Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

Area forecast discussion...updated 
National Weather Service Austin/San Antonio Texas
1149 am CST sun Feb 1 2015

Aviation.../18z taf cycle/

Kaus/ksat/kssf are MVFR as of 18z with kaus likely to remain MVFR
through much of the afternoon into early evening as a stratocumulus
deck pivots in from the north associated with a surface trough.
Ksat/kssf are on the cusp as of 18z going VFR but and will do so for
about an 1-2 hours. However...expect them to fall back to MVFR as
aforementioned cloud deck near kaus moves south. Kdrt is VFR as of
18z but it too will likely fall to MVFR by 19-20z given observations
upstream and limited mixing out of the cloud deck. A few sprinkles
and light rain could be possible with the lower clouds but felt
probability was too low to include directly in tafs at this time.
All sites will improve through the late evening and overnight to
VFR with only middle to high clouds.

Winds are SW/west but will turn sharply north through the afternoon
with the passage of the surface trough. Winds will be sustained
10-15 knots with gusts 20-25 through the late afternoon into the
overnight before calming towards dawn tomorrow. /Allen/

&&

Previous discussion... /issued 1113 am CST sun Feb 1 2015/

Update...
based on area radars photos...surface observations and latest hrrr
data output...we lowered probability of precipitation by 10% across the eastern zones for
this afternoon. A pre-frontal trough will push across the area
within the next few hours followed by the actual cold front around
middle afternoon. Isolated to scattered rain showers are possible
this afternoon mainly along and east of Interstate 35. There is
a slight chance for thunderstorms across the southeastern part of
south central Texas and coastal plains. Breezy northerly winds
are expected in the wake of the cold front of 15 to 20 miles per hour with
gusts up to 30 miles per hour. A dry and cooler airmass is in store with
overnight lows dropping to the lower 30s across The Hill Country
to middle and upper 30s along the I-35 corridor and lower 40s in the
coastal plains area. Updated zones out shortly.

Previous discussion... /issued 536 am CST sun Feb 1 2015/

Aviation.../12z tafs/
light rain has moved east of the region this morning with drizzle
and fog remaining. Ceilings vary from LIFR to MVFR with a few
locations even up to VFR. For the tafs will start out with
LIFR/MVFR ceilings. After 16z-18z should begin to see
improvements to MVFR/VFR. South and southwest winds 5-10 knots are
expected this morning. Should see a pre-frontal trough push into the
region 18z-20z with a strong cold front 21z at kaus and kdrt then
around 23z for ksat/kssf. Scattered showers and thunderstorms are
possible along and ahead of the front...mainly I-35 east were the
best moisture will be located. Have only included a tempo group at
kaus to cover the expected convection. At this time only looking
for isolated convection near the ksat/kssf terminals. Northerly
winds will increase to 15 to 25 knots with higher gusts behind the
front and likely continue through 02/09z-12z...then decrease to
near 10 knots.

Previous discussion... /issued 346 am CST sun Feb 1 2015/

Short term (today through monday)...fog through sunrise across
western areas of the County Warning Area. Will monitor closely for dense fog
development...with hi res models indicating this potential and
visibilties trending this was at some sites. Otherwise...yesterdays
shortwave has pushed well northeast of the area...and we are left
with just very patchy drizzle.

A pre-frontal trough will approach the I-35 corridor midday...with
actual cold front entering The Hill Country and Austin area around
21z and southern County Warning Area and San Antonio area around 00z. Low and middle
level flow turns west with the pre-frontal...resulting in drying
west of I-35 and the better moisture pool across the eastern County Warning Area.
A few hi res models indicated isolated showers developing ahead of
the pre-frontal trough around the Austin area...becoming more
scattered across the far eastern County Warning Area...where better moisture pool
resides. Have retained a slight chance of thunder...mainly for
the far eastern zones. Falling temperatures middle to late afternoon across
The Hill Country and Austin area behind the actual cold front...
with a breezy north wind developing this evening across much of
the area. Depending on partial clearing this afternoon...could see
high temperatures ahead of the front in the low to middle 70s across
southern areas.

A light freeze is possible across The Hill Country Monday
morning. Drier and cooler across the County Warning Area on Monday...with highs
only in the upper 40s northeast to middle 50s south and west.

Long term (monday night through saturday)...the upper level low
cut off near the tip of Baja California California is forecast to lift
northeast into north-central Mexico Tuesday. Ahead of the
system...both the GFS and European model (ecmwf) are indicating a middle and upper
level vorticity axis along with deeper moisture lifting southwest
to northeast through the area on Tuesday...resulting in rain. High
end chance to likely probability of precipitation are forecast across central and southern
areas Tuesday. Cool temperatures given the cloud cover and precipitation...with
highs only in the low 50s Tuesday. Would not be surprised if a few
locations struggle to make it out of the upper 40s across central
and southern areas.

The rain chances continue into Tuesday night and Wednesday morning
as the upper level low approaches...although western areas may
begin to see middle level drying...with best probability of precipitation confined mainly
across the eastern half of the County Warning Area. Elevated lapse rates steepen
during this time...and can not rule out isolated thunder.

Another cold front will drop south through the area Thursday
morning...behind the departing upper level system phasing into the
northern stream trough. Clouds may linger across northern and
eastern areas during the day on Thursday. Mostly clear and dry
conditions Friday and Saturday.

&&

Preliminary point temps/pops...
Austin Camp Mabry 69 37 51 37 54 / 20 - 0 0 40
Austin Bergstrom international Airport 69 36 51 34 53 / 20 - 0 0 40
New Braunfels Muni Airport 70 38 53 37 52 / 20 10 0 0 60
Burnet Muni Airport 65 32 49 33 54 / 20 0 0 0 20
del Rio International Airport 68 41 56 41 52 / 10 - 0 0 30
Georgetown Muni Airport 67 34 49 33 54 / 20 0 0 0 20
Hondo Muni Airport 71 39 56 38 51 / 10 10 0 0 60
San Marcos Muni Airport 69 37 51 36 52 / 20 10 0 0 50
La Grange - Fayette regional 71 38 50 36 54 / 40 10 0 0 60
San Antonio International Airport 70 39 54 38 52 / 20 10 0 0 60
Stinson Muni Airport 71 40 55 39 52 / 20 10 0 0 60

&&

Ewx watches/warnings/advisories...
none.
&&

$$

Mesoscale/aviation...15
synoptic/grids...17
public service/data collection...30

National Weather Service Glossary of Abbreviations