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

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FXUS64 KEWX 101128
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
528 AM CST Sun Dec 10 2017

.AVIATION... /12Z TAFS/
Vfr skies are expected through the period with only some high clouds
spilling into TX from the west. Winds will be mainly less than 6
knots with most directions from the west or northwest.

&&

.PREV DISCUSSION... /ISSUED 325 AM CST Sun Dec 10 2017/

SHORT TERM (Today through Monday)...

No weather highlights this period as a gradual warm-up continues
today and into Monday above climatological normals. Plenty of sun
with cool mornings expected both days.

Synoptic pattern this morning across the CONUS per water vapor and
RAP analysis depicts a longwave trough across the east coast with
northwest low to mid-level flow occurring back across the Central
Plains. A H5 ridge exists over the west coast with a weak closed low
anchored to the south of this ridge west of Mexico over the east Pacific
Ocean. This closed low is trapped by the ridge to the north but some
mid and upper-level moisture from this system will shift into the
base of the longwave trough over Texas and some high clouds will
stream over the region today. Despite the northwest surface to H850
winds, boundary layer modification continues with the winter sun and
H925 temperatures warming vs. yesterday. Surface temperatures should
climb into the upper 60s to low 70s.

Another cool night expected Monday morning but not quite as cold as
this morning. H925 temperatures warm even more Monday and low to mid
70s look to be quite likely for the entire region. These readings
will be about 8-10F degrees above normal for this time of year.

LONG TERM (Tuesday through Saturday)...

No weather highlights expected in the long-term other than a weak
cold front Tuesday morning and another Thursday that will cool the
area down back to near normal temperatures. While rain low-end rain
chances will need to be monitored next weekend, confidence is low at
this time given the spread of model guidance.

By Tuesday, a stronger longwave trough will pivot across the
Mississippi/Ohio River Valleys and increase northwest flow throughout
the atmospheric column across Texas. The northwest flow will bring
in a weak cold front early Tuesday morning. No rain is expected with
the passage of the front as moisture depth will be quite limited.
The cold front will bring H925 temps back down to 9-11C and allow for
surface high temperatures in the 60s Wednesday.

Low-level wind flow becomes southerly briefly Wednesday and Thursday
as low-level ridging shifts east of the area. Greater low-level cloud
cover is likely thursday morning but this will be short-lived as
another cold front moves through Thursday. No precipitation is
expected with this frontal passage as well.

Model differences appear late next week as GFS advertises greater
southwest flow ahead of a shortwave trough over Mexico vs. ECMWF/CMC
indicating deeper troughing and NW flow. Have gone with a drier and
cooler solution with the ECMWF/CMC weighting vs. the GFS outlier
solution for this forecast. Stay tuned as pattern evolves for late
next week and weekend.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              70  41  74  43  64 /   0   0   0   0   0
Austin Bergstrom Intl Airport  69  37  73  39  63 /   0   0   0   0   0
New Braunfels Muni Airport     69  38  74  39  65 /   0   0   0   0   0
Burnet Muni Airport            68  37  71  38  62 /   0   0   0   0   0
Del Rio Intl Airport           69  37  69  40  68 /   0   0   0   0   0
Georgetown Muni Airport        70  38  74  40  62 /   0   0   0   0   0
Hondo Muni Airport             71  34  74  38  68 /   0   0   0   0   0
San Marcos Muni Airport        69  37  74  40  65 /   0   0   0   0   0
La Grange - Fayette Regional   67  37  73  41  64 /   0   0   0   0   0
San Antonio Intl Airport       70  40  73  42  67 /   0   0   0   0   0
Stinson Muni Airport           69  38  73  41  67 /   0   0   0   0   0

&&

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

$$

Mesoscale/Aviation...Oaks
Synoptic/Grids...Allen



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