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

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FXUS64 KEWX 050235 AAA

Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
935 PM CDT Sat Jul 4 2020

Both WV and IR channels are showing a cluster of upper level clouds
over central Texas pushing to the south. Area Doppler radars are
showing only light echoes associated with this activity at this time.
Latest HRRR and NAM 3Km do not show any convection making it down to
our region for the tonight period. However, some of the outflow
boundaries coming out of this activity will act as focus for possible
showers and storms across the Hill Country on Sunday afternoon.
Otherwise, a warm overnight period with lows in the low to mid 70s
and Sunday`s high temperatures in the upper 90s to 105 degrees for
Del Rio.


.PREV DISCUSSION... /ISSUED 651 PM CDT Sat Jul 4 2020/

/00Z TAFS/
VFR conditions are expected across area airports through the
forecast period. Winds should remain light through Sunday morning and
from the southeast and south for the most part with gusts up to 20
knots especially over KDRT before sunset (between 02Z and 03Z
Sunday). HiRes models suggest for showers and storms to fire up on
Sunday afternoon across central Texas and then move closer to the
Hill Country and the Austin area. At this time, there is low
confidence on this outcome and decided to keep out mentioning
convective activity. Winds will remain from the southeast and south
on Sunday afternoon while averaging from 7 to 10 knots with gusts up
to 16 knots along the Rio Grande/KDRT/


SHORT TERM (Tonight through Sunday Night)...
The upper level ridge which has kept South Central Texas hot and dry
for the last several days has shifted to the west. At the same time
a mid-level area of low pressure is beginning to take shape across
Mississippi and Louisiana. This leaves Texas caught in the middle
with generally northerly or northwest flow aloft.

After another hot day today and mild night with little to no cloud
cover tonight, changes begin on Sunday. With the weakness in the
ridge convection will be possible well to our N and NW tonight along
a weak boundary. While this activity itself should dissipate long
before it reaches South Central Texas, outflows from that activity
could approach the Hill Country and Austin Metro area Sunday
afternoon. Combined with decent moisture and plentiful sunshine
there may be enough lift to generate some very isolated shower and
thunderstorm activity. This is depicted  in all of the short term
models like the Texas Tech WRF, HRRR, NAM, NMM/ARW, and others,
while the global models and NBM remain dry tomorrow. While most
folks won`t see rain on Sunday, there could be a lucky few that see
a brief downpour before the sun returns. Increased cloud cover from
the remnant convection across north Texas and cumulus hanging around
Central Texas tomorrow should keep temperatures a degree or two
cooler than today, but upper 90s to near 100 are still expected.

With the weakness in the ridge the rain chances Sunday and continued
slight rain chances in the first few periods of the long term are
all low confidence events with very little in terms of a focus for
convection but plenty of heat and moisture to work with should
anything get going.

LONG TERM (Monday through Saturday)...
Midlevel ridge will have since fractured and retreated westward with
a slowly retrograding upper level trough over the Mississippi Valley
by Monday. This trough looks to meander around the Arklatex Monday
and Tuesday bringing likely chances for showers and storms for the
eastern portion of the state. Upper level pattern will be somewhat
favorable over our northeastern/eastern CWA for some storm activity
early next week along with pwat values nearing 2 inches. Slight
chances to chances of showers and storms for Monday and Tuesday with
the possibility of persisting into Wednesday. Euro is the only model
as of now that has storms that far west still on Wednesday. This
added moisture will keep high temperatures suppressed to the mid 90s
for these northeastern areas but will make it difficult to cool off
at night with overnight lows forecasted to remain in the upper 70s.

Although high temperatures will be in the mid 90s, heat indices will
still remain above 100 degrees for a good portion of the region. Heat
indices will be something to monitor closely much of next week.
Currently calling for 105 to 108 heat index values along the Rio
Grande and 103 to 106 for I-35 corridor and Coastal Plains, Monday
through Friday. Should remain below heat advisory criteria for all
areas but will come within a few degrees for our eastern zones.

Subtropical ridge begins to expand from the west on Wednesday and
forms a broad area of high pressure over the southern US in
conjunction with ridging over the central Gulf by end of the week.
This will usher away any other chances for rain and usher in a
gradual warm up of temperatures back into the upper 90s for most of
the area and remaining 100 to 103 along the Rio Grande.

Blended guidance in the long term suggests daily afternoon chances
for seabreeze driven convection for far southeastern counties but
did not give this much credence give the large subsidence pattern
expected to anchor in place.


Austin Camp Mabry              77 101  76  96  77 /   0  20  -   -   10
Austin Bergstrom Intl Airport  74  99  73  96  76 /   0  20  -   -   10
New Braunfels Muni Airport     73  99  73  97  76 /   0  -   -   -   10
Burnet Muni Airport            75  98  73  94  74 /   0  20  10  -   20
Del Rio Intl Airport           78 105  79 105  80 /   0   0  -    0  -
Georgetown Muni Airport        77  99  74  97  76 /   0  20  10  10  20
Hondo Muni Airport             71 102  73 101  76 /   0  -    0   0  -
San Marcos Muni Airport        73  99  75  97  75 /   0  -   -   -   10
La Grange - Fayette Regional   76  98  77  97  77 /  -   10  -   10  10
San Antonio Intl Airport       77 100  78  99  77 /   0  -   -   -   10
Stinson Muni Airport           74 101  76  98  77 /   0  -   -   -   -




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