Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 08/23/20
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
624 PM CDT Sat Aug 22 2020
.AVIATION...
Prevailing VFR conditions through the TAF period. East to
southeasterly winds around 5 to 10 knots will also prevail through
the period. No other hazards anticipated.
&&
.PREV DISCUSSION... /ISSUED 355 PM CDT Sat Aug 22 2020/
SHORT TERM (Tonight through Sunday Night)...
A widespread convective complex that passed through the area this
morning and early afternoon has moved out of the area to the south.
Winds left in the wake of this complex are quite variable at the
moment, and the predominant southeasterly direction should recover
soon. A second, weaker disturbance may move south through our
western counties, though have kept the POPs quite low as the
convective allowing models (CAMs) have either not picked up on the
disturbance, or have kept coverage at the extreme minimum. Tonight
should be mostly clear with overnight lows in the upper 60s across
the Hill Country, and low 70s elsewhere. Tomorrow looks to be mostly
dry with the exception of a few stray showers in our far eastern
counties.
LONG TERM (Monday through Saturday)...
The main issue in the long-term forecast will be the tropics and what
ultimately happens with Marco and Laura as they enter the Gulf of
Mexico. Marco is expected to enter the gulf later this afternoon and
the latest aircraft fixes on its center have shown strengthening
today. Marco has strengthened quicker than what was expected and we
mentioned in our discussion yesterday afternoon that if Marco was a
stronger system, a more northerly track was most likely to be
favored. The initial thinking was that the northerly track may put
it somewhere closer to the TX/LA border. However, models have come
into decent agreement with the 12z suite that Marco may make a
landfall as far east as Mississippi or southeastern Louisiana.
What is interesting is that our over performing complex of storms
last night could be playing an impact on the eventual evolution of
Marco. Models have always progged a weak trough axis over Texas to
continue late this weekend and early next week that would lead to the
weak shear that was forecasted to weaken Marco. However, the
shortwave from the complex of storms has reached the Texas coast this
afternoon. With an abundance of latent heat release from the
activity that was not in previous model runs,the GFS/ECMWF and other
models as a result strengthen the upper trough over the Texas Coast
and even close it off later this evening. This cut off low is
expected to meander around South Texas through Monday before it moves
west. The counter-clockwise flow around the closed low should also help
steer Marco to the north rather than an eventual west track. This in
addition to the thought of a stronger system getting pulled into the
main trough axis increases confidence in the 12z models solutions of
a much more eastward track away from South-Central Texas.
The latest 4 PM advisory from the National Hurricane Center shows
this trend as well with the forecasted landfall shifted all the way
to New Orleans. As a result, have lowered PoPs for the area by
and capped them at 20 percent. Did not want to completely take them
out and will leave that up to the midnight shift to prevent any huge
run-to-run flip flops in the models. As Marco clears the Gulf by
Monday night or Tuesday, Laura will be right behind it. The latest
guidance from Laura also brings it to the Louisiana coast with some
ensemble members to the left or to the right of that track. Not
expecting it to be a player for our weather at this time. Will keep
low rain chances in the forecast through the period, but confidence
is not high for the Pops.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 74 93 73 98 74 / - - - - 10
Austin Bergstrom Intl Airport 71 92 71 97 73 / - - - - 10
New Braunfels Muni Airport 73 93 71 97 73 / - - - - 10
Burnet Muni Airport 71 91 71 96 72 / - 0 0 - -
Del Rio Intl Airport 76 97 74 99 74 / - - - - -
Georgetown Muni Airport 72 93 72 99 73 / - - - - 10
Hondo Muni Airport 72 94 71 99 73 / - - 0 - 10
San Marcos Muni Airport 72 93 71 97 72 / - - - - 10
La Grange - Fayette Regional 72 95 72 99 74 / - 10 - - 10
San Antonio Intl Airport 73 94 74 98 74 / 10 10 - - 10
Stinson Muni Airport 74 94 74 97 74 / - - - - 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term/Aviation...EWilliams
Long-Term...04
Area Forecast Discussion
National Weather Service Great Falls MT
744 PM MDT Sat Aug 22 2020
.SYNOPSIS...
It will remain dry with a warming trend through Monday, with
afternoon highs peaking in the lower to mid 90s at lower
elevations Monday. Breezy winds are expected today across parts
of North Central Montana as a weather system moves through
Alberta. Shower and thunderstorm potential increases again later
Monday through the middle of next week, while temperatures trend
back closer to seasonal averages.
&&
.UPDATE...
A southwesterly flow aloft continues to direct smoke from the
California fires, northeastward into The Treasure State. This has
had the effect of reducing air quality, especially across southern
Montana, where the smoke is most dense. Inherited forecast is
performing as planned; therefore, no adjustments to the forecast
will be made, at this time.
- Fogleman
.DISCUSSION...
This evening through Monday night...
The upper level ridge will remained flattened out this evening and
tonight as a moisture-bereft shortwave trough slides east and
across the Northern Rockies. As it traverses the CWA during the
day a weak, gusty west winds have developed and will continue
through the rest of the afternoon, then diminish into the evening
hours. A weak surface cold front will also push southeast across
North Central and Central Montana, bringing about a wind shift
from west to north here. The gusty winds this afternoon, combined
with forecast RH values below 20 percent, led to a Red Flag
Warning being issued for Fire Wx Zone 112, but it is slated to be
dropped this evening as winds calm down. After a night with low
temps largely near normal from the mid-40s to mid-50s, high temps
Sunday are forecast to range from the mid-80s to low 90s outside
of the mountains. By Sunday night upper level ridging will begin
briefly to build back across the Northern Rockies, with the ridge
amplifying during the day on Monday ahead of the next approaching
shortwave moving into the Pacific Northwest. Monday will be the
warmest day of the week for most areas, with high temperatures in
the upper 80s to upper 90s.
Areas of smoke and haze can be expected over the next several
days, especially across Southwest and Central Montana as upper
level winds transport particulates from wildfires burning across
the Western CONUS into the region. The weak front passing this
evening may provide some relief from haze for much of the CWA
tonight into Sun morning, but returning SW`ly surface winds may
allow low level smoke and haze to advance north across the CWA
again later Sunday. By Monday afternoon the shortwave over the
Pacific Northwest will begin to approach the Northern Rockies,
which will promote the transport of Pacific moisture into the
region via southwesterly flow. This increasing moisture combined
with diurnal heating and the approaching shortwave will promote
isolated to scattered showers and thunderstorms over the higher
terrain of Southwest Montana initially, with the activity then
lifting northeast and across portions of Central and North Central
Montana during the overnight hours on Monday. -Kredensor/Moldan
Tuesday through Wednesday night...Moisture associated with the
Southwest Monsoon begins to circulates back in across the Northern
Rockies through Wednesday as the upper level flow transitions from
southwest to nearly zonal. This will lead to daily chances for
afternoon showers and thunderstorms over Southwest and portions of
Central and North Central Montana through the middle of the work
week, with areas along and south of the I-90 corridor having the
highest chance of seeing a shower or storm. We will need to watch
the CAPE and shear forecasts closely for the potential for strong
or severe storms, but at this point, CAPE is largely looking on
the weaker side in most models. -Kredensor/Moldan
Thursday through next Saturday...Longer range models/ensembles are
showing some potential relief from the longer duration warm weather
pattern we have been experiencing beginning next weekend. While the
details are still fairly uncertain, there is good agreement on
larger scale troughing to deepen over the NW US and Western Canada
next weekend downstream of a more amplified ridge in the eastern
Pacific. This would at least suppress the strong ridging that has
been in place over the western US and likely bring some cooler
temperatures to the Northern Rockies and MT.
&&
.AVIATION...
615 PM MDT Sat Aug 22 2020 (23/00Z TAF Period)
With a plume of smoke stretched across the region from southwest
Montana, through the central part of the state and into the east,
MVFR conditions are forecast at KBZN and KWYS where the obscuration
is most dense. All other airfields are forecast to remain VFR.
Additionally, expect mountain obscuration in smoke. Gusty winds, up
to about 25KT, are forecast at the onset of this period; however,
within the first hour or two, winds become light and remain light.
In association with hot daytime temperatures, light aircraft will
feel the impacts of thermals. The associated turbulence is forecast.
- Fogleman
Refer to weather.gov/zlc for more detailed regional aviation weather
and hazard information.
NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing
runway closure.
&&
.FIRE WEATHER...
A weather disturbance moving across the Northern Rockies today
will result in a period of stronger winds along the Hi-Line
through this afternoon. West winds gusting up to 25-35 mph are
forecast to continue across the plains of North Central MT
through the afternoon hours, then diminish this evening. Further
south and east, breezy west winds with gusts of 20-25 mph are
possible, with winds becoming northwesterly by late this afternoon
and then diminishing this evening. Relative humidity will lower
to around 15 to 20% by this afternoon for most areas as well. A
Red Flag Warning remains in effect for Fire Weather Zone 112,
including Glacier, Toole, Liberty and Pondera counties, where the
strongest winds are expected and will coincide with critically low
RH for a sustained period of time. Further east, winds and RH may
both reach RFW criteria for a few hours, but may not be long
enough to warrant a warning.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 53 91 56 93 / 0 0 0 10
CTB 45 86 50 90 / 0 0 0 10
HLN 53 92 56 92 / 0 0 0 20
BZN 47 92 54 93 / 0 0 0 10
WYS 38 86 45 86 / 0 10 0 20
DLN 46 89 53 87 / 0 0 0 20
HVR 51 90 55 97 / 0 0 0 0
LWT 52 88 56 93 / 10 0 0 10
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until 9 PM MDT this evening Eastern Beaverhead
National Forest.
&&
$$
http://www.weather.gov/greatfalls