Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/01/23
Area Forecast Discussion
National Weather Service Detroit/Pontiac MI
753 PM EDT Fri Mar 31 2023
.UPDATE...
During the next two to three hours, there will be a rapid increase in
ascent across Se Mi as a 60-70 knot low level jet noses into Se Mi.
This increaed low level inflow will drive elevated instability
(possibly up toward 1200 J/kg of CAPE). The 00Z DTX sounding, latest
ACARS soundings from srn Lower Mi and nrn Indiana, and most recent
RAP soundings suggest a fair amount of boundary layer stability will
prevail through at least 06Z. This will make it challanging for
severe wind gusts to reach the surface. However, with this amount of
elevated instability and extremely strong forced ascent, large hail
(greater than one inch diameter) is going to be a concern with the
storms tonight. This will be especially true across the southern half
of the forecast where there will be a higher degree of elevated
instability. The storm reports out of northern Indiana have also been
primarily large hail. In terms of the forecast itself, it remains
valid. The only change will be to add some fog across the Saginaw
Valley and thumb region this evening.
&&
.PREV DISCUSSION...
Issued at 638 PM EDT Fri Mar 31 2023
AVIATION...
A rapidly deepening low pressure system will track across eastern
Iowa and into southern Wisconsin this evening. Intense low level wind
fields will lift across Indiana into Srn Lower Mi this evening.
While these winds will largely be elevated and thus inhibit strong
sfc gusts, they will drive a plume of deep layer moisture and
elevated instability across Se Mi. This will result in widespread
rain with scattered thunderstorms. The latest hi res suite continue
to suggest thunderstorm timing will be between 02Z and 05/06Z across
Se Mi. The warm front that lifted into the I-69 corridor this
afternoon now appears to have become stationary. Ongoing low level
moisture transport across this frontal system has already allowed IFR
and lower conditions from PTK northward with some VLIFR conditions
across MBS, conditions that will prevail through the evening.
As the sfc low lifts toward northern Lake Mi overnight, a strong
push of subsidence will expand across Se Mi in the wake of the
occluded front. This is likely to scour low clouds out and will end
showers/thunderstorms after 06/07Z. Model soundings suggest a weak
near sfc stable layer may keep peak wind gusts within the post
frontal environment overnight at or below 25 knots, even though 2-3k
ft wind speeds will be 45 to 50 knots.
For DTW...The region of thunderstorms upstream is expected to
traverse the metro area between 02Z and 04Z. There may be a brief
break in the convection between 04Z and 05Z before a line of
convection moves across the area in the 05Z to 06Z time frame.
DTW THRESHOLD PROBABILITIES...
* High in ceilings below 5000 feet this evening and on Saturday. Low
overnight.
* Moderate in thunderstorms this evening.
PREV DISCUSSION...
Issued at 425 PM EDT Fri Mar 31 2023
DISCUSSION...
Thunderstorm potential tonight is the primary issue in this forecast
cycle as a powerful low pressure system migrates across the Midwest
and Great Lakes. Afternoon observations show the warm front making
northward progress through southern Lower MI at pace close to model
estimates. Generous coverage of warm sector clouds also follows the
general model trend of both coverage and boundary layer stability
estimates. Warm sector stability is also holding up well against the
peak of meaningful late March/early April daytime heating, judging
by the wave texture in low clouds shown in visible imagery, and
likely with further support from lingering mid level subsidence
associated with the short wave ridge. HREF forecasts of surface
based CAPE and individual model soundings show surface/boundary
layer stability then holding as ongoing IL/IN convection reaches
Lake MI and SW Lower MI around 00Z. Zero surface based CAPE is then
projected after 00Z over all of SE MI while MUCAPE fails to reach
1000 J/kg. This supports the elevated case and less severe potential
this evening while a new round of moisture transport/theta-e
advection maintains coverage and moderate intensity. That leaves
storms along the cold front as the final concern for any severe
conditions tonight as it moves into the region toward midnight.
Closer examination of forecast soundings across hi-res model
membership indicates a few hours of near neutral boundary layer
thermal profiles. This suggests enough potential to monitor for
damaging wind gusts in any storms that can remain organized near the
Ohio border while the front itself is also capable of a few 40 mph
wind gusts across the rest of SE MI.
The front sweeps showers and thunderstorms out of Lower MI not long
after 06Z tonight. Low to mid level cold advection and associated
gusty wind potential then follows for the late night into Saturday
morning. At first glance, the wind field appears strongly forced by
the intense mid level circulation/vort max, although the surface
based stable layer mostly holds or is reestablished during the late
night pointing to low level cold advection and momentum transport
somewhat disrupted by elongation of the surface pressure pattern.
For the rest of Saturday, cloud and precipitation character become
cold core dominated during Saturday as the mid level trough axis
moves nearly overhead by afternoon. Forcing associated with the
primary vorticity maximum is accompanied by 500 mb temperature
dropping to around -25C, both of which support renewed coverage of
showers during the morning through about mid afternoon and then
ending as the system exits eastward.
High pressure building into the region Saturday night lasts through
Sunday. It brings dry weather at the expense of slightly below
normal temperatures, especially by Sunday morning as the day starts
off after lows in the mid to upper 20s. This is followed by a quick
temperature rebound to start next week as a new long wave ridge
builds over the Midwest and Great Lakes. Guidance high temperatures
return to around 60 Monday and make a run toward 70 by Wednesday.
MARINE...
A warm front associated with a strong low pressure system across the
upper Mississippi Valley will continue lifting slowly northward
through the central Great Lakes into tonight. Meanwhile, the surface
low will track further northeastward from central Lake Michigan this
evening, to central Lake Huron tonight, and eventually into the St.
Lawrence River valley by late in the day Saturday. The strong low
pressure system will further deepen into the mid 980s hPa with the
system`s powerful cold front sweeping through the local waters late
tonight and into early Saturday morning. As the surface low tracks
across the Great Lakes, it may break off into two distinct low
pressure centers with impressive dynamics in place.
Continued northward transport of warm, moist air will lead to fairly
stable over-lake conditions across the local waters with prevailing
southerly flow limited to gusts below gales through the first half
of tonight. As the center of the low approaches tonight, winds will
turn northeasterly across the northern Lake Huron basin and
southwesterly across the remaining local waters. Strong cold air
advection behind the cold front passage along with a northerly wind
shift will lead to a period of gales across all of the local waters,
with the strongest winds across the open Lake Huron basin. Gale
Warnings are in effect for all of Lake Huron, Lake St. Clair, and
western Lake Erie late tonight through late Saturday evening.
Widespread rain with embedded thunderstorms will be possible as the
low pressure system tracks across the region this evening and
through tonight. Especially across the far southern half of Lake
Huron, Lake St. Clair, and western Lake Erie, there is a low
potential for thunderstorms to produce gusty winds in excess of 35
knots with a strong low-level wind field in place. The best
potential for this occurrence will be from 8pm-2am.
Wind speeds will rapidly decrease Saturday night as high pressure
from the upper Midwest builds into the Great Lakes and ends the
threat for gales. As the high pressure drifts southeast throughout
the day Sunday, another low pressure system moving across the
northern Great Lakes Monday will bring an increase in winds speeds
again approaching gale strength.
HYDROLOGY...
A strong low pressure system tracking through the central Great
Lakes brings another round of showers and a chance of thunderstorms
tonight. Additional rainfall totals of 0.25 to 0.75 inch are
expected, combined with similar amounts from this morning, for event
totals of 0.75 to 1.5 inches before the system exits late tonight.
The flood hazard remains minimal in this event, especially given the
lengthy afternoon break affording drainage a chance to keep pace.
Ponding of water on roads and minor flooding of prone poor drainage
areas remain possible. Within-bank rises on area rivers and streams
is also likely and which will continue through the weekend.
&&
.DTX WATCHES/WARNINGS/ADVISORIES...
MI...None.
Lake Huron...Gale Warning from 4 AM to 10 PM EDT Saturday for LHZ361>363-421-422-
441>443-462>464.
Dense Fog Advisory until 4 AM EDT Saturday for LHZ361>363-421-422-
441>443-462>464.
Lake St Clair...Gale Warning from 4 AM to 10 PM EDT Saturday for LCZ460.
Michigan waters of Lake Erie...Gale Warning from 4 AM to 10 PM EDT Saturday for LEZ444.
&&
$$
UPDATE.......SC
AVIATION.....SC
DISCUSSION...BT
MARINE.......IRL
HYDROLOGY....BT
You can obtain your latest National Weather Service forecasts online
at www.weather.gov/detroit.
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
646 PM CDT Fri Mar 31 2023
...New AVIATION...
.SHORT TERM...
(Tonight through Saturday night)
Issued at 220 PM CDT Fri Mar 31 2023
A cold front will sweep through South-Central Texas late this
afternoon and bring slightly cooler and drier conditions to the
region overnight. However, the "cooldown" will be short-lived as
easterly to east-southeasterly surface flow rapidly resumes on
Saturday afternoon. Temperatures will be quite warm today ahead of
the frontal boundary, with compressional warming resulting in many
locations in the upper 80s to lower 90s. While the Storm Prediction
Center does have portions of Williamson and Lee County in a Marginal
Risk (Level 1 of 5), the cap is expected to hold strong for our neck
of the woods, with substantial capping still noted at the 850mb
level on Austin ACARS soundings. Nevertheless, there is still some
decent instability and deep layer shear to warrant such a risk, so
don`t let your guard down, as any storm that can get going would
quickly turn severe, with large hail to golf ball size and wind
gusts to 60 mph being the primary concerns.
Saturday will be "cooler" with highs in the 80s, but still quite
warm for the first day of April. That`s no fools joke either. It
should be a great day to get outdoors though, as temperatures start
in the 50s in the morning, followed by plenty of sunshine and light
easterly winds in the afternoon. Surface moisture will begin to
increase ahead of our next shortwave disturbance with an outside
shot of isolated showers and storms over the Rio Grande Plains late
in the day and stretching into Saturday evening. Some of the CAMs do
indicate the possibility of a strong storm or two, but the threat is
highly conditional at this time.
&&
.LONG TERM...
(Sunday through Friday)
Issued at 220 PM CDT Fri Mar 31 2023
As a lee-side surface trough strengthens over west Texas on Sunday,
allowing southerly flow in the low-levels to return to all areas by
late morning. A change in the wind direction will occur during the
afternoon hours across the southern Edwards Plateau and western Hill
Country as the dryline mixes eastward. As the dryline surges eastward
during the afternoon, an upper level shortwave trough will also move
eastward across north Texas. To the east of the dryline, we will see
plenty of moisture in place and with some weak lift from the
shortwave trough, we will keep a low end chance for showers and
thunderstorms in the forecast for the Hill Country and along and east
of the I-35 corridor. We are currently not outlooked for any severe
thunderstorms on Sunday. However, we will certainly need to keep an
eye on the dryline as it moves into the Hill Country during peak
heating hours. The stronger lift is likely to remain north of the
region, but will need to monitor our far northern counties, including
Llano, Burnet and Williamson.
Monday and Tuesday look to remain dry and very warm across the region
as the low-level thermal ridge amplifies across western Texas into
portions of central Texas. Record highs are possible both days as
highs are expected to be in the 90s to near 100 along the Rio Grande.
Thick morning clouds should at least partially mix out during the
afternoon on Monday, with a better shot at mixing on Tuesday as they
dryline mixes eastward to near the I-35 corridor. If clouds stay
thicker than anticipated, record highs could be a little tougher to
break for our climate sites along I-35. As mentioned above, we will
keep the forecast dry on Monday and Tuesday. However, with well above
normal warmth and plenty of low-level moisture in place, some low
chances for showers and storms may need to be added to the forecast
at a later time.
On Wednesday, a cold front will push southward across the region,
with rain chances in the forecast from the Hill Country eastward
across the Interstate 35 corridor and into the coastal plains. The
latest round of medium range models keep northerly winds in the low-
levels in place for Thursday and Friday. In the upper levels, an
increasingly active southwest flow aloft will move in from the west.
While the details remain unclear, it does appear a gradual increase
in rain chances is in store across all areas for Thursday and Friday.
&&
.AVIATION...
(00Z TAFS)
Issued at 646 PM CDT Fri Mar 31 2023
A front moving across the I-35 corridor will move through KAUS by
01Z and KSAT/KSSF around 03Z or 04Z. Any SHRA/TSRA will pass to the
northeast of KAUS with no impacts expected there. VFR flying
conditions will prevail with clouds AOA FL050. With sunset
approaching, winds will decouple to less than 7 KTs, with all sites
becoming N-NW upon the frontal passage. On Saturday, winds gradually
turn to NE-E at the I-35 sites and to SE at KDRT.
&&
.CLIMATE...
Issued at 220 PM CDT Fri Mar 31 2023
April 3 April 4
Location Record Maximum (Year) Record Maximum (Year)
Austin Camp Mabry 90 (2017) 92 (2019)
Austin Bergstrom 89 (1989) 92 (1958)
Del Rio 99 (1964) 94 (1964)
San Antonio 97 (1989) 93 (1893)
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 55 86 60 84 / 0 0 0 20
Austin Bergstrom Intl Airport 53 85 58 85 / 0 0 0 20
New Braunfels Muni Airport 56 87 61 86 / 0 10 0 20
Burnet Muni Airport 51 82 57 82 / 0 0 0 30
Del Rio Intl Airport 56 88 66 91 / 0 10 10 0
Georgetown Muni Airport 51 83 57 83 / 0 0 10 30
Hondo Muni Airport 55 87 63 89 / 0 10 10 10
San Marcos Muni Airport 54 86 59 85 / 0 10 0 20
La Grange - Fayette Regional 57 83 60 82 / 20 10 0 30
San Antonio Intl Airport 58 86 63 86 / 0 10 10 20
Stinson Muni Airport 61 87 65 89 / 0 10 0 10
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Short-Term...MMM
Long-Term...Platt
Aviation...04
Area Forecast Discussion...UPDATED
National Weather Service Indianapolis IN
945 PM EDT Fri Mar 31 2023
.Mesoscale Update...
Issued at 945 PM EDT Fri Mar 31 2023
The supercell in Clay County, Illinois should reach Sullivan and
Vigo County by 10:30pm. Latest KVWX VWP-derived hodograph shows a
very favorable low-level shear environment for supercells and
tornadoes. Continued 2-m theta-e advection and large scale ascent
from approaching trough may effectively erode current area of
inhibition on the Indiana side of the state line. Eventual merging
with the surging QLCS is expected, but until then there may be at
least a small window spatiotemporally for tornadoes, albeit
somewhat low probability given thermodynamic limitations mentioned
above, at least into Sullivan County.
Additional convection southwest of our area will continue to merge
and move northeastward impacting Knox, Daviess, and Martin
counties also by approximately 10:30pm.
&&
.Mesoscale Update...
Issued at 842 PM EDT Fri Mar 31 2023
Deep closed low is currently located over eastern Nebraska and is
moving eastward now. Intense DCVA and associated strong forcing will
primarily track over the northern portion of the area into the
southern Great Lakes and this should be where a more
intense/widespread wind threat should evolve, from the line of
convection in northwest Illinois. Further south, trailing more
positively tilted vort maxima and still appreciable midlevel height
falls will likely still be sufficient for linear evolution with
time. Another factor favoring at least a quasi-linear trend is
veered low level flow and generally straight hodographs supporting
splits and cell mergers which have been observed over western
Illinois the last hour or two.
0-3-km shear vector orientation is more parallel to these
southernmost segments that will impact much of central Indiana into
the evening, somewhat limiting the QLCS mesovortex/tornado threat
some. Nevertheless, any embedded mesocyclones or localized surges
and resultant line reorientations will need to be watched closely
for tornado potential. Even if shear vector orientations aren`t
optimal, the magnitude of shear is particularly high and can
compensate.
Latest ACARS from IND shows a trend toward stronger ascent with
cool/moist PBL below capping EML deepening as CIN decreases. Near-
term model guidance continues to show a fairly narrow corridor of
enhance instability and little/no inhibition ahead of the QLCS. In
fact, thermodynamic profiles may be quite favorable for deep
coupling with stronger momentum aloft, and strong winds (locally
significant). Wind damage continues to be the main threat.
&&
.Mesoscale Update...
Issued at 646 PM EDT Fri Mar 31 2023
Latest ACARs soundings and the 21Z HRRR 0 hour forecast soundings
are both showing that the previously mentioned cap at 850mb is
eroding away with only a minor bump noted at 2235Z. Parcels are
still not surface based, but this won`t stop any ongoing storms that
move into the area. Thoughts from earlier this afternoon are still
in line with the main timeframe for severe weather being from 9PM to
12AM.
Latest radar imagery shows a line that has become to congeal across
western Illinois into Missouri with widespread severe weather being
reported along the line. With Indiana well within the exit region
of the jet and a strong push of southwesterly flow behind the line,
there shouldn`t be any problem keeping this complex together as it
arrives into Indiana. Models are maintaining the thought that the
thermodynamic profiles will be favorable by the time of storm
arrival.
Relevant portions of previous discussions below....
A sounding from Purdue in Lafayette showed at around 545PM the cap
that was advertised earlier remains in place with good shear.
Instability remains generally locked above the cap. Latest ACARs
soundings over IND show a similar profile. Expectations are that
this will erode between 6PM and 8PM with the severe threat rapidly
ramping up afterwards.
Expect additional discussions through the evening.
&&
&&
.Short Term...(This evening through Saturday)
Issued at 301 PM EDT Fri Mar 31 2023
***SEVERE WEATHER EXPECTED TONIGHT***
- Central Indiana now under a MODERATE RISK for severe weather.
- Main Severe Threat tonight will be damaging straight line winds to
70 mph
- Showers/Storms Possible late this afternoon
- WIND ADVISORY 800 PM - Sat 500 PM
Surface analysis this afternoon shows deep low pressure in place
over western IA. This was providing a quick southwest flow in place
across Indiana and the Ohio Valley. Dew points have crept into the
lower 50s. THe initial moisture plume as shown by GOES16 has now
shifted farther east of Indiana and the rest of the afternoon should
be spent within the warm and somewhat dry sector. Radar mosaics show
convection developing upstream in two areas. Severe storms were
developing over N MO and IA, and also over Arkansas and MO. The
storms over Arkansas and MO will be the storms of concern for
Central Indiana tonight. Water vapor imagery shows negatively tilted
upper low over NB. This low was providing diffluent flow aloft over
the Mississippi Valley where storm development was currently ongoing.
Tonight...
ACARS soundings this afternoon at IND show an inversion remaining in
place within the lower levels. This will keep convective development
from progressing over the next 2-3 hours. However as some clearing
and drier air arrives from the west, heating may allow this
inversion to weaken, allowing a more unstable column aloft to allow
convection. Showers developing over southern IL may be the trigger
for this, and thus we will need to continue some chc pops through
the afternoon and early evening.ight and people should be prepared
to activate their severe weather preparedness plan.
As the squall line exits overnight, some clearing is expected within
the dry slot as forecast soundings show a quickly drying column
overnight as cold air advection begins. Thus will trend toward
decreasing cloudiness overnight, however strong dynamics will remain
present aloft. Furthermore the strong pressure gradient across the
area will allow for the continued wind gusts of 30-40 mph. Thus the
wind advisory will be in effect at that point. We will expect lows
mainly in the lower 40s.
Saturday...
Models continue to suggest strong dynamics will still be pushing
across the Great Lakes on Saturday as an associated upper trough
axis is dragged across Central Indiana. Strong winds will persist
across the area on Saturday as a LLJ of near 50 knots will remain
aloft ahead of the trough axis. Forecast soundings show initially a
dry column in the wake of the cold front. However as convective
temperatures in the mid 40s are reached, forecast soundings show
lower level saturation amid cyclonic flow in place across the
region. This is indicative for convective showers. Thus will include
chance pops by late morning and afternoon. The wind advisory will
remain in place, as the ongoing strong pressure gradient will remain
in place, but will gradually diminish by late afternoon as the low
departs northeast and the gradient weakens. Expect only minimal
temperature rises to highs in the middle 40s as cold air advection,
and showers will remain in play for the afternoon.
&&
.Long Term...(Saturday night through Friday)
Issued at 305 PM EDT Fri Mar 31 2023
* Temperatures well above normal at times, particularly Monday-
Wednesday
* Showers and thunderstorms at times early to mid week, with severe
weather possible Tuesday afternoon - Tuesday night.
The long term period will begin with fast quasi-zonal flow across
the country, with temperatures fairly close to seasonal normals late
in the weekend. At the surface, high pressure traversing the region
Saturday night into Sunday evening will keep the area dry during
this period with ample sunshine Sunday.
As early as late Sunday night, shower chances will be required as
low amplitude disturbances move through the aforementioned fast flow
aloft, along with modest moisture return ahead of a low level
baroclinic zone.
This frontal zone will persist somewhere in the region as the upper
level flow amplifies early in the week, and broad
southerly/southwesterly flow and attendant increasing warmth and
moisture return through the low to mid levels of the troposphere
will allow for continued chances for showers and thunderstorms, with
PoPs increasing significantly Monday night into Tuesday.
Tuesday into Tuesday night, an extremely strong low pressure system
is likely to develop over the central High Plains into the upper
Midwest in response to the aforementioned amplifying flow aloft.
Strong dynamics and good moisture return as the Gulf remains wide
open appear likely to produce a regional severe weather event in the
region well outlined by SPC in the day 4-8 outlook - with the
highest threat at this time looking to be to our west over the lower
Missouri Valley and mid Mississippi Valley Tuesday afternoon. Late
Tuesday into Tuesday night, a severe weather threat is definitely in
the cards across central Indiana. Ample instability and extremely
strong low and deep layer shear values again appear likely across a
broad area in the open warm sector of the low. Pattern recognition
suggests this would most likely take the form for central Indiana of
one or more line segments with all hazards on the table, but cannot
completely rule out any convective mode, depending on degree and
timing of destabilization in the warm sector and other mesoscale
details that are too far out in time to resolve at this point.
Precip/storm threat should come to an end at least briefly Thursday
into Thursday evening as the cold front associated with the strong
low sweeps across the area. Shower chances may return very late in
the period, but are far more uncertain owing to growing model
differences.
&&
.Aviation...(00Z TAF Issuance)
Issued at 646 PM EDT Fri Mar 31 2023
Impacts:
-Southerly wind gusts to 40kts through the TAF period, brief
westerly gusts in excess of 50kts during line of storms.
-MVFR cigs to briefly IFR cigs this evening
-Line of storms expected from 02Z to 05Z, IFR vsbys during rain.
-LLWS through the TAF period.
Discussion:
A line of storms is expected to impact the terminals between 02Z and
05Z with the potential for wind gusts in excess of 50kts. Gradient
winds outside of storms will gust to around 40kts at times,
especially after 05Z. Vsbys will remain VFR outside of the heavier
rain. Cigs will remain MVFR through 05Z with low VFR conditions
afterwards. LLWS will be a concern with a very strong LLJ even with
surface gusts to 40kts. Winds will then gradually become more
westerly and eventually northwesterly tomorrow afternoon.
&&
.IND WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM EDT Saturday for INZ021-028>031-035>049-
051>057-060>065-067>072.
&&
$$
Mesoscale...BRB
Short Term...Puma
Long Term...Nield
Aviation...White