Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 10/12/23
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
701 PM CDT Wed Oct 11 2023
...New UPDATE...
.UPDATE...
Issued at 701 PM CDT Wed Oct 11 2023
Made an update this evening to increase the coverage of fog in the
forecast grids for tonight through mid-morning tomorrow as most
near-term guidance shows a decent coverage of reduced visibilities at
or below 5SM with some isolated areas of visibilities around 1SM.
-Gale
&&
.SHORT TERM...
(Tonight through Thursday night)
Issued at 226 PM CDT Wed Oct 11 2023
Synopsis/Mesoanalysis: GOES water vapor imagery and ACARS soundings
are showing a west to east drying trend in-progress early this
afternoon. Said drying trend, in tandem with a departing upper right
entrance region & area of surface cyclogenesis over the Gulf of
Mexico, has translated to precipitation departing east down the
Interstate 10 Corridor over the last several hours. Largely
precipitation-free conditions will prevail through the remainder of
the period in the wake of this activity, though patchy
drizzle/streamer showers will be possible during the predawn periods
over portions of Hill Country and the southern Edwards Plateau.
Currently evident across the Pacific Northwest, a broad area of
upper low pressure will translate quickly to the southeast through
tonight, approaching the lee of the Rocky Mountains by daybreak
tomorrow. Already apparent in Central & Southern Plains surface
observations, surface pressure falls & lee troughing will continue
to become better defined through this afternoon, with cyclogenesis
forecast to occur in the Central Plains by the mid-evening hours
tonight. The infant surface low will pivot east-northeast along the
KS-NE border vicinity through tomorrow morning, eventually occluding
as it enters the Missouri Valley nearing the end of the period. The
surface low will drag a cold front to the southeast in the process,
which will overtake a leading dryline as it progresses into the
state tomorrow night. The latest progs place the boundary along an
axis extending from the Red River southeast into the Edwards Plateau
by sunrise Friday morning, with progression into South-Central Texas
expected during the first periods of the long term.
Tonight: Expect low temperatures primarily in the mid-upper 60s
across the majority of the region. A few locations along the US-77
Corridor may bottom out in the lower 60s. Some patchy fog is
possible following midnight over portions of the Coastal Plains.
Additional patchy fog & drizzle/showers are possible over portions
of the southern Edwards Plateau and Hill Country closer to daybreak,
where the nocturnally-maximized & largely southerly low level jet
will be favorably aligned with the terrain of the Balcones
Escarpment. Measurable precipitation is not expected in any predawn
drizzle or light showers.
Thursday: Southerly winds, as well as significantly more afternoon
sunshine compared to today, will lead to milder high temperatures at
or just above normal areawide. The afternoon update shows widespread
readings in the mid-upper 80s across the region, with a few low 90s
expected along the Rio Grande. Have kept the forecast completely
dry, though the 12Z Wednesday run of the HRRR does suggest the
development of scattered streamer showers over the Coastal Plains
during the peak heating of the day. Have inserted some silent 10%
precip probabilities south of I-10 and east of I-37 in light of this
low end potential, and will continue to monitor trends for
potentially higher precip probs over the next 12 hours.
Thursday Night: Expect milder low temperatures relative to tonight.
Mid-upper 60s are forecast over Hill Country and the Coastal Plains,
with low 70s probable along the majority of the I-35 Corridor and
the Rio Grande. Similar to tonight, patchy fog, drizzle, and
streamer shower development is possible once more over Hill Country
and the southern Edwards Plateau during the predawn hours.
Measurable precip is not expected.
&&
.LONG TERM...
(Friday through Wednesday)
Issued at 226 PM CDT Wed Oct 11 2023
Friday a dry, Pacific cold front will move into South Central Texas.
Ahead of the front southeasterly flow will continue to push warm air
into the region. The front should reach our northern border by around
noon. In addition to the warm advection there will be compressional
warming ahead of the front. High temperatures will climb into the
upper 80s to middle 90s Friday before the boundary moves through. The
front should be across our southern border by the middle of the
evening. It looks like the only chance for precipitation will be over
the Rio Grande Plains and chances will be low. Cooler, drier air will
filter in Saturday. Lows and highs will be around ten degrees cooler
than Friday. As we suspected, the sky condition forecast is getting
more detailed with more cloud cover for Saturday. It`s starting to
look like there will be partly to mostly cloudy skies southwest of
the a line from the Rocksprings to Hondo. Northeast of there still
looks mostly sunny. High pressure will dominate over the region for
the remainder of this period keeping the weather dry and temperatures
fairly steady Sunday through Wednesday.
&&
.AVIATION...
(00Z TAFS)
Issued at 639 PM CDT Wed Oct 11 2023
MVFR cigs are beginning the period at most terminals which should
continue through the evening hours. Cigs are expected to become IFR
between 06-12z, and possibly as low as LIFR at KSAT/KSSF. Visibility
reductions as low as 1SM in BR will be possible as well, with the
lowest visibility expected around KSAT/KSSF. A slow, gradual
improvement in cigs/vis is then expected through the remainder of the
morning and into the early afternoon hours, with a return to VFR
conditions expected at all terminals by 12/20z. Southerly to
southeasterly flow will continue around 6-12 kts, with gusts to
around 20 kts possible during the afternoon and evening hours.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 66 88 69 92 / 0 0 0 0
Austin Bergstrom Intl Airport 65 88 70 92 / 0 0 0 0
New Braunfels Muni Airport 67 89 70 94 / 0 0 0 0
Burnet Muni Airport 66 87 70 89 / 0 0 0 0
Del Rio Intl Airport 69 93 72 95 / 0 0 0 0
Georgetown Muni Airport 65 87 71 91 / 0 0 0 0
Hondo Muni Airport 67 87 69 91 / 20 20 20 0
San Marcos Muni Airport 64 89 69 93 / 0 0 0 0
La Grange - Fayette Regional 63 87 69 89 / 0 10 0 0
San Antonio Intl Airport 68 87 71 91 / 10 0 0 0
Stinson Muni Airport 67 89 72 92 / 10 0 0 0
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...Quigley
Long-Term...05
Aviation...Gale
Area Forecast Discussion
National Weather Service Indianapolis IN
900 PM EDT Wed Oct 11 2023
.Forecast Update...
Issued at 859 PM EDT Wed Oct 11 2023
Showers and thunderstorms have developed along a line extending from
just northeast of Terre Haute to the northern suburbs of
Bloomington. These are gradually lifting northeastward. Low-level
convergence exists, but does not appear to be a contributing factor.
Instead, a variety of factors seem to be at play here.
A developing low-level jet and a weak mid-level wave, combined with
favorable jet-dynamics aloft (right entrance region) and some
isentropic upglide, has lead to large-scale lift. ACARs soundings
out of IND show a small positive area rooted at 700mb extending to
400mb, with about 200 J/kg MUCAPE. Roughly 30kt shear has allowed
these updrafts to sustain and gain some organization despite the
weak amounts of instability. Small hail and brief gusty winds may be
possible in the strongest cells.
Recent runs of hi-res guidance do not depict the current activity,
so conceptual models and understanding of the environment will be
critical for keeping the short term forecast on track this evening /
overnight. Given favorable dynamics, there is no reason for this
activity to disappear within the next few hours. Showers and
thunderstorms should continue to lift northeastward through the
evening/overnight and eventually out of our CWA.
Updated PoPs accordingly.
&&
.Short Term...(This evening through Thursday)
Issued at 256 PM EDT Wed Oct 11 2023
Today...
Ridging has build above modest LL WAA out ahead of a developing
frontal zone. This has allowed for dry air to seep in, of which is
now mixing to the surface. This should keep any developing showers
along the frontal zone from reaching eastern portions of central
Indiana, with the caveat of isolated sprinkles. Further to the west,
the dry air is not quite as abundant, and the deformation in the mid
levels is stronger creating a better environment for isolated
showers. Still, QPF will likely be marginal throughout the day.
Clouds will continue to stick around, with some mixing induced
breaks this afternoon and evening. Cloud cover will be thicker over
northern portions of the region as the boundary stalls. Expect
afternoon highs in the mid to upper 60s for most of the area. A few
locations in far SW central Indiana will be in the 70s as the warm
sector arrives prior to the departure of peak heating.
Tonight...
The aforementioned warm front is expected lift north of the area
overnight. While much of the forcing associated with the warm front
shifts north, models show a strong nocturnal LLJ developing out
ahead of a weak mid level wave. This will support the potential for
scattered showers and storms over far northern central Indiana.
Latest guidance has pushed this boundary further north with the low
over SE Canada weakening. For this reason PoPs and QPF have been
lowered slightly.
The delayed surface warm front should move through late overnight
with winds becoming more south-southwesterly by the morning. A
strengthening pressure gradient will keep winds elevated resulting
in much milder temperatures. Expect lows to only fall into the 50s.
&&
.Long Term...(Thursday night through Wednesday)
Issued at 256 PM EDT Wed Oct 11 2023
* Very warm to start the long term, turning much cooler over the
weekend into next week.
* Ample opportunity for at least light showers.
Central Indiana will begin the long term period firmly entrenched
within the warm sector of a potent mid-latitude cyclone centered
over the central Plains/mid Missouri valley.
This cyclone will steadily fill and shift eastward into the region
into the early portion of the weekend. A surface cold front will
push through the area, perhaps followed by a secondary boundary,
Friday night into Saturday evening. Widespread showers (and isolated
to perhaps widely scattered thunderstorms) can be expected with both
boundaries.
Instability will be difficult to come by given poor mid-
level lapse rates as the cyclone occludes, though decently strong
dynamics may be able to compensate and provide enough forcing for
deep enough updrafts to support charge separation. If updrafts can
tap into the stronger flow aloft, a strong storm with gusty winds
(in the background of already fairly strong winds synoptically-
speaking) cannot be ruled out. Day 3 marginal comes right up to our
border, and given the diurnal timing of the initial boundary, this
appears reasonable.
Precipitable water values are likely to approach or exceed one inch
Friday into Saturday, briefly getting as high as around 1.3-1.4" or
roughly at or above 90th percentile climatologically, so briefly
heavy downpours and solid rainfall amounts will be likely, although
storm motions should be rapid enough to limit impacts, particularly
in light of antecedent dryness.
In the wake of the initial system early in the period, it appears
that large scale cyclonic flow, potentially in the form of a closed
upper low reinforced by one or more additional upper level shortwave
troughs, will persist over the Ohio Valley into the mid-Appalachians
much of the long term period. This will necessitate at least slight
chance to low chance pops much of the time over the weekend into
early next week, although this precipitation will be quite showery
and light at any one time.
Temperatures, which will be quite warm for the time of year very
early in the long term, will become significantly cooler under the
influence of the persistent negative height anomalies through the
remainder of the period - with highs later in the period potentially
cooler than lows early in the period. NBM appears to be handling
this transition well and required no significant adjustments.
&&
.Aviation...(00Z TAF Issuance)
Issued at 747 PM EDT Wed Oct 11 2023
Impacts:
* Scattered showers near LAF early tonight.
* Southeast winds become southwesterly, then easterly again.
Discussion:
Generally VFR flying conditions are expected through the TAF period.
The only exception would be near LAF during rain showers which are
currently passing through (as of 00z). Cloud cover will limit fog
initially, but clearing from IND southward overnight may allow some
patchy ground fog to develop by morning. Confidence in this
occurring is low, however.
Winds will be quite variable through the TAF period. A warm front
draped across central Indiana has induced southeasterly winds from
IND southward, with easterly winds near LAF which is closer to the
boundary. Winds here (LAF) may even become northeasterly at times
overnight. By morning, the front will lift northward allowing winds
to become southwesterly during the day Thursday. By Thursday
evening, the front is then expected to drop back southward shifting
winds to northeasterly.
Wind speeds should remain light, sustained at 10kt or less through
much of Thursday. Speeds in excess of 10kt are possible Thursday
evening as the front retreats southward again. No significant wind
gusts are expected, but an isolated gust to 18kt is possible when
winds increase out of the southwest tomorrow afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
Update...Eckhoff
Short Term...Updike
Long Term...Nield
Aviation...Eckhoff
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
658 PM CDT Wed Oct 11 2023
.MESOSCALE DISCUSSION...
Issued at 658 PM CDT Wed Oct 11 2023
Currently monitoring elevated convection west of the Mississippi
River developing in response to a gradually-intensifying
frontogenetic circulation. With effective inflow bases around 850
mb, 1-6 km bulk shear values as high as 40-45 kts have evidently
been sufficient within a marginally-unstable environment (MUCAPE
values around 500 J/kg) to support ephemeral large hailers across
east-central Iowa (have seen several quarter to even ping pong
ball-sized hail reports across DVN`s area). In addition, have
recently noted signs of potentially intensifying surface winds
with fairly classic equally-spaced elevated cells with divergent
velocity couplets out of the linear convection approaching
Davenport suggestive of gravity wave-induced downbursts.
Short term model guidance suggests the f-gen circulation will be
intensifying more readily across northern Illinois over the next
2-4 hours, supporting a gradual increase in the coverage of
showers and embedded storms through 10-11 PM. Instability isn`t
forecast to be quite as robust in our forecast area, but with
similar effective deep layer shear values, suspect a few cores may
get rambunctious enough to product up to quarter-sized hail.
We`ll additionally keep an eye on the strong/gusty wind threat out
of elevated cores into our area this evening.
The threat for locally heavy rainfall and isolated instances of
flooding appears on track tonight as well, mainly along and north
of I-80.
Carlaw
&&
.SHORT TERM...
Issued at 320 PM CDT Wed Oct 11 2023
Through Thursday night...
Key Forecast Messages:
* Threat for heavy rain and localized flash flooding near and
north of I-80 late this evening and overnight, primarily between
10PM and 5AM
* Threat for isolated instances of marginally severe hail this
evening and overnight up to the I-80 corridor
* Tight temperature gradient associated with a warm front draped
south of I-80 on Thursday with lower to mid 70s to the south and
mid 50s to lower 60s to the north.
Discussion:
There are no significant changes in forecast thinking tonight
through Thursday, though some trends have been noted that may
augment the potential footprint of locally heavy rainfall and an
associated flooding threat tonight.
The very dry antecedent air mass that supported temperatures in
the upper 20s to mid 30s and frost away from Chicago early this
morning has hung tough as of this writing. As such, temperatures
were able to climb solidly above previous forecasts, well into the
60s, and dew points have hung out in the 30s, and only recently
started to gradually climb. Earlier aircraft soundings showed
extensive dry air down near and below 800 mb. With this in mind,
the anticipated rain marching northward has narrowed in north to
south extent and its north and eastward progress has been slowed.
In addition, while the regional radar mosaic is starting to look a
bit more impressive, the aforementioned dry low levels have
rendered the narrow band of rain/showers to be high based and
of lighter intensity. Thus, ASOS and AWOS sites reporting rain
have generally had 10 mile visibility, speaking to the light
intensity. The above will change with time this evening as the
column moistens, but expectation for the leading edge rain
gradually lifting east- northeastward is for primarily light rain
through a couple hours past sunset, with the focus settling north
of I-80.
Tonight, a relatively stout low-level jet is expected to
redevelop across the middle Mississippi River Valley ahead of a
rapidly deepening surface low pressure system in the Plains. As a
result, coverage and intensity of showers and thunderstorms should
increase after dark near and just to the north of a developing
stationary front draped across northern Illinois and northwestern
Indiana. With westerly mid-level steering flow parallel to and
PWATs of 1.1-1.3" along the front in a region of increasing
diffluence near the right entrance region of a developing upper-
level jet streak, heavier showers and embedded thunderstorms near
the front may have a tendency to train in a regime generally
consistent with the Maddox frontal flash flood set-up. In concert
with the improving upper level support, model guidance has come
into better agreement in a strengthening 850-700 mb frontogenetical
circulation, though interestingly this axis may favor areas mostly
near and north of I-80.
The 11.12Z run of the HREF featured a narrow axis of 24-hour LPMM
QPF in the neighborhood of 1-2.5" valid for tonight, centered on
I-80 (with a bit of a step down from the 00z HREF). Experience
and the near term f-gen forecast describe above suggests such an
axis may actually develop a county or two to the north. With 3-and
6- hour flash flood guidance (FFG) in the neighborhood of 2.5-3"
and some potential for the training thunderstorms to intersect the
urban Chicago metropolitan area, the evening shift may need to
consider the issuance of a targeted short-fused Flood Watch
depending on how things trend this evening. The higher
thunderstorm coverage may tend to be south of the axis of highest
rain coverage tied to the f-gen circulation, given later arriving
steepening lapse rates and higher MUCAPE with southward extent.
The above being said, should thunderstorm coverage end up higher
farther north, that would potentially increase the flash flooding
threat. We`re continuing to message as a level 1 of 5 flooding
threat in line with WPC`s marginal risk ERO, though again, some
consideration may need to be given for a Flood Watch if the
vulnerable Chicago and south suburban areas end up in a corridor
of training and higher rain amounts.
It`s also worth continuing to note that the strongest thunderstorms
tonight may produce small to locally damaging (marginally severe)
hail given modest mid-level shear (30-35kt from 1-8km) and a centroid
of 250-500 J/kg of MUCAPE within the -10 to -30C hail growth
layer. As a testament to the threat, several thunderstorms near
Kansas City produced 1" hail prompting the issuance of Severe
Thunderstorm Warnings in the pre-dawn hours of this morning. The
SPC Level 1/5 threat for hail near and south of I-80 thus remains
appropriate for the overnight hours.
Shower and thunderstorm intensity should wane toward and especially
after sunrise on Thursday as the low-level jet wanes and the EML
plume becomes exhausted. Scattered showers will likely continue
throughout the day (focused north) as remnant warm air advection
(WAA) acts upon the slowly northward-moving warm front (coverage
should become confined to areas near the Wisconsin state line by
early afternoon). South of the front, which looks to drape near
the Illinois and Kankakee River corridor, southerly flow will
help temperatures jump into the lower to mid 70s in spite of
cloud cover, while brisk (and strengthening with time during the
afternoon) easterly winds north of the front (with a trajectory
off Lake Michigan) will hold readings in the mid 50s to lower 60s.
After an lull in shower activity Thursday evening and early
overnight, rain/shower chances should start to uptick from the
northwest in the pre-dawn hours of Friday. The rest of the busy
forecast stretch we`re entering in is described in detail in the
long term discussion below.
Castro/Borchardt
&&
.LONG TERM...
Issued at 246 PM CDT Wed Oct 11 2023
Friday through Wednesday...
Key Messages:
* More widespread rain and a few thunderstorms on Friday.
* Level 1 of 5 threat for severe weather favored south of I-80,
which translates to a 5% chance of damaging winds
* Level 2 of 5 threat for localized flooding on Friday
* Noticeably cooler temperatures this weekend with high confidence
and breezy conditions with some continued showers
The wound-up storm system off the east coast (currently with a 120-
140 kt upper level jet) will be situated across the central Plains.
The system will be nearing its peak strength upstream of our local
area, but it will wobble in intensity as it moves through the
southern Great Lakes on Friday and off to the eastern Great Lakes
this weekend. This will therefore maintain the risk for another
period of showers and even a few thunderstorms on Friday.
Several synoptic features support the widespread showers and
thunderstorms. The aforementioned upper jet will drift to our
southeast on Friday placing our area in the left exit region, the
upper level low will be moving across the area with continued height
falls, and this system will be accompanied by a stout cold front.
There looks to be a leading band of rain, followed by more showers
and even a some thunderstorms into the evening as areas south of I-
80 have a brief window of time in the warm sector of the system.
Probability of > 1" of rain with this second band of rain exceed
about 60% north of I-80 (10% of > 2"), slightly lower farther south.
Some guidance is trending farther north with the heavier rains (I-88
north). Therefore there is still a localized flooding concern for
some areas, especially for areas that receive decent rains earlier.
There is still a threat for severe weather mainly in the form of
damaging winds on Friday, given the fact that track of the surface
low will place at least a portion of the local area into a somewhat
narrow warm sector. The window for this will be Friday afternoon and
early evening. While the entire area is progged for a day 3 marginal
risk outlook (5% chance of severe), the highest confidence area is
south of I-80 and also focused west of I-39 as the GFS/EC/GEM
ensemble probability of > 500 J/Kg is near zero in our area. Now
later season severe does not need that much CAPE for severe given
deep layer shear > 40 kt being more than sufficient to
compensate.
The large system looks to intensify again to our east,
and this will lead to a bit stronger pressure gradient across
northeast IL and northwest IN on Saturday. Expect stronger
northeasterly winds of 30 to even 35 mph during the day as the NBM
probabilities of > 34 kt peak at 60-80% north of I-80 and close to
the lake shore. Wrap-up around forcing with additional vort maxes
rotating through in the deformation region of the storm will lead to
additional showers, though more scattered in coverage. To add to
that, temperatures will only top off in the lower to mid 50s under
mostly cloudy skies, making for a chilly day especially when
raining.
The trough will linger in the region into early next week. The
resultant sensible weather will be continued cool highs in the 50s,
more clouds than sun, and occasional widely scattered showers (30-
40% coverage). The shower coverage will be higher closer to Lake
Michigan as northeast flow continues to drive some lake effect rain
at times. This system will likely finally exit later Tuesday into
Wednesday.
KMD
&&
.AVIATION...
Issued at 0634 PM CDT Wed Oct 11 2023
For the 00Z TAFs...
Key Messages:
* Light showers continue to pass over area terminals this evening
* Chances for heavier rain and potentially isolated thunderstorms
overnight
* MVFR to IFR cigs through the night, as well as periods of
reduced visibility for the heaviest rain
* Easterly winds through the TAF period with the potential for
gusts 15 to 20 knots Thursday afternoon
Showers have moved into the area. They have been fighting the
drier air which prevented it earlier, but as the atmosphere has
moistened, light showers are starting to make it to the surface.
Showers are expected at and around area terminals through Thursday
morning.
The warm front is expected to lift through the evening providing a
chance for an increase in rainfall intensity which can lead to
periods of time reduced visibility of 3SM, potentially as low as
2SM. In addition to the heavy rain, isolated thunderstorms are
possible. However, due to the isolated nature of the storm
development, confidence was too low to add it even as a TEMPO, but
VCTS was kept in the TAF as it will be monitored throughout the
night. Lastly, recent high-res guidance came in suggesting the
potential for IFR cigs early Thursday morning with the heaviest
storms. Current guidance has it hovering right around the 1000
foot mark, but enough to add it prevailing. The chances that the
IFR cigs last longer than when the VCTS ends will be revisited in
subsequent TAF packages or amends.
Winds are around or just under 10 knots and out of the east, and
will maintain that way for much of the TAF period. However, winds
will increase as early as 18Z on Thursday with the potential for
stronger gusts up to 20 knots. Given that confidence is low for
gusts to over top 20 knots (or if they do, it is expected to be an
isolated ob), it was kept to stronger prevailing winds. Light rain
continues through the TAF, but there is a chance for a drier
period potentially Thursday afternoon, but MVFR cigs remain around
the region.
DK
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...LMZ740-LMZ741-LMZ742...4 PM Thursday to
10 AM Saturday.
Small Craft Advisory...LMZ743-LMZ744-LMZ745...7 PM Thursday to
10 PM Friday.
&&
$$
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