Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Corpus Christi Texas
554 am CST sun Dec 28 2014
Discussion...see aviation section for 12z tafs.
Aviation...large area of rain continues east of a Pleasanton to
Hebbronville line early this morning. Low MVFR ceilings with
sporadic MVFR visibilities/IFR ceilings in the stronger downpours. This will
continue through most of the morning hours until the strong upper
level disturbance south of the Texas Big Bend moves closer to the
region. Ceilings expected to gradually lift through the afternoon
with VFR conditions expected at ali by 20z...crp at 21z and vct
around 02z Monday. Drier air will invade the region from the
west as the upper disturbance moves by with clear skies/VFR conds
expected through the night.
Previous discussion... /issued 432 am CST sun Dec 28 2014/
Short term (today through monday)...water vapor imagery shows the
strong middle to upper level short wave trough just west of the
Texas Big Bend. Large precipitation shield covers south Texas into
southeast Texas in the right entrance region of the strong 25h jet
downstream from the trough axis. Expect precipitation will cover
most of the area this morning with any threat for thunderstorms
over the waters. Will maintain categorical rain chances for the
coastal counties and coastal waters with likely probability of precipitation just inland.
The short wave trough will move into The Hill Country by 18z today
and into southeast Texas this afternoon. Much drier air will
advance into the region from west to east during the afternoon.
Kept probability of precipitation in the forecast for early this afternoon as light rain
could linger for a few hours past 18z. Went slightly below
guidance for highs today. Surface high pressure settles into the
coastal plains for tonight. With light winds...radiational cooling
will lead to temperatures falling into the 30s except for along
the coast and along the Rio Grande. There could be some isolated
areas in drainage regions along the upper Nueces that could reach
freezing tonight. Surface ridge axis shifts to the east on Monday
with temperatures warming into the 60s over the brush country.
Marine...north winds have diminished over the bays to scec levels.
Canceled Small Craft Advisory for this region this morning. A moderate to strong
offshore flow will perist through the day over the Gulf waters.
Made a slight change to the expiration time of the Small Craft Advisory for the
offshore waters...extending by an hour. Coastal waters will see
widespread rain this morning with isolated thunderstorms with the
precipitation diminishing during the afternoon.
Long term (monday night through saturday)...models have
consistently trended with a slower return of moisture to south Texas
and onstart of weak warm air advection. Am thinking much of Monday night would
result in thickening cloud coverage...with a slight chance for light
rain across the far southern zones early Tuesday morning with slight
chance increasing in coverage through the afternoon as the next
frontal boundary moves further south. A developing coastal low
offshore will add to the isentropic lifting Tuesday night through
the latter half of the week...keeping upper chance probability of precipitation in the
forecast for much of area. Temperatures during the period should
remain roughly below seasonal normal under overcast skies...light
rain and northeasterly flow. Models continue to draw the coastal low
and the bulk of the moisture north along the coast on Friday. The
next upper trough/low swings through the Central Plains Friday
afternoon kicking a surface low across the southern High Plains and
its associated frontal boundary east. Timing at the surface with the
frontal passage continues to be off so will maintain a compromise between
GFS/Euro bringing the front through Saturday morning...thus keeping
rain chances Friday night before further drying on Saturday.
Preliminary point temps/pops...
Corpus Christi 50 37 61 48 63 / 80 0 0 10 20
Victoria 47 34 60 42 60 / 70 0 0 10 10
Laredo 56 41 66 46 61 / 20 0 0 10 20
Alice 52 36 63 46 62 / 50 0 0 10 20
Rockport 50 38 58 50 62 / 90 0 0 10 20
Cotulla 54 33 64 40 60 / 30 0 0 10 20
Kingsville 51 35 61 47 62 / 70 0 0 10 20
Navy corpus 51 41 59 53 63 / 90 0 0 10 20
GM...Small Craft Advisory until noon CST today for the following
zones: coastal waters from Baffin Bay to Port Aransas out
20 nm...coastal waters from Port Aransas to Matagorda Ship
Channel out 20 nm.
Small Craft Advisory until 4 PM CST this afternoon for the
following zones: waters from Baffin Bay to Port Aransas
from 20 to 60 nm...waters from Port Aransas to Matagorda
Ship Channel from 20 to 60 nm.