Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Austin/San Antonio Texas
1130 PM CST Thursday Dec 18 2014
ceilings and visibilities will bounce around with the rain showers/thunderstorms and rain developing
and moving north across the region. I-35 terminals are currently
LIFR/IFR. Will continue to see LIFR/IFR ceilings over the east with
periods of MVFR with the rain showers/thunderstorms and rain passing through. MVFR ceilings
developing at kdrt currently then fall to IFR from 12z through
16z. Did maintain the tempo group for thunderstorms and rain at kdrt although most
convection should remain showers. North/NE winds 8-12 knots are
expected overnight and into Friday afternoon. Cloud cover will
likely hang tough into Saturday with IFR/MVFR ceilings.
Previous discussion... /issued 856 PM CST Thursday Dec 18 2014/
Update... /no changes planned for this evening/
evening conditions are gradually coming into alignment with the
high pop forecast for this evening and late tonight. Quantitative precipitation forecast amounts
continue to favor the easternmost counties with the afternoon and
evening model run consensus showing the highest rainfall totals
over the hgx County warning forecast area. Temperature and dew points appear to be within
a couple degrees of projections...so will leave the forecast as is
Previous discussion... /issued 525 PM CST Thursday Dec 18 2014/
IFR/MVFR ceilings east to VFR/MVFR ceilings west will rapidly
deteriorate to LIFR/IFR/MVFR between 01z-03z and continue into Friday
morning. Rain showers/isolated thunderstorms and rain will continue to develop to the south
and move north. Convection will increase after 03z and continue
through 16z at the eastern taf sites. North/NE winds will increase to
near 10 knots overnight and remain 10-15 knots through 20/00z.
After precipitation ends will see gradual improvement in ceilings
from LIFR to IFR to MVFR. After 20z-23z terminals should be VFR.
Previous discussion... /issued 339 PM CST Thursday Dec 18 2014/
Short term (tonight through Friday night)...
early afternoon surface observations show a stationary front along
the Texas coast with a surface low in deep south Texas. Temperatures
varied considerably and areas stuck beneath the clouds were in
the middle 50s while locations with some sunshine have jumped into
the middle and upper 60s. Elsewhere...the latest radar data shows a
few showers developing along the coastal plains. These showers
will continue to develop and move northward through tonight.
Meanwhile...an upper level trough will approach from the west. The
cold pool aloft along with a Stout upper level jet will spread
across the region after midnight. This will bring an increase in
shower and thunderstorm activity to the region. We could see a
strong storm or two mainly west of Highway 281 tonight...with hail
being the main concern. Farther east...the hail concern will
decrease and transition into a locally heavy rainfall concern. The
latest models are not quite as strong with the low-level moisture
return across our region as the stationary front should remain a
little farther south than previously anticipated. We/ll continue
to retain high rain chances for tonight into Friday morning...but
we did opt to shift the mention of locally heavy rainfall to areas
east of I-35. Average rainfall totals for tonight and Friday
morning will be lowest along the Rio Grande where roughly 0.10"
can be expected. Amounts increase to near 1" along the I-35
corridor... with 1 to 2" east of I-35. Can/T completely rule out
an isolated 3" total east of a Karnes City to La Grange line. A
quick decrease in shower and thunderstorm activity is in store
Friday afternoon as the upper level trough axis begins to move
east. All precipitation is expected to end Friday night as
northerly winds bring drier air into the region.
Long term (saturday through thursday)...
dry and cool conditions are in store for the upcoming weekend as
surface high pressure and zonal flow aloft remain in place. Another
upper level trough will move through Texas on Sunday...but no
precipitation is expected as the atmosphere remains fairly dry.
Temperatures warm ahead of a weak Pacific cold front on Monday.
Given plenty of sunshine and southwesterly winds...we have increased
Monday/S high temperatures into the upper 60s to middle 70s. The cold
front does push through Monday night into Tuesday and this will help
knock temperatures down closer to climatological normals. Southerly
flow quickly returns on Wednesday and Thursday with another cold
front moving through just beyond the end of the current forecast
Preliminary point temps/pops...
Austin Camp Mabry 51 57 45 57 43 / 90 70 - - -
Austin Bergstrom international Airport 52 56 46 56 41 / 90 70 - - -
New Braunfels Muni Airport 54 57 45 58 44 / 90 70 - - -
Burnet Muni Airport 48 54 40 55 41 / 80 60 - - -
del Rio International Airport 55 64 44 60 47 / 40 20 - - -
Georgetown Muni Airport 49 53 41 55 42 / 90 70 - - -
Hondo Muni Airport 55 62 42 59 44 / 80 50 - - -
San Marcos Muni Airport 52 57 45 57 43 / 90 70 - - -
La Grange - Fayette regional 54 57 47 58 44 / 100 100 10 - -
San Antonio International Airport 55 59 45 58 44 / 90 70 - - -
Stinson Muni Airport 56 60 45 60 45 / 90 70 - - -
public service/data collection...32