#3628 Postby weatherdude1108 » Mon Feb 08, 2021 4:42 pm
Here's the EWX discussion. GFS is smokin' something. They're lowering their temps for the weekend, but not to the 12Z GFS numbers. Ensembles vary. I'd rather have upper teens to 20s rather than single digits. Our homes aren't quite built for that kind of 12Z GFS craziness.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
311 PM CST Mon Feb 8 2021
.SHORT TERM (Tonight through Tuesday Night)...
A rather tricky forecast for the short term as a cold front will
attempt to move through the area, but likely get hung up somewhere
within our northern and eastern counties Tuesday afternoon. An
arctic cold front is slowly pushing southward over NW Texas and the
Panhandle into portions of Texhoma, as high level clouds stream in
from the southwest over South-Central Texas. Morning clouds and low
stratus have begun mixing out, allowing for sunshine to filter
through. Temperatures should easily top out in the 70s today, but
enjoy it, as this could be one of our warmest days for quite some
time.
For tonight, expect winds to turn more southerly and variable, with
nearly calm conditions at the sfc ahead of the approaching cold
front. Widespread fog is expected to form tonight, as shallow
moisture pools over the Coastal Plains/Hill Country/I-35 Corridor
through Tuesday morning. Visibilities could drop to less than a 1/2
mile for locations mainly along and east of I-35, but some dense fog
could materialize at times in the San Antonio and Austin Metros. The
fog should lift by mid-morning Tuesday, but then things get even
more interesting. The cold front we`ve been talking about for what
seems like weeks, will begin pushing into our northeastern counties
Tuesday afternoon. This will present a challenge for high
temperatures. Have opted to go with a blend of the NAM/TTWRF/GFS
with this boundary slipping as far south as the Comal, Caldwell, and
Fayette counties Tuesday afternoon. Temperatures north of the front
will struggle to get out of the upper 50s and lower 60s, whereas
south of the boundary, widespread 70s and even lower 80s look
likely. Temperatures will also be on the cooler side behind the
boundary for Tuesday night, as it holds up/stalls out over the
Coastal Plains and Hill Country.
With regard to precipitation chances, the airmass is rather shallow,
and so is the moisture when looking at model soundings. We may some
drizzle or light mist out of those clouds Tuesday night into early
Wednesday am, but not enough to mention any PoPs at this time. Upper
level support will arrive just outside of the short term forecast
period, warranting precipitation chances.
&&
.LONG TERM (Wednesday through Monday)...
A challenging forecast period is in store from mid-week through the
upcoming weekend across south central Texas. The main concern will
be the potential for much colder temperatures late this week into
early next week.
Beginning Wednesday morning, we will likely see the leading edge of a
shallow cold front in place across portions of the Hill Country near
Burnet eastward into the I-35 and Highway 77 corridors. With shallow,
cold air near the surface and moist air just above this layer, this
warm air advection pattern favors light shower development across
most areas, except out west along the Rio Grande. A few rumbles of
thunder are also possible Wednesday afternoon, but overall chances
for thunderstorms remain fairly low at this time. The temperature
forecast will be tricky as the leading edge of the front may slow
its southward progress or retreat northward during the afternoon
hours. The cold front looks like it will make some southward progress
Wednesday night and with southerly flow just above the cold air
remaining in place, some additional showers and possibly a
thunderstorm or two (mainly west/south of I-10) can be expected.
The cold air looks to deepen on Thursday as a mid and upper level
trough approaches from the west. Intermittent showers along with a
low chance for a thunderstorm or two along the Rio Grande are in the
forecast. With fairly high rain chances in the forecast and cold air
advection, we have lowered the high temperature forecast for
Thursday. If the rain is a little more persistent, we will need to
lower our forecast high temperatures on Thursday. As the upper level
trough passes over and eventually to our east Thursday night into
Friday morning, we will see a quick decrease in rain chances from
west to east. For now, we will only keep a 20% chance of rain
Thursday evening for areas east of I-35, then go with a dry forecast
as we head into early Friday morning. We do have a decent amount of
atmospheric moisture in place as the cold front and upper level
trough interact across the region. Rainfall amounts Wednesday and
Thursday should average less than one-tenth of an inch across the Rio
Grande plains, with amounts increasing to around one-quarter of an
inch for the Hill Country and along the I-35/I-37 corridors. Amounts
increase over the coastal plains and Highway 77 corridor with average
amounts around one-half inch.
The forecast for late this week into early next week continues to
present a challenge. The upper air pattern late this week (Friday)
does favor Arctic air moving southward into the southern U.S.
plains. There is plenty of cold air bottled up over northwest Canada
and northern Alaska with afternoon temperatures around -35 to -40F
and surface pressures close to 1060mb. The mid-level flow pattern
somewhat resembles a McFarland signature on Friday, with a ridge
just off the west coast and a east-west oriented trough along the
Canadian/U.S. border. As of now, it appears this pattern does not
remain intact for too long. While our confidence is good we will see
colder temperatures, the amount of cold air that will be able to move
this far south remains in question. For now, we will keep highs in
the mid 40s to mid 50s on Friday, with temperatures set to trend
downward for the upcoming weekend into early next week. We have not
trended the forecast toward the latest 12Z GFS. We continue to see
quite the spread among the ensemble model members and our forecast in
the GFS numbers is not very high at this time. However, we did opt
to drop our forecast highs and lows for the upcoming weekend, with
highs in the 30s and 40s on Sunday, with lows in the teens to upper
20s.
The forecast for early next week bears watching as the medium range
models show an upper level trough moving in from the west. The
atmosphere looks to remain dry as this system moves through, so we
will not mention any precipitation in the forecast at this time.
Last edited by
weatherdude1108 on Mon Feb 08, 2021 4:47 pm, edited 2 times in total.
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