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000
FXUS64 KFWD 251241 AAA
AFDFWD

Area Forecast Discussion...UPDATED
National Weather Service Fort Worth TX
741 AM CDT Wed Apr 25 2018


.AVIATION...
12 UTC TAF Cycle

Concerns---Showers/thunderstorm potential and ceiling/visibility
trends.

For the Metroplex TAFs---Pre-dawn convective activity has waned,
with a new batch of showers and embedded thunderstorms noted
upstream. This activity should move into Metroplex TAF sites
over the next 2-4 hours. Trends in total lightning will be
monitored and a quick amendment for a brief window for TS may be
needed. At this time, mesoanalysis indicates slightly subsiding
instability values near the I-35 corridor, so for now I`ll only
advertise VCSH. Impacts to the Bowie cornerpost and westbound
departures are almost certain, however, given the current radar
presentation. Northerly flow has overspread all TAF sites and this
will be the predominant wind direction through the entire TAF
cycle. MVFR stratus continues to build southward from Oklahoma and
should arrive at Metroplex TAF sites around mid- morning. Cigs
could intermittently fall below FL020 and I`ve inserted a tempo
group to address this.

MVFR will prevail into the afternoon as low level moisture
remains in place. As stronger lift arrives late this morning and
into the afternoon hours, showers and isolated thunderstorms
should blossom. Have prevailed SHRA this afternoon and given the
isolated nature of thunderstorms have elected to append VCTS as
opposed to TEMPO TS or TSRA. There could be some reduction in
visibility (down to around 4 SM) due to pockets of moderate rain.
VFR should return around 00 UTC Thursday (7pm Wednesday), though
we will have to monitor the potential for some patchy BR.

For the Waco TAF---VFR will be the rule for a good portion of the
Waco TAF cycle. North winds are already observed, though slightly
stronger north winds will likely arrive a little later this
morning. MVFR stratus will also arrive after the noontime hour
with a potential for SHRA and VCTS. VFR should return late this
evening. Slightly lower wind speeds aloft may also support some
patchy BR, but at this time, confidence is too low to include in
the forecast at this time.

24

&&


.SHORT TERM... /Issued 341 AM CDT Wed Apr 25 2018/
/Today and Tonight/

The main challenge in the short term will revolve around the
passage of a pretty stout front. Rain and perhaps a few
thunderstorms appear probable near and behind the front. Severe
weather isn`t anticipated at this time.

Nocturnal convection continues to wane across North Texas this
morning as outflow has outrun the parent thunderstorm updrafts.
Farther west, across the Big Country, a small convective complex
continues to be fed by modest 850-700mb warm air advection per
VWP and RAP mesoanalysis. This activity is slowly drifting
towards the east and may impact areas west of Highway 281 and
south of I-20. Cloud top warming, however, suggests that this
complex of storms will weaken through the pre-dawn hours.

Mesoscale subsidence in the wake of the overnight convection may
mean that much of the area remains rain-free through the morning
hours, especially with large scale ascent still across the
Oklahoma and texas Panhandles. I`ve lowed PoPs down into the
chance category through 15 UTC as a result, with the most probable
area for rain being across the Big Country and western Red River
Valley through mid-morning. Instability isn`t great, but given the
presence of a few lightning strikes to the northwest, I`ll keep a
mention of isolated storms. The aformentioned forcing across the
Panhandles will dive southward towards North Texas through the
morning hours and should help to drive the true cold front
southward. Strong isentropic ascent along the 305-310 K theta
surfaces should be efficient at generating scattered to numerous
convective activity along and behind the front. Overall
instability is quite meager and most of the high-res NWP
advertises only a small amount of elevated instability. There may
be enough of a shear/instability combination to support limited
lightning production and I`ll continue to mention the potential
for isolated storms in the forecast. The small amount of
instability will preclude a severe weather threat. Activity will
generally move from northwest to southeast starting as early as
the mid to late morning hours and lasting into the evening hours.

Temperatures today are tricky, but I believe its safe to say a
majority of North and Central Texas will experience below normal
temperatures. With the widespread cloud cover and decent surface
cold air advection, most areas will only climb into the 50s and
60s behind the front. Farther south, ahead of the frontal
boundary, compressional warming ahead of the frontal boundary will
allow temperatures to soar into the upper 70s to near 80 degrees.

Clearer conditions are expected tonight with the passage of the
front. With clear skies and recent rain, we will have to keep an
eye on the potential for some fog. Right now, it appears that the
most likely area would be across the Big Country (really areas
south of I-20 and west of I-35) due to weaker flow aloft. For
other locations, 925mb winds of around 20 to 25 knots may preclude
this threat all together. For now, will let the dayshift have a
closer look at this potential. Overnight low temperatures into
Thursday morning will be 10 to almost 15 degrees lower, especially
west of I-35 where conditions are more prime for ideal
radiational cooling.

24

&&

.LONG TERM... /Issued 341 AM CDT Wed Apr 25 2018/
/Thursday through Tuesday/

A surface ridge axis will be in place across North Texas early
Thursday morning with northwest flow aloft continuing. Another
shortwave trough will be diving southeast through the Plains and
should approach the Red River by Thursday evening. This
disturbance will send another cold front into the region during
the overnight hours Thursday. Moisture will be more limited with
this front, so other than some very low rain chances in the
northeast, most areas will stay dry. On the back side of this
system, mid and upper level ridging will build into the region
Friday and Saturday resulting in a few very nice days with
temperatures steadily warming into the upper 70s and lower 80s.
The weekend is shaping up to be quite nice with seasonal
temperatures and almost no chance of rain.

As we head into early next week, the pattern over the CONUS will
become more amplified. The first in a series of mid level
perturbations will dig into California on Monday. Pressure falls
in the lee of the Rockies will result in increasing southerly
winds and a northward transport of moisture into the region.
Eventually, a slow moving upper low is likely to spread east
through the week. This could set the stage for a more active
weather pattern with afternoon/evening bouts of severe
thunderstorms across west Texas. We`ll continue to monitor this
over the coming days.

Dunn

&&

.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth    62  47  74  52  75 /  70   0   0   5   5
Waco                71  42  77  51  77 /  50  40   0   5   5
Paris               61  45  70  49  71 /  70   5   0  10   5
Denton              61  42  74  49  74 /  60   0   0  10   5
McKinney            61  43  72  49  74 /  70   0   0  10   5
Dallas              64  47  75  53  76 /  70   5   0   5   5
Terrell             66  45  73  50  75 /  70  20   0   5   5
Corsicana           70  45  74  51  76 /  50  50   0   5   5
Temple              79  44  78  52  78 /  40  50   0   5   5
Mineral Wells       58  39  76  48  75 /  60   0   0   5   5

&&

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

$$

24/91