Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX

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FXUS64 KEWX 280442
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1042 PM CST Mon Feb 27 2017

.AVIATION... /06z TAF Package/
Little change to the 06z TAF package compared to the 00z TAFs. The
main change is to push back the progression from MVFR to IFR to LIFR
due to the stratus being slower than expected. As of 430z the stratus
is approaching the I-35 terminals and MVFR cigs should begin by 05z.
From there cigs will continue to drop to IFR along I-35 by 07z and
LIFR by 09z. DRT will also see low stratus and fog overnight, but
should only drop to IFR around day break. Winds will be southerly
through the period helping the low clouds overnight, but a front is
expected late Tuesday night into Wednesday morning which will bring a
return to north winds. This is just inside the 30 hour TAF window.

&&

.PREV DISCUSSION... /ISSUED 546 PM CST Mon Feb 27 2017/

AVIATION...
With southerly flow continuing low clouds and fog are expected to
develop tonight. VFR conditions will prevail through the evening
hours, but late in the evening MVFR stratus should begin to develop.
This will drop to IFR and then LIFR cigs by 09z across the I-35
corridor. Visibility will drop to around 1 mile at the I-35
terminals. While some brief dips in visibility are possible, winds
staying up between 6 to 8 knots should keep visby up slightly. Low
cigs and fog will remain through most of Tuesday morning before
finally breaking out into VFR conditions by 18z. DRT will also see
low stratus and fog overnight, but should only drop to IFR around day
break.

PREV DISCUSSION... /ISSUED 307 PM CST Mon Feb 27 2017/

SHORT TERM (Tonight through Tuesday Night)...

No major highlights through the short-term as well-above normal
temperatures are ongoing this afternoon and even warmer temperatures
expected tomorrow after early morning clouds and areas of fog.

Clouds continue to mix out across the region with most locations
reaching into the mid 70s to low 80s as weak zonal to slightly
southwest flow continues. Surface dewpoints are in the mid 50s west
to mid 60s east and this low-level moisture along with cooling this
evening will aid in abundant low clouds and patchy fog once again.
Dewpoint depressions are projected to be near or less than a degree
Tuesday morning and this could support localized patchy dense fog
with widespread areas of fog. Have also added patchy light drizzle
from 4am to 10am given the near-surface saturation.

After diurnal mixing occurs and clouds break apart, H925 temps are
expected to be slightly warmer Tuesday then today per BUFR soundings
and thus higher surface temperatures are anticipated. Some areas will
be nearly 20F degrees above normal for this time of year. Austin
could approach its record of 87F set back in 1978.

LONG TERM (Wednesday through Monday)...

A stronger shortwave trough will shift across the central CONUS
Wednesday and bring a mostly dry cool front through the region.
Temperatures will fall back to near normal through the end of the
week. Rain chances will increase going into Friday and the weekend as
a slow moving cut-off low and associated disturbances shift towards
the region.

A sharper trough axis currently off the California coast will shift
across north Texas by late Tuesday into early Wednesday morning. This
trough passage and stronger surface high pressure will aid in
northern airmass infiltration and temperatures Wednesday will be
tempered down about 10-15F degrees from Tuesday`s highs with north
winds. Given the timing of the front and lack of deeper forcing, only
light showers (if that) are expected along the front as it shifts
through the region by mid to late morning.

Thursday will be a dry and clear day behind the front and likely the
coolest morning with some sporadic mid 30s in the Hill Country. No
freezing temperatures are expected at this time.

By Friday and into the weekend - a slowly moving cut-off low is
expected to shift across north Mexico towards central or south
Texas. Both the GFS and ECMWF agree that a potential ejecting
shortwave trough will occur ahead of the main parent low Saturday as
moisture return commences back from the Gulf of Mexico. While there
may be some pockets of heavy rain, overall moisture return pattern
may remain better farther south that could favor any concentrated
heavy rain threat. As the parent low nears south Texas on Sunday, it
appears to open up and slowly weaken. Have a persistence of 30-50%
rain shower coverage across the southern 2/3rd of south-central
Texas given this pattern through the day Sunday. Models disagree in
the long range on Monday if a stronger northern-stream trough can
bring a front down into the region just following the exit of the
weakening cut-off low. Have kept low-end rain chances in given the
uncertainty.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              78  66  86  61  70 /  20  10  20  20  10
Austin Bergstrom Intl Airport  79  66  86  62  70 /  20  10  20  20  10
New Braunfels Muni Airport     79  65  87  62  72 /  20  10  20  20  10
Burnet Muni Airport            75  62  82  56  65 /  20  10  20  20  -
Del Rio Intl Airport           85  59  88  58  76 /  -   -   -   -   -
Georgetown Muni Airport        78  64  84  59  67 /  20  10  20  20  10
Hondo Muni Airport             81  63  89  59  77 /  10  10  10  10  -
San Marcos Muni Airport        78  66  87  62  71 /  20  10  20  20  10
La Grange - Fayette Regional   81  68  85  65  71 /  20  10  20  20  20
San Antonio Intl Airport       80  66  87  62  73 /  10  10  20  20  10
Stinson Muni Airport           81  66  87  63  74 /  10  10  20  10  10

&&

.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Mesoscale/Aviation...Treadway
Synoptic/Grids...LH
Public Service/Data Collection...30



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