Forecast Discussions mentioning any of
"ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 04/13/22
Area Forecast Discussion
National Weather Service Austin/San Antonio TX
752 PM CDT Tue Apr 12 2022
.UPDATE...
Severe thunderstorms have moved out of our CWA and we do not expect
any more severe storms to develop tonight. We have cancelled the
Tornado Watch for all of the counties in our CWA.
&&
.PREV DISCUSSION... /ISSUED 735 PM CDT Tue Apr 12 2022/
AVIATION... /00Z TAFS/
Dry-line to retreat west this evening and moderate the near record
temps along and west of I-35. Dew points in the low 70s over the
Coastal Prairies should help with drawing surface temps down to where
a low level cig should form, but it will probably not happen until
around midnight. With upper troughing still to the west, we`ll see
the overnight winds stay up and even be gusty to near 20 knots at
times. This should point to the cigs staying in the MVFR levels. No
convection is expected as the CAP is supposed to strengthen, but a
few streamer showers can`t be ruled out. Clouds should get kicked
out by around 15Z when the Pacific front arrives and kicks up the
wind gusts up to around 25 knots again.
PREV DISCUSSION... /ISSUED 423 PM CDT Tue Apr 12 2022/
UPDATE...
Thunderstorms have begun to form along the dryline and will continue
to move toward the northeast. Low level wind shear is quite strong in
the warm airmass to the east. Supercell thunderstorms will be
possible as the dryline moves into this warm air and some storms
could be severe. While large hail is the most likely threat,
tornadoes will also be possible and SPC has issued a Tornado Watch
for Burnet, Blanco, Hays, Travis, and Williamson Counties until 11
PM.
PREV DISCUSSION... /ISSUED 208 PM CDT Tue Apr 12 2022/
SHORT TERM (Tonight through Wednesday Night)...
Bottom line: confidence in storms developing somewhere in the area
is higher than it was this morning. However, coverage is still
expected to be widely scattered so not every location will be
impacted.
The forecast remains on track today with a somewhat diffuse dryline
beginning to push across the Rio Grande just after 18Z, just a bit
behind an H5 shortwave evident in water vapor imagery and RAP
analysis that was over the Rio Grande Plains. Behind the dryline,
we`ll see RH dip into the teens and winds increase to 10-15 mph, and
a Red Flag Warning remains in effect for our western counties
through 9pm. One small storm on radar clipped our far southeastern
counties early this afternoon, but otherwise skies are now clear
west and continue to clear out east.
If the dryline can tighten up the Td gradient a bit and advance
east, it`s ascending branch would easily mix out our capping
inversion in tandem with the mid-level PVA-induced lift moving
through. ACARS soundings and the 18Z DRT RAOB indicate the cap
continues to weaken but is not quite fully eroded. With storms
developing to our north from Menard to Runnels counties, we are
gaining confidence that storm development is imminent somewhere in
our area soon. Not 100% confident just yet, but we anticipate storms
are likely to develop somewhere in the area between the longitudes
of Rocksprings and Austin between 2:30-6pm. If they do they`ll have
3kJ/kg to work with along with increasing deep layer shear near 40
knots. Mainly discrete, supercellular modes are favored initially,
and large to very large hail will be the primary risk should storms
develop, with damaging winds also possible. However, there is also a
low-end threat for tornadoes, particularly over our far northeastern
counties. Should storms develop, they`ll likely be moving across the
highly populated I-35 corridor during the evening rush hour before
exiting our area to the east by 9pm.
The warm, moist airmass will remain in place overnight. Expect the
cold front to move in through the morning hours Wednesday. There is
a very low chance for frontal showers or perhaps a storm in the
morning over our far northeastern areas, but most guidance keeps
this activity out of our area. That said, can`t completely rule out
an isolated severe storm in the morning along the US-77 corridor.
Winds shift to the NW and advect in much drier air behind the front
as well as clear skies. With temperatures not too much cooler,
(highs still in the 80s and 90s), RH will likely dip into the single
digits for many areas Wednesday afternoon. Winds will increase to 15-
22 mph over western and northern portions of the area and 10-18 mph
for the Coastal Plains during the day gusts as high as 25-30 mph may
occur along and west of I-35 for a few hours. Will hold the Fire
Weather Watch as is for now but it will be upgraded to a Red Flag
Warning after today`s expires. Winds drop off quickly during the
evening and we`ll have some more comfortable lows by Thursday
morning in the upper 40s north and 50s elsewhere.
LONG TERM (Thursday through Tuesday)...
A zonal flow aloft is forecast to prevail across the area from
Thursday into Saturday. By Saturday afternoon into the evening, the
flow shifts to the northwest and pushes a series of disturbances
over our area. At the surface, an east to southeast wind is forecast
for Thursday and shifting to the southeast and south during the day
on Friday as a surface high pressure ridge develops across the
region. The GFS solution likes to bring light QPF across the coastal
plains and southeast counties on Friday afternoon while the ECMWF
brings a cluster of storms across the Burnet and Llano Counties. The
NAM is dry while the Canadian shows light QPF across the coastal
plains during the morning period. Due to the uncertainties shown by
the models, we are going for a slight chance for showers and storms
mainly for areas southeast of Interstate 35.
Dry weather conditions continue into the first part of the weekend.
However, there is a lot of uncertainties during the Saturday and
Sunday time frame. And here is why. The GFS pushes the frontal
boundary across the Hill Country on Saturday afternoon with some
light QPF across the Edwards Plateau and western Hill Country. The
ECMWF and Canadian solutions keep the area dry with the boundary
remaining to our north.
By Sunday morning, the GFS pushes back the boundary to the north
while the ECMWF and Canadian models push the frontal boundary to the
south and into the Hill Country. So, this coming weekend could be
dry for some people with some communities getting lucky with much
needed rain.
Rain chances continue on Monday and Tuesday as a stronger frontal
boundary signal is evident in all medium range models.
As far as temperatures go for later in the week into the weekend
expect highs in the 80s and 90s on Thursday through Sunday and near
100 across the southwest on Saturday and Sunday afternoons.
FIRE WEATHER...
Fire weather concerns still in place for Thursday as near critical
to critical weather exist for areas along and west of Highway 183.
&&
.PRELIMINARY POINT TEMPS/POPS...
Austin Camp Mabry 70 92 53 86 61 / 20 20 0 - -
Austin Bergstrom Intl Airport 71 92 51 86 60 / 20 20 0 - -
New Braunfels Muni Airport 71 94 52 88 61 / 20 - 0 - -
Burnet Muni Airport 68 89 50 85 61 / 20 10 0 0 -
Del Rio Intl Airport 67 92 55 92 66 / 0 0 0 0 0
Georgetown Muni Airport 71 92 50 85 59 / 20 20 0 0 -
Hondo Muni Airport 69 95 52 92 61 / 10 0 0 - -
San Marcos Muni Airport 69 94 51 88 60 / 20 20 0 - -
La Grange - Fayette Regional 72 91 56 86 63 / 20 30 0 - -
San Antonio Intl Airport 71 94 55 88 63 / 10 0 0 - -
Stinson Muni Airport 72 98 57 91 65 / - 0 0 - -
&&
.EWX WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Wednesday morning through Wednesday evening
for Atascosa-Bandera-Bexar-Blanco-Burnet-Comal-Dimmit-Edwards-Frio-
Gillespie-Guadalupe-Hays-Karnes-Kendall-Kerr-Kinney-Llano-Maverick-
Medina-Real-Travis-Uvalde-Val Verde-Williamson-Wilson-Zavala.
Red Flag Warning until 9 PM CDT this evening for Dimmit-Edwards-
Kinney-Maverick-Real-Uvalde-Val Verde-Zavala.
&&
$$
Short-Term/Aviation...Oaks
Long-Term...05
Decision Support...Treadway
Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
942 PM CDT Tue Apr 12 2022
.UPDATE...
Issued at 935 PM CDT Tue Apr 12 2022
The theme for tomorrow`s convective forecast and associated severe
weather risk retains the "clear as mud" character as we assess
some of the new data coming in. Aside from some leftover patchy
intermittent drizzle this hour that was due to strong isentropic
ascent, most of the rest of the night will be precipitation free.
As we`ve been noting leading into this evening, a very stout EML
with exceptionally steep mid-level lapse rates has enveloped the
region, as shown on the DVN and ILX 00z RAOBs and recent aircraft
soundings. This will certainly provide a helmet to any thunderstorms
through the early overnight given lack of large scale forcing
amidst gradual height rises.
While the rest of the evening will be quiet weather wise, it is
windy as the warm front blasts north with very strong flow just
off the deck and lack of decoupling. Thus expect frequent 30-35
mph southerly gusts, with sporadic gusts up to 40 mph possible.
The two key features overnight into Wednesday morning are the
extensive QLCS back across Iowa (and convectively induced short-
wave impulse), and the lead southern short-wave with convection
in the Arklatex and Mid South. The IA MCS will undergo weakening
as it moves into a progressively more capped air mass while
crossing the MS River after midnight. Meanwhile, showers with
embedded thunderstorms from the lead southern wave should also be
lifting north into Wednesday morning.
Some slight mid-level cooling and inherent forcing with the
decaying MCS (with severe weather unlikely) should be able to
breach the cap to produce some lightning as it moves into the west
and northwest CWA during the pre-dawn hours. This should continue
to push east while southern wave and associated embedded
convection at least clips locales near and southeast of I-55.
While confidence isn`t high in the exact thunderstorm coverage
tomorrow morning, combined effects of extensive cloud cover and
overturning of steep lapse rates greatly lowers confidence in
realizing much instability as the main short-wave and cold front
punches in during the mid to late afternoon. We can`t ignore the
strong kinematics of the synoptic system offering increasing deep
layer and low-level shear Wednesday afternoon, but the likely
messy convective evolution and lack of insolation casting doubt on
destabilization means that assessing the severe threat magnitude
will be an entirely mesoanalysis/nowcast type process once the
morning convective effects have been ironed out.
For all these reasons, think the going level 2 (north of I-80)
and level 3 (south of I-80) severe weather risk in day 2 outlook
continue to roughly approximate the relative threat, though wonder
if even our southern areas are seeing an overall lowering of the
potential ceiling of any instances of severe weather, albeit with
certainly not being able to rule out mesoscale enhanced corridors
as alluded to in short term discussion below. Regardless of the
occurrence of severe weather, we do expect decent at least
scattered thunderstorm coverage with associated CG lightning and
mainly brief (due to fast storm motions) heavy downpour threats.
Extensive shower coverage will persist past sunset Wednesday
evening, though with a quick loss of MUCAPE, expect quickly
dwindling thunderstorm coverage.
Castro
&&
.SHORT TERM...
Issued at 345 PM CDT Tue Apr 12 2022
Through Wednesday night...
Main forecast concern for the period is the severe thunderstorm
threat from an advancing cold front that moves through Wednesday
evening.
A developing low pressure system over the northern plains is
pushing a warm front north across southern Illinois this afternoon
which will move through the remainder of the state this evening.
Further upstream showers and thunderstorms are expected to develop
across the central plains along a frontal boundary that will push
east towards our area overnight. Storms are expected to rapidly
develop upscale into a an organized line given the deep layer
shear oriented parallel to the boundary that will push east of the
Mississippi river overnight. As the boundary pushes east the
storms should be on a weakening trend given strong convective
inhibition caused by the warming 700 mb temperatures ahead of the
boundary. Any thunderstorms that do survive are expected to move
north of our area, but a brief rumble of thunder is not completely
out of the question along the Illinois-Wisconsin border this
evening.
As boundary pushes into our area Wednesday morning widespread
showers and thunderstorms are expected to move across the area
during the morning hours. At the same time, an upper-level wave is
expected to move northeast across central Illinois which will
further add to the ongoing showers and storms over the area. These
early storms should be below severe limits given the generally
limited instability in place and fairly weak deep layer shear that
should temper the development of organized convection. There is
good deal of uncertainty in how these early storms will impact
the environment. If they linger and remain more expansive
throughout the morning, this would limit the afternoon severe
potential associated with the main cold front as it pushes in
Wednesday afternoon.
Guidance continues to develop a line of thunderstorms Wednesday
afternoon as the atmosphere destabilizes during the late morning
and early afternoon. Strong wind shear will be present as the
instability returns which could allow some storms to become severe
with damaging winds, hail, and possibly a few tornadoes. If any
robust northeast-oriented mesovortices manage to develop, 30-35+
kt of 0-3 km bulk shear (expected to increase through the
afternoon) would support locally enhanced corridors of wind
damage. As previously mentioned, the likelihood of persistent
morning convection currently looks to hold the bulk of the severe
threat mainly south of I-80 (and even south of the Kankakee River)
where the Storm Prediction Center has an enhanced risk for severe
weather, but isolated severe storms will be possible across our
entire CWA between the hours of 1 PM and 8 PM Wednesday.
The cold front will clear the area late Wednesday evening which
will bring the severe and thunderstorm threat to an end from west
to east. Behind the front conditions are expected to improve with
clearing skies and breezy westerly winds that will gradually ease
and turn southwesterly by Thursday morning.
Yack
&&
.LONG TERM...
Issued at 237 PM CDT Tue Apr 12 2022
Thursday through Tuesday...
Primary forecast concern is strong winds on Thursday.
Low pressure will be pinwheeling across Ontario Thursday as it
slowly weakens Thursday night and finally shifts east Friday into
Friday night. This will result in a tight gradient across the area
in addition to cold air advection with strong west/southwest
winds still on track for Thursday. Forecast soundings suggests
gusts into the 40kt range will be possible across the northern cwa
and current forecast gusts near advisory levels have these trends
handled well. Winds appear to diminish quickly with sunset
Thursday evening though breezy conditions may persist into the
evening.
Another cold front will move across the area Friday into Friday
evening with a weak upper wave moving across the area bringing a
chance of some light precipitation during this time period. Still
some uncertainty regarding how much precip will materialize, but
low chance pops warranted across the entire area.
Precip chances continue for Sunday/Monday and again toward the
middle of next week. ECMWF still showing an upper low by early/mid
next week but is more progressive with its movement. Thermally, it
may be cold enough for a rain/snow mix or some light snow at night
but confidence from this distance is low. No changes to blended
chance pops Sunday afternoon through the middle of next week. cms
&&
.AVIATION...
For the 00Z TAFs...
Forecast concerns through Wednesday evening for ORD and MDW:
* Gusty south-southeast winds this evening as well as low-level
wind shear developing and persisting overnight
* Multiple potential periods of thunder, at least nearby, on
Wednesday -- one in the morning and one more probable in the
mid to late afternoon which could briefly produce 35+ kt gusts
* MVFR likely during the day Wednesday and a non-zero IFR chance
* Cold front passage early Wednesday evening turning winds to the
west-northwest with gusts around 30 kt
The potential for any showers and thunderstorms in the immediate
area through this evening remains low. However, southeast winds
are gusty, with already regular gusts of 30 kt or above having
been observed. These winds should slowly veer to around due south,
although the rate of that veering is slower than had been
forecast. Expect that the wind direction will largely be 150-170
degrees at ORD through 04Z-06Z. While the surface winds are high,
a deepening weather system in the Plains is resulting in a strong
(50+ kt) low-level jet overhead and the likelihood of some low-
level wind shear.
Robust convection in Iowa ongoing early this evening will
gradually merge into more of a linear mode and work its way
eastward across Iowa late this evening and overnight. This is
expected to reach northwest Illinois around daybreak Wednesday
morning but likely be in a gradual weakening state. There also is
an upper level disturbance that will be moving northeastward over
eastern Illinois into Indiana during the middle of Wednesday
morning. Both of these mechanisms may result in convection over
or at least near Chicago. The time window we are keeping an eye on
for possible TSRA inclusion at ORD and MDW would be 14Z-17Z.
The time for most favored for greatest coverage of TSRA remains in
the mid to late afternoon into early evening. An organized area of
convection is probable in central Illinois northward to near the
Chicago metro, but with large uncertainty how far north from
there. It is because of that uncertainty, as well as some timing
specifics, that we have opted to keep a PROB30 for TSRA in the
afternoon as opposed to a TEMPO. Will be evaluating this, as well
as the aforementioned morning potential, with latest guidance for
the 03Z amendment.
A cold front will sweep through shortly after the afternoon
convection, so sometime in the early evening for ORD and MDW. This
will turn winds sharply to the west-northwest with a re-increase
in gusts. Showers will likely continue behind the frontal passage
for a few hours.
MTF
&&
.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...Small Craft Advisory...nearshore waters until 7 AM Thursday.
Gale Watch...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...7 AM
Thursday to 7 PM Thursday.
&&
$$
Visit us at weather.gov/chicago
Follow us on Facebook, Twitter, and YouTube at:
www.facebook.com/NWSChicago
www.twitter.com/NWSChicago
www.youtube.com/NWSChicago
Area Forecast Discussion
National Weather Service Phoenix AZ
446 PM MST Tue Apr 12 2022
.UPDATE...Updated Aviation discussion.
&&
.SYNOPSIS...
High pressure will build into the region the remainder of the week
resulting in widespread dry weather and gradually warming
temperatures. Readings slightly below normal Wednesday will increase
closer to the seasonal average by the weekend. Eventually by early
next week, afternoon highs will push to around 10 degrees above
normal.
&&
.DISCUSSION...
A seasonally deep PV anomaly was progressing through the Great Basin
early this afternoon with the trailing trough axis and
midtropospheric front only slowing descending through northern
Arizona. However, the sfc-H8 front has already propagated into
eastern Arizona with ACARS soundings sampling pronounced cooling
resulting in afternoon highs some 10F lower than Monday. WV imagery
reveals only limited moisture content associated with these
boundaries, and in situ observations depict only shallow cumulus
fields. Thus, the greatest impacts will continue to align with
increased winds where diurnal momentum transfer will allow frequent
gusts ~30 mph mixing through the H7 layer. While blowing dust could
become an issue, similar wind gusts yesterday produced only very
isolated instances tied directly to local land use on small scales.
With height falls translating away from the forecast area and the
post-frontal pressure gradient weakening, wind speeds should relax
markedly this evening reverting closer to nocturnal tendencies
Wednesday morning. Height rises will be rather modest and slow to
spread into the SW Conus while thermal profiles will remain dampened
(especially in the lower troposphere). Perhaps the most interesting
facet of this system is the low temperatures Wednesday morning,
forecast by the NBM well into the 40s across the entire area. Should
KPHX fall below 50F (75% chance per NBM output), this would be the
first sub-50F at this station during the month of April since 2011.
During the latter half of the week through early next week, ensemble
guidance remains in very good agreement highlighting quasi-
zonal/somewhat anti-cyclonic flow across the forecast area with
heights steadily increasing as subtropical ridging builds and
intensifies over central/northern Mexico. NAEFS mean output yields
minimal spread among membership with only minor differences in
timing of shortwaves cresting the northern periphery of the ridge
resulting in uncertainty with respect to the magnitude of warming.
Nevertheless, H5 heights by the end of the week should fall in a 572-
576dm range leading to temperatures near to slightly above average.
Strong evidence exists that heights will increase closer to a 582-
585dm range sometime early next week yielding temperatures ~10F
above normal. While no longer seasonally unusual for mid/end of
April, NBM probabilities of 100F peak in a 20-40% range with these
building heights.
Lighter winds are anticipated Wednesday as a strong low pressure
system in the Plains moves further eastward.
&&
.AVIATION...Updated at 2345Z.
South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will taper off this evening. However, before they do gusts
could reach as high as 30-35 kt at KPHX and up to 25-30 kt
elsewhere through about 03z. The flow will then diminish enough
for an easterly drainage flow to develop after midnight. A switch
back to the west is expected Wednesday afternoon, though lighter
winds generally below 10 kt are anticipated as a strong low
pressure system in the Plains moves further eastward.
Southeast California/Southwest Arizona including KIPL and KBLH:
Winds will continue to taper off this evening and will generally
drop below 10 kt at KIPL/KBLH after 03z. Lighter winds are
anticipated Wednesday as a strong low pressure system in the
Plains moves further eastward.
&&
.FIRE WEATHER...
Friday through Tuesday:
Near normal temperatures during the end of the week will warm to
around 10F above average early next week under strong high pressure.
Wind speeds will be typical for mid April with the usual afternoon
upslope gustiness around 15-25 mph. Minimum afternoon humidity
levels will generally fall into the single digits following poor to
fair overnight recovery of 20-40%. Weather conditions will provide
an excellent opportunity for any prescribed burning during this time
frame.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
Visit us on Facebook, Twitter, and at weather.gov/phoenix
DISCUSSION...18
AVIATION...Hirsch
FIRE WEATHER...18