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

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FXUS64 KEWX 100417

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
1017 PM CST Fri Dec 9 2022

...New AVIATION...

(Tonight through Saturday night)
Issued at 217 PM CST Fri Dec 9 2022

Yet another warm and muggy day across South-Central Texas with
temperatures climbing into the mid to upper 70s and lower 80s once
again. Changes are on the way though, as a cold front is scheduled
to arrive Sunday morning, but not before a shot at some strong to
perhaps severe thunderstorms Saturday evening/early Sunday morning.

A quick look at GOES-16 Water Vapor shows our next weathermaker
coming into view over Southern California. A compact shortwave
trough will lift out of southeastern New Mexico early Saturday
afternoon and into the Texas Panhandle by early evening. With
continued southerly to southeasterly surface flow ahead of this
approaching 500mb shortwave, ample surface moisture will be in place
to support thunderstorm development Saturday evening into very early
Sunday morning. At the surface, a low will develop over SE Oklahoma
by early Saturday evening, with a trailing cold front extending
along the I-20 Corridor. The latest SPC Day 2 Outlook places
locations generally north of US-290 in a Marginal Risk for damaging
wind. A hail threat looks to exist over the northern Hill Country,
and remains mostly north of our CWA at this time, but isolated hail
reports to the size of quarters remain possible as wind fields
strengthen ahead of the sfc cold front Saturday evening.
Additionally, given 12Z HREF mean 0-3km SRH of 100-200 m2/s2, and
some modest MUCAPE of 750-1250 J/kg, the threat for a quick spin up
is possible for areas east of the I-35 Corridor and north of US-290
Saturday evening into early Sunday morning. Model forecast soundings
are in agreement on some backing of weak low-level flow Saturday
evening into early Sunday morning, so the threat for strong to
severe storms is there, but mid-level wind fields aren`t quite as
pronounced. Hi-res guidance is in fairly good agreement on showers
and storms developing over the Coastal Plains early Saturday
afternoon and continuing through the evening hours, becoming more
robust as mid-level energy arrives from the west, closer to sunset.
Rainfall totals will be on the order of 1/4 - 1/2 inch, mainly north
and east of the I-10 Corridor, with perhaps a lucky few picking up a
quick 3/4 inch in the heaviest downpours. The associated cold front
should begin pushing south and eastward through the Hill Country pre-
dawn, with passage through the remainder of the CWA by midday Sunday.


(Sunday through Friday)
Issued at 217 PM CST Fri Dec 9 2022

The weak frontal boundary will be pushing south Sunday morning and
will bring with it continued chances of rain along and behind the
boundary mainly before noon. Lingering cloud cover should keep
temperatures a bit cooler as well with high temperatures likely
ranging from the middle 60s to middle 70s. Can`t completely rule out
some cooler temperatures as well if the airmass
behind the weak front is a bit cooler. Southerly flow quickly
returns on Monday as a large scale trough moves into the western
CONUS. A very low chance of warm-air advection showers is possible,
but probabilities were too low to mention in the forecast for now.

The trough will move east and initially send a Pacific front into
the area Monday night into Tuesday and this feature could bring some
scattered showers and perhaps a thunderstorm to mainly our northern
and eastern counties into Tuesday afternoon and evening. The best
dynamics will be to our north and we will most likely just be
clipped with the heavier activity to our north. The main trough will
pass to our northeast Wednesday night into Thursday and the more
significant front will arrive on Thursday. High temperatures Monday
and Tuesday will be in the upper 60s and 70s for most areas.
Temperatures will drop into the 60s for highs behind the Pacific
front on Wednesday with highs in the 50s on Friday behind the more
polar front. Lows will also be on the downtrend with lows Friday
morning most likely back in the 30s and 40s.


(06Z TAFS)
Issued at 1017 PM CST Fri Dec 9 2022

Continued S-SE lower level flow maintains a moist airmass tonight
through Saturday evening. MVFR CIGs have formed over KSAT and will
form over KAUS/KSSF/KDRT by 07Z. CIGs then lower to IFR, possibly
LIFR with restrictions to VSBYs overnight into Saturday morning.
CIGs/VSBYs slowly rise to MVFR late morning, then VFR in the
afternoon. MVFR CIGs return Saturday evening. Although flow shifts
to N-NE with passage of a cold front, moist overrunning S-SE flow
maintain IFR/MVFR CIGs. There is a good potential for SHRA/TSRA at
the I-35 sites Saturday evening into the nighttime hours due to the
approach and passage of the cold front. Have changed VCSH to VCTS at
KAUS and introduced VCTS at KSAT/KSSF. Later shifts may have to go
with prevailing TSRA.


Austin Camp Mabry              67  76  62  70 /  10  10  70  20
Austin Bergstrom Intl Airport  67  78  62  70 /  10  10  70  20
New Braunfels Muni Airport     67  80  63  70 /   0  10  60  20
Burnet Muni Airport            64  73  58  67 /  10  20  70  10
Del Rio Intl Airport           64  74  59  73 /   0  10  10   0
Georgetown Muni Airport        66  76  60  68 /  10  20  70  10
Hondo Muni Airport             66  76  62  74 /   0  10  30  10
San Marcos Muni Airport        67  79  62  70 /  10  10  60  20
La Grange - Fayette Regional   68  81  64  72 /  10  20  70  30
San Antonio Intl Airport       66  77  63  71 /  10  10  60  20
Stinson Muni Airport           68  80  65  72 /   0   0  50  20




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