National Weather Service Raw Text Product

Displaying AFOS PIL: AFDFWD Received: 2019-01-12 18:27 UTC


200 
FXUS64 KFWD 121827 AAB
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
1227 PM CST Sat Jan 12 2019

.AVIATION...
/18Z TAFs/

Midday winds are generally from 290-300, and with some gusts
topping 25kts, there may be some minor crosswind issues early this
afternoon on DFW's north/south runways. This would be limited to 
smaller aircraft, and as the winds continue to veer this
afternoon, any crosswind concerns should abate. Wind speeds will
subside this evening, north/northwest winds prevailing thereafter
generally 8-12kts.

The postfrontal stratus deck has slipped south of the I-20
corridor, the southern edge of which may flirt with Central Texas
airports this afternoon. With additional dry advection into the
sub-cloud layer, this thin stratus will likely scatter this
evening. But with a massive postfrontal cloud deck upstream that 
is continuous into the Canadian Prairie Provinces, the cooling
boundary layer should allow MVFR ceilings to return during the
predawn hours Sunday. The GFS MOS is used to eventual clearing in
a postfrontal air mass, but its perfect prog inputs continue to be
cloudy. Waco may remain south of this deck, but that potential
will need to be reassessed with subsequent TAF packages.

This moisture will remain trapped beneath the frontal inversion
Sunday afternoon, but it may not be sufficient enough to maintain
ceilings. Will introduce an optimistic VFR period in the extended
portion of the DFW TAF, but this is a low confidence forecast.

25

&&

.UPDATE... /Issued 609 AM CST Sat Jan 12 2019/
/Early This Morning/

It appears models were a little slow with both the surface cold
frontal progression and the mid level trough, though less so with
that feature. Regardless, it appears the better moisture, lift,
and low convective chances have shifted east of our far eastern
counties. I have removed the very low thunder chances through
mid-morning. It'll still be brisk and colder with gusty northwest
winds 15-20 mph with a few gusts to near 30 mph today. 

Sans areas north of Highway 380 between Graham and Sulphur 
Springs this morning, the rest of the forecast area will see 
plentiful sunshine into late morning, before wrap-around clouds in
wake of our cold front and system migrate back south toward the
I-20 corridor by midday. Central Texas will remain sunny through 
the day. Clouds will expand back south and west later tonight. Be 
sure to take your coat or jacket before heading out the door 
today. 

05

&&

.SHORT TERM... /Issued 355 AM CST Sat Jan 12 2019/
/Today and Tonight/

A surface cold front was moving into Western North and Central 
Texas early this early this Saturday morning. Low clouds (or 
stratus), south winds at 10 mph, and isolated showers/tstorms were
skirting across areas mainly along and of I-35E and I-45. The 
residual convective activity was occurring on the back edge of the
richer moisture axis and in advance of the main mid-level trough 
and associated lift that was moving east across Western Oklahoma 
and Northwest Texas. Further west, winds at the surface were 
already veering west-northwesterly at 10-20 mph in the wake of the
cold front. Drier air was also entraining across this same area 
in behind the moist warm sector further to the east as was helping
to initially scour out the low level stratus across many of our 
western counties, though a finger of stratus extended from near 
DFW toward Comanche and Hamilton.

Our mid-level trough will move progressively east into the Ozarks
and Mid Mississippi Valley region through midday, with associated
flow over North and Central Texas becoming quickly zonal. This 
transition to a fast zonal aloft will help to support and move the
surface cold front quickly east through the remainder of our CWA.
In the cold front's wake, brisk northwest winds will increase to 
between 15-20 mph by midday, with occasional higher gusts. It'll 
be windy, but currently are not concerned with reaching wind 
advisory at this point. It certainly bears watching later today, 
however. 

Despite the early-mid morning west to east clearing of the 
current low level stratus, high resolution models indicate wrap- 
around stratus will filter back southward along the slow-deepening
frontal inversion and in wake of the mid level trough exiting 
northeast of the region. The stratus deck hanging around the Red 
River after sunrise this morning will spill back southward toward 
those areas along or slightly south of the I-20 corridor and 
generally along and east of U.S. 281. The saturated frontal 
inversion across the northern CWA and strong low level cold 
advection will make for a very challenging temperature forecast 
this afternoon. I will be following the RAP/HREF cloud and 
temperature models closely for the forecast. Afternoon 
temperatures will likely struggle to get out of the 40s under the 
stratus deck, while insolation (sunshine) helps values rise well 
into the 50s further across Central Texas. A word of caution: if 
the stratus deck was to extend further south or be possibly be 
less intrusive and farther north than the current forecast, then 
there is the potential for a big bust on today's high temperature 
forecast. What is certain is that it will be brisk and chilly.

Stratus clouds will hang around tonight over at least the 
northeast half of the CWA as strong north flow of 15-25 knots in 
the 925mb layer assists in drawing moisture southward across a 
good chunk of North-Central Texas. Despite the insulating lower 
cloud deck, the cold advection and low surface dew point 
temperatures in the 30s will combine with brisk north winds of 10-15
mph for a chilly Saturday night for those having outdoor plans. 
Low temperatures Sunday morning are expected to fall between 30-35
degrees. The chilly temperatures will combine with the brisk 
north winds to create winds chill temperatures by daybreak Sunday 
in the mid-upper 20s across all but the far southeast counties by
sunrise. 

05

&&

.LONG TERM... /Issued 355 AM CST Sat Jan 12 2019/
/Sunday through Friday/

Forecast Summary---The first part of the short term 
period will see below normal temperatures across North
and Central Texas. A warming trend is expected to get going on
Tuesday with temperatures climbing well above normal values by the
end of the week. Low rain chances are forecast late in the week 
with what could be a pretty substantial cool down next weekend.

Sunday and Monday---The start of the long term period will be
quite cool as north winds replace northwest flow at the surface.
These north winds will limit the downsloping and will also serve
to usher in colder air on Sunday. Model guidance continues to key
in on wrap around moisture on the backside of the 925mb low 
poised to scoot eastward towards the Ozarks on Sunday. This should
also keep conditions pretty chilly on Sunday, especially north of
the I-20 corridor where confidence is the greatest in widespread 
stratus. Farther south across Central Texas, confidence isn't as 
high in stratus, so I've kept temperature near the previous 
forecast here.

Generally weak northerly flow will continue into the daytime 
hours on Monday, though cloud cover shouldn't be quite as 
extensive, but with lack of return flow during the day on Monday 
below normal conditions should prevail. Return flow will likely 
commence late Monday into Tuesday morning. This should spell 
slightly warmer conditions than the previous night as well as an 
increase in cloud cover.

Tuesday and Wednesday---Tuesday morning will feature increasing
cloud cover, particularly south of the I-20 corridor as southerly
low level flow transports moisture northward. Despite this 
increase in moisture, rain chances will remain very low (under 
10%) given the shallow nature of the modified moist air. Afternoon
high temperatures should rebound nicely with near seasonal 
values. If the cloud cover is really dense, some cosmetic changes 
to temperatures may be required for Tuesday's high temperatures. 
Mild conditions are anticipated overnight into Wednesday across 
most of the area with low temperatures in the low to mid 40s.

Wednesday should be the first of a few days above normal
temperatures. A weak cold front will slide southward towards North
Texas during this time. The 00 UTC GFS remains the aggressor with
the southern progression of this front and advertises that it'll 
slip to the south of the I-20 corridor. The ECMWF, however stalls 
the front north of the US HWY 380 corridor. Given the zonal 
pattern aloft, I'm a bit more inclined to go with the ECMWF 
solution...keeping more areas of North/Central Texas in veered, 
southwesterly flow. This equates to a warm forecast with highs 
generally in the mid to upper 60s. The exception will be across 
the Red River Valley, where the magnitude of southwest/west winds 
will be lower...yielding temperatures in the low 60s. 

Moisture will lift northward on Wednesday across Central Texas and
a weak upper trough will translate eastward across the Concho
Valley and into the Big Country. At this time, it appears that the
best lift may be displaced to the south of our Central Texas
counties and I've kept late Wednesday rain-free. In addition, a
coastal low appears to develop and this turns some of the low
level flow to the east and northeast across the Texas Coastal 
Plain...hindering northward moisture transport.

Thursday and Beyond---Thursday should be well above normal in 
terms of high temperatures as southwest breezes continue. Raw 
guidance from ECMWF and GFS support widespread 70s and I've nudged
highs up towards these values. There may be a greater coverage of
clouds across East Texas as the Coastal Low moves eastward and a 
greater amount of moisture streams northward. I've kept 
temperatures a few degrees lower here with this in mind.

Low rain chances return to the forecast late Thursday into Friday,
mainly across the Brazos Valley where WAA will start to increase
ahead of the next upper trough progged to move towards the area.
It'll be a mild night Thursday night into Friday morning with the
increase in low level moisture. Friday should see low rain chances
across East Texas with above normal warmth. The rain potential 
ramps up late Friday and into Saturday. There are still some 
differences between the ECMWF and GFS so I expect some changes to 
the long term PoP forecast as we await a better model consensus. 
The ECMWF remains quite aggressive with QPF likely due to a 
stronger front, and slower/more amplified upper trough. The GFS 
is a bit swifter with the upper trough and a little less amplified
with this feature. For now, I'll remain conservative with only 
slight chance to chance PoPs late Friday into Saturday, but given 
the tendency for guidance to under amplify digging western CONUS 
troughs, the ECMWF may verify. If so, PoPs will need to be 
increased. The ECMWF also has a significantly colder airmass 
behind a shallow front, while the colder air in the GFS lags 
behind...possibly due to differences between the trough amplitude.
Not ready to sound the alarms just yet, but if the ECMWF solution
is to verify, there could be a possible brush with winter weather
for parts of the area. Stay tuned for details.

Bain

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    49  35  46  34  48 /   0   0   0   0   0 
Waco                55  34  49  34  50 /   0   0   0   0   0 
Paris               49  34  44  32  46 /  10   0   0   0   0 
Denton              48  33  45  32  48 /   0   0   0   0   0 
McKinney            49  34  45  33  47 /   5   0   0   0   0 
Dallas              51  35  46  34  48 /   0   0   0   0   0 
Terrell             52  35  46  33  47 /   5   0   0   0   0 
Corsicana           53  36  49  34  48 /   0   0   0   0   0 
Temple              56  35  49  35  50 /   0   0   0   0   0 
Mineral Wells       49  33  46  30  50 /   0   0   0   0   0 

&&

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

$$

25/11