Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 03/05/24
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
922 PM CST Mon Mar 4 2024
...New UPDATE...
.UPDATE...
Issued at 922 PM CST Mon Mar 4 2024
Storms near and east of the dryline have dissipated with loss of
heating. 00Z models indicate the possibility of re-development of
showers and storms just northeast of the region overnight, but 00Z
HREF members keep this development out of our area.
Attention turns to fog potential overnight and Tuesday morning. Dew
points are sitting in the low to mid 60s across most of the region.
Clearing of high clouds has taken place across western areas, and
will continue to clear west to east over the next several hours
across the remainder of the area. With winds light to calm this will
set the stage for fog development, which is already beginning along
the Rio Grande in Maverick County. 00Z HREF indicates the fog
developing through the Coastal Plains also as clearing takes place,
and potentially right up the I-35 corridor. HREF probabilities of
dense fog (1/4 mile or less) are around 60-80% across the Coastal
Plains to just east of I-35 and also along the Rio Grande and across
the Winter Garden region. We have updated to include dense fog in
the forecast for these areas.
&&
.UPDATE...
Issued at 621 PM CST Mon Mar 4 2024
ACARS soundings out of AUS and SPC mesoanalysis indicates the cap has
eroded. While forcing is relatively weak across the region, a
corridor of increased forcing is located back closer to the eastern
bulge of the dry line through the central Edwards Plateau. We have
recently seen the development of isolated showers and thunderstorm
in this area, from now northwest Llano County back west into Sutton
County. We will monitor trends across Burnet, Llano, northwest
Gillespie, and far northern Kerr and Edwards counties for this
isolated activity. Environmental conditions support isolated strong
to severe storms over the next couple of hours, with hail the primary
risk.
&&
.SHORT TERM...
(Tonight through Tuesday night)
Issued at 1251 PM CST Mon Mar 4 2024
GOES-16 visible satellite imagery into early this afternoon
indicates a decent number of cloud breaks and peeking sunshine
across the region. However, there is increasing high level clouds
moving in from the west. Have elected to raise high temperatures
slightly this afternoon with majority of the area climbing into
the low to mid 80s. Aircraft soundings out of Austin and San
Antonio continue to indicate a healthy capping inversion between
700 and 850 mb. While a weak shortwave is to approach from the
west through early this evening, it`s limited amount of forcing
looks like it will make it difficult to break that inversion, at
least within the metro corridor. Portions of the northern Hill
Country, a region from Brady/San Saba towards the Burnet county
area, could see an isolated storm develop. This particular region
seems to be where there is a slightly better potential for the
erosion of the cap as the dryline bulges farther eastward across
the SJT CWA. If a storm or two were to develop, they could become
strong to severe as of the result of the combination of moderate
instability and sufficient enough deep layer shear over the area.
If any cells develop in this region, they will likely quickly
fade after dark.
Tonight may also see some convection develop across portions of
the southeastern FWD and western HGX CWAs. We`ll monitor as some
short term guidance show that outflow from this convection may
help trigger isolated activity across perhaps portions of our
eastern most counties toward and into the overnight hours. Low
stratus and patchy fog will otherwise rule once more during the
overnight into Tuesday morning for areas mainly near and east of
the I-35 corridor. Out west, skies should gradually clear out
as the dryline starts to progress eastward into Tuesday.
Tuesday will be very warm and turns dry with sunny afternoon
conditions as the dryline advances east through majority of the
area. The daytime highs are to top out from the mid to upper 80s
into the low 90s. While relative humidity values drop below 20
percent for much of the region along and west of I-35, the wind
speeds are forecast to stay light enough to preclude any more
significant fire weather concerns. The dryline does retreat west
some from Tuesday night into early Wednesday. At the same time,
expect for a weak cold front to drop southward and stall into
portions of the Hill Country. This will result in a gradient in
temperatures entering Wednesday morning. Portions of the Hill
Country could see lows drop into the 40s while low 60s will be
common in the coastal plains with another round of some fog and
low stratus.
&&
.LONG TERM...
(Wednesday through Monday)
Issued at 1251 PM CST Mon Mar 4 2024
Key messages:
1) There is a threat for severe storms primarily late
Thursday night into early Friday morning for areas north of
Interstate 10. This forecast will need to be refined.
2) High fire danger is likely on Friday for our western counties. A
Rangeland Fire Danger statement may be needed for portions of the
region.
At the start of the long term period 12Z Wednesday, a weak cold
frontal boundary is likely to be draped near or just south of the
Austin/northern Hill Country region. Some fog will be possible to
it`s south in the AM, and then southerly flow will develop and push
the boundary back out. While not as hot as Tuesday, it`ll still be
seasonally warm with highs in the 80s, near 90 for far SW areas.
Broad troughing to our west will lead to the development of a
panhandle sfc low overnight. In the evening, a weak lead shortwave
may cross over the dryline with storm development possible near or
just north of the northern CWA border. These could impact our far
northern counties through the overnight, with chances potentially
increasing on Thursday for mainly northern/eastern areas. However, I
believe global guidance may be overdoing daytime QPF and this
forecast may need to be adjusted. The better potential for storms -
including the threat for strong to severe storms - is likely to
arrive with the Pacific cold front late Thursday night/early Friday
morning. It appears the environment will be low CAPE/high shear, and
it`s already caught the eye of the SPC which has the northeastern
quadrant of our CWA drawn into the Day 4 15% area. Depending on
timing, this risk could carry over into the daytime on Friday for
eastern areas. Lots of details to iron out before then.
Behind the Pacific front, breezy NW winds of 10-20 mph may gust to
25-30 mpg and will usher in a dry airmass. Afternoon RH will be in
the teens in our western 2 tiers of counties, and so high fire
danger will be possible in these regions if winds remain elevated
through the afternoon. A Rangeland Fire Danger statement may be
needed for portions of the region, but it`s possible winds die down
by the afternoon and limit this need.
As sfc high pressure builds across the central CONUS, a Polar cold
front should cross on Saturday morning with cooler than normal
temperatures forecast over the weekend. Aloft, the tail end of the
southern stream trough splits from the northern stream and is slow
to cross TX over the weekend as it weakens. At this time, the
weekend looks dry, but there could be some low-end rain chances
introduced in future forecasts to mainly northern portions of the
region if the upper trough is slower to weaken. Another warming
trend will start out next week.
&&
.AVIATION...
(00Z TAFS)
Issued at 621 PM CST Mon Mar 4 2024
VFR conditions will prevail through the evening hours. Very low
stratus and fog is indicated to develop over across the inland
Coastal Plains after 04Z, and could encroach into portions of the
I-35 corridor overnight, with HREF probabilities around 40-60% across
the San Antonio metro area. IFR to VLIFR conditions are indicated by
models where the stratus and fog do develop. The stratus and fog
should mix out around 15Z-17Z, with VFR conditions Tuesday afternoon.
Only other thing to mention is isolated TSRA have developed north of
a AQO-ECU line. This activity is not expected to impact the TAF
sites.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 62 90 59 83 / 10 0 0 0
Austin Bergstrom Intl Airport 61 89 56 83 / 10 0 0 0
New Braunfels Muni Airport 61 90 57 83 / 10 0 0 0
Burnet Muni Airport 57 87 52 81 / 10 0 0 0
Del Rio Intl Airport 55 90 57 89 / 0 0 0 0
Georgetown Muni Airport 60 89 54 82 / 10 0 0 0
Hondo Muni Airport 57 90 56 86 / 10 0 0 0
San Marcos Muni Airport 61 89 56 83 / 10 0 0 0
La Grange - Fayette Regional 65 87 60 81 / 10 0 0 0
San Antonio Intl Airport 62 90 59 84 / 10 0 0 0
Stinson Muni Airport 62 90 59 86 / 10 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...JR
Short-Term...Brady
Long-Term...KCW
Aviation...76
Area Forecast Discussion
National Weather Service Indianapolis IN
1006 PM EST Mon Mar 4 2024
.Key Messages...
- Rain tonight through Tuesday night, then again late week into the
weekend.
- Embedded thunderstorms possible late tonight and Tuesday. Severe
thunderstorms are not expected, although the strongest storms may
be able to produce small hail and heavy downpours.
- Rain chances return late Thursday with widespread precipitation
expected Friday/Friday night. Low chance for a few t-storms Friday.
- A return to more seasonable temperatures is expected this weekend.
&&
.Forecast Update...
Issued at 1006 PM EST Mon Mar 4 2024
No significant changes to the forecast this evening. Scattered
showers and thunderstorms have developed across Illinois and
Missouri. These should gradually build southeastward towards Indiana
by morning, likely arriving around 5am to 7am.
ACARS soundings out of IND show a still well-mixed layer from 850mb
and below. Above that, a small warm nose with modest lapse rates to
the equilibrium level (6.9 C/Km). The column above 850mb becomes
notably drier as well. Little change in wind speed with height
exists from the near-surface layer to about 500mb, with the
exception of a developing low-level jet (LLJ). In fact, the greatest
shear in the column is closer to the surface due to a very shallow
nocturnal inversion that is beginning to develop.
Going forward, model soundings show the column gradually moistening
up...with an increase in lapse rates due to wet bulb effects in the
mid-level dry layer. Guidance shows positive Theta-E advection
through the night, signifying continued advection of warm moist air.
With these factors in mind, the threat for convection should remain
in place through the night as a cold front approaches.
In terms of convective mode and hazards, the lack of significant
shear will help mitigate severe potential. Given the tall skinny
CAPE profile, modest lapse rates, and dry mid-level air...small hail
and potentially gusty winds are the primary hazards. CAMs tend to
develop an MCS across Illinois which then drifts southeast into
Indiana, becoming outflow-dominant as it does so. The mean shear
vector is roughly boundary-parallel, so a linear system is
preferred. With such a dry column to promote the generation of cold
outflow and a lack of shear to balance it...an outflow dominant
system makes sense as well. Preferred southward propagation is
possible, mainly because of the modest (35 to 45 knot) LLJ feeding
in the moist warm air.
Severe weather is not currently expected.
&&
.Short Term...(This evening through Tuesday)
Issued at 223 PM EST Mon Mar 4 2024
A cold front will bring showers and some thunderstorms to central
Indiana, mainly late tonight through Tuesday.
Rest of This Afternoon...
Clouds have broken up some this afternoon, allowing temperatures to
reach the 70s. As mixing continues, expect wind gusts over 25 mph at
times.
Tonight...
The evening will be quiet across the area, as forcing remains south
and west. Winds may continue to gust some, especially northwest, as
a low level jet moves in. Temperatures will remain mild.
Overnight, some upper level energy will approach from the southwest.
Meanwhile, a surface cold front will slowly move into far
northwestern portions of the forecast area by the end of the tonight
period.
Moisture will have increased across the area by the overnight thanks
to continue southwest flow and the low level jet. Convection will
have fired west of the area during the evening, and this should
survive in some form as it moves into the area late. Will go with
likely or higher PoPs across the west with lower PoPs east late.
Some of the convection to the west of the area may be strong with
decent instability and shear. However, by the time this reaches
central Indiana, both instability and shear will heave weakened.
While cannot rule out a strong storm west, believe that the severe
threat will remain west of Indiana.
Lows will be well above normal and in the 50s.
Tuesday...
The cold front will slowly move east across the area as a wave of
pressure rides along the front. Moisture should still be sufficient,
but will have to watch and see if convection to the south of the
robs any of the moisture from central Indiana.
Will continue with likely or higher PoPs at some point in the
morning or early afternoon. Forcing will diminish some during the
afternoon as the wave and front move east.
Instability and shear will be low enough to keep the threat of
severe weather out of the area.
Temperatures will be able to rise back into the 60s many areas
before cooler air moves in during the afternoon behind the exiting
wave.
&&
.Long Term...(Tuesday night through Monday)
Issued at 223 PM EST Mon Mar 4 2024
Tuesday night...
A cold front will be in the process of moving through Tuesday night
with the potential for isolated to scattered showers, mainly across
southeast portions of the area during the evening. The front should
then move towards the Ohio River late overnight. Any lingering
precipitation will likely diminish as the better forcing shifts
south. Low clouds will have a hard time clearing out behind the
front as subsidence aloft increases. Forecast soundings show a
shallow saturated layer beneath a strengthening subsidence inversion
which supports this. Light drizzle could persist through the
overnight depending on the depth of the saturated layer.
Wednesday through Thursday...
Quiet weather conditions are expected as strong surface high
pressure extends south from Canada along with subtle upper ridging
building in. Forecast soundings show the aforementioned subsidence
inversion persisting through Thursday which will make it difficult
for clouds to clear out completely. Some partial clearing is
possible during this period as low-level subsidence induced dry air
could advect into the area from the north, but it appears at least a
few-sct low cloud deck should remain. This along with northeasterly
flow will lead to cooler highs in the 50s for Wednesday. Similar
highs, maybe a degree or two warmer, are expected for Thursday due
to negligible thermal advection.
Thursday night onward...
A surface low associated with a southern stream shortwave is
expected to develop near the southern plains late Thursday before
moving northeast towards the region Friday into Saturday. Ensemble
guidance is still not in great agreement regarding timing and
location of the surface low which limits forecast confidence in
exact details. However, anomalous moisture return and increasing
dynamics will support widespread precipitation. The heaviest
rainfall is expected on Friday and Friday night when the greatest
forcing/moisture moves through. Weak destabilization could promote a
few thunderstorms.
Precipitation chances linger through early Sunday morning as a
northern stream trough dives south from Canada and phases with the
southern stream trough over the weekend. Breezy conditions are
likely during the latter half of the long term period due to a
tightening pressure gradient. Cold air advection will trend
temperatures closer to seasonal by this weekend.
&&
.Aviation...(00Z TAF Issuance)
Issued at 646 PM EST Mon Mar 4 2024
Impacts:
- MVFR ceilings returns between 10z and 13z.
- Convection possible after 10Z, with possible IFR conditions.
- MVFR ceilings to persist into Tuesday night.
- Wind shift to northerly on Tuesday.
Discussion:
VFR conditions to start the TAF period.
Some lingering low to mid clouds along with high cirrus will prevail
for the first 6 hours or so of the TAF period. By morning, a cold
front with associated showers and thunderstorms arrives between 10z
to 13z. Chance of showers is high, with thunder chances around 30
percent.
Ceilings look to drop into MVFR after as the rain arrives, perhaps
dipping into IFR for a time. By evening (00z), rain is expected to
diminish though lingering stratus may allow MVFR ceilings to persist
into the night and through the end of the TAF period.
Finally, wind gusts should die down quickly this evening but a 5 to
10 knot southerly breeze should persist. As the rain arrives, winds
may go variable for a time before becoming northerly as the cold
front sweeps through. The front should reach LAF first (in the
morning) and BMG last (in the evening).
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Update...Eckhoff
Short Term...50
Long Term...Melo
Aviation...Eckhoff
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
929 PM CST Mon Mar 4 2024
.KEY MESSAGES...
- Showers and thunderstorms will move across the area from west
to east through the overnight hours.
- Stronger storms may produce isolated hail up to one inch, and
isolated 40-50 mph wind gusts.
- A cooler and drier pattern will settle into the region
tomorrow. The coolest temperatures will be near Lake Michigan
due to onshore flow.
- The next opportunity for precipitation (which may include
snowflakes) is on track to arrive toward the end of the week.
&&
.UPDATE...
Issued at 928 PM CST Mon Mar 4 2024
Made some quick tweaks to temps/winds tonight based on frontal
position and timing, otherwise focus on convection in near term this
evening.
Surface cold front was moving slowly southeast across northern IL at
mid-evening, and was approximately along a line from just south of a
line from Waukegan to DeKalb to just north of Peru. Ahead of the
front, a line of thunderstorms have developed recently roughly
along the I-55 corridor from near Bloomington northeast through
Chicago. These storms, though likely slightly elevated above the
cooling boundary layer, will have the ability to produce some small
(pea to dime sized) hail and isolated 40-50 mph wind gusts over the
next couple of hours. Storms farther southwest along the front near
Peoria may have a little better/more organized wind potential as
they propagate into LaSalle and Livingston county in the next 1-2
hours, though radar trends have indicated some slow weakening with
these.
More generally, the cold front will continue to shift southeast
across the forecast area into the overnight hours. This will
undercut storms with cooler, more stable air in the low levels with
time and presenting more of a small hail threat. Thunder threat will
gradually decrease from west-east overnight, with some showers
lingering into Tuesday morning in northwest IN. Temps will fall
behind the front into the lower 40s in most areas (upper 30s by
morning along the lake), with blustery north-northeast winds. Going
forecast has these trends handled pretty well, so other than some
near term temp/wind tweaks associated with the frontal passage, no
other updates needed.
Ratzer
&&
.DISCUSSION...
Issued at 149 PM CST Mon Mar 4 2024
Through tonight:
A recent hand surface analysis depicts a 1006mb surface low
pressure system centered near Kansas City, MO along an elongated
stationary front that extends northeastward over southeastern
Iowa and along the Illinois and Wisconsin border. The warm
sector ahead of the front is unusually warm for the time of
year, with near record-breaking temperatures in the lower to mid
70s near/west of I-39 and current readings in the 60s to around
70F closer to Lake Michigan (50s far NE IL shore). When combined
with surface dew points in the mid to upper 50s and mid-level
lapse rates of 7 to 7.5 K/km, a relatively broad region of 1000
to 1500 J/kg of MLCAPE is present ahead of the front. However,
our region remains strongly capped by an inversion that
stretches from around 4000 to 6000 feet, as confirmed by recent
AMDAR soundings from aircraft arriving and departing Chicago
O`Hare. With that said, a few convective cells (including one
recently warned by NWS Quad Cities) continue to percolate along
and just ahead of the stationary front near the Mississippi
River where low-level confluence is strongest.
Over the next few hours, gradual synoptic-scale ascent within the
right entrance region of a 125kt 250mb jet streak will move
over the middle Mississippi River Valley. At the same time, the
aforementioned low pressure system will evolve into an elongated
low pressure trough, encouraging the stationary front to transition
into a southeastward-moving cold front. When combined with
decreasing capping (lifting via the approaching forcing as well
as moistening/heating from below), thunderstorms are poised to
erupt along and ahead of the front over the next few hours. (In
fact, an isolated shower or storm can`t be ruled out as far east
as Chicago as early as 4 PM. However, the highest coverage
should be near the front). With such a broad warm sector and
large-scale synoptic-scale forcing, as well as mean storm
motions and deep-layer shear vectors oriented along the
initiating boundary, upscale growth into a baggy multicell
convective system appears all but certain with time. With that
in mind, our entire area will see showers and storms tonight
from west to east as the frontal boundary gradually shifts east-
southeastward.
In terms of the threat for severe weather, 50 to 55kt of effective
bulk shear overlapping the frontal boundary and warm sector, as
well as relatively weak low-level storm relative flow through
early evening, a few storms this afternoon may produce damaging
hail. For any storm just ahead of the front, locally damaging
wind gusts and even a brief tornado may occur as well. Such a
threat appears highest northwest of a line from Dixon to Harvard,
Illinois, through 8 or 9 PM. Thereafter, the cold front is
expected to "undercut" the storms and limit the severe threat
for isolated damaging hail as they progress east-southeastward
across the rest of the area overnight.
Not to be forgotten, south to southwesterly winds ahead of the front
will become gusty this afternoon and evening as the low-level jet
intensifies and the moist boundary layer limits decoupling. Forecast
BUFKIT soundings suggest gusts could approach 45 mph between sunset
and midnight ahead of the front, but felt a conservative approach
with gusts of 35 to 40 mph was more appropriate for now (hence,
no Wind Advisory will be issued).
Borchardt
Tuesday through Sunday:
The threat of showers and storms will come to an end from northwest
to southeast through the morning on Tuesday as cold front finally
shifts southeast of the area. In its wake, drier and cooler weather
is expected Tuesday through Thursday as a surface ridge axis shifts
into the western Great Lakes region. Onshore northeasterly winds
will be favored with this pressure pattern. This will thus result in
the coolest weather (highs in the lower 40s) near the Lake Michigan
shores each day. Farther inland, however, highs are expected to
generally be in the low to mid 50s (about 10 degrees above normal
highs for this time of year). The next chance of precipitation
(which may include snowflakes at times) is on track to arrive
toward the end of the week.
KJB/Borchardt
&&
.AVIATION /00Z TAFS THROUGH 06Z WEDNESDAY/...
Issued at 517 PM CST Mon Mar 4 2024
Aviation Forecast Concerns:
- Strong south winds for Chicago terminals early this evening
with gusts 35-40 kt possible.
- Thunderstorms tracking across Chicago metro terminals mid-late
evening. Embedded thunder persists past midnight. Rain
lingers into Tuesday morning.
- Wind shift to north-northeast with gusts 25 kts behind cold
front which passes through Chicago sites roughly 04-06Z. Exact
timing somewhat tricky, with storms complicating the wind
field.
- Period of IFR ceilings overnight behind front. Improving to
MVFR Tuesday morning and scattering to VFR Tuesday afternoon.
A cold front stretches from eastern WI, through KRFD to just
west of KUIN as of 5 pm. An area of thunderstorms was occurring
along the front from near KMKE to KSQI and into MO, as well as
behind the front across parts of southeast/eastern IA. These
storms will spread east into the Chicago area toward mid-
evening, as the cold front continues to move east. While a few
isolated storms may develop ahead of the front, the greatest
coverage is expected to be immediately along and behind the
front, after 0230-0300Z. Gusty winds and hail are possible with
these storms. MVFR and patchy IFR ceilings can be expected
within the area of storms/rain, with ceilings lowering to IFR
overnight before improving to MVFR mid-morning Tuesday and
scattering out in the afternoon.
Ahead of the front, south winds will be quite strong early this
evening with recent gusts 40-45 kt noted at KDPA and KARR
respectively, though low-30 kt range will likely be more common.
Winds will turn north-northwest with the frontal passage,
before eventually coming around more northeast overnight. Gusts
in the 25+ kt range are likely with the northeast winds into
Tuesday morning, gradually easing in the afternoon.
Ratzer
&&
.CLIMATE...
Record warmth continues today. Here are the temperature records
for today at Chicago and Rockford.
Chicago Rockford
Monday 3/4 73 71
Record High 1983 1983
Monday 3/4 50 49
Record Warm Low 1983 1983
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory until 3 AM CST Wednesday for the IL and
IN nearshore waters.
&&
$$
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