Harper, Texas Weather Resources

000
FXUS64 KEWX 201833
AFDEWX

Area Forecast Discussion
National Weather Service Austin/San Antonio TX
133 PM CDT Sun Sep 20 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 131 PM CDT Sun Sep 20 2026

- Low chances (15-50%) for showers or storms across the Hill
  Country and Southern Edwards Plateau from Sunday night into 
  Tuesday.

- Low chances (mainly below 15%) for spotty rain across South Central
  Texas Tuesday night through next week with most staying dry.

- Oppressive heat continues into next weekend.

&&

.SHORT TERM...
(Tonight through Monday night)
Issued at 131 PM CDT Sun Sep 20 2026

A flattened upper ridge axis sits in an elongated SW-NE axis over 
the SE half of TX today with weak upper troughing has carved into 
the NW half of TX. A good sized mid level shortwave is moving into 
West Central TX and will be a focal point for afternoon and evening 
convection that will eventually spill south into parts of the 
southern Edwards Plateau and the Hill Country. Midday skies continue 
to contain a good amount of cirrostratus which has delayed cumulus 
growth in the area where storms are expected to initiate. This 
leaves the projection for rain chances in low confidence as there 
are not yet any surface boundaries. Looking at the some of the 
higher res model looks shows some surface outflow winds that could 
continue to support convective initiation as the shortwave drifts 
slowly SE. This suggest a possible slow moving cluster of storms and 
potentially an opportunity for a slightly upscaled system into a 
small MCS, but not many model solutions favor this. The WPC ERO 
covers for this area, and a 1-3 inch area of rain could be 
attainable. Hi-res QPFs a mostly under 2 inches for the higher 
amounts, but the normally excitable FV3 run did show a maxima over 
5 inches around JCT.

There is a more distinct frontal boundary that drops south of the 
Red River into North Central TX. The timing of this feature is not 
ideal, so the PoPs to choose from hold mostly close to the more 
conservative NBM population scheme. It should be noted that there 
are significant upticks in PoP in both the MAV and MET MOS products 
in the more populated areas of the I-35 Corridor, and hopefully this 
comes to fruition and is caught onto by the next runs of the NBM. 
Should we get more convection in our areas as suggested by GFS/NAM 
12Z runs, there could be an increase in downdraft winds approaching 
severe levels, especially if there's a well defined boundary to 
trigger convection over the Hill Country as the NAM suggests. 

Meanwhile over southern counties, we continue to see the hot, sticky 
conditions with not much winds and heat indices getting up into the 
100-107 degree range. With a slight NW flow pattern starting at 500 
mbs and increasing higher up, models show more nocturnal activity to 
set up where the front washes out which is at our northern CWA 
border, with southward slow cell motions to offer more chances for 
locally heavy downpours.

&&

.LONG TERM...
(Tuesday through next Sunday)
Issued at 131 PM CDT Sun Sep 20 2026

Late Tuesday our resident upper ridge gets better established again 
with the center over E/SE TX. While deep monsoonal flow works over 
the western periphery, abundant storm activity over Far W TX and NM 
will only enhance the inflow low level winds and enhance onshore 
winds. So while the ridge keeps the weather hot, the winds keep the 
RH values elevated for high heat indices topping 100 each day 
through mid week. A few showers and storms could get going in the 
afternoons, but the ridging overhead should keep the coverage closer 
to around 10 percent after Tuesday. The ridge continues to amplify 
late in the week which should lead to reduced onshore flow and a 
drier and more stable regime heading into the weekend. This will 
hopefully lower morning low temperatures and afternoon heat index 
values, but offer no relief from the ambient high temperatures. 

&&

.AVIATION...
(18Z TAFS)
Issued at 1244 PM CDT Sun Sep 20 2026

VFR CIGs should continue throughout the forecast. There is a very
low possibility of MVFR CIGs for KSAT and KSSF but kept mention
out of this TAF package for now. Otherwise expect light southerly
to southeasterly winds for all I-35 TAF sites. KAUS may briefly
have winds switch to the south southwest overnight before
returning southerly by daybreak. For KDRT VFR CIGS expected 
throughout with light southeasterly winds switching to easterly 
after sunset.

&&

.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry              76  99  76  99 /  20  10  10  10 
Austin Bergstrom Intl Airport  76  99  75  99 /  10  10  10  10 
New Braunfels Muni Airport     74  98  74  98 /  10  10  10  10 
Burnet Muni Airport            72  95  72  94 /  30  30  30  30 
Del Rio Intl Airport           75  99  75  97 /  10   0  30  10 
Georgetown Muni Airport        75  98  75  97 /  20  20  20  20 
Hondo Muni Airport             73  97  73  96 /  20  10  10  10 
San Marcos Muni Airport        74  99  74  98 /  10  10  10  10 
La Grange - Fayette Regional   76  99  75  99 /   0  10  10  10 
San Antonio Intl Airport       77  97  76  97 /  10  10  10  10 
Stinson Muni Airport           76  99  75  99 /  10  10  10   0 

&&

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

$$

SHORT TERM...18
LONG TERM....18
AVIATION...CJM