Best chances should be from the DFW Metroplex northeast to
Paris, with more scattered coverage across Central Texas. A strong
cold front still appears poised to arrive later on Sunday, before
clearing the area toward the Texas Coast Sunday night into Monday.
Mostly scattered rain chances will occur, with the better chances
along the low level convergence due to the strong cold front, 
especially Central Texas during this time period. Temperatures 
starting off mostly in the upper 50s and 60s will likely only warm
into the 60s across the northwest counties, with 70s in Central 
Texas falling in the afternoon. 

For Sunday night into the early half of next week, a noticeable
difference in temperatures will be noted behind the cold front 
and with an approaching mid level trough resulting in plenty of 
cloudiness and off/on post-frontal rainfall Monday into at least 
early Tuesday. Highs Monday may not make it out of the mid-upper 
40s across the northwest, with the remainder of the area 
struggling into the lower-mid 50s with low level cold advection, 
precipitation, and zero insolation to assist in diurnal warming. 
If you really wanted Fall to arrive, well here ya go! 

Lastly and most importantly will be the potential impacts from 
consecutive days of rainfall later this weekend into the early 
half of next week. Widespread amounts of 2-4 inches and isolated 
amounts up to 6-7 inches will eventually begin to run off quickly 
due to antecedent and moist soil conditions. Though flash flooding
is not expected to be a "widespread" threat, localized flash 
flooding will be possible. In addition, main stem rivers, 
especially those on the upper Trinity and Brazos basin are already
responsive and run off into these tributaries will likely occur 
quickly after the first inch or more of rain this weekend. This 
will likely lead to at least minor, if not a few points seeing 
moderate flooding on these tributaries. 

It's not going to be pleasant weather late this weekend into 
early next week with brisk, wet, and almost chilly conditions
Sunday night through Tuesday, so prepare for it now. The unsettled
pattern will continue through much of the week, but for now will 
keep POPs at low values until details become more clear. Highs 
will only modify into the 60s mid-late week. 

05/

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    57  69  61  70  63 /  10  60  40  80  70 
Waco                57  77  64  77  67 /   5  20  40  50  50 
Paris               53  63  56  66  61 /   5  40  20  60  80 
Denton              55  67  59  67  61 /  20  60  30  80  70 
McKinney            54  65  58  67  62 /  10  60  30  70  70 
Dallas              58  70  62  70  64 /  10  50  40  70  70 
Terrell             55  72  60  71  65 /   5  30  40  60  70 
Corsicana           57  73  62  75  65 /   0  20  40  50  60 
Temple              58  79  65  80  68 /   0  10  30  40  40 
Mineral Wells       56  71  60  68  60 /  20  60  40  80  50 

&&

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

$$

24/79