Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 01/12/21
Area Forecast Discussion
National Weather Service Fort Worth TX
613 PM CST Mon Jan 11 2021
...New Short Term, Aviation...
.SHORT TERM... /NEW/
Update:
No major updates are needed to the short term forecast package
this evening as the major trends below are still on track. We
tweaked the fog areas tonight/tomorrow morning based off trends in
the low level cloud cover and snowpack on the last few remaining
visible satellite images this evening.
We are still expecting a cold night tonight with everyone dropping
below freezing and many locations dropping to full saturation in
the early morning hours. Overnight lows across the southern third
of the forecast area were forced down to the dew point, and these
areas are where freezing fog was included in the forecast. We are
still unsure of exactly where/if dense fog will develop, so we
are still not planning on issuing a Dense Fog Advisory.
With that being said, freezing fog is one of the lesser understood
Winter hazards. It is a process where condensation of supercooled
water droplets form a mist or fog. These liquid droplets are in a
stable state until they make contact with something to agitate
the state of the individual drops. This causes the liquid drops to
freeze on contact and convert into ice. This can occur on bridges,
vehicles, stairs, metal railings, etc. creating slick spots in
unsuspecting places. If you must travel, please exercise caution
as freezing fog may deposit ice on roadways resulting in slick
road conditions. In addition, black ice will also be possible from
recent snowfall.
Bonnette
Previous Discussion... /Issued 116 PM CST Mon Jan 11 2021/
/This afternoon through Tuesday/
The primary concern in the short term forecast period will be the
threat for freezing fog tonight for Central Texas.
Visible satellite imagery reveals that cloud cover is slowly
eroding across much of the region. Snowpack from Sunday`s storm
was still quite evident, despite the clearing conditions. This
afternoon we will see temperatures largely in the 40s, though
parts of Central TX and the Big Country may struggle to get out of
the 30s thanks to the lingering snowpack.
Tonight, we`ll see excellent radiational cooling conditions with
mostly clear skies and winds generally under 10 mph. As a result,
overnight lows will dip down into the 20s and 30s for most areas.
Across our snow-covered East and Central Texas counties, temps
may flirt with the teens. The melting today will pump a little bit
more moisture into the boundary layer and with forecast soundings
near saturation, there seems to be a decent bet that we`ll see
some radiation fog develop tonight. With temperatures falling
below 32 degrees, we`ll have a threat of freezing fog and I`ve
inserted a mention of this this into the forecast. At this time,
I`ve tried to confine freezing fog to the areas that have snow on
the ground, largely south of I-20. The mention of freezing fog
may need to be expanded as far north as the I-20 corridor across
the Big Country, however, depending on model trends this
afternoon.
I contemplated issuing a Freezing Fog Advisory for our Central TX
counties, but the one fly-in-the-ointment will be winds at the
top of the boundary layer. At present time, winds may average
between 8 and 10 knots and this may induce a bit of turbulent
mixing atop the boundary and may disrupt fog formation. That
being said, the impact of the snowpack is hard to account for and
the extra moisture flux into the PBL could facilitate an
environment conducive for the development of fog/freezing fog
despite the strong flow aloft. For now, I`ll highlight the
potential of light icing and potential slick spots in a special
weather statement, in the hazardous weather outlook and in
graphics. The evening shift will have some additional guidance.
Tuesday should feature warmer conditions with another day of
continued melting. A compact upper low will dive southward into
the Big Country through the day. While there will be some ascent,
it appears that the only real consequence will be an increase in
mid/upper level cloud cover.
Bain
&&
.LONG TERM... /Issued 307 PM CST Mon Jan 11 2021/
/Tuesday night through Next Monday/
Another chilly night is in the forecast for Tuesday night. Overnight
lows will drop into the upper 20s to mid 30s with light southwest
winds and a few passing mid/high clouds. Despite some of the
high-resolution models trying to develop some light drizzle/rain
across parts of Central TX Tuesday night, there will be very
little moisture available in the environment. This will result in
nothing more than increase cloud coverage through Wednesday
morning.
Otherwise, the long-term portion of the forecast remains pretty
quiet with dry conditions expected through the week and most of the
upcoming weekend. Temperatures will stay above climatology
through Thursday with daytime highs ranging from the mid 50s to
mid 60s. The next cold front arrives Thursday evening, but it will
only bring the usual breezy northerly winds behind the front.
These breezy/gusty north-northwest winds will continue into Friday
especially across North TX, as this system moves towards the east
CONUS. Seasonal temperatures are expected into the weekend, with
another shot of CAA from the back edge of this upper system.
Looking beyond...it appears that our next rainmaker will arrive late
weekend or early next week. While details at this point in time
remain highly uncertain, a decent amount of both ECMWF and GEFS
members are showing some measurable QPF over our region. For now, we
will stick to the NBM PoPs for Sunday night through Tuesday until we
see better agreement in the timing of the progression of this
system.
Sanchez
&&
.AVIATION... /NEW/
/12z TAFs/
Concerns: Freezing fog tonight/tomorrow morning at KACT...
VFR and light winds should prevail for D10 through the valid TAF
period. The winds have become calm for most terminals, but should
become predominantly out of the southwest within the next couple
hours. A healthy stream of VFR upper clouds should move into the
area tonight and remain through the day tomorrow before exiting to
the east by tomorrow night.
A similar pattern is expected at Waco, except IFR visibility is
forecast to develop in the early morning hours. The combination
fresh snowpack and being in a slightly less urban setting will
lead to the development of patchy BR/FG tonight. Have maintained
BR developing around 09Z with prevailing 2SM, however, the onset
might be delayed as late as 11Z. The other question mark is how
low will the vsby go...There is a 10% chance of LIFR <1/4SM, which
is too low confidence to include in the TAF, but the potential of
a dense fog is there. With temperatures well below freezing (-3C),
any fog/mist would be supercooled and susceptible to rime
deposition on aircraft surfaces flying in/out of KACT. Aviators
without deicing equipment are urged to use extreme caution if
flying in areas with fog/mist tomorrow morning!
Bonnette
&&
.PRELIMINARY POINT TEMPS/POPS...
Dallas-Ft. Worth 30 52 33 60 39 / 0 0 0 0 0
Waco 26 50 30 58 37 / 0 0 0 0 0
Paris 27 51 30 56 36 / 0 0 0 0 0
Denton 26 53 30 60 36 / 0 0 0 0 0
McKinney 28 52 30 58 37 / 0 0 0 0 0
Dallas 30 54 34 60 41 / 0 0 0 0 0
Terrell 26 51 30 57 37 / 0 0 0 0 0
Corsicana 29 51 33 58 40 / 0 0 0 0 0
Temple 24 49 29 58 36 / 0 0 0 0 0
Mineral Wells 24 52 28 61 35 / 0 0 0 0 0
&&
.FWD WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$