NWS Corpus Christi on board the Wintry Mix train! What a winter!!!!!
000
FXUS64 KCRP 141125
AFDCRP
Area Forecast Discussion
National Weather Service Corpus Christi TX
525 AM CST Sun Jan 14 2018
.DISCUSSION...
Updated for 12Z aviation.
&&
.AVIATION...
VFR conditions continue through most of the period with high
pressure shifting southward. Will see onshore flow return today
which will increase moisture and as a result start to bring back
some clouds. By Sunday night could have some MVFR cigs for VCT,
but have kept all other terminals VFR for now.
&&
.PREVIOUS DISCUSSION... /Issued 446 AM CST Sun Jan 14 2018/
SHORT TERM (Today through Monday)...
Went ahead and issued a freeze warning for a few counties this
morning with VCT dropping to 30 degrees and Beeville approaching
freezing. Temperatures should return to above freezing by around
8am.
Will stay in a northwest flow aloft for one more day, however as
surface ridge shifts from the Great Lakes southward toward the
Gulf of Mexico, surface winds will become more southeasterly and
bring a gradual increase in moisture to the area. We could start
to see clouds today, but the most notable change will be much
warmer low temperatures tonight. Expect most locations to only
fall into the 40s...with portions of the coastal bend likely in
the lower 50s. Expect highs today warmer than yesterday...mainly
in the 60s. By monday, a few locations may warm into the 70s with
warmer 850mb temps. Expect light winds today, but a bit breezier
Monday as the pressure gradient increases between high pressure in
the Gulf and a cold front moving into North Texas.
LONG TERM (Monday Night through Saturday Night)...
WINTRY MIX POSSIBLE TUESDAY NIGHT ACROSS MUCH OF SOUTH TEXAS
No need to bury the lead here, looking like a mess of a forecast
and potential impacts beginning late Tuesday night into Wednesday
morning across much of South Texas with a light icing event. While
not completely confident, latest trends in the strength of the mid-
level trough driving the arctic front through with cold air sweeping
through quicker, does help to increase confidence in the event.
That being said, everything does hinge upon sub-freezing air, either
advected in from the north behind the front late Tuesday night, or
by the wet bulb effect. Drier boundary layer air does filter in
behind the front throughout the evening hours but we continue to see
isentropic lift occur along the 290K layer so light precipitation is
still expected well behind the front. This is where things get
tricky. Model soundings do show a substantial warm nose around 5kft,
GFS/NAM, with a lesser pronounced warm nose on the EC/GGEM though
its still there, which would allow near complete melting of any
frozen precipitation. Depending on the depth of the sub-freezing
temperatures in the boundary layer we could either see a liquid or
re-freezing of the liquid (sleet) reach the ground. We introduced a
large area of -FZRA/IP into the grids for the overnight Tuesday time
period. There is a possibility that we could see a light ice
accumulation early Wednesday morning making for treacherous travel
conditions, especially on area bridges and overpasses. Wind chills
will also be a concern as they drop into the teens to low-20s in a
lot of places.
We slowly warm during the day Wednesday to transition back over to
all liquid/rain by late morning though a majority of the
precipitation should be confined across the south and coastal areas
with coastal troughing developing. While we don`t completely dry
out, at least that is not what we expect at this time, another mid-
level shortwave trough of low pressure ejects out of West Texas and
the coastal troughing moves back inland on Thursday, thus rain
chances increases. As the coastal trough moves inland winds shift
around to the east allowing temperatures to warm a bit but still
remain below average. We went a little below guidance across the Rio
Grande Plains as we don`t think the easterly winds get there and
they keep more of a northeast surface flow helping to maintain a
weak cold-air damming setup.
The shortwave trough of low pressure moves east by early Friday and
we truly begin to dry out from west to east during the morning.
Temperatures warm nicely back towards average though we should fall
short by a couple degrees. Saturday looks dry as well and warmer as
better return flow develops with shortwave ridging moving off to the
east.
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